PSZ 19:16 (Pind. 1/07) UNIVERSITI TEKNOLOGI MALAYSIA DECLARATION OF THESIS / UNDERGRADUATE PROJECT PAPER AND COPYRIGHT Author’s full name : SHEENA FLANT LANGGANGON Date of birth : 1 FEBRUARY 1985 Title : MAINTENANCE OF CONCRETE DEFECT IN BUILDING Academic Session: 2007/2008 I declare that this thesis is classified as : √ CONFIDENTIAL (Contains confidential information under the Official Secret Act 1972)* RESTRICTED (Contains restricted information as specified by the organisation where research was done)* OPEN ACCESS I agree that my thesis to be published as online open access (full text) I acknowledged that Universiti Teknologi Malaysia reserves the right as follows : 1. The thesis is the property of Universiti Teknologi Malaysia. 2. The Library of Universiti Teknologi Malaysia has the right to make copies for the purpose of research only. 3. The Library has the right to make copies of the thesis for academic exchange. Certified by : SIGNATURE 850201-12-5450 (NEW IC NO. /PASSPORT NO.) Date : 18 APRIL 2008 NOTES : * SIGNATURE OF SUPERVISOR MR. BACHAN SINGH NAME OF SUPERVISOR Date : 18 APRIL 2008 If the thesis is CONFIDENTIAL or RESTRICTED, please attach with the letter from the organisation with period and reasons for confidentiality or restriction. “I/we* hereby declare that I/we* have read this final year project and in my/our* opinion this final year project is sufficient in terms of scope and quality for the award of the Bachelor of Civil Engineering” Signature : .................................................... Name of Supervisor : MR. BACHAN SINGH Date : 18 April, 2008 MAINTENANCE OF CONCRETE DEFECT IN BUILDING SHEENA FLANT LANGGANGON A report submitted in partial fulfillment of the requirement for the award of the degree of Bachelor of Civil Engineering Faculty of Civil Engineering Universiti Teknologi Malaysia APRIL, 2008 ii “I declare that this final year project entitled “Maintenance of Concrete Defect in Building” is the result of my own research except as cited in the references. The final year project has not been accepted for any degree and is not concurrently submitted in candidature of any other degree.” Signature : …………………………... Name : Sheena Flant Langgangon Date : 18 April 2008 iii To my beloved family iv ACKNOWLEDGEMENT Throughout the completion of this project, I have faced various challenges. Without the help of people around me giving support and guidance would make it harder to overcome these obstacles. First and foremost, I would like to express my deepest gratitude to my supervisor Mr. Bachan Singh for his time and unlimited guidance from the start to the completion of this study. His advice and motivation had indeed helped me a lot throughout this study. I would also like to thank the Public Work Department in Kota Kinabalu and Penampang district for their cooperation in providing me useful information and giving insights regarding my study. Lastly, I would like to thank my family and friends for their invaluable support. All of you have made this study possible. Thank you very much. v ABSTRACT Malaysia is a developing country and many projects are being implemented. Some of the projects involve construction of buildings. Nevertheless, some of the buildings are poorly constructed and maintained. One of the components that need attention is concrete. The concrete structure need to be inspected and maintained regularly. Poor maintenance of concrete components will lead to the buildings being rendered not fit for occupancy. The main objectives of this study are to determine the types of concrete defect, the factors that cause concrete defects, the method of repairs and the problems faced by the Public Work Department (PWD) in carrying out the maintenance work. The study is carried out on government buildings in Sabah. The data are collected through questionnaire and also from the records of the PWD. The data is analyzed by using average mean index. From the study, it was found that the main types of concrete defects are spalling and delamination. The factors that cause the defects are inefficient maintenance and poor construction method. The method of concrete repairs that are adapted by PWD are patching and sealing. vi ABSTRAK Malaysia adalah negara yang membangun dengan banyak projek-projek baru yang dilaksanakan. Antara projek ini adalah melibatkan pembinaan bangunan baru. Namun demikian, masih terdapat bangunan yang telah dibina dan diselenggara dengan tidak memuaskan. Salah satu komponen yang perlu diberi perhatian adalah konkrit. Pemeriksaan dan penyenggelaraan yang tetap adalah penting untuk struktur bangunan konkrit. Sistem penyenggelaraan yang tidak memuaskan boleh menyebabkan bangunan tersebut menjadi tidak sesuai untuk penghunian. Objektif utama kajian ini adalah untuk mengenalpasti jenis kerosakan konkrit, faktor-faktor yang menjadi punca kerosakan, teknik-teknik pembaikan dan masalah yang dihadapi oleh Jabatan Kerja Raya (JKR) dalam sistem penyenggelaraan bangunan. Skop kajian ini adalah pada semua bangunan kerajaan di Sabah. Data adalah dikumpul melalui borang soal selidik serta rekod kerja penyenggelaraan daripada JKR. Analisis data dilakukan dengan menggunakan Kaedah Purata Index. Daripada kajian ini, didapati kerosakan utama pada bangunan adalah spalling dan pengupasan. Faktor yang menyebabkan kerosakan ini adalah sistem penyenggelaraan yang tidak cekap dan teknik pembinaan yang tidak sempurna. Teknik pembaikan yang paling kerap digunakan adalah pembaikan tampalan dan sealing. vii TABLE OF CONTENTS CHAPTER 1 2 TITLE PAGE DECLARATION ii DEDICATION iii ACKNOWLEDGEMENTS iv ABSTRACT v ABSTRAK vi TABLE OF CONTENTS vii LIST OF TABLES xii LIST OF FIGURES xiii LIST OF SYMBOLS xv LIST OF APPENDICES xvi INTRODUCTION 1.1 Background of Study 1 1.2 Statement of Problem 3 1.3 Objectives of Study 4 1.4 Scope of Study 5 1.5 Summary of Study Methodology 5 LITERATURE REVIEW 2.1 Introduction 6 2.2 Maintenance 7 2.2.1 Planned Maintenance 8 2.2.1.1 Preventive Maintenance 8 2.2.1.2 Corrective Maintenance 8 viii 2.2.2 Unplanned Maintenance 9 2.3 Assessment of Existing Structure 9 2.3.1 Preliminary Investigation 11 2.3.1.1 Past Records 11 2.3.1.2 Visual Inspection 11 2.3.2 Detailed Investigation 12 2.3.3 Test and Inspection Techniques 12 2.3.3.1 Structural integrity 13 2.3.3.2 Concrete Quality 13 2.3.3.3 Steel Serviceability and Condition 14 2.4 2.5 2.6 Types of Defects 14 2.4.1 Corrosion of Reinforcement Steel 15 2.4.2 Cracks 16 2.4.2.1 Longitudinal Cracks 17 2.4.2.2 Transverse Cracks 17 2.4.2.3 Shear Cracks 18 2.4.2.4 Plastic Shrinkage Crack 18 2.4.2.5 Plastic Settlement Crack 18 2.4.2.6 Crazing 18 2.4.2.7 Map Crack 19 2.4.3 Spalling 19 2.4.4 Delamination 20 2.4.5 Honeycombing 21 2.4.6 Scaling 21 2.4.7 Popouts 22 Causes of Deterioration 22 2.5.1 Excessive Concrete Mix Water 22 2.5.2 Sulphate Deterioration 23 2.5.3 Faulty Design 23 2.5.4 Construction Defects 24 2.5.5 Alkali-Aggregate Reaction 25 2.5.6 Structural Overload 26 2.5.7 Faulty Materials 26 Repair System 26 ix 2.7 3 Repair Method 27 2.7.1 Cathodic Protection 28 2.7.2 Cathite Method 28 2.7.3 Decholorisation Technique 29 2.7.4 Crack Repair 29 2.7.4.1 Dormant Cracks 29 2.7.4.2 Live Cracks 30 2.7.5 Patch Repairs 31 2.7.6 Sealing 31 2.7.7 Sprayed Concrete 31 2.7.7.1 Dry-mix Process 32 2.7.7.2 Wet-mix Process 32 2.7.8 Pre-packed Grouting 33 2.7.9 Recasting 33 2.7.10 Dry Packing 34 2.7.11 Thin Bonded Resurfacing 34 2.7.12 Stitching 34 2.7.13 Caulking 34 METHODOLOGY 3.1 Introduction 35 3.1.1 Primary Data 35 3.1.1.1 Reports and Records 36 3.1.1.2 Questionnaire 36 3.1.1.3 Interview 36 Secondary Data 36 3.1.2 3.2 3.3 4 Data Analysis 37 3.2.1 37 Average Index Conclusion 38 CASE STUDY 4.1 Introduction 39 4.2 Building Works Department Sabah 40 4.3 Clients 41 x 5 4.4 Maintenance System 42 4.5 Problems Faced by PWD 43 DATA ANALYSIS AND RESULT 5.1 Introduction 45 5.2 Questionnaire Background and Number 46 Of Respondents 5.3 Party’s Involved in Carrying out Maintenance 47 Works on Government Buildings 5.4 Types of Maintenance Conducted on Government 48 Building 5.5 Types of Concrete Defect that Occur in Government Building 5.6 Factor’s that Causes Defects in Government Building 52 5.7 Method of Repair in Rectifying Concrete Defects 54 5.8 Factor’s Affecting Choice of Repair 56 5.9 Common Problems Faced by PWD in Building Maintenance 6 49 57 CONCLUSION AND RECOMMENDATION 6.1 Introduction 60 6.2 Conclusion 61 6.2.1 Types of Concrete Defect that Occur In Buildings 6.2.2 61 Factors that Causes the Concrete Defect In Buildings 62 6.2.3 Method of Concrete Repair Carried Out 62 6.2.4 Problems Faced by PWD in Maintenance Of Building 63 6.3 Recommendation 64 6.4 Recommendation for Further Study 64 xi REFERENCES 66 APPENDICES A 69 APPENDICES B 73 APPENDICES C 74 xii LIST OF TABLES TABLE NO. TITLE PAGE 4.1 Summary of Financial Report 40 5.1 Party to Carry Out Maintenance 47 5.2 Types of Maintenance 48 5.3 Types of Defect that Occur in Government Building 50 5.4 Factors that Causes Concrete defects in Government 52 Building 5.5 Method of Repair in Rectifying Concrete Defects 54 5.6 Factors Affecting Choice of Repair 56 5.7 Common Problems Faced by PWD in Building 58 Maintenance xiii LIST OF FIGURES FIGURE NO. TITLE PAGE 1.1 A Flow Chart of research Methodology 5 2.1 Forms of Maintenance 7 2.2 Typical Flow Chart for Assessment Programs 10 2.3 Core Samples to Determine Chloride 13 Contents 2.4 Corrosion of Steel Reinforcement 16 2.5 Crazing on Concrete Structure 19 2.6 Heavily Rusted Reinforcement and Spalling 20 of the Concrete 2.7 Scaling in Concrete 21 4.1 Organization Chart of Building Works 41 Department 5.1 Number of Respondent on Questionnaire 46 Distributed to PWD Sabah 5.2 Party to Carry Out Maintenance 47 5.3 Types of Maintenance Conducted on 49 Government Buildings 5.4 Types of Concrete Defects that Occur in 51 Government Building 5.5 Factors that Causes Concrete Defects in 53 Government Building 5.6 Method of Repair in Rectifying Concrete Defects 55 xiv 5.7 Factors Affecting Choice of Repair 57 5.8 Common Problems Faced by PWD in 59 Building Maintenance xv LIST OF SYMBOLS = - Equal to ≤ - Less than or equal to < - Less than ∑ - Total of % - Percentage xvi LIST OF APPENDICES APPENDIX TITLE PAGE A Example Questionnaire 69 B Computation Repair Work Form 73 C Repair Works Description Form 74 CHAPTER 1 INTRODUCTION 1.1 Background of Study After almost 50 years of independence, Malaysia once known as Malaya is going into a new era of globalization, unleashing its potential and competition worldwide. Both federal and state government worked hand in hand to make full utilization of the country’s source and expertise in expanding the infrastructure in Malaysia. Most recent attribute is Northern Corridor Economic Region (NCER) in which one of its main objectives is to promote social and community development that will contribute greatly to Malaysia’s growth and economy. As the technology advances and changes, the need of more infrastructures will be more apparent. Infrastructure includes buildings, roads, bridges, utilities, water supply, sewerage system, mechanical and electrical systems. All of these infrastructures are important because it helps civilians to be able to live in a more systematic and ease environment. It helps to save cost, traveling time and providing facilities that will make life easier. 