Qatar Foundation Annual Research Forum Proceedings, 2011
Abstract This paper presents the results of an experimental work and life cycle analysis of reinf... more Abstract This paper presents the results of an experimental work and life cycle analysis of reinforced mortar samples retrofitted with natural, and virgin and recycled polymers. The objectives of this study were to investigate the behavior of retrofitted concretes experimentally, and to compare the defined fiber reinforced concrete samples from environmental point of view using life cycle analysis. The mixtures of reinforced concretes was prepared as control mixture which includes no fibers, natural (palm) fiber reinforced mixture, virgin and recycled polypropylene (PP) and low density polyethylene (LDPE) reinforced concrete mixtures, natural fiber and virgin and recycled PP reinforced concrete mixtures, and natural fiber and virgin and recycled LDPE reinforced concrete mixtures. The experimental tests were performed to investigate the behavior of reinforced concrete samples in such a way that either durable or not. Moreover, those concrete mixtures were also compared using life cycle assessment method according to their environmental effects. Within the scope of the study, GaBi software was used for Life Cycle Assessment (LCA) analysis. Landfilling was considered as reference scenario and compared with filled recycled plastics. A quantitative impact assessment was performed for four environmental impact categories, global warming (GWP) over a hundred years, human toxicity (HTP), abiotic depletion (ADP) and acidification potential (AP) were taken into consideration during LCA. At the end of the study, according to the compressive strength tests results, it was seen that natural fiber reinforced concrete did not perform well at each testing age, and also according to the pore definition test, permeability of natural fiber reinforced concrete was higher than that of the control mixture which means that durability of natural fiber reinforced concrete against harsh environment is very low. Moreover, according to life cycle analysis, recycled polymer fibers reinforced concrete mixtures have lower environmental effect for all impact assessment categories. On the other hand, natural fiber reinforced concrete mixtures has the worst environmental effect, but when the natural fiber mixed with recycled or virgin polymers those concrete mixtures have better environmental effect.
Qatar Foundation Annual Research Forum Proceedings, 2011
Abstract Qatar is one of the largest producers of polymers in the Middle East, with a total annua... more Abstract Qatar is one of the largest producers of polymers in the Middle East, with a total annual turnover of $3.5 billion. The annual consumption of industrial and domestic polymers in the region generates significant amount of plastic waste in Qatar and in Gulf Corporation Countries (GCC). Recently, recycling of plastics has become an optimum waste management solution due to the efficiency of incorporating the plastic waste management stream into commodity and structural applications. One of the main obstacles in the region is collection and sorting of plastics, due to the variety and high volume of waste streams. To solve this problem, and to upgrade the recycled polymer applications, optimisation of additives and processing techniques were used in this work, such as the addition of glass fibre reinforcement, wood, mica and date palm fibre in selected volume fractions, in order to minimise the effect of the residual “secondary” polymers in the main composite. A tremendous improvement has been achieved...
This paper focuses on the experimental investigation carried out on self-consolidating concrete (... more This paper focuses on the experimental investigation carried out on self-consolidating concrete (SCC) reinforced with micro-steel fiber and hybrid fibers (combination of micro-steel fiber and recycled high density polyethylene fiber derived from municipal wastes). The physical properties of fresh and hardened concrete including flowability, setting time and durability, the mechanical properties, namely, compressive strength and flexural strength, and microstructural analysis were studied. Micro-steel fiber addition was seen to enhance the flowability of concrete than the non-fibrous and hybrid fiber reinforced concretes. The setting time of SCC mixtures prolonged with the addition of fibers into concrete mixtures. Hybrid fiber reinforced SCC mixtures have displayed reduction in drying shrinkage. The compressive and flexural strengths of the fiber reinforced concretes show a marginal reduction in strength- when compared with the strength of unreinforced concrete. The results of the m...
