Rana Tufail | Comsats University Islamabad (original) (raw)
Papers by Rana Tufail
Materials, Aug 24, 2020
This study examines the effect of elevated temperature on various properties of reactive powder c... more This study examines the effect of elevated temperature on various properties of reactive powder concrete (RPC) containing varying percentages of recycled fine aggregates as sand replacement. Recycled fine aggregates were collected from two sources, i.e., demolished normal strength concrete and demolished RPC. The specimens were prepared using 25%, 50%, and 75% replacement of natural sand with recycled fine aggregates, exposed to two different curing conditions and were subjected to four temperatures, i.e., 25, 200, 400, and 600 • C. Later, the specimens were tested for mass loss, compressive strength test, split-tensile strength test, flexural strength test, and water absorption test at all temperature ranges. Results determined that although the mechanical properties degraded with the temperature rise, the recycled aggregates can be employed as a partial replacement of natural sand in RPC without causing a significant decrease in the performance of RPC, and can help to produce more sustainable RPC by using recycled aggregates.
Journal of Engineered Fibers and Fabrics
The higher paste volume in Self Compacting Concrete (SCC) makes it susceptible to have a higher c... more The higher paste volume in Self Compacting Concrete (SCC) makes it susceptible to have a higher creep coefficient and cracking and has brittle nature. This brittle nature of concrete is unacceptable for any construction industry. The addition of fibers is one of the most prevalent methods to enhance the ductile and tensile behavior of concrete. Fibers reduce the cracking phenomena and improve the energy absorption capacity of the structure. Conversely, the addition of fibers has a negative impact on the workability of fresh concrete. In this research work, a detailed investigation of the influence of Nylon fibers (NFs) on fresh properties, durability, and mechanical properties of SCC was carried out. NFs were added into concrete mixes in a proportion of 0.5%, 1%, 1.5%, and 2% by weight of cement to achieve the research objectives. Durability assessment of modified SCC having Nylon fibers was performed using water absorption, permeability, carbonation resistance, and acid attack resi...
life science journal, 2013
This paper presents the experimental results of carbon fibre reinforced polymer (CFRP) jacketing ... more This paper presents the experimental results of carbon fibre reinforced polymer (CFRP) jacketing effect on wide range of cylindrical concrete compressive strengths. A total of sixty cylinders were cast and tested under axial compressive loading. The test variable was the compressive strength of concrete. The four grades of concrete compressive strength, low, normal, medium and high strength were used in this experimental study. The results of the carbon fibre reinforced polymer (CFRP) confined specimens of low,normal,medium and high grade strength concrete were compared with the un-confined specimens of low, normal, medium and high grade strength concrete specimens. The comparison was carried out in terms of un-confined to confined compressive strength and the gain in axial load carrying capacity for the low, normal, medium and high grade strength concrete cylinders. The results showed that the carbon fibre reinforced polymer jacketing is more effective for increasing the confined c...
This paper for the first time investigates the workability, compressive and tensile strength of c... more This paper for the first time investigates the workability, compressive and tensile strength of concrete containing Fly Ash, Rice Husk Ash and Waste Glass Powder. Seventy six cube specimen (150 150 150 mm were cast with different composition of Fly Ash, Rice Husk Ash ,Waste Glass Powder and steel fibers. The cubes were tested for axial compression and tensile tests. The research also investigated the effect of curing regime on the compressive and tensile strength of concrete cube specimen. The results revealed that the addition of 15 % Rice Husk Ash and 39% Fly Ash increased the workability of 25 % as compared to the controlled concrete. The sample containing 10 % Rice Husk Ash, 10% Waste Glass Powder and 39% micro silica produced worst workability as it decreased the workability up to 5 % of controlled concrete. The results for axial compressive strength shows that the addition of 15% Rice Husk Ash (RHA) and 39% of Fly Ash (FA) in concrete leads to the improvement of compressive ...
Materials
The purpose of this research is to study the effects of quarry rock dust (QRD) and steel fibers (... more The purpose of this research is to study the effects of quarry rock dust (QRD) and steel fibers (SF) inclusion on the fresh, mechanical, and microstructural properties of fly ash (FA) and ground granulated blast furnace slag (SG)-based geopolymer concrete (GPC) exposed to elevated temperatures. Such types of ternary mixes were prepared by blending waste materials from different industries, including QRD, SG, and FA, with alkaline activator solutions. The multiphysical models show that the inclusion of steel fibers and binders can enhance the mechanical properties of GPC. In this study, a total of 18 different mix proportions were designed with different proportions of QRD (0%, 5%, 10%, 15%, and 20%) and steel fibers (0.75% and 1.5%). The slag was replaced by different proportions of QRD in fly ash, and SG-based GPC mixes to study the effect of QRD incorporation. The mechanical properties of specimens, i.e., compressive strength, splitting tensile strength, and flexural strength, wer...