2 Many of these infrastructures will need proper maintenance to extend the lifespan besides promoting safety and reliability to the public. In the Malaysian Budget 2006, a total of RM4.3 billion have been provided to public agencies for maintenance and another RM 1 billion to the government for the maintenance of public facilities in the year 2007. Buildings in particular are important structures and are a main concern of the government to make sure it is maintained regularly to prevent it from deteriorating and eventually could pose as a threat to the public. Poor maintenance might result in structural failure and wastage in money. For example, six roof leakages were spotted on May 9, 2007 at the Parliament building in Malaysia. After inspection, it was found that the leakage was caused by cracks and seepage of water through the concrete roof. There was also no sign of maintenance done. Restoration and renovation works of the Parliament Building was previously done in 2005 with a total budget of RM90 million executed by Public Works Department (PWD). Although PWD had carried out a lot of repairs but there was reoccurring damage due to absence of maintenance (Daily Express, May 20, 2007). Even though the maintenance was under the responsibility of the Parliament building management unit and not PWD, the issue here is not who to blame but to prove that poor maintenance will result in repeated repairs and dire consequences. One of the major components of building that needed attention is concrete defects. Defects in concrete, if not repaired, will eventually lead to major maintenance. Failure to provide necessary maintenance will cause more expensive repairs or replacement of otherwise useful structures. Besides that, any negligence in any of the phases of its maintenance would lead to its deterioration and ultimately failure to perform its intended function. Therefore a proper and systematic maintenance management is required to reduce possible occurrence of disaster that may cause life injury due to structural failure. 3 1.2 Statement of Problem Concrete is a very high durable and versatile material as it can be cast in place with or without reinforcement and precast or prestressed for achieving any required strength. Therefore it is a very popular construction building material. Under normal conditions, concrete buildings are expected to have a long life service. However, concrete members can deteriorate due to several factors such as aggressive environment, faulty design and construction defects etc. Inadequate maintenance will leave these defects unattended thus compromising the integrity of the building. Many reasons can contribute to poor maintenance of concrete buildings such as local authorities as they often lack manpower when being confronted or challenged to check the safety of structures (Lee, 2004). The economical aspect is also a decisive factor on types of repair works that might be conducted. There is usually more than one method of repair in concrete defects. These techniques vary from each other in terms of cost, execution time and effectiveness. The more higher the cost, it would deter many building owners from executing essential repair works. Other than that, remedial works are only done on areas where the damage is visible. This is to avoid stability problems in the structure. Unfortunately what usually happens is reoccurrence of the damage shortly after the previous remedial work has been carried out and leads to repeated repairs. This only contributes to wastage in money and time besides compromising the safety factor of the structure. In Sabah, maintenance of many government buildings, schools and hospitals is under the custody of Public Work Department (PWD). The biggest challenge faced is conducting effective maintenance. As stated by Prime Minister Datuk Seri 4 Abdullah Badawi, the weakness of government department was that they lack a building maintenance culture. He also added that they will not see the need to inspect if they think it is a new building (The Star, April 13, 2007). A preliminary survey is conducted on government buildings in the district of Kota Kinabalu, Sabah. From the survey, it was found that the problems faced are poorly maintained buildings. Buildings have become an eyesore or a danger to general public. There were even cases of pieces of concrete falling from canopies, ceilings, pillars and walls of unattended buildings in Commercial Business District (CDB) areas and rainwater chute collapsing onto a car (Daily Express, April 16, 2006). The repair works for concrete defects will be carried eventually. Some defects are only visually disturbing and will not affect the structural integrity of the whole structure. Some on the other hand can be dangerous and lead to major failures. Hence, a study will be carried out as stated in the objectives in section 1.3. 1.3 Objectives of Study The objectives of carrying out this study are as follow: i. To study the types of concrete defects that occurs in buildings ii. To identify the factors that causes the concrete defects in buildings iii. To identify the method of concrete repair carried out iv. To identify the problems faced by PWD in maintenance of buildings 5 1.4 Scope of Study In relation with the objectives of the study, this study is carried out on buildings in Sabah under the supervision of Public Work Departments (PWD). All government buildings under PWD are taken into count. 1.5 Summary of Study Methodology Exploration of sources Problem Identification Discussion with supervisor Title Objective and Scope Data Collection Primary Data -Records -Questionnaire -Interviews -Observation Secondary Data -Reference books -Journals -Newspaper -Magazines Compile and organize Analyze -Using average mean index Conclusion and recommendation Figure 1.1: A Flow Chart of Research Methodology CHAPTER 2 LITERARURE REVIEW 2.1 Introduction Maintenance is a very important element for concrete structures. Although concrete is a very high durable building material, concrete can deteriorate and become defective under certain circumstances such as environmental conditions. To further probe this problem is poor maintenance. Improper maintenance work could lead to repetition repairs that can be more costly and wastage in materials. Therefore maintenance plays an important role as it sustains the building serviceability up to its required and expected standard. Maintenance works in Malaysia are under the concern of Public Work Department (PWD). PWD is in charge of inspection and performing maintenance on all for state and federal buildings. A through inspection on concrete structures would be determining the cause of defect, having adequate knowledge regarding the extent of the problem and carrying appropriate repair works that could minimize or eliminate the problem altogether. 7 2.2 Maintenance According to BS3811:1993 British Standard Glossary of Maintenance Terms in Terotechnology, the term maintenance is the combination of all technical and administrative actions, including supervision actions, intended to retain an item in, or restore it to, a state which it can perform its required function.” Generally, there are two process of building maintenance activities. There are rehabilitation and repair. i. Rehabilitation An activity to make sure the building is up to current acceptable functional conditions, often involving improvements. ii. Repair An action that is intended to restore a building back to its original appearance or state by renewal, replacement and restoration. Meanwhile maintenance can be divided into two main categories which is planned maintenance and unplanned maintenance. Maintenance Planned Maintenance Preventive Maintenance Unplanned Maintenance Corrective Maintenance Figure 2.1: Forms of Maintenance (BS3811, 1993) 8 2.2.1 Planned Maintenance As stated in BS3811(1993), planned maintenance can be described as the maintenance organized and carried out with forethought, control and the use of records to a predetermined plan. There are two sub categories of planned maintenance which is preventive and corrective maintenance. 2.2.1.1 Preventive Maintenance Preventive maintenance is the maintenance carried out at predetermined intervals or according to predescribed criteria and intended to reduce the probability of failure or the degradation of the functionality of an item. There are two different types of preventive maintenance which is scheduled maintenance and conditionbased maintenance. Scheduled Maintenance is the preventive maintenance carried out in accordance with an established time schedule. Meanwhile condition-based Maintenance is the maintenance carried out according to the need indicated by condition monitoring (BS3811, 1993). 2.2.1.2 Corrective Maintenance The type of maintenance carried out after fault recognition and intended to put an item into a state in which it can perform a required function. Scope of work comprises repair, restoration, rehabilitation or replacements of components (BS3811, 1993). 9 2.2.2 Unplanned Maintenance Unplanned maintenance is maintenance carried out to no predetermined plan. It consists of any maintenance activity that has no predetermined plan in all aspects including labor, materials, tools and equipment to perform the task (BS3811, 1993). 2.3 Assessment of Existing Structure The purpose of inspection is not only to document the type(s) and extent of deterioration but also to investigate the cause(s) of the deterioration and provide guidance on remedial action to prevent or mitigate against its occurrence. Assessment on existing structures is a systematic process of evaluating the condition and strength of the structure. This process includes two levels which is preliminary investigation followed by detailed investigation. The need to assess structures is due to (Singh, 1991):  Age of structure The more the age causes a decrease in concrete strength and corrosion related problems.  Change in occupancy Make sure structure is sound for additional loading.  Presents of defects Presents of cracks and other deformation may affect the overall performance of the structure.  Statutory requirements 10 Mandatory requirements to check on the structural integrity and safety of existing structure.  Other factors Accidental overloading, fire damage, seismic movements and etc. VISUAL INSPECTION GENERAL INFORMATION PLAN INVESTIGATION LOCATE ACCESS OVERALL SURVEY AND SELECTION OF AREAS FOR DETAILED STUDY INFORMATION FROM CONSTRUCTION RECORDS BLUE DETAILED MAPPING AND N.D.T OF SPECIFIED AREAS SAMPLING-CORING AND DRILLING INFORMATION FROM MAINTENANCE RECORDS LABORATORY TEST AND ANALYSIS ANALYSIS AND INTERPRETATION OF RESULTS REPORT AND RECOMMANDATION Figure 2.2: Typical flow chart for assessment program (Singh, 1991) 11 2.3.1 Preliminary Investigation Before planning an investigation, it is recommended to conduct a site visit first. Initial visual inspection is normally done by client representative and the consulting engineer. 