For the sustainable developments of the construction industry, there is a growing need for reduci... more For the sustainable developments of the construction industry, there is a growing need for reducing the usage of the rapidly depleting natural resources in building concrete structures. Re-utilisation of conventional wastes such as different grades of polymeric particulates derived from municipal wastes is being explored as a partial replacement of natural aggregates in making concretes. This poses new challenges to researchers as methods to evaluate the effects of new host particles on the mechanical strength characteristics of composite concretes at microscale and their subsequent effects on their bulk strength are not yet well established. In this research work, municipal polymeric wastes in various forms and fly ash from incineration of municipal solid wastes are used together as secondary raw materials for the preparation of concrete mixtures. The influence of various forms of polyethylene (PE) substitution on the local and global shear stress distribution are sensed whole-fiel...
Worldwide, there is a growing level of interest to develop sustainable cement-based products and ... more Worldwide, there is a growing level of interest to develop sustainable cement-based products and processes in which the usage of natural resources such as sand and limestone are reduced from the current levels. One of the ways to achieve this is by replacing them with suitable inclusions of recycled granular materials from municipal wastes where possible. However, to understand the effects of such inclusions in concrete structures, research advancements are needed to sense and characterise the distribution of stresses (/strains) at the local scale and to establish their links with the fracture and bulk strength characteristics under external loading environments, which is the focus here. In this research, polyethylene (PE)-based granular materials derived from municipal wastes and fly ash obtained from the incineration of municipal solid wastes are used together as secondary raw materials in preparing the concrete mixtures. Photo stress analysis (PSA) is performed here, making non-c...
AbstractThis paper reviews the methods adopted to produce high-performance concrete (HPC) and ult... more AbstractThis paper reviews the methods adopted to produce high-performance concrete (HPC) and ultrahigh-performance concrete (UHPC). The chronological development of these concretes in terms of the...
Journal of Performance of Constructed Facilities, 2018
AbstractThis paper presents the results of a field study carried out on three reinforced concrete... more AbstractThis paper presents the results of a field study carried out on three reinforced concrete (RC) structures built in the 1960s, 1970s, and 1980s to determine the main load (environmental) and...
We present a hybrid framework for simulating the strength and dilation characteristics of sandsto... more We present a hybrid framework for simulating the strength and dilation characteristics of sandstone. Where possible, the grain-scale properties of sandstone are evaluated experimentally in detail. Also, using photo-stress analysis, we sense the deviator stress (/strain) distribution at the microscale and its components along the orthogonal directions on the surface of a V-notch sandstone sample under mechanical loading. Based on this measurement and applying a grain-scale model, the optical anisotropy index K0 is inferred at the grain scale. This correlated well with the grain contact stiffness ratio K evaluated using ultrasound sensors independently. Thereafter, in addition to other experimentally characterised structural and grain-scale properties of sandstone, K is fed as an input into the discrete element modelling of fracture strength and dilation of the sandstone samples. Physical bulk scale experiments are also conducted to evaluate the load-displacement relation, dilation and bulk fracture strength characteristics of sandstone samples under compression and shear. A good level of agreement is obtained between the results of the simulations and experiments. The current generic framework could be applied to understand the internal and bulk mechanical properties of such complex opaque and heterogeneous materials more realistically in future.
Fracture toughness measures the resistance of a material to fracture. This fundamental property i... more Fracture toughness measures the resistance of a material to fracture. This fundamental property is used in diverse engineering designs including mechanical, civil, materials, electronics and chemical engineering applications. In spite of the advancements made in the past 40 years, the evaluation of this remains challenging for extremely heterogeneous materials such as composite concretes. By taking advantage of the optical properties of a thin birefringent coating on the surface of opaque, notched composite concrete beams, here we sense the evolution of the maximum shear stress distribution on the beams under loading. The location of the maximum deviator stress is tracked ahead of the crack tip on the experimental concrete samples under the ultimate load, and hence the effective crack length is characterised. Using this, the fracture toughness of a number of heterogeneous composite beams is evaluated and the results compare favourably well with other conventional methods using combi...
The influence of different types of polyethylene (PE) substitutions as partial aggregate replacem... more The influence of different types of polyethylene (PE) substitutions as partial aggregate replacement of microsteel fiber-reinforced self-consolidating concrete (SCC) incorporating incinerator fly ash was investigated. The study focuses on the workability and hardened properties including mechanical properties, permeability properties, sulfate resistance, and microstructure. Regardless of the polyethylene type, PE substitutions slightly decreased the compressive and flexural strength of SSC initially; however, the difference was compensated at later ages. Scanning electron microscope (SEM) analysis of the interfacial transition zone showed that there was chemical interaction between PE and the matrix. Although PE substitutions increased the permeable porosity and sorptivity, it significantly improved the sulfate resistance of SCC. The influence of PE shape and size on workability and strength was found to be more important than its type. When considering the disposal of PE wastes and saving embodied energy, consuming recycled PE as partial aggregate replacement was more advantageous over virgin PE aggregate-replaced concrete.