Journal of Building Engineering
International Journal of Environmental Research and Public Health
Frequent lane changes cause serious traffic safety concerns for road users. The detection and cat... more Frequent lane changes cause serious traffic safety concerns for road users. The detection and categorization of significant factors affecting frequent lane changing could help to reduce frequent lane-changing risk. The main objective of this research study is to assess and prioritize the significant factors and sub-factors affecting frequent lane changing designed in a three-level hierarchical structure. As a multi-criteria decision-making methodology (MCDM), this study utilizes the analytic hierarchy process (AHP) combined with the best–worst method (BWM) to compare and quantify the specified factors. To illustrate the applicability of the proposed model, a real-life decision-making problem is considered, prioritizing the most significant factors affecting lane changing based on the driver’s responses on a designated questionnaire survey. The proposed model observed fewer pairwise comparisons (PCs) with more consistent and reliable results than the conventional AHP. For level 1 of ...
Periodica Polytechnica Civil Engineering
This paper presents experimental versus theoretical comparison of carbon fiber reinforced polymer... more This paper presents experimental versus theoretical comparison of carbon fiber reinforced polymer (CFRP) confined rubberized concrete (a new structural material). A total of sixty six rubberized concrete cylinders were tested in axial compression. The specimens were cast using 0 to 50% rubber replacement. Twenty seven cylinders were then confined with one, two and three layers of CFRP jackets. Axial compression results of the experimental study were compared with the North American and European design guidelines. The results indicate that the addition of rubber content in the concrete leads to premature micro cracking and lateral expansion in concrete. This increased lateral dilation exploited the potential of FRP jackets. The axial compressive strength and strain values for CFRP confined RuC cylinders reached up to unprecedented 600 and 330 percent of unconfined samples. Furthermore, the current international design guidelines developed for conventional concrete confinement failed ...
Applied Sciences
This study presents the performance of quarry rock dust (QRD) incorporated fly ash (FA) and slag ... more This study presents the performance of quarry rock dust (QRD) incorporated fly ash (FA) and slag (SG) based geopolymer concretes (QFS-GPC) exposed to ambient and elevated temperatures. A total of five QFS-GPC mix types were prepared. The quantity of FA (50%) was kept constant in all the mixes, and SG was replaced by 5%, 10%, 15%, and 20% of QRD. The fresh, hardened properties of the QFS-GPC mixes, viz., workability, compressive strength, splitting tensile strength, and flexural strengths, and XRD for identification of reaction phases were evaluated. The prepared mixes were also heated up to 800 °C to evaluate the residual compressive strength and weight loss. The workability of the QFS-GPC mixes was observed to be reduced by increasing the dosage (0 to 20%) of QRD. Superplasticizer (SP) was used to maintain the medium standard of workability. The compressive, tensile, and flexural strengths were increased by replacing SG with QRD up to 15%, whereas a further higher dosage (20%) of Q...
Applied Sciences
Geopolymer concrete (GPC), also known as an earth friendly concrete, has been under continuous st... more Geopolymer concrete (GPC), also known as an earth friendly concrete, has been under continuous study due to its environmental benefits and potential as a sustainable alternative to conventional concrete construction. However, there is still a lack of comprehensive studies focusing on the influence of all the design mix variables on the fresh and strength properties of GPC. GPC is still a relatively new material in terms of field application and has yet to secure international acceptance as a construction material. Therefore, it is important that comprehensive studies be carried out to collect more reliable information to expand this relatively new material technology to field and site applications. This research work aims to provide a comprehensive study on the factors affecting the fresh and hardened properties of ambient cured fly ash and slag based geopolymer concrete (FS-GPC). Industrial by-products, fly ash from thermal power plants, and ground granulated blast furnace slag fro...
Iranian Journal of Science and Technology, Transactions of Civil Engineering
Significant research has been conducted in the past to develop simplified seismic evaluation proc... more Significant research has been conducted in the past to develop simplified seismic evaluation procedures for tall buildings. However, most of these procedures are based on the use of fundamental mode response while ignoring the responses from higher modes. Moreover, such seismic evaluation procedures are unable to accurately predict individual-member responses. Evaluation of individual-member responses is an important part of damage and loss prediction estimation due to seismic hazard. In this research work, a new nonlinear modal decomposition approach is proposed for seismic evaluation of tall RC core wall buildings that can take into account the higher mode effects. This procedure is an extension of the classical Uncoupled Modal Response History Analysis procedure. A 44-story reinforced concrete core wall building is selected to verify the accuracy of the proposed procedure. A comparison between the outcomes of the proposed procedure and the nonlinear response history analysis procedure shows that this procedure is reasonably accurate in predicting important global and member responses.
