Ahmed Senouci - Academia.edu (original) (raw)

Papers by Ahmed Senouci

Research paper thumbnail of Using Aerosol OT in Hexane Solution to Synthesize Calcium Nitrate Self-Healing Refined Microcapsules for Construction Applications

Buildings

The micro-encapsulation procedure of calcium nitrate in urea-formaldehyde shell is well known. Th... more The micro-encapsulation procedure of calcium nitrate in urea-formaldehyde shell is well known. The most recent developed method for the synthesis of the calcium nitrate self-healing micro-capsules was based on the in-situ polymerization using water-in-oil emulsion. Although the microcapsules’ yield was significantly improved using this approach, incorporating the micro-capsules into concrete mixes has been found to reduce strength. One potential strength reduction cause might be the presence of sulfonic acid as a component in the continuous (oil) phase. As the anionic surfactant, Aerosol OT (AOT) has been widely used to prepare water-in-oil emulsions and to form aggregates in non-polar solvents; submicron calcium nitrate refined microcapsules were synthesized using AOT in hexane solution. While the aqueous phase in the original encapsulation procedure has not been altered, the continuous organic phase was prepared by dissolving AOT in hexane. The prepared microcapsules were characte...

Research paper thumbnail of Current Supply Chain Management in Construction Industry

Proceedings of the Creative Construction Conference 2019, 2019

Supply Chain Management (SCM) in construction industry is a developing field of study. This paper... more Supply Chain Management (SCM) in construction industry is a developing field of study. This paper analyses the results of a questionnaire survey on supply chain management in top US construction industries. A survey was sent out via online tool to more than 100 contracting companies in the US, mapping the relationship between contractors and suppliers, the tools and methods employed in executing the supply chain practices. The survey results indicated that SCM in the construction industry is still in its developing state. They also indicated that the construction industry has been relatively slow in adopting SCM as a tactic due to its complexity and uniqueness. The study recommends several solutions to overcome the above mentioned problems and improve the efficiency of the SCM in the construction industry.

Research paper thumbnail of Current Supply Chain Management in Construction Industry

Proceedings of the Creative Construction Conference 2019, 2019

Research paper thumbnail of Safety Improvement on Building Construction Sites in Qatar

Procedia Engineering, 2015

The construction industry is an essential national backbone, especially for developing countries.... more The construction industry is an essential national backbone, especially for developing countries. Poor project performance and lack of construction control could have long-reaching detrimental effects on slowing down the country's development pace and on impacting the prosperity of its citizens. The State of Qatar is currently experiencing an unprecedented rate of economic growth and urban development. As the host of the FIFA World Cup in 2022, Qatar plans to invest over $40 billion in infrastructure projects in preparation of such a significant event. The plan includes a new airport, metro system, high-speed rail, and addition of 40,000 hotel rooms. Such an explosive boom has raised concerns about the construction industry, especially regarding its health and safety problems. Qatar National Provisional Safety Committee prepared a safety guide for construction work. The aim of the guide is to ensure worker safety and mandates that contractors, owners, and consultants abide by the established safety rules. The purpose of this study is to: 1) identify safety issues in Qatari jobsites, and 2) use risk management techniques to minimize the impacts of the risk factors. The risk management process consists of risk identification, risk assessment, risk response and risk control. In risk identification, 38 safety risk factors related to Qatari building construction sites were compiled based on an extensive literature review and recommendations of safety experts. The risk assessment was addressed through safety questionnaires to rank the risk factors in order to guide the application of risk management. Safety personnel were included in the data collection. After analyzing the questionnaires, the risk factors were ranked as low, moderate, and sever based on their degree potential impact. To address the risk response, interviews with safety experts were conducted to determine mitigation measures. These measures include: 1) developing comprehensive safety plans, 2) clearly defining the role of managers, supervisors, and employees in safety implementation and 3) teaming up managers and workers to accomplish the safety objectives.

Research paper thumbnail of Safety Improvement on Building Construction Sites in Qatar

