Workability

In this study, the shape of coarse aggregate particles has been related to the workability and compressive strength of cement concrete for rigid pavements. The shape characteristics such as elongation, flatness, shape factor, and sphericity were determined. Also,the slump and compressive strength of cement concrete were determined for various shapes of coarse aggregate. The test results indicated that there is a good correlation between some shape properties of aggregate, workability, and compressive strength.The highest compressive strength at different ages noted with concrete made from different shapes of coarse aggregates. Results indicate that the strength of concrete varies as a function of the shape of the coarse aggregate, which leads to the conclusion that the shape of aggregate shall be considered as an important parameter in deciding the suitability of coarse aggregate to prepare cement concrete for rigid pavements. I. INTRODUCTION To provide a stable and even surface for the traffic, the roadway is always provided with a suitably designed and constructed pavement structure. Thus, a pavement consisting of a few layers of pavement materials is constructed over a prepared layer of sub-grade to serve as a carriageway. Based on design consideration pavements can be classified as-Rigid pavements and Flexible pavement. Flexible pavements can be defined as the one consisting of a mixture of asphaltic or bituminous material and aggregates placed on a bed of compacted granular material of appropriate quality in layers over the subgrade. Rigid pavements are those, which possess noteworthy flexural strength or flexural rigid. The rigid pavement has the slab action and is capable of transmitting the wheel load stresses through a wider area below. Cement concrete is a composite material produced by the homogenous mixing of selected proportions of water, cement, and aggregates (fine and coarse). Strength is the most desired quality of a good concrete. It should be strong enough, at hardened state, to resist the various stresses to which it would be subjected. Aggregates are the most important constituents in cement concrete. For a long time aggregates were considered as inert materials, but after 1940 it was brought out that aggregates do show some reactivity. The mere fact that aggregates constitute 70-80% of the volume of concrete, their impact on various characteristics is undoubtedly considerable. Aggregates give the body to the concrete, reduce shrinkage, and affect the economy. Among all the characteristics of aggregates, the shape is most important because it affects the workability and compressive strength of cement concrete. Aggregates form the major portions of pavement structure and aggregates have to bear stresses occurring due to wheel loads on the pavement and on the surface-course they have to resist wear due to the abrasive action of traffic. Therefore, the properties of aggregates are of considerable significance to the highway engineers. Significant findings indicate that aggregate plays a more "active" role than was previously believed, and a better understanding will result from further research. Several authors have indicated the need for more research to determine the effect of aggregate particle shape on the properties of concrete at present there is only alimited amount of information concerning the effect of aggregate particle shape on concrete proportioning, workability, and strength. This lack of information is reflected in specifications that place conservative limits on allowable amounts of particles of certain shapes. The present study was undertaken to investigate the effect of different types of coarse aggregate effect on the fresh and hardened Portland cement concrete behavior by a means of aggregate shape indexes such as elongation, flatness, roundness, shape factor, and sphericity.

Concrete is no longer made of aggregates, Portland cement and water only it is not always incorporate so it requires at least one of the additional ingredients such as admixtures, supplementary Cementitious material or fibers to increase the strength and durability. Rice husk ash is one of the pozzolanic materials that can be blended with Portland cement for the production of durable concrete. Supplementary Cementitious materials prove to be effective to meet most of the requirements of durable concrete. Rice husk ash is found to be greater to other supplementary materials like silica fume and fly ash. In the current study an attempt has been made to investigate the strength parameters of M20 concrete (compressive and split tensile). For control concrete, IS method of mix design is adopted. Partial replacement of cement has been made with different percentage of RHA namely, 5%, 10% and 15%. Large range of curing periods starting from 7, 14 and 28 days are considered in the present study.

The objective of this study is to analyse the performance of Microsilica and Fly Ash in concrete when it is mixed in cement concrete for workability and strength of concrete using OPC 53 grade. Efforts are to improve and develop high performance concrete with the help of past years result which suggests that by the use of cement replacement materials for some determined percentage along with admixtures can help to increase the strength and consistency characteristics of concrete. This study analyzes the performance of concrete mix for compressive strength of cubes at 7 and 28 days and flexural strength of beams for 28 days respectively for M-25 grade concrete. To analyse these properties of concrete, the total investigation was conducted into three groups. The first beam will be a normal beam (Type N); in second beam we replace aggregate by microsilica and fly ash in tension zone (Type NT); in third beam we will replace aggregate in whole beam by fly ash and microsilica (Type NA). Super plasticizer was used to increase the workability at water-cement ratio of 0.43 for all combinations. On the basis of past result the replacement of cement by Microsilica and Fly Ash was found to increase in strength.

