ABSTRACT The applications and use of Rammed Earth in the tropics is gaining momentum. The sustain... more ABSTRACT The applications and use of Rammed Earth in the tropics is gaining momentum. The sustainable nature of rammed earth as a building material, coupled with the ease with which it blends with the natural environment stems from the fact that soils for rammed earth are usually sourced from the immediate environment. Some soils however are lacking in coarse aggregates. Tests have been carried out to establish the adequacy of supplementing aggregates with Palm Kernel shell (PKS) in regions that have this as a waste product of the oil palm industry. This report looks at the influence of PKS on the rate of sorption in rammed earth walls.
This paper reports results on the porosity and pore size distribution of cement paste containing ... more This paper reports results on the porosity and pore size distribution of cement paste containing varying amounts of simulated desulphurised waste (SDW). The water to binder ratio was 0.5. The binder consists of cement and SDW. The SDW is a combination of fly ash and gypsum ranging from 0-100%. Cement in the pastes was partially replaced with 25% SDW (by weight). The porosity and pore size distribution of cement pastes at 90 days of curing is reported. Increasing the amount of gypsum up does not change the pore volume, however, there is tendency of obtaining coarser pore structure in the presence of gypsum.
The influence of incorporating ground granulated blastfurnace slag (GGBS) and metakaolin (MK) on ... more The influence of incorporating ground granulated blastfurnace slag (GGBS) and metakaolin (MK) on concrete strength is investigated. Portland cement was partially replaced with 0–80% GGBS and 0–20% MK. The water to cementitious materials ratio was maintained at 0.5 for all mixes. The incorporation of MK causes an increase in strength, especially during the early ages of curing. However, the use
A potential alternative to acrylonitrile-butadiene-styrene (ABS) and polycarbonate+ABS (PC+ABS), ... more A potential alternative to acrylonitrile-butadiene-styrene (ABS) and polycarbonate+ABS (PC+ABS), pigmented mineral-filled polypropylene (PP) finds an opening in automotive interior components such as instrument panels, knee bolsters, consoles, etc. Because of the lack of surface aesthetics, pigmented mineral-filled PP is experiencing a limitation to its acceptance in many applications. This study focuses on exploring various mineral fillers and additives in polypropylene to provide a material with enhanced scratch resistance. Several physical properties including Rockwell and Shore D hardness are investigated, and it is determined that Filler W improves scratch resistance. It is also determined that Filler T-filled-PP has poor scratch resistance even with the addition of a lubricant.
The water absorption (WA) by total immersion and by capillary rise of concrete containing metakao... more The water absorption (WA) by total immersion and by capillary rise of concrete containing metakaolin (MK) is investigated. Cement was partially replaced with up to 20% MK. The results show that the presence of MK is greatly beneficial in reducing the WA by capillary action. There is a systematic reduction in absorption by capillary action with the increase in MK
Abstract The emission of SO2, NOx, and CO2 gasses, as a result of the combustion of fossil fuels ... more Abstract The emission of SO2, NOx, and CO2 gasses, as a result of the combustion of fossil fuels within the power industry, has been a major contributor to the pollution of the environment. To combat the effects of air pollution, controls measures have been implemented, including the reduction of sulphur dioxide (SO2), which is achieved by fitting desulphurisation systems to new and existing power installations. At present, there are available many types of desulphurisation processes, which produce a variety of wastes that vary in quality and quantity. Desulphurisation systems work by introducing alkaline sorbents, such as limestone, to the SO2 gasses, either during or after combustion. In wet processes, the limestone reacts with the SO2 gasses to form new insoluble materials such as gypsum. With semidry and dry processes, wastes are usually a blend of fly ash and some form of calcium sulphate, which results in a wide variation in chemical, physical, and mineralogical properties. The use of desulphurised wastes in the construction materials reduces the need for extraction, processing, and transportation of virgin materials, and thus can reduce the impact of the construction industry on the environment. This makes them suitable for high-volume applications within the construction industry, and specifically in the manufacture of normal and lightweight concrete, aggregate concrete blocks, and flowable fills. This chapter explores the utilisation of flue-gas desulphurisation (FGD) waste in the construction industry.
The paper presents results of an investigation on the effect of initial curing conditions on the ... more The paper presents results of an investigation on the effect of initial curing conditions on the sulphate resistance of concrete made with ordinary portland cement and using pfa, silica fume and ground granulated blast furnace slag for partial replacement of cement. In addition, porosity and pore structure analysis of representative pastes was carried out to examine the relationship between these properties and sulphate resistance of concrete. The depth of carbonation in specimens of pastes was also determined. Three different initial curing conditions immediately after casting of specimens were adopted, namely: WET/AIR CURED at 45°C, 25% RH; AIR CURED at 45°C, 25% RH; AIR CURED at 20°C, 55% RH. The results show that pore volume and pore structure of the paste bear no direct relationship with the sulphate resistance of concrete. The presence of a carbonated layer on the surface is generally accompanied by superior sulphate resistance—there are, however, important exceptions. Low humidity curing at high temperature (45°C) results in higher depths of carbonation but lower sulphate resistance than similar curing at 20°C. The sulphate resistance of concrete increases with the replacement of cement with 22% pfa, 9% silica fume and 80% ggb slag. The sulphate resistance also increases due to drying out of concrete during early curing at low relative humidity and due to carbonation. The possible common factor which leads to this improved sulphate resistance is the reduced Ca(OH)2 content which leads to smaller volume of the expansive reaction products with sulphate ions. The effect of initial curing at high temperature (45°C) is significantly harmful to the sulphate resistance of plain concrete but much less so to the blended cement concretes.