Procedia Engineering, 2015

The construction industry is an essential national backbone, especially for developing countries.... more The construction industry is an essential national backbone, especially for developing countries. Poor project performance and lack of construction control could have long-reaching detrimental effects on slowing down the country's development pace and on impacting the prosperity of its citizens. The State of Qatar is currently experiencing an unprecedented rate of economic growth and urban development. As the host of the FIFA World Cup in 2022, Qatar plans to invest over $40 billion in infrastructure projects in preparation of such a significant event. The plan includes a new airport, metro system, high-speed rail, and addition of 40,000 hotel rooms. Such an explosive boom has raised concerns about the construction industry, especially regarding its health and safety problems. Qatar National Provisional Safety Committee prepared a safety guide for construction work. The aim of the guide is to ensure worker safety and mandates that contractors, owners, and consultants abide by the established safety rules. The purpose of this study is to: 1) identify safety issues in Qatari jobsites, and 2) use risk management techniques to minimize the impacts of the risk factors. The risk management process consists of risk identification, risk assessment, risk response and risk control. In risk identification, 38 safety risk factors related to Qatari building construction sites were compiled based on an extensive literature review and recommendations of safety experts. The risk assessment was addressed through safety questionnaires to rank the risk factors in order to guide the application of risk management. Safety personnel were included in the data collection. After analyzing the questionnaires, the risk factors were ranked as low, moderate, and sever based on their degree potential impact. To address the risk response, interviews with safety experts were conducted to determine mitigation measures. These measures include: 1) developing comprehensive safety plans, 2) clearly defining the role of managers, supervisors, and employees in safety implementation and 3) teaming up managers and workers to accomplish the safety objectives.

Research paper thumbnail of Compressed Earth Blocks Using Sediments and Alkali-Activated Byproducts

Sustainability

Sediment dredging is necessary and vital to preserve maritime activities and prevent floods. The ... more Sediment dredging is necessary and vital to preserve maritime activities and prevent floods. The management of these sediments represent an environmental challenge for many countries all over the world. This study focuses on evaluating the feasibility of using dredged sediments for the manufacturing of compressed earth blocks (CEB). The alternative construction material has the potential of reducing the need for dredged sediment onshore storage or ocean dumping. Several experimental tests have been conducted on two geopolymer types, which were obtained by mixing sediments from the northern region of France, fly ash (FA), and grounded blast furnace slag (GBFS). The geopolymers, which were activated using an eight-molar concentrated sodium hydroxide solution (NH), were cured at a temperature of 50 °C. The results have shown that a geopolymer content of 36% of FA and 10% of GBFS along with (NH) alkaline solution has significantly improved the mechanical properties of CEBs, which have o...

Research paper thumbnail of Optimum Dispersion Parameters of Carbon Nanotubes: Concrete Strength by Response Surface Methodologies

Proceedings of the International Conference on Civil Infrastructure and Construction (CIC 2020)

This paper implements Response Surface Methodologies (RSM) techniques to illustrate the maximum c... more This paper implements Response Surface Methodologies (RSM) techniques to illustrate the maximum carbon nanotubes (CNTs)-concrete mechanical properties responses to the length, weight fraction and treatment variables. Mixes with different CNTs' content were prepared and tested for flexure, compression and tension. RSM analysis showed that the highest effect on the strengths was due to the CNTs' content variable. The analysis showed that a weight fraction of 0.3 wt.% of non-treated CNTs is required to achieve the maximum flexural, compressive and tensile strengths in a batch as per the predicted model. RSM analysis also showed that maximum flexural strength will be obtained by using 0.2 wt. % non-treated long CNTs, 0.25 wt. % non-treated short CNTs and 0.03 wt. % treated long CNTs, respectively.

Research paper thumbnail of Potential use and benefits of automation for traffic control in roadway construction

This paper addresses the impact of using automated flagging devices in road construction instead ... more This paper addresses the impact of using automated flagging devices in road construction instead of using construction workers. To examine the efficacy of automating this construction activity, a group of drivers with diverse characteristics/demographics was involved in the study. The diverse characteristics included gender, age, years of driving experience, and level of formal education (e.g., high school, college, and graduate degrees). Each participant was requested to view road construction scenarios involving the use of traffic control means/devices. The participants were requested to complete a questionnaire after viewing the scenarios to determine the drivers’ perceptions (that is, comfort/discomfort) in each scenario. The scenarios were displayed on a computer, and an eye-tracking software was used to determine where drivers focused their attention as they approached the road construction zones. During the viewing of the scenarios, the eye-tracking software recorded the driv...

Research paper thumbnail of Observations on Rubberized Concrete Behavior

Cement, Concrete, and Aggregates

... The paper uses a mathematical model to quantitate the effects of rubber aggregates on thecomp... more ... The paper uses a mathematical model to quantitate the effects of rubber aggregates on thecompressive and splitting tensile strength reduction of concrete. Files: HRIS. Pagination: p. 74-84. Authors: Eldin, NN. Senouci, AB. Publication Date: 1993. Serial: ...