This study concluded the results of a research on the features of cement based permeation grout, based on some important grout parameters, such as the rheological properties (yield stress and viscosity), coefficient of permeability to grout (kG) and the inject ability of cement grout (N and Nc assessment), which govern the performance of cement based permeation grouting in porous media. Due to the limited knowledge of these important grout parameters and other influencing factors (filtration pressure, rate and time of injection and the grout volume) used in the field work, the application of cement based permeation grouting is still largely a trial and error process in the current practice, especially in the local construction industry. It is seen possible to use simple formulas in order to select the injection parameters and to evaluate their inter-relationship, as well as to optimize injection spacing and times with respect to injection source dimensions and in-situ permeability. The validity of spherical and cylindrical flow model was not verified by any past research works covered in the literature review. Therefore, a theoretical investigation including grout flow models and significant grout parameters for the design of permeation grouting was conducted in this study. This two grout flow models were applied for three grout mixes prepared for w/c=0.75, w/c=1.00 and w/c=1.25 in this study. The relations between injection times, radius, pump pressure and flow rate for both flow models were investigated and the results were presented. Furthermore, in order to investigate these two flow model, some rheological properties of the grout mixes, particle size distribution of the cement used in this study and some geotechnical properties of the sand used in this work were defined and presented.

L’idée de recycler les bétons est apparue dans le but principal de préserver l’environnement et de s’intégrer ainsi au concept de développement durable. En effet, la réutilisation des bétons en tant que granulats dans des nouvelles compositions de béton permet de réduire les dépenses sur la gestion des déchets de démolition et, surtout, de protéger les gisements et les montagnes contre l’ouverture de nouvelles carrières. Les granulats provenant du recyclage de bétons peuvent remplacer une partie de granulats naturels lors de la fabrication de nouveaux mélanges de béton. Les taux de substitution des granulats naturels dans cette recherche sont 10, 20 et 30 %.
Le but de cette recherche est d’étudier expérimentalement l’influence des granulats recyclés sur les propriétés du béton telles que sa résistance à la compression, son ouvrabilité et sa porosité, ainsi que sa durabilité.

ABSTRACT: Concrete is the most widely used construction material developed by man. Because of its superior specialty of being cast in any desirable shape, it has replaced stone and brick masonry. Inspite of all this, it has some serious deficiencies which, but for its, remarkable qualities of flexibility, resistance and ability to redistribute stress, would have prevented its use as a building material. Prediction of mechanical behaviour of concrete is an important issue in the concrete industry, since the traditional laboratory approach to determine the strength of concrete attracts some drawbacks such as manual involvement, time consumption and chances of creeping of human error. An attempt is made to evaluate the mechanical properties of concrete such as compressive strength, split tensile strength and flexural strength. Experimental program was carried out on concrete specimens to evaluate various parameters involved. This study looked at the feasibility of waste glass inclusion as partial cement replacement. The study includes by incorporating waste glass as partial substitution for Portland cement in amounts of 10%, 20%, 30% and 40% were investigated. The workability increased with the increase of glass powder. The optimum dosage of glass powder is found to be at 20%.


KEYWORDS: glass powder, workability,

Electronic waste or e-waste describes discarded electrical or electronic devices. Used electronics which are destined for reuse, resale, salvage, recycling or disposal are also considered as e-waste. Informal processing of electronic waste in developing countries may cause serious health and pollution problems, as these countries have limited regulatory oversight of e-waste processing. Solid waste management is one of the major environmental concerns in our country now a day. The present study covers the use or recycled e-wastes as replacement of coarse aggregates in concrete. The main aim of the study is to investigate the change in mechanical properties of concrete with the addition of e-wastes in concrete. It is found that the use of e-waste aggregates results in the formation of lightweight concrete. In this dissertation coarse aggregate is partially replaced by coarse aggregate upto 25% with regular interval of 5%, along with fly ash partially replacing cement in concrete of grade M50.

Workability, flow and consistency are unique parameters that contribute to the quality and mechanical properties of Self-Compacting Concrete (SCC) in the hardened stage, in a bid not to compromise strength and quality. Workability, flow and consistency can be controlled in the fresh stage of SCC. This research assessed the workability and strength properties of self-compacting concrete using bakery ash as the need for a green approach in concrete technology is paramount in track with the trash to treasure initiative. To achieve the aim of this study, two brands of Portland limestone cement were used in developing twelve (12) concrete samples. The additive was used at 0, 5,10,15,20 and 25% replacement of cement. The flow, segregation and filling ability were investigated using the L-box, V-Funnel and the slump flow apparatus. The result of the experimental research showed that at 10% and above addition of bakery ash, the workability was unsatisfactory using EFNARC specifications. The compressive strength increased up to 10% addition of the bakery ash. However, at higher percentage addition, the strength reduced. The use of this concrete is recommended for the construction of low load bearing concrete infrastructures. The outcome of this research will serve as a guide for engineers, researchers and construction worker on the optimum quantity of this waste in the development of self-compacting concrete with satisfactory rheology.