... Um-Al-Afai landfill has nearly 80% of MSW. Because of the increased migration in Qatar, there... more ... Um-Al-Afai landfill has nearly 80% of MSW. Because of the increased migration in Qatar, there is a sharp rise in the volume and also in the variety of solid waste. ... Sufian MA, Bala BK (2007) Modeling of urban solid waste management system; the case of Dhaka city. ...
International Journal of Engineering and Technology, 2013
This paper presents the effect of curing conditions on freeze-thaw durability of self-consolidati... more This paper presents the effect of curing conditions on freeze-thaw durability of self-consolidating concrete. In order to determine the effect of curing conditions on the durability properties of self-consolidating concrete, some specimens were cured in air and the others in water. Moist-cured (M-C) specimens were kept in water for 14 days at a temperature of 23±2°C before they were subjected to freeze-thaw cycles. Air-cured (A-C) specimens were however left in ambient laboratory conditions and were saturated in water for a day before they were subjected to the same freeze-thaw cycles. From the permeability tests, it was concluded that air cured specimens have higher permeability. Furthermore, an increase in fly ash content resulted in a reduction in the permeation properties of self-consolidating concrete. On the other hand, more variations were observed in permeability results since only two specimens were used for permeability tests. During the freezing-thawing test, it was observed that air cured specimens were not affected by freezing-thawing and did not indicate any degradation since they were not totally saturated because of the lack of the saturation period that was employed.
Self consolidating concrete (SCC) is defined as an innovative concrete that does not require vibr... more Self consolidating concrete (SCC) is defined as an innovative concrete that does not require vibration for placing and compaction and it is able to flow under its own weight, completely filling formwork and achieving full compaction. Although significant amount of research has been carried out regarding the fresh properties, mix design, placing methods and strength of various SCC mixes, only a very limited amount of work has been done to assess the durability performance of SCC. Concretes in cold climates are subjected to freeze-thaw cycles which are one of the major durability problems, and if the concrete is in a saturated or nearly saturated condition, those cycles lead to expansion of the water in the capillary pores of concrete causing great internal stresses. For a durable concrete subjected to freeze-thaw cycles, an adequate air void system is obtained by using air-entraining admixtures. The performance of the air void system is characterized by air void parameters that are d...
Thermal characterization of Phase Change Materials (PCMs) compose of linear low-density polyethyl... more Thermal characterization of Phase Change Materials (PCMs) compose of linear low-density polyethylene (LLDPE), paraffin wax (W) with a melting point of 25 °C, and expanded graphite (EG), that are highly effective in thermal energy storage systems in the building industry, is reported. Thermal investigation of PCMs with various compositions of LLDPE, W and EG has been performed by nonconventional transient guarded hot plane technique (TGHPT) and compared with conventional Differential Scanning Calorimetry (DSC) measurements. An excellent agreement in determination of thermal characteristics by both methods was found. The highest values of the total amount of stored energy, sensible heat for solid and liquid states (Q total , Q s (solid) and Q s (liquid), respectively) were found for the PCMs with composition LLDPE/W/EG = 40/50/10 and 35/50/15 w/w/w. Moreover, thermal conductivity and diffusivity of PCMs have been significantly improved by adding EG. Additionally, life cycle assessment was performed to evaluate the environmental impact of three different materials as glass wool, rock wool and PCM used with brick wall.
Nondestructive Testing of Materials and Structures, 2011
Abstract This paper presents the effect of freezing-thawing on self consolidating concrete (SCC) ... more Abstract This paper presents the effect of freezing-thawing on self consolidating concrete (SCC) that contains different percentages of fly ash (FA) and air entraining agents (AEA). The effect of freezing-thawing on concrete is assessed on the basis of the change in the ...