Sādhanā
The use of rubber in concrete has been practiced in the engineering community for several years. ... more The use of rubber in concrete has been practiced in the engineering community for several years. However, the poor mechanical properties of rubberized concrete are a serious hurdle. This innovative research provides a closer look at improving the flexural strength of rubberized concrete beams with high rubber content using confinement technique. FRP jackets with different confinement thickness were used to recover the strength loss of rubberized concrete beams. In this paper, 66 rubberized concrete (RuC) beams having 0–50% rubber content were tested under four-point loading. RuC beams suffered up to 167% reduction in flexural strength. However, the FRP jackets were highly effective to improve the flexural strength of RuC beams. The statistical models were developed to predict the flexural strength of FRP confined rubberized concrete beams using response surface methodology (RSM). In this regard, the effect of two principle variables; unconfined strength and number of FRP layers on the flexural strength of FRP confined rubberized concrete beams was investigated. The models were found significant because the predicted and adjusted R 2 was less than 0.2 (a limit proposed by Design Expert software). The predicted and experimental results for FRP confined rubberized concrete beams were found in good agreement. The developed statistical models provide insights into the sensitivity of parameters affecting the flexural strength. The proposed models can improve the reliability of the experiments and reduces the design and analysis time.
Journal of Earthquake Engineering
This paper studies the seismic performance of precast concrete shear walls with horizontal bolted... more This paper studies the seismic performance of precast concrete shear walls with horizontal bolted joints. A fiber-based finite-element analysis (FEA) model was developed to simulate the seismic beh...
Sustainability, 2021
Self-compacting concrete (SCC) is a special type of concrete that is highly flowable, nonsegregat... more Self-compacting concrete (SCC) is a special type of concrete that is highly flowable, nonsegregating and spread into place by its own weight, completely filling the formwork even in the presence of dense reinforcement and then encapsulating the rebar without the need for any additional compaction. This research was carried out to evaluate the effects of bentonite clay and wheat straw ash as a partial substitution for cement in SSC. Bentonite clay and wheat straw ash were added in proportion of 0%, 5.0%, 10%, 15%, and 20% of the weight of the cement. Fresh characteristics were evaluated based on its passing ability and flowability using slump flow, slump T50, L-box, and V-funnel tests. After 7 days, 14 days, and 28 days of curing, cylinders of standard size were cast and tested for compressive and split tensile strength. The test results indicate that bentonite clay and wheat straw ash decrease the passing ability and filling ability of SCC. Furthermore, the concrete specimens’ tests...
ISPRS International Journal of Geo-Information
Land use types and anthropogenic activities represent considerable threats to groundwater polluti... more Land use types and anthropogenic activities represent considerable threats to groundwater pollution. To effectively monitor the groundwater quality, it is vital to measure pollution levels before they become severe. In our research area, located in Gilgit Baltistan in northern Pakistan, groundwater supplies are diminishing due to urban sprawl. In this study, we used a GIS-based DRASTIC model (Depth to water, Recharge, Aquifer media, Soil media, Topography, Impact of the vadose zone, Hydraulic conductivity) to analyze the area’s hydrological attributes to assess the groundwater susceptibility to pollution. Considering the importance of anthropogenic activities, this research primarily utilizes an adjusted DRASTIC model called DRASTICA, which incorporates anthropogenic impact as a parameter in the model. The resulting map, which depicts vulnerability to groundwater contamination, reveals that 19% of the study area is classed as having high vulnerability, 42% has moderate vulnerability...