2.3.1.1 Past Records The survey done in preliminary level is observation and identifying the existing defects, loading, conditions and alterations in the structure. Information could be obtained from past drawings, past records and other documents related. Past records will be able to provide important information regarding layout and sectional views, past weather and climatic records, original design which include architectural, structural, mechanical, electrical, structural design calculations and type of construction materials. Service history such as maintenance record will provide information about previous defects and remedial work done. 2.3.1.2 Visual Inspection Visual inspection is a visual survey on the whole structure. All apparent signs of distress, deterioration and damage can be detected. The outcome of conducting a visual survey is to provide a general picture of existing structure so that more detailed investigation may be planned to assess the structure. It is important that these surveys are conducted by experienced personnel capable of making careful observations and record findings in a systematic manner. Engineers may take photographic survey and non-destructive test measurements to assess the structures structural integrity. 12 2.3.2 Detailed Investigation After visual survey is conducted and there are signs of defects, deformation and deterioration a more detailed investigation is conducted. It is a thoroughly examination on al members to determine the cause and then to propose a suitable remedial work. The detailed inspection will identify the crack size, extent of spalling, depth of carbonation and extent of corrosion besides basic geometry on existing members such as shape, size, cross section and location of embedded elements such as steel bars. Destructive and non-destructive testing will be conducted to check on the structural capacity of every key member and foundation. Analysis of the result will be conducted and engineers for further action. 2.3.3 Test and Inspection Techniques There are various methods and techniques available for in situ during inspection or on samples removed from the structure for laboratory testing. There are three categories on test and inspection techniques (Mays, 1992): i. Those dealing with determination of structural integrity ii. Those dealing with determination of concrete quality iii. Those dealing with determination of steel serviceability and condition 13 2.3.3.1 Structural integrity As mentioned previously, visual survey is important as it provides information on the condition of the structure. Tapping survey is an in situ testing whereas a small hammer is used to sound the concrete surface to detect spalls and delaminations over the reinforcement. For deeper delaminations, more suitable equipments can be used such as ‘Delamtech’ and instrumental delamination device (IDD). Through these techniques, the main and secondary reinforcement, minimum cover and location of reinforcing steel can be determined. Other than that, acoustic emissions, thermograph, dynamic response and radar can yield information on structural integrity of concrete structure. 2.3.3.2 Concrete Quality Core sampling is capable of producing sample most suitable for the use of laboratory testing. To obtain a core sample, usually water cooled diamond bits are used. Diameter of sample ranges from 40mm to over 200mm and the depth of core is equivalent to the diameter. Figure 2.3: Core samples to determine chloride content (Strecker, 1988) 14 To determine the chloride content and sulphate profiles in concrete, powder drilled samples of hardened concrete are taken at various depths usually at 5-25mm. 25-50mm, 50-75mm and 75-100mm. However this technique is not recommended for determining alkali content due to alkali-silica reaction. To investigate the depth of carbonation, phenolphthalein indicator is sprayed upon fractured surface of concrete. The indicator will give a measurement of total carbonation in concrete. 2.3.3.3 Steel Serviceability and Condition Corrosion of steel reinforcement is most common symptom of defective concrete. However what actually affects the mechanical stability of concrete structure is spalls and cracking as a result of corrosion. Half-cell potential mapping can be used to delineate anodic and cathodic areas of reinforcement. Potential of steel in concrete is expressed by the potential developed by common current flow that is normally potential from both anodic and cathodic corrosion processing. The rate of corrosion is measured by determining the conductivity or resistivity particularly using surface contact probes. 2.4 Types of Defects Design and construction defects can at the least cause minor cracking or spalling leading to a major source of a structural failure. Many other causes of deficiencies such as alkali-aggregate reaction, sulphate deterioration and structural overloading can lead to defects in concrete structures. Following are common types of defects in reinforced concrete structures. 15 2.4.1 Corrosion of reinforcement steel Numerous concrete structures have been repaired due to corrosion problems of steel reinforcement. There are several causes that trigger this problem which are irregular and insufficient concrete cover of the reinforcement, unsuitable concrete mixture proportions for outdoor structure and insufficient concrete curing (Raupach, 2006). The corrosion of steel in concrete is generally initiated by a chemical reaction related to the composition of the constituent parts and the influence of one or more of the following (Berkeley, 2001): (i) Chloride concentration (ii) Carbonation penetration (iii) Other acid radicals (iv) Oxygen concentration (v) Degree of moisture ingress (vi) Bacterial action The alkalinity of the Portland cement used in concrete normally creates a passive, basic environment (pH of about 12) around the reinforcing steel which protects it from corrosion. When that passivity is lost or destroyed, or when the concrete is cracked or delaminated sufficiently to allow free entrance of water, corrosion can occur. Corrosion at reinforcement can occur provided that sufficient oxygen and moisture are available. Corrosion of steel reinforcement may only be revealed only after years of exposure. It can be due to the concrete cover being too thin or by cracks that makes it exposed to aggressive environment that can penetrate through the reinforcement 16 and rust it. If not properly repaired, it will gradually deteriorate to the extent that the reinforcement is completely exposed. Figure 2.4: Corrosion of reinforcement steel 2.4.2 Cracks Cracking is the most common phenomenon in concrete defects. Cracking can be the result of one or a combination of factors, such as drying shrinkage, thermal contraction, restraint (external or internal) to shortening, and applied loads. Cracks can also be a sign of corroded reinforcement. Cracking can be significantly reduced when the causes are taken into account and preventative steps are utilized. Cracks are divided into two groups which are structural cracks and non-structural cracks. Structural cracks are cracks that are caused by dead loads, applied forces or other totally external influences. It can develop on structure element such as beam, slab, column and foundation. Structural is much more critical compared to nonstructural cracks because it interferes with stability and safety factor of the building. It is fundamental that hardened reinforced concrete cracks in the tensile zone when 17 subjected to externally imposed loadings such as false in design, false in construction, overloading and accident such as fire and earthquake. There are three common structural cracks which are tensile cracks, compressive cracks and shear cracks (See Shiou Ling, 2006). Tensile cracks happen when the structural element fails to resist imposed tensile load. It usually occurs on beams and slab. These elements are also subjected to shear cracks. Meanwhile compressive cracks are cracks when compressive strength of material is less than imposed loads. Concrete column are more open to this problem. Concrete is also liable to crack in both plastic and hardened state due to stresses sustain by the nature of its constituents materials. Concrete containing them may often be summarily and unjustifiably condemned. There are various types of cracks in concrete structures that appear such as plastic cracks, early thermal contraction, and long term drying shrinkage, longitudinal and transverse cracks, map cracks and surface crazing. 2.4.2.1 Longitudinal Cracks Longitudinal cracks are cracks directly over reinforcing bars. This type of cracks occurs due to rust forming on the reinforcement leading to spalling and complete loss of cover. 2.4.2.2 Transverse Cracks Transverse cracks form after the concrete hardened and is caused by shrinkage, thermal condition, thermal contraction or structural loading. If there is an 18 absence of secondary reinforcement, cracks will only transverse to main reinforcement and are harmless except if it is very wide. 2.4.2.3 Shear Cracks Shear cracks form due to structural loading or movement. Cracks develop when the shear capacity of element is less than shear force acting on it. 2.4.2.4 Plastic Shrinkage Crack Plastic shrinkage cracks form during construction if rapid evaporation causes a large moisture loss from the surface. It is harmless unless the cracks are exposed to salts or contaminated dust. 2.4.2.5 Plastic Settlement Crack Plastic settlement crack form during construction if there is a high amount of bleeding and there is some restraint. If the concrete mix is workable, solids can settle and allow water to bleeds at the top. This type of crack forms longitudinally over the reinforcement. 2.4.2.6 Crazing Crazing is a pattern of fine cracks. It does not penetrate below the surface and usually is cosmetic problem only. Crazing is barely visible except when the concrete is drying after the surface is wet. Cracking of the surface layer into small 19 irregular shaped areas depend on the environmental condition and not necessarily affected by time. Figure 2.5: Crazing on concrete structure 2.4.2.7 Map Crack Map crack is caused by alkali-aggregate reaction. This type of concrete deterioration occurs when the active mineral constituents of some aggregates react with the alkali hydroxides in the concrete. Alkali-aggregate reactivity occurs in two forms—alkali-silica reaction (ASR) and alkali-carbonate reaction (ACR). Indications of the presence of alkali-aggregate reactivity may be a network of cracks, closed or spalling joints, or displacement of different portions of a structure. 