Concrete has occupied an important place in construction industry in the past few decades and it is used widely in all types of constructions ranging from small buildings to large infrastructural dams or reservoirs. It is the most widely used man-made construction material in the construction world. Ever since concrete has been accepted as material for construction, civil engineers have been trying to improve its quality, strength etc., against adverse conditions. The OPC is one of the main ingredients used for the production of concrete. However in the context of increased awareness regarding over exploitation of natural resources to manufacture cement, an eco-friendly technology has to be developed for the effective management of resources. The replacement of natural resources in the manufacture of cement is the present issue in the present construction scenario. With increase in demand of concrete, more and more new methods and new materials are being developed for production of concrete. Hence in the current study an attempt has been made to minimize the cost of cement with concrete mix grades M20 and M30 by studying the mechanical behaviour of these concrete mixes by replacing with advanced mineral admixture such as GGBS in concrete mixes as partial replacement of cement. GGBS is a waste industrial by-product from the blast furnaces used to make iron. Use of GGBS does not only reduce the cost of construction but also helps to reduce the impact on environment by consuming the material generally considered as waste product. Therefore an experimental study is conducted to evaluate the workability and strength characteristics of hardened concrete, by partially replacing the cement by various percentages of GGBS for M20 and M30 grades of concrete at different ages. The mixes were designed using IS Code method. In this project, properties of concrete have been assessed by partially replacing cement with GGBS. The cement has been replaced by GGBS accordingly in the range of 0% (without GGBS), 10%, 20%, 30%, 40% and 50% by weight of cement for M20 and M30 mix. Concrete mixtures were produced, tested and compared in terms of compressive, split tensile and flexural strength with the conventional concrete.

Fiber reinforced cementitious composites are gaining attention in construction industry because of the high strength, ductility and energy absorption capacity. Concrete production is still under consideration to improve the sustainability and environmentally safety. Therefore, natural fiber reinforced concrete is the good alternative. Although sheep wools are producing a huge amount of waste, which can be utilized as building material in concrete if properly recycled. The addition of sheep wool in concrete mix was not very new, it has been used for insulation purposes. In this research the mechanical properties of sheep wool fiber reinforced concrete (SWFRC) were investigated. Total sixty cylindrical specimens and prisms were tested in this experiment to assess the fresh and hardened properties of SWFRC. The aim study was fulfilled by the results obtained from the split tensile test and flexural test. The weak tensile strength of concrete was enhanced by the addition of high tensile sheep wool and the cracks bridging effect of smooth and elastic fibers were worked to enhance the ductility and flexural capacity of concrete. Meanwhile, the compressive strength reduction due to addition of sheep wool in concrete can be minimized by proper treatment, which must need to investigate correspondingly.

Concrete is a mixture of cement, water and aggregates. It is widely recognized that proportioning and mixing of the constituents of concrete such as cement, sand and coarse aggregates and water are important steps in concrete making process. Quality control measures are expected to keep a check on the quality of concrete being produced. These include tests on wet concrete and hardened concrete. But due to large use of concrete as the construction material availability of raw material is being questioned. Therefore other replacing materials are need to be find out. E-waste like Printed Circuit Board is generating in very large quantity. So it is essential to dispose. The e-waste like non-metals part of PCBs can be recovered and can be use as a ingredient in concrete. So we can partial replace the material to achieve desire concrete in terms of their properties. This paper presents an overview on possible use of E-waste in concrete by the different researchers. There research shows strongly possibility of E-waste being used as substitute of fine aggregate. More use of this tends to decreases the use natural aggregates in concrete and it is of prime importance that substitute of fine aggregates can be explored.

The investigation concerns the use of the optimum mix proportion of two locally available pozzolanic waste materials, namely, ground granulated blast furnace slag (GGBS) and palm oil fuel ash (POFA), together with metakaolin (MK) as binders. In addition, another local waste material, manufactured sand (M-sand), was used as a replacement for conventional sand in the development of green geopolymer mortar. Twenty-four mortar mixtures were designed with varying binder contents and alkaline activators. The oven dry curing was also kept consistent for all the mix proportions at a temperature of 65 degrees C for 24 hours. The highest 28-day compressive strength of about 48 MPa was obtained for the mortar containing 20% of MK, 35% of GGBS, and 45% of POFA. The increment of MK beyond 20% leads to reduction of the compressive strength. The GGBS replacement beyond 35% also reduced the compressive strength. The entire specimen achieved average 80% of the 28-day strength at the age of 3 days. The density decreased with the increase of POFA percentage. The finding of this research by using the combination of MK, GGBS, and POFA as binders to wholly replace conventional ordinary Portland cement would lead to alternate eco-friendly geopolymer matrix.

Link to full text articles :
http://www.hindawi.com/journals/amse/aa/647071/

In the present day construction industry in developing countries, concrete has emerged as the most common building material. Hence careful consideration must be given to factors that affect its strength. For sand having above 3.4% of clay content used in a 1:1: 2 (M-25) mix of concrete resulted in the production of concrete with compressive strength less than 25 N/mm2.Therefore, this work was conducted to investigate the amount of cement needed for sand samples with varying amount of clay/silt cement from 0% to 10% to produce concrete with compressive strength not less than 25 N/mm2 for mix 1:1:2.The sieved clay/silt is added to each of the parts of the washed sand from 1% to 10% by weight of the sand. The amount of cement necessary to be added to each part of the sand with varying cement content of clay/silt 1% to 10%, so as to achieve minimum strength of 25 N/mm2 for the mix ratio 1:1:2 was determined. It was discovered that the higher the clay/silt content, the compressive strength of concrete is decreases. It is concluded that the higher amount of cement dosage is needed to maintain the compressive strength of concrete.