Construction and Building Materials
Abstract This paper presents an experimental study on improving the post-cracking and the fractur... more Abstract This paper presents an experimental study on improving the post-cracking and the fracture behavior of engineered geopolymer composite containing polyvinyl alcohol (PVA) fibers. Two classes of fibers designated as coarse and fine were investigated. The single fiber volume governed the total number of fibers dispersed in the unit volume of the matrix (Nv), which caused significant effects on the post-cracking and the fracture behavior of the composite. The molarity of the NaOH solution is an important parameter that controlled the geopolymerization process and affected the strength and other properties of the composite. Three different molarity of NaOH solution, 8 M, 12 M, and 16 M, were investigated. The results showed that the specimens made of 8 M matrix containing fine fibers (0.04 mm diameter and 8 mm and 12 mm in length) performed well in the post-cracking stage and satisfied the criteria for pseudo strain hardening (PSH). The direct tensile strength results showed that 8 mm and 12 mm long fine fibers in the 8 M matrix achieved the strength ratio of ultimate to the first crack strength as 1.7 and 1.66, respectively. The strength ratio criterion for PSH suggested a value greater than 1.3. Similarly, from the notched-beam bending test, the energy performance index of 8 mm, and 12 mm long fine fibers in the 8 M matrix were estimated as 7.77 and 6.52, respectively. In contrast, a value of greater than 3 is recommended for PSH behavior. Fine fibers added in the 12 M and 16 M matrix also satisfied the criteria for PSH behavior. Whereas, the coarse fibers (0.2 mm diameter and 18 mm and 24 mm in length) performed well in resisting direct compression and showed higher fracture energy and the modulus of elasticity. The best combination was observed as a 12 M matrix containing fine fibers of 0.04 mm diameter and 8 mm in length.
Sustainability
The world’s ecosystem is severely affected by the increase in the rate of soil erosion and sedime... more The world’s ecosystem is severely affected by the increase in the rate of soil erosion and sediment transport in the built environment and agricultural lands. Land use land cover changes (LULCC) are considered as the most significant cause of sediment transport. This study aims to estimate the effect of LULCC on soil erosion potential in the past 20 years (2000–2020) by using Revised Universal Soil Loss Equation (RUSLE) model based on Geographic Information System (GIS). Different factors were analyzed to study the effect of each factor including R factor, K factor, LS factor, and land cover factor on the erosion process. Maps generated in the study show the changes in the severity of soil loss in the Chitral district of Pakistan. It was found out that 4% of the area was under very high erosion risk in the year 2000 which increased to 8% in the year 2020. An increase in agricultural land (4%) was observed in the last 20 years which shows that human activities largely affected the st...
This study examines the effect of elevated temperature on various properties of reactive powder c... more This study examines the effect of elevated temperature on various properties of reactive powder concrete (RPC) containing varying percentages of recycled fine aggregates as sand replacement. Recycled fine aggregates were collected from two sources, i.e., demolished normal strength concrete and demolished RPC. The specimens were prepared using 25%, 50%, and 75% replacement of natural sand with recycled fine aggregates, exposed to two different curing conditions and were subjected to four temperatures, i.e., 25, 200, 400, and 600 • C. Later, the specimens were tested for mass loss, compressive strength test, split-tensile strength test, flexural strength test, and water absorption test at all temperature ranges. Results determined that although the mechanical properties degraded with the temperature rise, the recycled aggregates can be employed as a partial replacement of natural sand in RPC without causing a significant decrease in the performance of RPC, and can help to produce more...
ISPRS International Journal of Geo-Information
Land degradation caused by soil erosion is considered among the most severe problems of the 21stc... more Land degradation caused by soil erosion is considered among the most severe problems of the 21stcentury. It poses serious threats to soil fertility, food availability, human health, and the world ecosystem. The purpose of the study is to make a quantitative mapping of soil loss in the Chitral district, Pakistan. For the estimation of soil loss in the study area, the Revised Universal Soil Loss Equation (RUSLE) model was used in combination with Remote Sensing (RS) and Geographic Information System (GIS). Topographical features of the study area show that the area is more vulnerable to soil loss, having the highest average annual soil loss of 78 ton/ha/year. Maps generated in the study show that the area has the highest sediment yield of 258 tons/ha/year and higher average annual soil loss of 450 tons/ha/year. The very high severity class represents 8%, 16% under high, 21% under moderate, 12% under low, and 13% under very low soil loss in the Chitral district. The above study is help...
Construction and Building Materials
Abstract An experimental program was designed to investigate the residual properties of high stre... more Abstract An experimental program was designed to investigate the residual properties of high strength concrete (HSC) modified with different percentages of graphite nano/micro platelets (GNMPs) after exposure to elevated temperature. Mechanical properties such as compressive and tensile strength, stress–strain response, elastic modulus and mass loss have been studied at elevated temperature in 23–800 °C range. Non-destructive testing technique such as ultrasonic pulse velocity (UPV) was used to investigate the quality of concrete in the post fire exposure. Further, the energy dissipation characteristics have also been observed in detail. Scanning electron microscopy (SEM) was used for the study of morphological changes such as crack formation, microstructural damage and the dispersions of GNMPs. Results showed better retention of mechanical and physical properties of high strength concretes containing GNMPs. Data obtained was utilized to formulate mathematical relationships for expressing mechanical, durability and energy related properties of HSC modified with different percentages of GNMPs as a function of temperature.