2.4.3 Spalling Spalling is commonly known as concrete cancer. Steel reinforcing rods that are affected by moisture or salt from the environment cause the steel to rust and 20 expend. Thus pushing off surface that encases the reinforcement steel. Carbonation that triggers corrosion in reinforcement and insufficient concrete cover also cause spalling. Figure 2.6: Heavily rusted reinforcement and spalling of the concrete 2.4.4 Delamination There are many reasons that can contribute delamination in concrete. It can be a result from bleed water and bleed air being trapped below the prematurely densified mortar surface. Disruptive stresses from chloride-induced corrosion of steel reinforcement results delamination that are deeper called spalls. This defect can be detected by using sounding method by dragging a chain on the surface of tapping using a hammer. Hollow sounds produced indicate delaminated areas. 21 2.4.5 Honeycombing Formation of honeycombing is due to the presence of air and bubble at the surface of the formwork and results a separation between aggregates and cement mixture. Other than that, improper consolidation during construction process such as not properly vibrating the concrete mixture will cause honeycombing to occur. 2.4.6 Scaling Scaling is quite similar to spalling however not as serious. Scaling happens when water is added to increase workability of concrete. The rate of water cement ratio in the concrete will increase and further reduce the strength and durability of the concrete. Figure 2.7: Scaling in concrete 22 2.4.7 Popouts Popout is a conical fragment that breaks out of the surface of concrete thus leaving a hole usually displaying fractured aggregate particle at the bottom of the hole. Contributory factors to popouts in concrete can be either due to pieces of porous rocks having a high rate of absorption and relatively low specific gravity or swelling of aggregates under moisture conditions. It forms a pressure that ruptures the concrete surface. 2.5 Causes of Deterioration There are many causes of deterioration in concrete structures. This problem can bring defects such as cracking, corrosion of steel reinforcement, spalling of the concrete and blemishes such as popouts, scalling, honeycombing etc. 2.5.1 Excessive Concrete Mix Water. The use of excessive water in concrete mixtures is the single most common cause of damage to concrete. Excessive water reduces strength, increases curing and drying shrinkage, increases porosity, increases creep, and reduces the abrasion resistance of concrete. High durability is associated with low water-cement ratio and the use of entrained air. Damage caused by excessive mix water can be difficult to correctly diagnose because it is usually masked by damage from other causes. Freezing and thawing cracking, abrasion erosion deterioration, or drying shrinkage cracking, for example, is often blamed for damage to concrete when, in reality, 23 excessive mix water caused the low durability that allowed these other causes to attack the concrete. Extreme cases of excessive mix water in hardened concrete can sometimes be detected by the presence of bleed water channels or water pockets under large aggregate. 2.5.2 Sulphate Deterioration. Sodium, magnesium, and calcium sulfates are salts commonly found in the alkali soils and ground waters. These sulfates react chemically with the hydrated lime and hydrated aluminate in cement paste and form compounds that have volume greater than initial volume. The volume of these reaction byproducts results in tensioning and cracking, causing disruption of the concrete from expansion. 2.5.3 Faulty Design Design faults can create many types of concrete damage. One type of design fault that is somewhat common is positioning embedded metal such as electrical conduits or outlet boxes too near the exterior surfaces of concrete structures. Cracks form in the concrete cover and around such metal features and allow accelerated freeze-thaw deterioration to occur. Bases of handrails or guardrails are placed too near the exterior corners of walls, walkways, and parapets with similar results. These bases or intrusions into the concrete expand and contract with temperature changes at a rate different from the concrete. Tensile stresses, created in the concrete by expanding metal cause cracking and subsequent freeze thaw damage. 24 Insufficient concrete cover over reinforcing steel is also a common cause of damage. Reclamation usually requires a minimum of 3 inches of concrete cover over reinforcing steel, but in corrosive environments, this can be insufficient. Concrete exposed to the corrosive effects of sulfates, acids, or chlorides should have a minimum of 4 inches of cover to protect the reinforcing steel. Insufficient cover allows corrosion of the reinforcing steel to begin. The iron oxide byproducts of this corrosion require more space in the concrete than the reinforcing steel and result in cracking and delaminating in the concrete. 2.5.4 Construction Defects Some of the more common types of damage to concrete caused by construction defects are rock pockets and honeycombing, form failures, dimensional errors, and finishing defects. Honeycomb and rock pockets are areas of concrete where voids are left due to failure of the cement mortar to fill the spaces around and among coarse aggregate particles. More likely, the resulting defect is either simply accepted by the owner, or the contractor is required to remove the defective concrete and reconstruct that portion of the structure. Whenever possible, it usually is best to accept the resulting deficiency rather than attempt to repair it. If the nature of the deficiency is such, that it cannot be accepted, then complete removal and reconstruction is probably the best course of action. Occasionally, dimensional errors can be corrected by removing the defective concrete and replacing it with epoxy-bonded concrete or replacement. Finishing defects usually involve over finishing or the addition of water and/or cement to the surface during the finishing procedures. In each instance, the 25 resulting surface is porous and permeable and has low durability. Poorly finished surfaces exhibit surface spalling early in their service life. 2.5.5 Alkali-Aggregate Reaction. Certain types of sand and aggregate, such as opal, chert, and flint, or volcanics with high silica content, are reactive with the alkalis of Portland cement released during hydration. Some concrete containing alkali reactive aggregate shows immediate evidence of destructive expansion and deterioration. However other concrete might remain undisturbed for many years. The product of alkali-aggregate reaction shows that a gel will form around the reactive aggregate. This gel undergoes extensive expansion in the presence of water or water vapor (a relative humidity of 80 to 85 percent is all the water required), creating tension cracks around the aggregate and expansion of the concrete. Usually, some type of whitish exudation will be evident in and around the cracked concrete. In extreme instances, these cracks have opened 1.5 to 2 inches. In large concrete structures, alkali-aggregate reaction may occur only in certain areas of the structure. Only portions of the structure constructed with concrete containing alkali reactive sand and/or aggregate will exhibit expansion due to alkali-aggregate reaction. 26 2.5.6 Structural Overload Defects as a result of structural overload will be obvious and easy to detect. It will show distinctive patterns of cracking that indicates the source and cause of excessive loading and point load application. Overloading can weaken the concrete and make it incapable of carrying the design loads. Damage can be repaired with the expectation that the cause of damage neither will nor reoccur in the future. 2.5.7 Faulty Materials Concrete that is contaminated with a significant level of chloride from the original mix materials or as a result of chloride penetration from salty environment must be cut away and replaced with uncontaminated concrete wherever it is close to the reinforcement (Strecker, 1988). 2.6 Repair System It is essential to have a solid plan and specifications for repair works. Improper planning will lead to more tedious and unnecessary works besides not being cost effective. Therefore a systematic and detailed system is important. Among the important criteria are (Emmons, 1993):  Diagnosis of the causes(s) of damage The cause of damage must be correctly determined to prevent unsuitable repairs that may further provoke the damage on the structure. 27  Diagnosis of the extent of the damage It is wise to know the effect of existing deterioration on current and future structural efficiency. Engineers will have to investigate the progression of the damage and the possibility of the damage to aggravate further. Investigative methods are mentioned in the earlier part which is by preliminary and detailed investigation.  The need of repair Repair is required if the damage effects the structural stability and safety operation of the structure. Non-structural cracks due to drying shrinkage can be justified for cosmetic purpose. Meanwhile structural cracks will usually require repair. However the precise evaluation on the current status is extremely difficult and depends on a more subjective appraisal of an experienced engineer. Clients on the other hand might delay repair to fit their maintenance plan or to avoid disruption at difficult times (Grantham, 1997).  Costs There is no clear guideline on what the costs of repairs will be as data for basing estimates of cost are sparse. In repair works, the economic decision is usually made on whether a regular sequence of local repairs is needed or a more expensive corrective measure that will be less costly in the future. Besides that early detection of damage will allow orderly budgeting of funds for the cost of repair. 2.7 Repair Method The concrete repair industry is both specialized and huge. Many of the repair methods, when applied correctly are perfectly adequate for the purpose for which they are intended. However the types of repair method are crucial as choosing the wrong technique will be more costly and further deteriorates the concrete structure. 28 There are various factors affecting choice of repairs such as degree of deterioration, available budget and cost of repair, accessibility to site (Singh, 1991). 2.7.1 Cathodic Protection Cathodic protection is another option for repairing corroded reinforcement. This process will be able to nullify the corrosion current thus stopping corrosion process (Ho N Y, 1991). An external will receive external current from a direct current source and forcing the current into or on the concrete. Induced current generated opposes the electrochemical reaction that is responsible for corrosion problems. Cathodic protection may not necessarily be the only acceptable method of controlling corrosion at a specific location but it will always remain the only technique which is capable of totally reversing the chemical and electrical phenomena causing reinforcement corrosion. On the other hand, it is probably one of the less economical techniques for small isolated repairs (Berkeley, 1990). 