ABSTRACT The applications and use of Rammed Earth in the tropics is gaining momentum. The sustain... more ABSTRACT The applications and use of Rammed Earth in the tropics is gaining momentum. The sustainable nature of rammed earth as a building material, coupled with the ease with which it blends with the natural environment stems from the fact that soils for rammed earth are usually sourced from the immediate environment. Some soils however are lacking in coarse aggregates. Tests have been carried out to establish the adequacy of supplementing aggregates with Palm Kernel shell (PKS) in regions that have this as a waste product of the oil palm industry. This report looks at the influence of PKS on the rate of sorption in rammed earth walls.
This paper reports results on the porosity and pore size distribution of cement paste containing ... more This paper reports results on the porosity and pore size distribution of cement paste containing varying amounts of simulated desulphurised waste (SDW). The water to binder ratio was 0.5. The binder consists of cement and SDW. The SDW is a combination of fly ash and gypsum ranging from 0-100%. Cement in the pastes was partially replaced with 25% SDW (by weight). The porosity and pore size distribution of cement pastes at 90 days of curing is reported. Increasing the amount of gypsum up does not change the pore volume, however, there is tendency of obtaining coarser pore structure in the presence of gypsum.
The influence of incorporating ground granulated blastfurnace slag (GGBS) and metakaolin (MK) on ... more The influence of incorporating ground granulated blastfurnace slag (GGBS) and metakaolin (MK) on concrete strength is investigated. Portland cement was partially replaced with 0–80% GGBS and 0–20% MK. The water to cementitious materials ratio was maintained at 0.5 for all mixes. The incorporation of MK causes an increase in strength, especially during the early ages of curing. However, the use
A potential alternative to acrylonitrile-butadiene-styrene (ABS) and polycarbonate+ABS (PC+ABS), ... more A potential alternative to acrylonitrile-butadiene-styrene (ABS) and polycarbonate+ABS (PC+ABS), pigmented mineral-filled polypropylene (PP) finds an opening in automotive interior components such as instrument panels, knee bolsters, consoles, etc. Because of the lack of surface aesthetics, pigmented mineral-filled PP is experiencing a limitation to its acceptance in many applications. This study focuses on exploring various mineral fillers and additives in polypropylene to provide a material with enhanced scratch resistance. Several physical properties including Rockwell and Shore D hardness are investigated, and it is determined that Filler W improves scratch resistance. It is also determined that Filler T-filled-PP has poor scratch resistance even with the addition of a lubricant.
The water absorption (WA) by total immersion and by capillary rise of concrete containing metakao... more The water absorption (WA) by total immersion and by capillary rise of concrete containing metakaolin (MK) is investigated. Cement was partially replaced with up to 20% MK. The results show that the presence of MK is greatly beneficial in reducing the WA by capillary action. There is a systematic reduction in absorption by capillary action with the increase in MK
Abstract The emission of SO2, NOx, and CO2 gasses, as a result of the combustion of fossil fuels ... more Abstract The emission of SO2, NOx, and CO2 gasses, as a result of the combustion of fossil fuels within the power industry, has been a major contributor to the pollution of the environment. To combat the effects of air pollution, controls measures have been implemented, including the reduction of sulphur dioxide (SO2), which is achieved by fitting desulphurisation systems to new and existing power installations. At present, there are available many types of desulphurisation processes, which produce a variety of wastes that vary in quality and quantity. Desulphurisation systems work by introducing alkaline sorbents, such as limestone, to the SO2 gasses, either during or after combustion. In wet processes, the limestone reacts with the SO2 gasses to form new insoluble materials such as gypsum. With semidry and dry processes, wastes are usually a blend of fly ash and some form of calcium sulphate, which results in a wide variation in chemical, physical, and mineralogical properties. The use of desulphurised wastes in the construction materials reduces the need for extraction, processing, and transportation of virgin materials, and thus can reduce the impact of the construction industry on the environment. This makes them suitable for high-volume applications within the construction industry, and specifically in the manufacture of normal and lightweight concrete, aggregate concrete blocks, and flowable fills. This chapter explores the utilisation of flue-gas desulphurisation (FGD) waste in the construction industry.
The paper presents results of an investigation on the effect of initial curing conditions on the ... more The paper presents results of an investigation on the effect of initial curing conditions on the sulphate resistance of concrete made with ordinary portland cement and using pfa, silica fume and ground granulated blast furnace slag for partial replacement of cement. In addition, porosity and pore structure analysis of representative pastes was carried out to examine the relationship between these properties and sulphate resistance of concrete. The depth of carbonation in specimens of pastes was also determined. Three different initial curing conditions immediately after casting of specimens were adopted, namely: WET/AIR CURED at 45°C, 25% RH; AIR CURED at 45°C, 25% RH; AIR CURED at 20°C, 55% RH. The results show that pore volume and pore structure of the paste bear no direct relationship with the sulphate resistance of concrete. The presence of a carbonated layer on the surface is generally accompanied by superior sulphate resistance—there are, however, important exceptions. Low humidity curing at high temperature (45°C) results in higher depths of carbonation but lower sulphate resistance than similar curing at 20°C. The sulphate resistance of concrete increases with the replacement of cement with 22% pfa, 9% silica fume and 80% ggb slag. The sulphate resistance also increases due to drying out of concrete during early curing at low relative humidity and due to carbonation. The possible common factor which leads to this improved sulphate resistance is the reduced Ca(OH)2 content which leads to smaller volume of the expansive reaction products with sulphate ions. The effect of initial curing at high temperature (45°C) is significantly harmful to the sulphate resistance of plain concrete but much less so to the blended cement concretes.
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