Materials, Aug 24, 2020
This study examines the effect of elevated temperature on various properties of reactive powder c... more This study examines the effect of elevated temperature on various properties of reactive powder concrete (RPC) containing varying percentages of recycled fine aggregates as sand replacement. Recycled fine aggregates were collected from two sources, i.e., demolished normal strength concrete and demolished RPC. The specimens were prepared using 25%, 50%, and 75% replacement of natural sand with recycled fine aggregates, exposed to two different curing conditions and were subjected to four temperatures, i.e., 25, 200, 400, and 600 • C. Later, the specimens were tested for mass loss, compressive strength test, split-tensile strength test, flexural strength test, and water absorption test at all temperature ranges. Results determined that although the mechanical properties degraded with the temperature rise, the recycled aggregates can be employed as a partial replacement of natural sand in RPC without causing a significant decrease in the performance of RPC, and can help to produce more sustainable RPC by using recycled aggregates.
Journal of Engineered Fibers and Fabrics
The higher paste volume in Self Compacting Concrete (SCC) makes it susceptible to have a higher c... more The higher paste volume in Self Compacting Concrete (SCC) makes it susceptible to have a higher creep coefficient and cracking and has brittle nature. This brittle nature of concrete is unacceptable for any construction industry. The addition of fibers is one of the most prevalent methods to enhance the ductile and tensile behavior of concrete. Fibers reduce the cracking phenomena and improve the energy absorption capacity of the structure. Conversely, the addition of fibers has a negative impact on the workability of fresh concrete. In this research work, a detailed investigation of the influence of Nylon fibers (NFs) on fresh properties, durability, and mechanical properties of SCC was carried out. NFs were added into concrete mixes in a proportion of 0.5%, 1%, 1.5%, and 2% by weight of cement to achieve the research objectives. Durability assessment of modified SCC having Nylon fibers was performed using water absorption, permeability, carbonation resistance, and acid attack resi...
life science journal, 2013
This paper presents the experimental results of carbon fibre reinforced polymer (CFRP) jacketing ... more This paper presents the experimental results of carbon fibre reinforced polymer (CFRP) jacketing effect on wide range of cylindrical concrete compressive strengths. A total of sixty cylinders were cast and tested under axial compressive loading. The test variable was the compressive strength of concrete. The four grades of concrete compressive strength, low, normal, medium and high strength were used in this experimental study. The results of the carbon fibre reinforced polymer (CFRP) confined specimens of low,normal,medium and high grade strength concrete were compared with the un-confined specimens of low, normal, medium and high grade strength concrete specimens. The comparison was carried out in terms of un-confined to confined compressive strength and the gain in axial load carrying capacity for the low, normal, medium and high grade strength concrete cylinders. The results showed that the carbon fibre reinforced polymer jacketing is more effective for increasing the confined c...
This paper for the first time investigates the workability, compressive and tensile strength of c... more This paper for the first time investigates the workability, compressive and tensile strength of concrete containing Fly Ash, Rice Husk Ash and Waste Glass Powder. Seventy six cube specimen (150 150 150 mm were cast with different composition of Fly Ash, Rice Husk Ash ,Waste Glass Powder and steel fibers. The cubes were tested for axial compression and tensile tests. The research also investigated the effect of curing regime on the compressive and tensile strength of concrete cube specimen. The results revealed that the addition of 15 % Rice Husk Ash and 39% Fly Ash increased the workability of 25 % as compared to the controlled concrete. The sample containing 10 % Rice Husk Ash, 10% Waste Glass Powder and 39% micro silica produced worst workability as it decreased the workability up to 5 % of controlled concrete. The results for axial compressive strength shows that the addition of 15% Rice Husk Ash (RHA) and 39% of Fly Ash (FA) in concrete leads to the improvement of compressive ...
Materials
The purpose of this research is to study the effects of quarry rock dust (QRD) and steel fibers (... more The purpose of this research is to study the effects of quarry rock dust (QRD) and steel fibers (SF) inclusion on the fresh, mechanical, and microstructural properties of fly ash (FA) and ground granulated blast furnace slag (SG)-based geopolymer concrete (GPC) exposed to elevated temperatures. Such types of ternary mixes were prepared by blending waste materials from different industries, including QRD, SG, and FA, with alkaline activator solutions. The multiphysical models show that the inclusion of steel fibers and binders can enhance the mechanical properties of GPC. In this study, a total of 18 different mix proportions were designed with different proportions of QRD (0%, 5%, 10%, 15%, and 20%) and steel fibers (0.75% and 1.5%). The slag was replaced by different proportions of QRD in fly ash, and SG-based GPC mixes to study the effect of QRD incorporation. The mechanical properties of specimens, i.e., compressive strength, splitting tensile strength, and flexural strength, wer...