2.7.2 Cathite Method Cathite method is suitable to repair concrete that has been damaged by corroded reinforcement. reinforcement. It acts by halting the electrolytic action within the This process will offer high electrical resistance between anode (steel) and cathode (envelopes between the bars). 29 2.7.3 Decholorisation Technique This process is based on electomosis principle (Ho N Y, 1991) which is the extraction of chlorides electrochemically and realkalised the affected area. The affected area is the area with corroded reinforcement. Concrete surface is covered with mesh electrode that is covered with alkaline gel. Electrical connection between electrode and existing reinforcement will cause the hydroxyl ions to migrate into carbonated zones thus increasing its pH. The cost is low compared to cathodic protection. 2.7.4 Crack Repair There are two purpose of deciding the most suitable repair for cracks. Before proposing repair works, it should be determine if it is dormant cracks or live cracks. 2.7.4.1 Dormant Cracks Dormant cracks are unlikely to open, close or extend further. There are three categories of dormant cracks (Turton et al, 1992): i. Fine cracks - up to 1 mm wide ii. Wide cracks - from 1-6 mm wide iii. Fractures - over 6 mm wide 30 The common method of repair for fine cracks is by injecting the crack with epoxy resin or other suitable synthetic resin. Epoxy resins will displace water from a crack and adhere well to damp surface. However it is hard to seal the reverse face of cracked structure for structures such as slabs or retaining walls. Sealing of the reverse surface will prevent the resin from flowing out. The usage of thixotropic resins will eliminate this problem as it will cease to flow when the injection pressure is released. (Turton et al, 1992) Wide cracks can occur on vertical or horizontal surfaces. Injection of epoxy resin is an option for both conditions. There is a more other simpler option for horizontal wide cracks that can be treated by sealing the underside (Turton et al, 1992). A slight ‘V’ opening is done on the upper surface and repair material is poured in. The materials that can be used are epoxy resins or cement grouts such as ordinary Portland and fast hardening cement. Usually the repair method for fractures relies more on the economic factor. Epoxy resin mortar or grout will be a suitable option for shallow fractures. Another option is to open out the fracture and pour mortar or concrete mix. However, precautions should be taken to prevent premature drying out and to ensure proper curing. 2.7.4.2 Live Cracks Live cracks can be subjected to more movement from external loadings. Therefore it is important to choose the right method of repair in relation to the crack movement. Flexible resin can only be used on live cracks with a certain movement. In cases of large and rapid cyclic movement, the cracks should be treated as movement joints. Repair works should cater anticipated movement, cut along the line of crack then sealed with appropriate sealant (Turton et al, 1992). Whereas if the 31 concrete is carbonated or contaminated with chlorides, it must be broken out and replaced. 2.7.5 Patch Repairs Patch repairs is an option for repairing spalled concrete or honeycombing. Concrete mix can be used in cases of large voids. It is important to make sure that the concrete surface is clean and free from dusty materials that can interfere with the bond between patching materials and existing surface. Coats are used as bonding agent. Epoxy mortar and epoxy concrete can be used on relatively small damage of corrosion besides insufficient cover to steel. 2.7.6 Sealing When a concrete member is generally porous it is not suitable to use patching method. The whole surface must be sealed. There are various sealant materials such as silicone or a propriety deep penetration compound. 2.7.7 Sprayed Concrete Sprayed concrete, or gunite, is not a new convention. Today the term “sprayed concrete” and “shortcrete” are commonly used (Bernard, 2001). It is a 32 repair method for corrosion problems, fire-damaged concrete members and distressed structure requiring large area of reconstruction. Air pressure is an important element as it ‘shoots’ mixed concrete. The high velocity will deposit layers of concrete on the surface and each layer gets compacted as a result of impacting action of subsequent layering. The main advantage of guniting is producing a high strength concrete with low permeability without formwork. Sprayed concrete can be divided into two categories which are dry process spraying and wet process spraying. 2.7.7.1 Dry-mix Process Dry-mix process is a technique in which the content and aggregate are batched either at site based plant or pre-batched. Dry mix system virtues is a simple system and few mechanical and mix design issues that can go wrong. However, every process has its drawbacks. For dry-mix method (Bernard, 2001): (i) Low equipment performance (ii) In terms of quality control, sprayed concrete, materials have a great degree of variance due to the inadequate mixing between the nozzles of the substrate. 2.7.7.2 Wet-mix Process The wet-mix sprayed concrete process uses concrete that is batched in a similar way to conventional concrete, making it possible to check and control the water content ratio and thus the quality at any time. The advantages of wet-mix method are its ability to produce homogeneous product with uniform quality throughout the process. Other advantages are low dust levels, effective use of admixing material and better total economy for applied sprayed concrete. The disadvantages are higher demands on mix design, cleaning cost and limited open time/workability (Bernard, 2001). 33 2.7.8 Pre-packed Grouting Plate bonding can strengthen members that are under strength or require accepting greater loading. In this process, steel plates are bonded onto the structural members using bolts and epoxy adhesive. Epoxy is used to bond two different surfaces which is the steel and concrete. Plate bonding is very economical and effective at the same time. After repair works is conducted, the cross section size is not altered drastically. 2.7.9 Recasting Recasting is a method recommended when exposed concrete finish needs maintenance and is done by ordinary manpower. In large replacement concrete, ordinary Portland cement is an economical option. Concrete is mixed in ordinary mixers to ensure that the mix obtained is workable and achieve required slump. 2.7.10 Dry Packing Dry packing is appropriate for vertical members with cavities that have greater depth than width. Concrete surface should be cleaned before hand. Only after it is free from dust, bonding agent is applied. Dry pack mortar is added with certain amount of water so that the mix can be rammed into the place without slumping. 34 2.7.11 Thin Bonded Resurfacing Improvement of surfaces that have deteriorated through impact of heavy loading or displaying uneven profile can be repaired by thin bonded resurfacing. Mortar is applied uniformly on the prepared surface. It is important to make sure that each layer is cured properly to make sure there is a strong bond between each layer. 2.7.12 Stitching Stitching is a technique to provide structural continuity in repairs. In tension cracks, U-shaped anchors are placed inside drilled holes on both sides of the crack. These holes will then be filled with a non-shrink grout. 2.7.13 Caulking Caulking is suitable for small or medium width crack repair. Plastic material is used to fill the narrow raptures in the concrete member. Materials usually used for dormant cracks are Portland cement mortar or expanding mortar. elastomeric caulking materials are used for live cracks. Meanwhile, CHAPTER 3 RESEARCH METHODOLOGY 3.1 Introduction In order to achieve the objectives of this research, it is important to have a planned and structured study methodology. This is to ensure smoothness and effectiveness while conducting the study process. Data collection is an important element of research to provide more knowledge and information for this study. There are two types of data which is primary and secondary data. 3.1.1 Primary Data Primary data refers to all real data collected within the study area. These data can be obtained through questionnaires, interviews, observations and many more. 36 3.1.1.1 Reports and records By collecting reports and records from Public Work Department (PWD), Sabah will give an overview on the maintenance done by PWD. In doing so it will help to accomplish the objectives of this study such as to identify what are the most common defects in concrete building under PWD, cause of deterioration and the method of repair. 3.1.1.2 Questionnaire The purpose of a questionnaire is to obtain answers and opinions for questions that are made in relation to the objectives of the study. Questionnaires are prepared beforehand by referring to information and sources gathered in literature review. 3.1.1.3 Interview Interview sessions are two-way communication which permits exchange in ideas and information. It is conducted with professional and experienced officers from PWD regarding concrete building maintenance. These sessions will provide important ideas and opinions from officers on the common practice of maintenance done by PWD that cannot be collected through questionnaires. 3.1.2 Secondary Data Secondary data are data collected from references books, journals, newspapers, magazines, conference papers, unpublished materials etc. 37 3.2 Data Analysis All the data and information that have been collected through reports, questionnaires, interviews and literature review will need to be organized, summarized and analyzed. Information that will be analyzed is conclusive of type of defects in concrete structures, cause of these defects and the most common practice of repair. Results will be analyzed using frequency counts and other descriptive statistics method. It is then presented in a clearer manner by using graphs such as histogram, frequency polygon, pie charts etc. Tables and pictures are attached to give illustration of the result obtained. 3.2.1 Average Index The average index is calculated based on the following formula: a x i i Average Index = x i Where: ai = Constant expressing the weight given to i xi = Variable expressing the frequency of respondent, for i = 1, 2, 3, 4, 5 38 Average index method is used to determine the frequency of adoption of defects occurrence and method of repair. The categories of scales are: 3.3 1 = least frequent 1.00 ≤ min index < 1.50 2 = less frequent 1.50 ≤ min index < 2.50 3 = average 2.50 ≤ min index < 3.50 4 = frequent 3.50 ≤ min index < 4.50 5 = very frequent 4.50 ≤ min index ≤ 5.00 Conclusion This research utilizes various types of data collection technique. After the data have been analyzed and tabulated for easy reference, conclusions will be made by the results obtained in conjunction with the objectives of the study. Recommendations will be made for future study as well as improvements in maintenance for defective concrete. CHAPTER 4 CASE STUDY 4.1 Introduction Sabah is one of a state in east Malaysia. It is a part of Borneo which consists of Sabah and Sarawak. Also known as the land below the wind, Sabah is now vast developing with implementations of various projects. Many developments of facilities and infrastructure are set up to improve the quality of life of residents in Sabah. In line with that, many new buildings are being built as well as maintaining old ones. Government buildings in Sabah can also be classified into state and federal building. Public Work Department (PWD) is in charge of maintaining government buildings throughout the districts in Sabah. Owners of government buildings are considered as clients in whom they are also partly responsible in conducting maintenance upon buildings with the supervision of PWD. Table 5.1 shows the summary of financial report of building projects implemented from the year 20022004. 