Self-compacting concrete (SCC) can consume low levels of cement and more
Supplementary cementitious materials. SCC is a viable technique conserves energy
and achieves strength more than conventional concrete.
This work is focused on the fresh and hardened properties of Self-compacting
concrete (SCC) replacing cementitious material by weight with the optimized
percentages of fly ash. Self-compacting concrete mix is designed at water-to-binder
ratio of 0.36 in all mixtures and 497 kg/m3 of binder content with Fly Ash as partial
replacement of cement (30% by weight). Compressive and split tensile strengths at the
age of 7 and 28 days are determined with the use of plastic electronic waste as partial
replacement of fine aggregate up-to 40%. Fresh property i.e., workability of selfcompacting
concrete mixtures is performed with slump flow diameter, V-funnel flow
time and L-box height ratio. The strength values indicate the reduction but satisfying
the design mix criteria up to 30% replacement for sand. Hence Plastic electronic
waste can be easily replaced up to 30% in SCC for good workability and strength.
High Impact Polystyrene aggregate in concrete is the suitable substitute of sand for
waste disposal serving an economic purpose.

In recent years, significant attention has been given to use superplasticizer as a chemical admixture on concrete. However, the use of chemical admixtures in concrete is a common solution to achieve high performance concrete. The past researchers have been underscored the use of chemical admixtures imparts the desirable properties to concrete in both fresh and hardened state. This paper has been made an attempt to study the influence of superplasticizer dose of 0.6, 0.8, 1.2, 1.8 and 2.5 percentage on performance of concrete. The experimental tests for fresh and hardened properties of concrete for M35 grade are studied and the results are compared with normal concrete. The tests considered for study are, slump test and compressive strength test The results show that the increase of superplasticizer dose in concrete leads to gain of good ability in addition to slump. Moreover, there is also slightly increase in compressive strength than that of normal concrete.

The objective of this research is to design and improve works, workstations and environment in the production process of the Arc Stack Medium in order to increase productivity and reduce injury. The research applied Ergonomic principle to analyze and improve the processes including incoming material receiving, production process, quality inspection, and packaging by emphasizing on three main components which are workers, work and workstations, and working environment. Techniques and tools used in the study were health survey questionnaire, Abnormal Index assessment, environment impact assessment, as well as equipment for inspecting light intensity, sound, and dust. The preliminary analysis found many problems concerning improper conditions of work and environment in the production processes. In the incoming material receiving process, the abnormal index (AI) was 2.65 exceeding the standard of 2 and light illuminance was 194 Lux which was lower the standard. In the production process, volume of dust was found to be 18.15 mg. /m.3which was over the standard. In the quality inspection process, condition and dimension of a table and a desk were inappropriate for workers. In the packaging process, the unsuitable lifting posture of workers resulted in the lifting index of 3.3, which was over the standard. To overcome these problems, the improvement were performed by designing a new table for inspecting the incoming materials, installing a dust collector, redesigning a table and a chair for quality inspection tasks, increasing light illuminance in the workstation, and designing lifting equipment. Results from the improvement showed that abnormal index of all the processes was within the standard and working environment such as light, sound, and dust were acceptable. Moreover, this research was able to increase the overall productivity and reduce wastes of time caused by improper poster and motion of the workers.

KEY WORD:  WORK DESIGN / ENVIRONMENTAL IMPACT ASSESSMENT / ERGONOMICS / ABNORMAL INDEX ASSESSMENT

The use of alternative aggregate like silica sand is a natural step in solving part of depletion of natural aggregates. The investigation on alternative material for concrete making started before half a century. Concrete made from silica sand waste as fine aggregate was studied for workability, compressive strength, Split tensile strength and Flexural strength. Further, study of its durability will ensure greater dependability in its usage. So here in this project, Silica sand had been used as replacement of fine aggregate by different percentage for making concrete of M-20, with w/c ratio 0.50 & 0.45. The percentage replacement will be 0%, 10%, 20%, 30%, 40%, 50%, 60% and 70% with natural fine aggregates. For making concrete OPC-53 grade cement is used. Cubes, beams and cylinders will be casted and tested compressive strength, Split tensile strength, and flexural strength as well as for durability properties. Optimum replacement of silica sand can be used in structural concrete.

Solid unreinforced cement concrete paver blocks is a versatilely used for the construction of roads. This project is part of a study investigating the structural characteristics of cement concrete paver blocks using various combinations of Natural River sand and quarry fines. Here quarry fines will complete replace river sand as fine aggregate in concrete. Samples of concrete cube were made using varying contents of River Sand and quarry dust as fine aggregate. The quantity of River Sand was varied from 0% to 100% against quarry fines at intervals of 20%. The samples were cured for specified periods and tested in the laboratory for compressive strength. Workability tests were earlier carried out to determine the optimum water/cement ratios for three different mixes. M40 mix was designed as per IS specification with water cement ratio 0.40.