Qatar Foundation Annual Research Forum Proceedings, 2011
Abstract This paper presents the results of an experimental work and life cycle analysis of reinf... more Abstract This paper presents the results of an experimental work and life cycle analysis of reinforced mortar samples retrofitted with natural, and virgin and recycled polymers. The objectives of this study were to investigate the behavior of retrofitted concretes experimentally, and to compare the defined fiber reinforced concrete samples from environmental point of view using life cycle analysis. The mixtures of reinforced concretes was prepared as control mixture which includes no fibers, natural (palm) fiber reinforced mixture, virgin and recycled polypropylene (PP) and low density polyethylene (LDPE) reinforced concrete mixtures, natural fiber and virgin and recycled PP reinforced concrete mixtures, and natural fiber and virgin and recycled LDPE reinforced concrete mixtures. The experimental tests were performed to investigate the behavior of reinforced concrete samples in such a way that either durable or not. Moreover, those concrete mixtures were also compared using life cycle assessment method according to their environmental effects. Within the scope of the study, GaBi software was used for Life Cycle Assessment (LCA) analysis. Landfilling was considered as reference scenario and compared with filled recycled plastics. A quantitative impact assessment was performed for four environmental impact categories, global warming (GWP) over a hundred years, human toxicity (HTP), abiotic depletion (ADP) and acidification potential (AP) were taken into consideration during LCA. At the end of the study, according to the compressive strength tests results, it was seen that natural fiber reinforced concrete did not perform well at each testing age, and also according to the pore definition test, permeability of natural fiber reinforced concrete was higher than that of the control mixture which means that durability of natural fiber reinforced concrete against harsh environment is very low. Moreover, according to life cycle analysis, recycled polymer fibers reinforced concrete mixtures have lower environmental effect for all impact assessment categories. On the other hand, natural fiber reinforced concrete mixtures has the worst environmental effect, but when the natural fiber mixed with recycled or virgin polymers those concrete mixtures have better environmental effect.
Qatar Foundation Annual Research Forum Proceedings, 2011
Abstract Qatar is one of the largest producers of polymers in the Middle East, with a total annua... more Abstract Qatar is one of the largest producers of polymers in the Middle East, with a total annual turnover of $3.5 billion. The annual consumption of industrial and domestic polymers in the region generates significant amount of plastic waste in Qatar and in Gulf Corporation Countries (GCC). Recently, recycling of plastics has become an optimum waste management solution due to the efficiency of incorporating the plastic waste management stream into commodity and structural applications. One of the main obstacles in the region is collection and sorting of plastics, due to the variety and high volume of waste streams. To solve this problem, and to upgrade the recycled polymer applications, optimisation of additives and processing techniques were used in this work, such as the addition of glass fibre reinforcement, wood, mica and date palm fibre in selected volume fractions, in order to minimise the effect of the residual “secondary” polymers in the main composite. A tremendous improvement has been achieved...
This paper focuses on the experimental investigation carried out on self-consolidating concrete (... more This paper focuses on the experimental investigation carried out on self-consolidating concrete (SCC) reinforced with micro-steel fiber and hybrid fibers (combination of micro-steel fiber and recycled high density polyethylene fiber derived from municipal wastes). The physical properties of fresh and hardened concrete including flowability, setting time and durability, the mechanical properties, namely, compressive strength and flexural strength, and microstructural analysis were studied. Micro-steel fiber addition was seen to enhance the flowability of concrete than the non-fibrous and hybrid fiber reinforced concretes. The setting time of SCC mixtures prolonged with the addition of fibers into concrete mixtures. Hybrid fiber reinforced SCC mixtures have displayed reduction in drying shrinkage. The compressive and flexural strengths of the fiber reinforced concretes show a marginal reduction in strength- when compared with the strength of unreinforced concrete. The results of the m...