40 Table 4.1: Summary of Financial Report (Laporan Tahunan, 2002-2004) Year Project Total Allocation (RM) Total Expenditure (RM) Number of Projects 2002 State 21,799,648.29 17,967,038.48 18 Federal 49,569,862.00 39,946,393.98 31 2003 State 28,983,501.00 14,093,932.75 18 Federal 38,681,725.15 33,852,725.15 29 2004 State 86,243,000.00 40,850,653.00 15 Federal 43,577,200.00 18,621,283.00 8 4.2 Building Works Department Sabah In the year 2005, Building Works Department or previously known as Building Department was established in Public Work Department (PWD), Sabah. The main objectives of this department are (Laporan Tahunan 2005):  Planning, budgeting, implementation and monitoring of all building projects of state and federal government.  Coordinating, monitoring and reporting of all buildings under Public Work Department (PWD) while construction to handing over.  Managing PWD building maintenance system  Inspecting and maintaining all state and federal buildings 41 Next is the organization chart of Building Works Department (PWD) Sabah. KETUA PENOLONG PENGARAH ARKITEK KANAN PEMELIHARAAN PERANCANGAN DAN PEMANTAUAN JURUTERA JURUTERA PENTADBIRAN DAN AKAUN PEMBANTU TADBIR Figure 4.1: Organization Chart of Building Works Department (Laporan Tahunan 2004) 4.3 Clients Clients will either request Public Work Department (PWD) to inspect their building or conduct maintenance. Below are among the lists of PWD clients in Sabah (Laporan Tahunan 2002-2005): 1. Jabatan Arkib Negara 2. Jabatan Bomba 3. Jabatan Hidupan Liar 4. Jabatan Hutan Sabah 5. Jabatan Imigresen 6. Jabatan Kastam, Malaysia 42 7. Jabatan Kebajikan 8. Jabatan Kerja Raya (JKR) 9. Jabatan Ketua Menteri 10. Jabatan Perhutanan 11. Jabatan Pertanian dan Industri Makanan 12. Jabatn Perpustakaan Negara 13. Kementerian Kebudayaan, Belia dan Sukan 14. Kementerian Kehakiman 15. Kementerian Kesihatan 16. Kementerian Pelancongan, Kebudayaan dan Alam Sekitar 17. Kementerian Pembangunan dan Luar Bandar 18. Kementerian Pembangunan Infrastruktur 19. Marine Polis 20. Pejabat Daerah 21. Perpustakaan Negeri 4.4 Maintenance System Building maintenance upon government buildings should be conducted annually. Upon request from clients, Public Work Department (PWD) personnel will conduct inspection. PWD from the related district will send request and visual pictures of the defects to PWD Headquarters in Kota Kinabalu, Sabah. Then, PWD lab department will be informed to conduct investigation. PWD team which consists of engineers and technician will go to the site and do visual inspection. Recordings of defects and its severity will be reported. Meanwhile Schmidt Hammer test will be conducted to determine the structural integrity of the concrete structure. More detailed and close-up photographs are taken. The engineer will then prepare a report which consists of findings including 43 defects, test results, comments and recommendation. Structural Department will receive this report and do assessment on the structural integrity of the building. After full validation by both lab department and structure department, recommendations will be sent back to District PWD and thereafter to the clients. Clients then will decide whether or not they will conduct maintenance and also by whom. If the client agrees to conduct repair work, PWD Headquarter will be informed. Cost and estimates will be done and the maintenance work will be open out for tender if the total cost is more than RM50, 000.00. If the total cost is less, it will proceed with quotation. Sometimes PWD conduct maintenance by themselves, however it must comply with certain term and conditions. Elected contractor will conduct the maintenance work but with the supervision of PWD superintending officer (S.O). The contractor carrying out concrete repairs must comply with the J.K.R. General Specification for Building Works (September 1974, revised April 1989 edition) except if indicated in the specification provided by Public Work Department itself. After all repair work is completed, a joint checking between PWD, contractor and client will be done. 4.5 Problems Faced by Public Work Department (PWD) There are various problems faced by PWD in building maintenance. The responsibilities of making sure the building is safe for occupancy lies in the hand of both clients and PWD. However, the building maintenance culture is still not efficient enough. Clients do not usually conduct yearly maintenance. They will only see the need to inspect and maintain the building when there are serious defects and reports of major failure in other buildings. Meanwhile PWD faces challenges in the delay of maintenance procedure. 44 In Sabah, the problem defective concrete is still prominent in some government buildings. According to several cases from previous reports, the use of sea sand in concrete mix in which it is widely used as fine aggregate for construction in 1980’s have further aggravated the problem of steel reinforcement corrosion in buildings. However there are some building that use sea sand are still in perfect condition. The main factor is poor treatment and site workmanship that has elevated the problem. The maintenance of these buildings can be tedious and could eventually lead to major failure. For most concrete defect, patching is the most common repair technique that is adapted. According to J.K.R. General Specification for Building Works (September 1974, revised April 1989 edition), mortar patching will be used to repair horizontal repairs. Meanwhile for overhead and vertical repairs will use free flow cementitious grout and also patch repair mortar. However, some defects have reoccurred even though maintenance has been done. This can be due to many factors. Insufficient previous maintenance such as plastering of spalling concrete and others usually causes the problem to reoccur. This eventually led to more repetitive repairs. CHAPTER 5 DATA ANALYSIS AND RESULT 5.1 Introduction Maintenance is an important part in a building to ensure it is safe for occupancy and is able to function at its intended function. Poor maintenance will result in repetitive, expensive repairs and replacement of otherwise useful structures. Federal and state building in Sabah are under the supervision of Public Work Department (PWD. In this chapter, analysis have been carried out to study the type of maintenance done by PWD, types of concrete defects that occur in building, factors that causes these defects, method of repair to rectify defects and also problems faced by PWD in building maintenance. All the data analysis are collected through questionnaires to PWD personnel and supported by PWD records. Primary data are collected from questionnaires, interview and observation on government building in Sabah. Meanwhile secondary data are obtained from reference books, journals and unpublished materials. All collected data are analyze 46 by using average mean index method by using statistical software and are presented in the form of tables, charts and graphs to make it easier for interpretation. 5.2 Questionnaire Background and Number of Respondents A total of 40 questionnaires have been sent to district engineers, engineers at building department and lab investigation department throughout the districts of Sabah. These questionnaires have been manually distributed to the district office in Kota Kinabalu and Penampang. Other questionnaires are distributed through email to the other districts in Sabah. However, out of 40 questionnaire forms, there were only 20 completed replies returned and is used for this study. Figure 5.1 shows 50% of forms returned and the other 50% not replied. Questionnaire Respondent 60% 50% 50% Replied Not Replied Percentage (%) 50% 40% 30% 20% 10% 0% Figure 5.1: Number of respondents on questionnaire distributed to Public Work Departments (PWD) Sabah 47 5.3 Party’s Involved in Carrying out Maintenance Works on Government Buildings Government buildings needs to be maintained to ensure its reliability and is safe for occupancy. There are two parties involved in the maintenance of government building. The two parties are Public Work Department (PWD) and contractor. From the questionnaire analysis, it is known that most maintenance works are conducted very frequently by contractor under the supervision of Public Work Department (PWD). This is shown by an average index of 4.50 from Table 5.1. However it is up to the client (building owner) to whether contractor or PWD will conduct the maintenance works. PWD does conduct maintenance works but under certain terms and condition only. However, it is quite seldom as compared to contractor with a mean index of 2.05. The average means index can also be seen in Figure 5.2 which shows the plotted distribution of party to carry out maintenance. Table 5.1: Party to Carry Out Maintenance Number of Respondents Party to Carry out Min Maintenance 1 2 3 4 5 Index a. Public Work Department 4 14 1 1 0 2.05 b. Contractor 0 0 2 6 12 4.50 1 – Least frequent 2 – less frequent 3 – average 4–frequent 5- Very frequent Party to Carry Out Maintenance Public Work Departm ent, 2.05 Contractor, 4.5 Figure 5.2: Party to Carry Out Maintenance 48 5.4 Types of Maintenance Conducted On Government Building Government buildings consist of federal and state building. It is both under the custody of Public Work Department (PWD) to inspect and maintain these buildings. There are two types of maintenance which is planned maintenance which is both preventive and corrective and unplanned maintenance. The type of maintenance with the highest average mean index is unplanned maintenance (3.35). Meanwhile the average index for corrective maintenance and preventive maintenance is 3.10 and 2.65 respectively. This shows that maintenance that is done the most is done without any predetermined plans. Through the interview conducted with district engineer at Kota Kinabalu, he stated that all government buildings are required to conduct yearly maintenance. However, in Sabah most maintenance action is only done when the defects have already occurred to certain extent. Table 5.2 shows the mean index for each type of maintenance. Table 5.2: Type of Maintenance Types of Maintenance 1 Number of Respondents 2 3 4 a) Planned Maintenance (i) Preventive Maintenance 3 6 (ii)Corrective Maintenance 0 6 b) Unplanned maintenance 1 2 1 – Least frequent 2 – less frequent 3 – average 5 Min Index 6 5 0 2.65 10 4 0 3.10 6 11 0 3.35 4–frequent 5- Very frequent Figure 5.3 shows the rating for each type of maintenance. For unplanned maintenance is average with a mean index of 3.35. For corrective maintenance is also in the rank of average (3.10). Lastly is preventive maintenance which is average but with a lower mean index (2.65). 