This paper reports a part of an ongoing experimental laboratory investigation being carried out to evaluate the mechanical properties of concrete made by Fine Material Associated with Coarse Aggregate Production (FMACAP) is considered a solid waste in Libya. However, based on previous researchers, Fine materials production with coarse aggregate is considered a pozzolanic materials waste that causes environmental pollution. In order to limit this pollution And it can act as additive and improve the properties of concrete, the fine wastes are being used as an alternative to imported materials such as fly ash and silica fume which adding to concrete for producing concrete with high strength, low cost and good durability of concrete. Therefore, the superplasticizer which is one type of chemical admixtures will be added to blended cement concrete in order to improve the workability of concrete. But strength development of Fine Material Associated with Coarse Aggregate Production (FMACAP) concrete, there will be some effects when chemical admixtures are added. In this study, the Concrete specimens were tested and compared with plain concrete specimens. However, mixes concrete with fineness namely 75 mic and consists of 5%, 7.5%, 10%, 12.5% and 15% as additive materials. However, mixes contain superplasticizer with percentage 1.6%. To investigate the fresh concrete properties, the slump test and flow table test were conducted. While for hardened concrete properties, compressive strength test was conducted. Strength development of Fine Material Associated with Coarse Aggregate Production (FMACAP) concrete was studied during all tests for hardened concrete properties. Conclusively, superplasticizer added into Fine Material Associated with Coarse Aggregate Production (FMACAP) concrete will improve workability and strength of Fine Material Associated with Coarse Aggregate Production (FMACAP) concrete and such concrete can be effectively used in structural applications.

In this paper an attempt has been made to study various properties of concrete produced from shredded polythene bags as plastic waste and fly ash. Plastics are causing damage to environment, it is require finding out whether they can be successfully used in concrete. Conversion of waste into a resource material is an age-old practice of civilization. Fly ash was varied by 0%, 5%, 10%, 15% and 20% by weight of cement with plastic waste at a constant dosage of 0.6% by weight of concrete. The specimens were prepared for M25 grade and water to cementitious material ratio (w/c) was maintained as 0.45. Fresh concrete property like workability was examined during casting the specimens. Hardened properties were found out by carrying out the experimental work on cubes, cylinders and beams which were casted in laboratory and their behavior under test were observed at 7 & 28 days for compressive strength and at 28 days for density, flexural strength, dynamic modulus of elasticity, abrasion resistance, water permeability and impact resistance.

Day by day, the Concrete consumption is increasing world over. Ever increasing cost of Cement, the main ingredient of concrete, is on one side and depletion of natural resources like Lime Stone (to manufacture Cement), Coarse and fine Aggregates on other side over the Globe is compelling to think for alternatives.. Added to this,  60% OPC + 20% Metakaoline + 20% GGBS However, the maximum compressive strength and split tensile strength of concrete at 28 days is observed for the mix with OPC replaced by mineral admixtures 20% Fly ash + 20% GGBS @1.0% glass fibers as 9 % and 33% respectively. Replacement shall result about 20 to 25% economy in production of Concrete and retard the rate of global warming as well as the depletion of natural resources.

— Waste paper sludge is waste product of paper industry, during manufacturing of paper white mud comes out during the process is called paper sludge or hypo sludge or brine sludge. This project is based on the viability of use of waste paper sludge, an industrial waste comes out during manufacturing of paper as partial replacement of cement in cement concrete. Concrete is widely used building material which is used all over the world. Cement which is used as a binding material in concrete contain silica, this cement release poisonous gages during hydration of cement and pollute environment. Although cement is also a costly material, using waste material as partial replacement of cement can save environment and also make concrete economical. Particular this study is based on utilization of paper sludge as partial replacement of cement in concrete, M30 and M40 concrete is manufactured which contains paper sludge 5% to 40% at interval of 5%. Concrete which contains waste paper is tested for compressive strength, flexural strength and split tensile strength, also slump cone test to check workability.

This project work involves in an experimental study on the concrete by using stone dust and brick dust on the mechanical properties of the concrete. In this experimental study two types admixtures are used in preparation of concrete mix. Stone dust and brick dust are added from 0% to 25% by weight of fine aggregate with increment of 5%. A comparative analysis has been carried out for conventional concrete to that of the admixture concrete in relation to their compressive, split tensile and flexural strength properties. As the stone dust and brick dust content increases in cement concrete, the compressive and split tensile values are proportionally increasing. It is observed that at 20% of stone dust and brick dust is the optimum dosages for concrete mixture.

Transparent concrete is the new type of concrete introduced in modern era which carries special property of light transmitting due to presence of glass fibres & is also known as translucent concrete or light transmitting concrete. It is lighter than conventional concrete having special features such as low density and thermal conductivity with main advantage of reduction in dead weight, faster building rate in construction, lower haulage & handling cost. Light is transmitted from one surface of the brick wall to the other due to optical fibres strands along the overall width of the wall which allows light to pass through. An optical fibre (or optical fibre) is a flexible, transparent fibre made of glass (silica) or plastic, slightly thicker than a human hair & can function as waveguide, or " light pipe " to transmit light between the two ends. Main aim of the study is to design translucent concrete blocks with the use of glass optical fibres with sand & cement then analyse their various physical & engineering properties with respect to conventional concrete blocks by adding glass optical fibres of 1%, 2 %, 3 % 4 % 5% at 0.5 cms & 1.0 cms spacing respectively. From the study, it can be concluded that there is 5% to 10% increase in initial compressive strength for 7 days & also 10% to 15% increase in initial compressive strength for 28 days to an optical fibres mix up to 3% whereas the initial & final characteristic compressive strength gradually decreases with an increase in Optical fibres in the concrete mix.