Journal of Building Engineering
International Journal of Environmental Research and Public Health
Frequent lane changes cause serious traffic safety concerns for road users. The detection and cat... more Frequent lane changes cause serious traffic safety concerns for road users. The detection and categorization of significant factors affecting frequent lane changing could help to reduce frequent lane-changing risk. The main objective of this research study is to assess and prioritize the significant factors and sub-factors affecting frequent lane changing designed in a three-level hierarchical structure. As a multi-criteria decision-making methodology (MCDM), this study utilizes the analytic hierarchy process (AHP) combined with the best–worst method (BWM) to compare and quantify the specified factors. To illustrate the applicability of the proposed model, a real-life decision-making problem is considered, prioritizing the most significant factors affecting lane changing based on the driver’s responses on a designated questionnaire survey. The proposed model observed fewer pairwise comparisons (PCs) with more consistent and reliable results than the conventional AHP. For level 1 of ...
Periodica Polytechnica Civil Engineering
This paper presents experimental versus theoretical comparison of carbon fiber reinforced polymer... more This paper presents experimental versus theoretical comparison of carbon fiber reinforced polymer (CFRP) confined rubberized concrete (a new structural material). A total of sixty six rubberized concrete cylinders were tested in axial compression. The specimens were cast using 0 to 50% rubber replacement. Twenty seven cylinders were then confined with one, two and three layers of CFRP jackets. Axial compression results of the experimental study were compared with the North American and European design guidelines. The results indicate that the addition of rubber content in the concrete leads to premature micro cracking and lateral expansion in concrete. This increased lateral dilation exploited the potential of FRP jackets. The axial compressive strength and strain values for CFRP confined RuC cylinders reached up to unprecedented 600 and 330 percent of unconfined samples. Furthermore, the current international design guidelines developed for conventional concrete confinement failed ...
Applied Sciences
This study presents the performance of quarry rock dust (QRD) incorporated fly ash (FA) and slag ... more This study presents the performance of quarry rock dust (QRD) incorporated fly ash (FA) and slag (SG) based geopolymer concretes (QFS-GPC) exposed to ambient and elevated temperatures. A total of five QFS-GPC mix types were prepared. The quantity of FA (50%) was kept constant in all the mixes, and SG was replaced by 5%, 10%, 15%, and 20% of QRD. The fresh, hardened properties of the QFS-GPC mixes, viz., workability, compressive strength, splitting tensile strength, and flexural strengths, and XRD for identification of reaction phases were evaluated. The prepared mixes were also heated up to 800 °C to evaluate the residual compressive strength and weight loss. The workability of the QFS-GPC mixes was observed to be reduced by increasing the dosage (0 to 20%) of QRD. Superplasticizer (SP) was used to maintain the medium standard of workability. The compressive, tensile, and flexural strengths were increased by replacing SG with QRD up to 15%, whereas a further higher dosage (20%) of Q...
Applied Sciences
Geopolymer concrete (GPC), also known as an earth friendly concrete, has been under continuous st... more Geopolymer concrete (GPC), also known as an earth friendly concrete, has been under continuous study due to its environmental benefits and potential as a sustainable alternative to conventional concrete construction. However, there is still a lack of comprehensive studies focusing on the influence of all the design mix variables on the fresh and strength properties of GPC. GPC is still a relatively new material in terms of field application and has yet to secure international acceptance as a construction material. Therefore, it is important that comprehensive studies be carried out to collect more reliable information to expand this relatively new material technology to field and site applications. This research work aims to provide a comprehensive study on the factors affecting the fresh and hardened properties of ambient cured fly ash and slag based geopolymer concrete (FS-GPC). Industrial by-products, fly ash from thermal power plants, and ground granulated blast furnace slag fro...
Iranian Journal of Science and Technology, Transactions of Civil Engineering
Significant research has been conducted in the past to develop simplified seismic evaluation proc... more Significant research has been conducted in the past to develop simplified seismic evaluation procedures for tall buildings. However, most of these procedures are based on the use of fundamental mode response while ignoring the responses from higher modes. Moreover, such seismic evaluation procedures are unable to accurately predict individual-member responses. Evaluation of individual-member responses is an important part of damage and loss prediction estimation due to seismic hazard. In this research work, a new nonlinear modal decomposition approach is proposed for seismic evaluation of tall RC core wall buildings that can take into account the higher mode effects. This procedure is an extension of the classical Uncoupled Modal Response History Analysis procedure. A 44-story reinforced concrete core wall building is selected to verify the accuracy of the proposed procedure. A comparison between the outcomes of the proposed procedure and the nonlinear response history analysis procedure shows that this procedure is reasonably accurate in predicting important global and member responses.