49 Type of Maintenance Conducted on Government Building Average Mean Index 4 3.5 3 3.35 3.1 2.65 2.5 2 1.5 1 0.5 0 Preventive Maintenance Corrective Maintenance Unplanned Maintenance Figure 5.3: Type of Maintenance Conducted on Government Buildings 5.5 Types of Concrete Defect that Occur in Government Buildings There are many types of concrete defects that can occur in building. Various types of concrete defects have been studied in literature review and are listed down in the questionnaire. The frequency of these defects to occur in government building is as analyzed and the mean index is as follows. Table 5.3 and Figure 5.4 both shows that the average means index for concrete defects ranges from 1.90 to 3.45. The list of defects through the questionnaire shows that the most frequent defect that occurs is spalling of concrete with an average mean index of 3.45. This is followed by delamination with 3.25. Other defects such as cracks have an average mean index ranging from 2.85 to 2.00. The highest for cracks is plastic shrinkage crack (3.00) followed by longitudinal crack (2.85), plastic settlement crack (2.55), transverse crack (2.50), shear crack (2.25) and crazing map crack (2.00). Scaling has an average mean index of 2.65. The 50 lowest mean index which shows the defect that is less frequent is popouts (1.95) and honeycombing (1.90). Throughout the questionnaire it is also known that the main factor that triggers defect is the corrosion of steel reinforcement that leads cracks and further spalling of concrete. Table 5.3: Types of Defect that Occur in Government Building Types of Defect 1. Longitudinal Crack 2. Transverse Crack 3. Shear Crack 4. Plastic Shrinkage Crack 5. Plastic Settlement Crack 6. Crazing Map Crack 7. Spalling 8. Delamination 9. Honeycombing 10.Scaling 11.Popouts 1 3 3 3 5 3 5 1 1 6 1 4 Number of Respondents 2 3 4 2 12 1 4 13 0 10 6 1 1 4 9 5 10 2 11 3 1 0 9 9 2 8 9 11 2 1 6 12 1 13 3 0 1 – Least frequent 2 – less frequent 3 – average 5 2 0 0 1 0 0 1 0 0 0 0 4–frequent Min Rank Index 2.85 4 2.50 7 2.25 8 3.00 3 2.55 6 2.00 9 3.45 1 3.25 2 1.90 11 2.65 5 1.95 10 5- Very frequent Type of Concrete Defects Types of Concrete Defects 1.95 Popouts 2.65 Scaling 1.90 Honeycombing 3.25 Delamination 3.45 Spalling 2.00 Crazing Map Crack 2.55 Plastic Settlement Crack Plastic Shrinkage Crack 3.00 Shear Crack 2.25 Transverse Crack 2.50 2.85 Longitudinal crack 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 Average Mean Index 51 Figure 5.4: Types of Concrete Defects that Occur in Government Building 52 5.6 Factor’s that Causes Concrete Defects in Government Buildings Many factors’ can cause concrete defects in buildings. These defects must be attended accordingly to prevent more dangerous failure. Therefore it is important to understand the nature of defects before taking steps to rectify the defects. Many factors can lead to concrete defects. Table 5.5 show the average mean index for respondent’s response to the factor’s that causes concrete defect in government building. Table 5.4: Factors that Causes Concrete Defect in Government Building Factors That Cause Concrete Defects 1. Construction Defect a. Faulty Material b. Poor Construction Method c. Deficiencies in Quality Control 2. Faulty Design 3. Sulphate Deterioration 4. Alkali-aggregate Reaction 5. Structural Overloading 6. Inefficient Maintenance 7. Fire Damage 8. Seismic Movements 1 – Totally disagree 2 – Disagree Number of Respondents 1 2 3 4 5 1 0 0 1 0 0 0 0 1 1 10 3 1 14 11 4 11 3 4 11 5 11 12 5 8 13 7 3 14 8 3 – Average 3 3 4 0 1 2 2 9 1 0 4 – Agree 1 3 3 0 0 1 0 5 0 0 Min Index Rank 3.30 3.45 2.20 2.25 2.50 3.00 2.55 3.80 2.75 2.35 3 2 10 9 7 4 6 1 5 8 5 – Totally agree According to past reports from Public Work Department (PWD), reoccurring defects are due to failure of previous maintenance to arrest or deter the deterioration of structure. This is also shown by inefficient maintenance being the having the highest mean index of 3.80. Meanwhile for construction defects such as poor construction method has an average of 3.45. Other ratings for factor’s that causes concrete defect can be referred to Figure 5.6. Factors That Cause Concrete Defect in Government Building Factors that cause defects Seismic Movements 2.35 Fire Damage 2.75 Inefficient Maintenance 3.80 Structural Overloading 2.55 Alkali-aggregate Reaction 3.00 2.50 Sulphate Deterioration Faulty Design 2.25 Deficiencies in Quality Control 2.20 3.45 Poor Construction Method Faulty Material 0.00 3.30 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 Average Mean Index Figure 5.5: Factor’s that Causes Concrete Defects in Government Buildings 53 54 5.7 Method of Repair in Rectifying Concrete Defects There are many methods that can be adopted to repair concrete defects. Through this part of the questionnaire will identify the methods that are used by Public Work Department (PWD) in rectifying concrete defects. Table 5.5: Method of Repair in Rectifying Concrete Defects Method of Repair Number of Respondents 1 2 3 4 1. Crack Injection 4 9 7 0 2. Patch Repairs 0 0 4 8 3. Sprayed Concrete 0 14 6 0 4. Grouting 3 11 3 1 5. Cathite Method 10 10 0 0 6. Cathodic Method 9 11 0 0 7. Decholorisation Method 7 12 1 0 8. Sealing 3 0 8 9 9.Dry Packing 4 12 3 1 10.Thin Bonded Resurfacing 4 1 6 9 11.Stitching 7 11 2 0 12.Caulking 10 9 1 0 13.Recasting 1 1 11 7 1 – Least frequent 2 – less frequent 3 – average 4–frequent 5 0 8 0 2 0 0 0 0 0 0 0 0 0 Min Rank Index 2.15 7 4.20 1 2.30 6 2.40 5 1.50 13 1.55 11 1.70 10 3.30 2 2.05 8 3.00 4 1.75 9 1.55 12 3.20 3 5- Very frequent Table 5.4 shows the results in which the most common repair technique used by Public Work Department (PWD) to rectify concrete defect is by patching. According to the analysis shows that the average mean index is 4.20 which is significantly high. This is followed by sealing and recasting with 3.30 and 3.20 each. The methods which are least used are caulking (1.55), cathodic method (1.55) and cathite method (2.50). The distribution of method of repair is further described in Figure 5.5. Method of Repair Carried Out in Rectifying Concrete Defects Recasting 3.20 Method of Repair Caulking 1.55 Stitching 1.75 Thin Bonded Resurfacing 3.00 Dry Packing 2.05 Sealing 3.30 Decholorisation Method 1.70 Cathodic Method 1.55 Cathite Method 1.50 Grouting 2.40 Sprayed Concrete 2.30 Patch Repairs 4.20 Crack Injection 0.00 2.15 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 Average Mean Index Figure 5.6: Method of Repair in Rectifying Concrete Defects 55 56 5.8 Factor’s Affecting Choice of Repair There are various choices of concrete repairs depending on the type of defect that occur and its severity of damage. This part of the questionnaire asks respondents regarding the factors that affect the choice of repair done by PWD. In PWD Sabah the two departments that are in charge of proposing method of repair are lab investigation department and building (structural) department. Through Table 5.6, it clearly shows that the four main factors are clearly important. However, most respondents agreed that repair cost which consists of material and labor with an average mean index of 3.90 plays an important role in the choice of repair. Others agreed that the severity of defects (3.70) also is dependent on the choice of repair. Meanwhile the time needed to execute the repair work is also taken into consideration with a mean index of 3.40. Lastly is the lowest mean index (3.10) for the total manpower available to conduct work. Table 5.6: Factors Affecting Choice of Repair Factors Affecting Choice Of Repair a. Severity of defects b. Time needed to execute the repair work c. Repair cost (material and labour) d. Total manpower available to conduct work 1 –Totally disagree 2 – Disagree 1 0 0 0 0 3 – Average Number of Respondents 2 3 4 3 4 9 2 10 6 0 5 12 3 12 5 4 – Agree 5 0 2 3 0 Min Index 3.70 3.40 3.90 3.10 5 – Totally agree Meanwhile Figure 5.6 shows the bar chart for the factors and its average mean index. 57 Average Mean Index Factors Affecting Choice of Repair 4.50 4.00 3.50 3.00 2.50 2.00 1.50 1.00 0.50 0.00 3.70 Severity of Defects 3.90 3.40 3.10 Time Needed to Execute the Repair Work Repair cost (material and labour) Total manpower available to conduct work Factors Figure 5.7: Factors Affecting Choice of Repair 5.9 Common Problems Faced by PWD in Building Maintenance In building maintenance, there are more than one party involved and various procedures. This part of the questionnaire is to identify the common problems faced by Public Work Department (PWD) in building maintenance. From Table 5.7, the average mean index for the common problems faced by PWD ranges from 2.75 to 3.65. Figure 5.8 shows that the most frequent problem faced is delay in maintenance procedure (3.65) followed by delay from contractor (3.35), inefficient funding (3.25), lack of manpower (3.10), unavailability of previous records of building (3.10), less exposure to current technologies (3.00), incomplete and outdated tools/equipment (2.95) and the lowest mean index is personnel lack of experience and skills (2.75). 58 Table 5.7: Common Problems Faced by PWD in Building Maintenance Common Problem in Building Maintenance Number of Min Rank Respondents Index 1 2 3 4 5 1. Insufficient Funding 0 2 11 7 0 3.25 3 2. Lack of Manpower 1 4 10 2 3 3.10 4 3. Personnel lack of experience and skills 0 8 10 1 1 2.75 8 4. Incomplete and outdated tools/equipment 0 6 10 3 1 2.95 7 5. Delay in maintenance procedures 0 0 8 11 1 3.65 1 6. Less exposure to current technologies 0 4 12 4 0 3.00 6 7. Unavailability of previous records of building 0 6 7 6 1 3.10 5 8. Delay from contractor 0 0 13 7 0 3.35 2 1 – Totally disagree 2 – Disagree 3 – Average 4 – Agree 5 – Totally agree Common Problems Faced PWD in Building Maintenance Common Problems Delay from contractor 3.35 Unavailibility of previous records of building 3.10 Less exposure to current technologies 3.00 Delay in maintenance procedures 3.65 Incomplete and outdated tools/equipment 2.95 Personnel lack of experience and skills 2.75 Lack of Manpower 3.10 Insufficient Funding 0.00 3.25 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 Average Mean Index Figure 5.8: Common Problems Faced by PWD in Building Maintenance 59 CHAPTER 6 CONCLUSION AND RECOMMENDATION 6.1 Introduction This research has been carried out to study the maintenance of concrete defects in government building. The scope includes maintenance done by Public Work Department (PWD) throughout Sabah. The data collected consists of data from PWD past records, interviews, observation and questionnaires. Analysis of data has been carried out using SPSS software and results are shown in chapter 4. From the analysis, the conclusion is made in relation to these following objectives: v. To study the types of concrete defects that occurs in buildings vi. To identify the factors that causes the concrete defects in buildings vii. To identify the method of concrete repair carried out viii. To identify the problems faced by PWD in maintenance of buildings 61 6.2 Conclusion Conclusions are drawn based on the outcome of analysis from the previous chapter. All of the results are based on the questionnaire distributed. Besides that, past records and information that is collected from Public Work Department (PWD) are also used as comparison and added value to this whole research. From the study these are the conclusions that are described as follow. 