Customary cement is solid in pressure and powerless in strain with a specific end goal to conquer the shortcoming steel fortification is being given. Scrutinizes endeavored to acquire the malleable property by presenting engineered filaments, for example, poly propylene, asbestos and so on., and steel strands, yet they are costly. Henceforth they are endeavoring to utilize the common strands, for example, straw, elephant grass, palm leaf, coconut coir and so forth to consolidate rigidity in traditional cement. So that the customary steel fortification on cement can be decreased. In this exploration, sisal is being utilized as a part of cement. In this way, the mechanical properties, for example, compressive quality, split-elasticity, and modulus of burst of M40 evaluation concrete and by changing the measurement of fiber substance from 0.1%, 0.2%, 0.3%, 0.4%, and 0.5%, by volume of bond with ideal length of 35mm got from writing survey, were found. The ideal dose of sisal fiber was observed to be 0.3%. The flexural conduct of fortified solid shafts with 0.3% sisal fiber was contrasted and customary solid properties of M40 evaluation.

Abstract: Many countries are witnessing a rapid growth in construction industry which involves use of natural resources for the development of infrastructure. This growth poses a threat to natural resources that are available. Copper slag is considered as waste material and can be used as replacement of fine aggregates. M30 grade of concrete mix with water-cement ratio of 0.45 is used to determine the various mechanical properties. This research work mainly consist of two parts, in the first part, substitution of natural sand partially by copper slag in concrete is done with replacement of 0%, 35%, 40% and 45%. The optimum value obtained for 40% replacement of copper slag. The 28 days average compression strength was observed to increase by about 0.45% - 23.6%, split tensile strength by 16.61% - 34.98% and flexural strength of concrete by 27.78% - 38.89% when compared with control mix.  In the second part, the flexural behavior of reinforced concrete beams with optimum copper slag content is studied. The reinforcement is varied from 0.62% - 0.89% in the flexure zone and the parameters like deflection, surface strain, cracking load, ultimate load and crack width of reinforced concrete beams was experimentally noted and compared with theoretical values as per code is: 456-2000.
Keywords: copper slag, workability, compressive strength, split tensile strength, flexural strength, deflection, surface strain, crack width, cracking moment, ultimate moment.
Title: Experimental Study on Flexural Behavior of Reinforced Concrete Beams by Replacing Copper Slag as Fine Aggregate
Author: Deepak Gowda. B, Dr. H. B. Balakrishna
International Journal of Civil and Structural Engineering Research
ISSN 2348-7607 (Online)
Research Publish Journals

The concurrent effects of recycled concrete aggregate (RCA) and polypropylene fibers (PPF) on workability of self-consolidating concrete (SCC) are not quantified in literature. Different SCC series containing 25% to 100% RCA and 0.25% to 1.75% PPF are investigated in this study; the water-to-binder ratio varied from 0.38 to 0.5, while high-range water reducer adjusted to maintain slump flow at 700 ± 25 mm. Flowability, cohesiveness, passing ability, and segregation resistance were evaluated and compared with the limitations specified by the European Guidelines for SCC. Test results have shown that SCC rheological properties and passing ability dramatically curtailed with PPF inclusions, especially when mixtures are proportioned with higher RCA replacement rates. This was attributed to combined effects of fiber additions that hinder the cement matrix deformation together with increased RCA surface roughness that accentuates internal friction and resistance to flow. Mixtures containing increased RCA and PPF concentrations exhibited better stability, reflected by reduced aggregate segregation. Series of regression models were proposed to predict the coupled effects of RCA and PPF additions on SCC workability responses.

Conventionally concrete is mixture of cement, sand and aggregate. But now a days, natural river sand is hard to obtained and also extraction of sand from river has posed a great threat to environment. Also government has applied restriction on extraction of sand from river. Hence, Scarcity of good quality Natural River sand due to depletion of resources and restriction due to environmental consideration has made concrete manufactures to look for suitable alternative fine aggregate. Manufactured sand is such potential alternative. Though manufactured sand has been in use in concrete manufacturing in India, the percentage of its contribution is still very negligible. A well processed manufactured sand as partial or full replacement to river sand is the need of time as a long term solution in Indian concrete industry until other suitable alternative fine aggregate are developed. This study is carried out on experimental basis to use manufacture sand of Chikhli region of Gujarat state in India. Also, the cost parameter is checked.

— Concrete has occupied an important place in construction industry in the past few decades and it is used widely in all types of constructions ranging from small buildings to large infrastructural dams or reservoirs. It is the most widely used man-made construction material in the construction world. Ever since concrete has been accepted as material for construction, civil engineers have been trying to improve its quality, strength etc., against adverse conditions. The OPC is one of the main ingredients used for the production of concrete. However in the context of increased awareness regarding over exploitation of natural resources to manufacture cement, an eco-friendly technology has to be developed for the effective management of resources. The replacement of natural resources in the manufacture of cement and sand is the present issue in the present construction scenario. Copper slag is an industrial by-product material produced from the process of manufacturing copper. Use of Copper slag does not only reduce the cost of construction but also helps to reduce the impact on environment by consuming the material generally considered as waste product. Hence in the current study an attempt has been made to minimize the cost of cement and sand with concrete mix grade M25 by studying the mechanical behavior of these concrete mixes by partial replacing with advanced mineral admixture such as Copper slag in concrete mixes as partial replacement of cement and sand. In this study, partial replacement of Cement and fine aggregate with Copper Slag considered. Experimental study is conducted to evaluate the workability and strength characteristics of hardened concrete, by partially replacing the cement and sand by various percentages of copper slag for M25 grade of concrete at different ages. The mixes were designed using IS Code method. In this project, properties of concrete have been assessed by partially replacing cement and sand with Copper slag is separately done in two different phase. The cement has been replaced by Copper slag accordingly in the range of 0% (without Copper slag), 5%, 10%, 15%, and 20% is one phase and sand has been replaced by Copper slag accordingly in the range of 0% (without Copper slag), 10%, 20%, 30%, 40% and 50% is second phase by weight of cement for M25 mix. Concrete mixtures were produced, tested and compared in terms of compressive, flexural and split strength with the conventional concrete.