For the sustainable developments of the construction industry, there is a growing need for reduci... more For the sustainable developments of the construction industry, there is a growing need for reducing the usage of the rapidly depleting natural resources in building concrete structures. Re-utilisation of conventional wastes such as different grades of polymeric particulates derived from municipal wastes is being explored as a partial replacement of natural aggregates in making concretes. This poses new challenges to researchers as methods to evaluate the effects of new host particles on the mechanical strength characteristics of composite concretes at microscale and their subsequent effects on their bulk strength are not yet well established. In this research work, municipal polymeric wastes in various forms and fly ash from incineration of municipal solid wastes are used together as secondary raw materials for the preparation of concrete mixtures. The influence of various forms of polyethylene (PE) substitution on the local and global shear stress distribution are sensed whole-fiel...
Worldwide, there is a growing level of interest to develop sustainable cement-based products and ... more Worldwide, there is a growing level of interest to develop sustainable cement-based products and processes in which the usage of natural resources such as sand and limestone are reduced from the current levels. One of the ways to achieve this is by replacing them with suitable inclusions of recycled granular materials from municipal wastes where possible. However, to understand the effects of such inclusions in concrete structures, research advancements are needed to sense and characterise the distribution of stresses (/strains) at the local scale and to establish their links with the fracture and bulk strength characteristics under external loading environments, which is the focus here. In this research, polyethylene (PE)-based granular materials derived from municipal wastes and fly ash obtained from the incineration of municipal solid wastes are used together as secondary raw materials in preparing the concrete mixtures. Photo stress analysis (PSA) is performed here, making non-c...
AbstractThis paper reviews the methods adopted to produce high-performance concrete (HPC) and ult... more AbstractThis paper reviews the methods adopted to produce high-performance concrete (HPC) and ultrahigh-performance concrete (UHPC). The chronological development of these concretes in terms of the...
Journal of Performance of Constructed Facilities, 2018
AbstractThis paper presents the results of a field study carried out on three reinforced concrete... more AbstractThis paper presents the results of a field study carried out on three reinforced concrete (RC) structures built in the 1960s, 1970s, and 1980s to determine the main load (environmental) and...
We present a hybrid framework for simulating the strength and dilation characteristics of sandsto... more We present a hybrid framework for simulating the strength and dilation characteristics of sandstone. Where possible, the grain-scale properties of sandstone are evaluated experimentally in detail. Also, using photo-stress analysis, we sense the deviator stress (/strain) distribution at the microscale and its components along the orthogonal directions on the surface of a V-notch sandstone sample under mechanical loading. Based on this measurement and applying a grain-scale model, the optical anisotropy index K0 is inferred at the grain scale. This correlated well with the grain contact stiffness ratio K evaluated using ultrasound sensors independently. Thereafter, in addition to other experimentally characterised structural and grain-scale properties of sandstone, K is fed as an input into the discrete element modelling of fracture strength and dilation of the sandstone samples. Physical bulk scale experiments are also conducted to evaluate the load-displacement relation, dilation and bulk fracture strength characteristics of sandstone samples under compression and shear. A good level of agreement is obtained between the results of the simulations and experiments. The current generic framework could be applied to understand the internal and bulk mechanical properties of such complex opaque and heterogeneous materials more realistically in future.
Fracture toughness measures the resistance of a material to fracture. This fundamental property i... more Fracture toughness measures the resistance of a material to fracture. This fundamental property is used in diverse engineering designs including mechanical, civil, materials, electronics and chemical engineering applications. In spite of the advancements made in the past 40 years, the evaluation of this remains challenging for extremely heterogeneous materials such as composite concretes. By taking advantage of the optical properties of a thin birefringent coating on the surface of opaque, notched composite concrete beams, here we sense the evolution of the maximum shear stress distribution on the beams under loading. The location of the maximum deviator stress is tracked ahead of the crack tip on the experimental concrete samples under the ultimate load, and hence the effective crack length is characterised. Using this, the fracture toughness of a number of heterogeneous composite beams is evaluated and the results compare favourably well with other conventional methods using combi...
The influence of different types of polyethylene (PE) substitutions as partial aggregate replacem... more The influence of different types of polyethylene (PE) substitutions as partial aggregate replacement of microsteel fiber-reinforced self-consolidating concrete (SCC) incorporating incinerator fly ash was investigated. The study focuses on the workability and hardened properties including mechanical properties, permeability properties, sulfate resistance, and microstructure. Regardless of the polyethylene type, PE substitutions slightly decreased the compressive and flexural strength of SSC initially; however, the difference was compensated at later ages. Scanning electron microscope (SEM) analysis of the interfacial transition zone showed that there was chemical interaction between PE and the matrix. Although PE substitutions increased the permeable porosity and sorptivity, it significantly improved the sulfate resistance of SCC. The influence of PE shape and size on workability and strength was found to be more important than its type. When considering the disposal of PE wastes and saving embodied energy, consuming recycled PE as partial aggregate replacement was more advantageous over virgin PE aggregate-replaced concrete.