6.2.1 Types of Concrete Defects that Occurs in Buildings From the study, the types of concrete defects that occur in government buildings under the supervision of Public Work Department (PWD) can be determined. Below are the lists of defects from highest to lowest occurrence. (i) Spalling (ii) Delamination (iii) Plastic Shrinkage Crack (iv) Longitudinal crack (v) Scaling (vi) Plastic Settlement Crack (vii) Transverse crack (viii) Shear Crack (ix) Crazing Map Crack (x) Pop outs (xi) Honeycombing 62 6.2.2 Factors that Causes the Concrete Defects in Buildings From the study, the factors that cause concrete defects in buildings are identified and analyzed to obtain each average mean index. The conclusion are as below from highest to lowest mean index. (i) Inefficient maintenance (ii) Poor Construction Method (iii) Faulty Materials (iv) Alkali-aggregate Reaction (v) Fire Damage (vi) Structural Overloading (vii) Sulphate Deterioration 6.2.3 Method of Concrete Repair Carried Out From the study, the method of repair adopted by PWD can be identified. Different types of method apply to different type of defects. These are the method of concrete repair that are rated from highest to lowest mean index. (i) Patch Repairs (ii) Sealing (iii) Recasting (iv) Thin Bonded Resurfacing (v) Grouting (vi) Sprayed Concrete (vii) Crack Injection 63 (viii) Dry Packing (ix) Stitching (x) Decholorisation Method (xi) Cathodic Method (xii) Caulking (xiii) Cathite Method 6.2.4 Problems faced by PWD in Maintenance of Buildings From the study, the most common problems faced by PWD are identified based on the replies of respondents. The ratings are as below from highest to lowest average mean index. (i) Delay in maintenance procedures (ii) Delay from contractor (iii) Insufficient Funding (iv) Lack of Manpower (v) Unavailability of previous records of building (vi) Less exposure to current technologies (vii) Incomplete and outdated tools/equipment (viii) Personnel lack of experience and skills 64 6.3 Recommendation Based on the study, these are a few recommendations that can be made to improve the maintenance done by PWD. (i) There should be proper documentation of building maintenance records by PWD. A system database can provide the faster and easier access to information rather searching manual documentation. (ii) Inspection and supervision on government buildings should be stricter as regular maintenance can reduce the possibility of structural failure that is more expensive and time consuming to rectify. (iii) Personnel should undergo more training to gain more exposure on current technologies and techniques. 6.4 Recommendation for Further Study From this study, a few recommendations are made for further study. There are as listed below: (i) Detailed study on building maintenance procurement (ii) To study the selection of material and repair technique in maintenance of concrete defect (iii) To study the relationship between cost and defects in buildings 65 (iv) To study the difference of building maintenance works done by PWD and by contractor (v) To study the selection of contractor by PWD to conduct works (vi) To study the implementation of information system in building maintenance 66 REFERENCES Abdul Hakim bin Mohammed and Wan Min bin Wan Mat (1991). Teknologi Penyenggelaraan Bangunan. Kuala Lumpur: Dewan Bahasa dan Pustaka. Abid, A. and Ribakov Y. (2006). Non-destructive measurements of crack assessment and defect detection in concrete structures. Material and Design. 1-9. Bernard,E.S (2001). Shortcrete: Engineering Developments. Netherland: Swets & Zeitlinger Publishers. Campbell,D and Allen (1977). Cracking in Concrete. Cracks, codes and creep. 27 July. Concrete Institute of Australia. Emmons, P.H (1993). Concrete Repair and Maintenance Ilustrated. Kingston: R.S. Means Company. Grantham, M.G., Barret, Herts and Dr Broomfield, J. (1997). The Use of Linear Polarisation Corrosion Rate Measurements in Aiding Rehabilitation Options for the Deck Slabs of Reinforced Concrete Underground Carpark. Construction and Building Material. Volume (II). 215-224 Hans, B. (2005). Corrosion in Reinforced Concrete Structures. Woodland: Woodland Publishing Limited. 67 Ho. N. Y. (1991). Techniques of Repairing Concrete Structures. Buletin IEM (20-25) Mays, G. (1992). Durability of Concrete Structures: Investigation, Repair, Protection. London: Chapman and Hall. Pathmanaban, S and Berkeley K. G. C. (1990). Cathodic Protection of Reinforcement Steel in Concrete. Cornwall: Butterworth & co Ltd Raupach, M. (2006). Patch Repairs on RC Structures: Model Investigations on the Required Size and Practical Consequences. Cement and Concrete Composites. Volume (28). 679-684 Said, K.and Romdane, B. (2003). Evaluation and repair of Algiers new airport building. Cement and Concrete composites. Volume (25). 633-641 Sansalone, M. and Arino, N.J. (1986). Detecting honeycombing, the depth of surfaceopening cracks, and un-grouted ducts. ACI Annual Convention, San Antonio SchieBl, P., Breit, N., and Raupach, M. (1994). Durability of local repair measures on concrete structures damaged by reinforcement corrosion. 22-25 May 1994. Third International Conference, Nice France. See Shiou Ling (2006). Periodical Inspection on Reinforced Concrete Building. Bachelor Degree . Universiti Teknologi Malaysia, Skudai Singh, P (1991). Seminar on Repair and Maintenance of Concrete Structures, 28 August. Institut Teknologi Mara Strecker, P.P. (1988). Corrosion Damaged Concrete Assessment and Repair. Essex: Anchor Brendon Ltd. Turton et al. (1992). Non Structural Cracks in Concrete: Third Edition. Concrete Society 68 Uemote, T. (2000). Maintenance of concrete structures and application of nondestructive inspection in Japan.1-11 Yeng Kim Ling (2006). Bridge Maintenance. Bachelor Degree (Constuction Management). Universiti Teknologi Malaysia, Skudai 69 UNIVERSITI TEKNOLOGI MALAYSIA FACULTY OF CIVIL ENGINEERING SKUDAI JOHOR QUESTIONNAIRE FORM MAINTENANCE OF CONCRETE DEFECTS IN BUILDING This research is conducted to have a better understanding on the maintenance of government buildings throughout Sabah. ALL GIVEN INFORMATION IS STRICTLY CONFIDENTIAL AND STRICTLY FOR ACADEMIC PURPOSES ONLY Section A For question 1-5, please refer to the rating below. Please circle the numbers. As: 1 – Least frequent 5- Very frequent 2 – less frequent 3 – average 4–frequent 1. The type of maintenance conducted on government buildings: (a) Planned Maintenance (i) Preventive Maintenance (ii) Corrective Maintenance (b) Unplanned Maintenance 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5 2. Maintenance works on government buildings are usually carried out by: a) Public Work Department (PWD) b) Contractor 1 1 2 2 3 3 4 4 5 5 3. According to your experience, how soon in the life of a structure do defects start to occur? a) b) c) d) <1 years 1-5 years 6-10 years >10 years 1 1 1 1 2 2 2 2 3 3 3 3 4 4 4 4 5 5 5 5 70 4. Types of concrete defects that frequently occur in government buildings? a) Corrosion of steel reinforcement 1 b) Cracks 1 i. Longitudinal crack 1 ii. Transverse crack 1 iii. Shear Crack 1 iv. Plastic Shrinkage Crack 1 v. Plastic Settlement Crack 1 vi. Crazing Map Cracks 1 c) Spalling 1 d) Delamination 1 e) Honeycombing 1 f) Scaling 1 g) Pop outs 1 h) Others (please state) ____________________________________1 ____________________________________1 ____________________________________1 ____________________________________1 ____________________________________1 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 4 4 4 4 4 4 4 4 4 4 4 5 5 5 5 5 5 5 5 5 5 5 5 5 2 2 2 2 2 3 3 3 3 3 4 4 4 4 4 5 5 5 5 5 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 4 4 4 4 4 4 4 4 4 4 4 5 5 5 5 5 5 5 5 5 5 5 5 5 2 2 2 3 3 3 4 4 4 5 5 5 5. The method of repair carried out in rectifying concrete defects: a) b) c) d) e) f) g) h) i) j) k) l) m) n) Crack injection 1 Patch Repairs 1 Sprayed concrete 1 Grouting 1 Cathite method 1 Cathodic method 1 Decholorisation method 1 Sealing 1 Dry packing 1 Thin bonded resurfacing 1 Stitching 1 Caulking 1 Recasting 1 Others (please state) ____________________________________1 ____________________________________1 ____________________________________1 71 Section B For question 6-8, please refer to the rating below. Please circle 1 – Totally disagree 2 – Disagree 3 – Average 4 – Agree the number. As: 5 – Totally agree ____________________________________________________________________ 6. Factors that usually causes concrete defects in government buildings: a) Construction defect i. Faulty materials ii. Poor construction method iii. Deficiencies in quality control b) Faulty design c) Sulphate deterioration d) Alkali-aggregate reaction e) Structural overloading f) Inefficient maintenance g) Fire damage h) Seismic movements i) Others (please state) ___________________________________ ___________________________________ ___________________________________ ___________________________________ 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 4 4 4 4 4 4 4 4 4 5 5 5 5 5 5 5 5 5 1 1 1 1 2 2 2 2 3 3 3 3 4 4 4 4 5 5 5 5 7. The factors affecting the choice of repair technique to rectify concrete defects: a) b) c) d) e) Severity of defects 1 Time needed to execute the repair work 1 Repair cost (material and labour) 1 Total manpower available to conduct work 1 Others (please state) ____________________________________1 ____________________________________1 ____________________________________1 ____________________________________1 2 2 2 2 3 3 3 3 4 4 4 4 5 5 5 5 2 2 2 2 3 3 3 3 4 4 4 4 5 5 5 5 72 8. Common problems faced by PWD in building maintenance a) b) c) d) e) f) g) h) i) Insufficient funding Lack of manpower Personnel lack of experience and skills Incomplete and outdated tools/equipment Delay in maintenance procedures Less exposure to current technologies in repair technique Unavailability of previous records of building Delay from contractor 1 1 1 1 1 1 2 2 2 2 2 2 3 3 3 3 3 3 4 4 4 4 4 4 5 5 5 5 5 5 1 2 3 4 5 1 2 3 4 5 Others (please state) __________________________________ 1 __________________________________ 1 __________________________________ 1 __________________________________ 1 2 2 2 2 3 3 3 3 4 4 4 4 5 5 5 5 73 74 75 76 77