The by-products obtained from industries such as Silica Fume (SF) and Fly Ash (FA) can be utilized to improve the strength and durability of High-Performance Concrete (HPC). The application of these industrial by-products is becoming common all over the world because of the reduction of their potentially dangerous effects on the environment. This paper investigates the behavior of Silica Fume as a fractional replacement to Ordinary Portland Cement (OPC) on the parameters such as water permeability, compressive strength, split tensile strength and flexural tensile strength of High-Performance Concrete (HPC). HPC mixes with silica fume contents of 0 %, 5%, 7.5%, and 10% and a constant proportion of 10% fly ash was adopted in the trial mixes. Superplasticizer in optimum dosage was added to achieve required workability. Tests were conducted to determine the optimum proportion of Silica fume which yields appreciable Fresh and hardened state properties.

In this research paper for described the replacement by the cement by silica fume for various percentage. For present scenario concrete are the most adjustable structure materials for the reason that it can be designed to survive the harshest environments while taking on the most encouraging forms. In the present scenario most concrete mixture contains additional cementitious material which forms element of the cementitious element. The major benefit of supplementary cementitious material is their ability to return certain amount of cement and still capable to present cementitious property, for result reduced cost of using portland cement. For waste materials which can be used as additional cementitious material like silica fume. For this purpose silica fume is replaced by 0%, 5%, 7.5%, 12.5%, 15%, 20% & 25% by the weight of cement. Tests were conducted in the research which showed the results of the same percentage at the different of 0% 5%, 7.5%, 12.5%, 15%, 20% & 25% for the time period of 7, 14, and 28 days curing as a substitution of cement by micro silica on compressive strength test. The results show the maximum increase in strength of concrete occurred when 15% cement replacement was done with silica fume.

Several previous studies have shown that the success of a corporation is strongly influenced by the individual performance of its employees. Every company will always attempt to get the best performance from its employees, with the hope that what the company's goals are going to be achieved. This study aims to research several variables which will affect employee performance, namely: work motivation, work environment, and workability. Do these variables simultaneously and partially affect employee performance. The hypotheses proposed during this study are as follows: (1) allegedly work motivation, work environment and workability simultaneously affect employee performance. (2) it's suspected that work motivation, work environment and workability partially affect employee performance.

Delays may occur after the completion of the mixing process for several reasons beyond the existing ability on the site. This study was conducted to determine the feasibility of re-mix concrete (mechanical mixing), after leaving it in the open air. The concrete mixtures were left after completion of mixing process in room temperature (25 o C) for different periods of times 0, 15, 30, 45, 60 and 75 minutes then returned the mixing process then, placed in its moulds. Results were compared to those samples cast within the mould immediately after mixing. A number of 144 standard cubes were cast to measure the concrete compressive strengths at 7, 28 days. To improve the properties of concrete after re-mixing different additives were used. The used additives were water or cement mortar or workability additive compared to mixing without any additions to improve the mixing process. The most important results of the study confirm that the compressive strength of the samples increases when the mix left then re-mixed after 15 minutes. The mix could be also re-mixed after leaving in the fresh air for periods of up to 75 minutes. The results also showed that the values of compressive strength were lower than that recorded for control, but it could be used with loss of strength by about 18% of the maximum compressive strength. For re-mixing concrete it was preferred to use cement mortar to provide best results.

In recent years, significant attention has been given to use superplasticizer as a chemical admixture on concrete. However, the use of chemical admixtures in concrete is a common solution to achieve high performance concrete. The past researchers have been underscored the use of chemical admixtures imparts the desirable properties to concrete in both fresh and hardened state. This paper has been made an attempt to study the influence of superplasticizer dose of 0.6, 0.8, 1.2, 1.8 and 2.5 percentage on performance of concrete. The experimental tests for fresh and hardened properties of concrete for M35 grade are studied and the results are compared with normal concrete. The tests considered for study are, slump test and compressive strength test The results show that the increase of superplasticizer dose in concrete leads to gain of good ability in addition to slump. Moreover, there is also slightly increase in compressive strength than that of normal concrete.