Sādhanā
The use of rubber in concrete has been practiced in the engineering community for several years. ... more The use of rubber in concrete has been practiced in the engineering community for several years. However, the poor mechanical properties of rubberized concrete are a serious hurdle. This innovative research provides a closer look at improving the flexural strength of rubberized concrete beams with high rubber content using confinement technique. FRP jackets with different confinement thickness were used to recover the strength loss of rubberized concrete beams. In this paper, 66 rubberized concrete (RuC) beams having 0–50% rubber content were tested under four-point loading. RuC beams suffered up to 167% reduction in flexural strength. However, the FRP jackets were highly effective to improve the flexural strength of RuC beams. The statistical models were developed to predict the flexural strength of FRP confined rubberized concrete beams using response surface methodology (RSM). In this regard, the effect of two principle variables; unconfined strength and number of FRP layers on the flexural strength of FRP confined rubberized concrete beams was investigated. The models were found significant because the predicted and adjusted R 2 was less than 0.2 (a limit proposed by Design Expert software). The predicted and experimental results for FRP confined rubberized concrete beams were found in good agreement. The developed statistical models provide insights into the sensitivity of parameters affecting the flexural strength. The proposed models can improve the reliability of the experiments and reduces the design and analysis time.
Journal of Earthquake Engineering
This paper studies the seismic performance of precast concrete shear walls with horizontal bolted... more This paper studies the seismic performance of precast concrete shear walls with horizontal bolted joints. A fiber-based finite-element analysis (FEA) model was developed to simulate the seismic beh...
Sustainability, 2021
Self-compacting concrete (SCC) is a special type of concrete that is highly flowable, nonsegregat... more Self-compacting concrete (SCC) is a special type of concrete that is highly flowable, nonsegregating and spread into place by its own weight, completely filling the formwork even in the presence of dense reinforcement and then encapsulating the rebar without the need for any additional compaction. This research was carried out to evaluate the effects of bentonite clay and wheat straw ash as a partial substitution for cement in SSC. Bentonite clay and wheat straw ash were added in proportion of 0%, 5.0%, 10%, 15%, and 20% of the weight of the cement. Fresh characteristics were evaluated based on its passing ability and flowability using slump flow, slump T50, L-box, and V-funnel tests. After 7 days, 14 days, and 28 days of curing, cylinders of standard size were cast and tested for compressive and split tensile strength. The test results indicate that bentonite clay and wheat straw ash decrease the passing ability and filling ability of SCC. Furthermore, the concrete specimens’ tests...
ISPRS International Journal of Geo-Information
Land use types and anthropogenic activities represent considerable threats to groundwater polluti... more Land use types and anthropogenic activities represent considerable threats to groundwater pollution. To effectively monitor the groundwater quality, it is vital to measure pollution levels before they become severe. In our research area, located in Gilgit Baltistan in northern Pakistan, groundwater supplies are diminishing due to urban sprawl. In this study, we used a GIS-based DRASTIC model (Depth to water, Recharge, Aquifer media, Soil media, Topography, Impact of the vadose zone, Hydraulic conductivity) to analyze the area’s hydrological attributes to assess the groundwater susceptibility to pollution. Considering the importance of anthropogenic activities, this research primarily utilizes an adjusted DRASTIC model called DRASTICA, which incorporates anthropogenic impact as a parameter in the model. The resulting map, which depicts vulnerability to groundwater contamination, reveals that 19% of the study area is classed as having high vulnerability, 42% has moderate vulnerability...