... Um-Al-Afai landfill has nearly 80% of MSW. Because of the increased migration in Qatar, there... more ... Um-Al-Afai landfill has nearly 80% of MSW. Because of the increased migration in Qatar, there is a sharp rise in the volume and also in the variety of solid waste. ... Sufian MA, Bala BK (2007) Modeling of urban solid waste management system; the case of Dhaka city. ...
International Journal of Engineering and Technology, 2013
This paper presents the effect of curing conditions on freeze-thaw durability of self-consolidati... more This paper presents the effect of curing conditions on freeze-thaw durability of self-consolidating concrete. In order to determine the effect of curing conditions on the durability properties of self-consolidating concrete, some specimens were cured in air and the others in water. Moist-cured (M-C) specimens were kept in water for 14 days at a temperature of 23±2°C before they were subjected to freeze-thaw cycles. Air-cured (A-C) specimens were however left in ambient laboratory conditions and were saturated in water for a day before they were subjected to the same freeze-thaw cycles. From the permeability tests, it was concluded that air cured specimens have higher permeability. Furthermore, an increase in fly ash content resulted in a reduction in the permeation properties of self-consolidating concrete. On the other hand, more variations were observed in permeability results since only two specimens were used for permeability tests. During the freezing-thawing test, it was observed that air cured specimens were not affected by freezing-thawing and did not indicate any degradation since they were not totally saturated because of the lack of the saturation period that was employed.
Self consolidating concrete (SCC) is defined as an innovative concrete that does not require vibr... more Self consolidating concrete (SCC) is defined as an innovative concrete that does not require vibration for placing and compaction and it is able to flow under its own weight, completely filling formwork and achieving full compaction. Although significant amount of research has been carried out regarding the fresh properties, mix design, placing methods and strength of various SCC mixes, only a very limited amount of work has been done to assess the durability performance of SCC. Concretes in cold climates are subjected to freeze-thaw cycles which are one of the major durability problems, and if the concrete is in a saturated or nearly saturated condition, those cycles lead to expansion of the water in the capillary pores of concrete causing great internal stresses. For a durable concrete subjected to freeze-thaw cycles, an adequate air void system is obtained by using air-entraining admixtures. The performance of the air void system is characterized by air void parameters that are d...
Thermal characterization of Phase Change Materials (PCMs) compose of linear low-density polyethyl... more Thermal characterization of Phase Change Materials (PCMs) compose of linear low-density polyethylene (LLDPE), paraffin wax (W) with a melting point of 25 °C, and expanded graphite (EG), that are highly effective in thermal energy storage systems in the building industry, is reported. Thermal investigation of PCMs with various compositions of LLDPE, W and EG has been performed by nonconventional transient guarded hot plane technique (TGHPT) and compared with conventional Differential Scanning Calorimetry (DSC) measurements. An excellent agreement in determination of thermal characteristics by both methods was found. The highest values of the total amount of stored energy, sensible heat for solid and liquid states (Q total , Q s (solid) and Q s (liquid), respectively) were found for the PCMs with composition LLDPE/W/EG = 40/50/10 and 35/50/15 w/w/w. Moreover, thermal conductivity and diffusivity of PCMs have been significantly improved by adding EG. Additionally, life cycle assessment was performed to evaluate the environmental impact of three different materials as glass wool, rock wool and PCM used with brick wall.
Nondestructive Testing of Materials and Structures, 2011
Abstract This paper presents the effect of freezing-thawing on self consolidating concrete (SCC) ... more Abstract This paper presents the effect of freezing-thawing on self consolidating concrete (SCC) that contains different percentages of fly ash (FA) and air entraining agents (AEA). The effect of freezing-thawing on concrete is assessed on the basis of the change in the ...
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