Natural resources are depleting Worldwide while at the same time the generated wastes from the industry are increasing substantially. Disposal of these waste materials has become a challenge in present era. Waste management strategies are developed to utilize these wastes in construction. Some of the industrial by-products have been used in construction industry for the production of concrete. Copper slag is one of the waste material which can be used in construction industry as partial replacement of fine aggregates i.e., (river sand). This paper presents the experimental work carried out by replacing fine aggregate with Copper slag. M20 and M35 grades of Concrete were used as reference mixes. The fine aggregate (sand) was replaced with percentages 0% (for conventional concrete mixture), 10%,20%, 30%, 40%,50% of Copper slag by weight and tests were conducted on the properties of fresh and hardened concrete. Slump-cone test, Compaction factor test and Vee Bee Consistometer tests were performed to evaluate the workability characteristics of fresh Concrete. Compressive strength, flexural strength and split tensile strength were determined at the age of 7,28,56,91 days respectively. The results indicate that workability increases with increase in Copper Slag percentage which is due to the low water absorption capacity of copper slag. As the percentage of replacement of fine aggregate with copper slag increases, the compressive strength increases up to 40% replacement. There is also a similar increase in the Split tensile strength and flexural strength of Concrete.

Calcium aluminate cement (CAC) suffers from loss of workability in less than an hour (~15 minutes) after first touch of water. Current superplasticizers that are utilized to modify the viscosity of cement admixtures are designed to target ordinary Portland cement (OPC). The high affinity between these superplasticizers and cement particles were found to be detrimental in CAC systems. Utilization of a monomer that, instead, facilitates gradual adsorption of a superplasticizer provides workability retention. For the first time in literature, we report a superplasticizer that caters to the properties of CAC such as high rate of surface development and surface charge. While neat CAC was almost unworkable after 1 hour, with the addition of only 0.4% of the optimized superplasticizer, 90% fluidity retention was achieved. CAC is the cement of choice for high performance applications such as those requiring resistance to abrasion, corrosion, and temperature 1–3. Due to its high early heat and strength gain, CAC has also become an attractive binder for cold environments and situations that necessitate rapid repairs (e.g., highways, bridge decks, and airport runways). In general, long term durability of cementitious mixtures requires low water/cement ratio (w/c). At low water contents, superplasticizers, which are polymers that can facilitate the dispersion of cement particles , are utilized to provide necessary workability. Superplasticizers adsorb onto the surface of the cement particles through their charged backbone and provide electrostatic repulsion 4,5. They release the entrapped water from flocculated structures and modify the viscosity of cement mixtures 6,7. Latest generations, poly(carboxylate ether)-based superplasticizers, (PCEs), have acrylate groups in the backbone and also contain side chains (i.e., poly(ethylene oxide)) that protrude from the cement surface into the pore solution to produce steric hindrance effect 8,9. These grafted polymers exhibit superior dispersing ability compared to other types of superplasticizers (e.g., melamine and naphthalene based polycondensates) and are efficient in the preparation of high performance concrete 5,10,11. The formulations of PCEs have always targeted OPC since it is the most frequently used binder in cement industry. However, these superplasticizers are incompatible with CAC due to i) the rapid hydration reaction of monocalcium aluminate as the principal active phase in this type of cement and ii) layered structure of hydration phases in CAC compared to amorphous calcium-silicate-hydrate (C-S-H) in OPC 6,12,13. The use of PCEs in CAC systems resulted in poor fluidity retention (~15 min) and intercalation/sequestration of PCEs into lamellar calcium aluminate hydrates 13,14. Due to the absence of CAC-optimized superplasticizer, CAC systems are utilized in their neat form and consequently lose their workability in a relatively short amount of time 15. Therefore, for wider and more efficient use of CAC, there is a need for the design of superplasticizers that can accommodate the characteristic properties of CAC. Here, we report a modified PCE-based superplasticizer that can address the underlying mechanisms of hydra-tion kinetics, development of surface area, and surface charges in CAC systems. To incorporate into the acrylic acid (AA) backbone of PCEs, we have chosen two co-monomers i) 2-acrylamido-2-methylpropane sulfonic acid (AMPS) and ii) vinylphosphonic acid (VPA), with different ionic character and ability of association with mul-tivalent cations. AMPS exhibits strong ionic character 16 whereas VPA demonstrates strong complexation ability with divalent cations 17,18. To comprehend the criteria of adsorption and workability retention, we cross-compared the performance of superplasticizers that contain varying amounts of AMPS and VPA in both OPC and CAC

The present work is directed towards developing a better understanding on strengths characteristics of concrete using as a partial replacement of cement by marble dust powder and sand by stone dust. The Dissertation work is carried out with M30 grade concrete for which the marble powder is replaced by 0%, 5%, 10%, 15%, 20% by weight of cement. For all the mixes compressive, flexural and split tensile strengths are determined at different days of curing apart from this the beams were casted and tested under flexural, the load and deflection are noted simultaneously and also the crack pattern were observed. In addition to this, sand is replaced with stone dust (SD) by 10%, 20% and 30% along with cement is replaced with MP by 0%, 10% and 20% by weight for M30 grades of concrete. Only 3 cubes were casted for various percentage replacements of sand with SD and cement with MP for 7days and 28 days compressive strength. The results of the present investigation indicate that marble dusts incorporation results insignificant improvements in the compressive, flexural and split tensile strengths of concrete and The load carrying capacity of RMP RCC beams {mix2 and mix3} is more compared to RCC conventional beams up to 10% of replacement and also for stone dusts and marble dust incorporation results insignificant improvements in the compressive strengths of concrete up to 20% of SD and 10% of MP of replacement.