Construction and Building Materials
Abstract This paper presents an experimental study on improving the post-cracking and the fractur... more Abstract This paper presents an experimental study on improving the post-cracking and the fracture behavior of engineered geopolymer composite containing polyvinyl alcohol (PVA) fibers. Two classes of fibers designated as coarse and fine were investigated. The single fiber volume governed the total number of fibers dispersed in the unit volume of the matrix (Nv), which caused significant effects on the post-cracking and the fracture behavior of the composite. The molarity of the NaOH solution is an important parameter that controlled the geopolymerization process and affected the strength and other properties of the composite. Three different molarity of NaOH solution, 8 M, 12 M, and 16 M, were investigated. The results showed that the specimens made of 8 M matrix containing fine fibers (0.04 mm diameter and 8 mm and 12 mm in length) performed well in the post-cracking stage and satisfied the criteria for pseudo strain hardening (PSH). The direct tensile strength results showed that 8 mm and 12 mm long fine fibers in the 8 M matrix achieved the strength ratio of ultimate to the first crack strength as 1.7 and 1.66, respectively. The strength ratio criterion for PSH suggested a value greater than 1.3. Similarly, from the notched-beam bending test, the energy performance index of 8 mm, and 12 mm long fine fibers in the 8 M matrix were estimated as 7.77 and 6.52, respectively. In contrast, a value of greater than 3 is recommended for PSH behavior. Fine fibers added in the 12 M and 16 M matrix also satisfied the criteria for PSH behavior. Whereas, the coarse fibers (0.2 mm diameter and 18 mm and 24 mm in length) performed well in resisting direct compression and showed higher fracture energy and the modulus of elasticity. The best combination was observed as a 12 M matrix containing fine fibers of 0.04 mm diameter and 8 mm in length.
Sustainability
The world’s ecosystem is severely affected by the increase in the rate of soil erosion and sedime... more The world’s ecosystem is severely affected by the increase in the rate of soil erosion and sediment transport in the built environment and agricultural lands. Land use land cover changes (LULCC) are considered as the most significant cause of sediment transport. This study aims to estimate the effect of LULCC on soil erosion potential in the past 20 years (2000–2020) by using Revised Universal Soil Loss Equation (RUSLE) model based on Geographic Information System (GIS). Different factors were analyzed to study the effect of each factor including R factor, K factor, LS factor, and land cover factor on the erosion process. Maps generated in the study show the changes in the severity of soil loss in the Chitral district of Pakistan. It was found out that 4% of the area was under very high erosion risk in the year 2000 which increased to 8% in the year 2020. An increase in agricultural land (4%) was observed in the last 20 years which shows that human activities largely affected the st...
This study examines the effect of elevated temperature on various properties of reactive powder c... more This study examines the effect of elevated temperature on various properties of reactive powder concrete (RPC) containing varying percentages of recycled fine aggregates as sand replacement. Recycled fine aggregates were collected from two sources, i.e., demolished normal strength concrete and demolished RPC. The specimens were prepared using 25%, 50%, and 75% replacement of natural sand with recycled fine aggregates, exposed to two different curing conditions and were subjected to four temperatures, i.e., 25, 200, 400, and 600 • C. Later, the specimens were tested for mass loss, compressive strength test, split-tensile strength test, flexural strength test, and water absorption test at all temperature ranges. Results determined that although the mechanical properties degraded with the temperature rise, the recycled aggregates can be employed as a partial replacement of natural sand in RPC without causing a significant decrease in the performance of RPC, and can help to produce more...
ISPRS International Journal of Geo-Information
Land degradation caused by soil erosion is considered among the most severe problems of the 21stc... more Land degradation caused by soil erosion is considered among the most severe problems of the 21stcentury. It poses serious threats to soil fertility, food availability, human health, and the world ecosystem. The purpose of the study is to make a quantitative mapping of soil loss in the Chitral district, Pakistan. For the estimation of soil loss in the study area, the Revised Universal Soil Loss Equation (RUSLE) model was used in combination with Remote Sensing (RS) and Geographic Information System (GIS). Topographical features of the study area show that the area is more vulnerable to soil loss, having the highest average annual soil loss of 78 ton/ha/year. Maps generated in the study show that the area has the highest sediment yield of 258 tons/ha/year and higher average annual soil loss of 450 tons/ha/year. The very high severity class represents 8%, 16% under high, 21% under moderate, 12% under low, and 13% under very low soil loss in the Chitral district. The above study is help...
Construction and Building Materials
Abstract An experimental program was designed to investigate the residual properties of high stre... more Abstract An experimental program was designed to investigate the residual properties of high strength concrete (HSC) modified with different percentages of graphite nano/micro platelets (GNMPs) after exposure to elevated temperature. Mechanical properties such as compressive and tensile strength, stress–strain response, elastic modulus and mass loss have been studied at elevated temperature in 23–800 °C range. Non-destructive testing technique such as ultrasonic pulse velocity (UPV) was used to investigate the quality of concrete in the post fire exposure. Further, the energy dissipation characteristics have also been observed in detail. Scanning electron microscopy (SEM) was used for the study of morphological changes such as crack formation, microstructural damage and the dispersions of GNMPs. Results showed better retention of mechanical and physical properties of high strength concretes containing GNMPs. Data obtained was utilized to formulate mathematical relationships for expressing mechanical, durability and energy related properties of HSC modified with different percentages of GNMPs as a function of temperature.