Research paper thumbnail of Performance of Concrete Mixes Containing TBM Muck as Partial Coarse Aggregate Replacements

Materials

This study investigated the potential utilization of the TBM muck obtained from the Gold Line of ... more This study investigated the potential utilization of the TBM muck obtained from the Gold Line of the Doha Metro Project as a partial replacement of coarse aggregates in concrete mixes. First, the TBM muck particles were screened to coarse aggregate standard sizes. Then, concrete mixes were prepared using 0%, 25%, 50%, and 75% TBM muck replacement of coarse aggregates. The compressive and flexural strengths were determined for all mixes at 28 and 56 days. Moreover, the results obtained were validated using EDX analysis and SEM images. A t-statistical analysis did not show a significant impact of TBM muck usage on the compressive strength results of the concrete mixes. However, another t-statistical analysis showed that TBM muck replacement of coarse aggregates had adversely affected the flexural strength results. The EDX analysis indicated the presence of Na+ ions, which can replace the Ca2+ ions in the C-S-H gel, cause discontinuities of it, and hence reduce the strength at later ag...

Research paper thumbnail of Safety Performance in Industrial Construction: A Case Study

Journal of Civil Engineering and Construction

This paper presents a case study of a safety training program developed by an international leadi... more This paper presents a case study of a safety training program developed by an international leading construction firm. The study was prompted by the continuing challenge of work- related accidents in the construction industry. Even with the measurable safety improvements in the last several decades, the construction industry still exhibits high rate of occupational fatal injuries compared to other industries. A linear regression model was developed using Microsoft Excel to determine the level of impact of the number of training hours on the resulting safety performance. The analysis confirmed that the number of training hours had a strong impact on reducing safety incidents. The coefficient of determination (R2) demonstrated that the number of training hours accounted for 81% of the variance in the incidents rate. The study results should assist in quantifying the cost-benefits of implementing safety programs, and in justifying the mandating of a certain number of training hours.

Research paper thumbnail of Optimization of an Eco-Friendly Hydraulic Road Binders Comprising Clayey Dam Sediments and Ground Granulated Blast-Furnace Slag

Buildings

This study investigated the potential use of Zerdezas dam Calcined Sediments (CS) and El-Hadjar B... more This study investigated the potential use of Zerdezas dam Calcined Sediments (CS) and El-Hadjar Blast Furnace Slag (GGBS) from northern Algeria as a partial replacement of cement (C) in normal hardening hydraulic road binders. Two binder mix designs were optimized using a Response Surface Methodology (RSM). The first mix, 50C35GGBS15CS, consisted of 50% cement, 35% blast furnace slag, and 15% calcined sediment. The second mix, 80C10GGBS10CS, consisted of 80% cement, 10% blast furnace slag, and 10% calcined sediments. The tests of workability, setting time, volume expansion, compressive and flexural strengths, porosity, and SEM were conducted to ensure that both mixes meet the standard requirements for road construction binders. The two proposed mixes were qualified as normal hardening hydraulic road binder. The reuse of the sediments will contribute to a better disposal of dam sediments and steel industry waste and to preserve natural resources that are used for manufacturing cement...

Research paper thumbnail of Impact of weather conditions on construction labour productivity in Qatar

Middle East J. of Management

Qatari construction projects frequently encounter significant delays. One of the major causes of ... more Qatari construction projects frequently encounter significant delays. One of the major causes of these delays is ignoring Qatar's extreme weather conditions on labour productivity. This paper studies the impact of temperature, humidity, and wind on labour productivity in Qatar for four construction trades, namely, formwork, masonry, plaster, and ceramic tiles. These trades were chosen because they are time-consuming and commonly found in most construction projects. Weather and trade labour productivity data were recorded between July 2013 and February 2014. The results showed that weather conditions have a high impact on trade labour productivity. They also showed that the labour productivity in the summer can be as low as half of that in the winter. Linear regression models were developed to predict trade productivity on a given day of the year.

Research paper thumbnail of Characterization of TBM Muck for Construction Applications

Applied Sciences

This paper investigates the potential utilization of the Tunnel Boring Machine (TBM) muck generat... more This paper investigates the potential utilization of the Tunnel Boring Machine (TBM) muck generated from Doha’s Metro Gold Line in different construction applications. The properties of the raw TBM muck were studied, and the results were compared to the specifications of Qatari Construction Standards (QCS 2014) of concrete aggregates, fill material under buildings and road subgrades. Compared to the requirements of concrete aggregates, the results indicated that the gradation of the raw TBM muck does not comply with the QCS 2014 requirements, and hence, sieving and screening may be essential. Moreover, the tests’ results showed that the properties of the muck meet the requirements of the concrete coarse aggregates, except for the water absorption, loss by magnesium sulphate soundness, loss by Los Angeles abrasion and the acid-soluble sulphate. As fill material under buildings or road subgrades, the gradation of the TBM muck complies with the QCS 2014 requirements, while the liquid l...

Research paper thumbnail of Resource-Constrained Construction Scheduling Using Agent Based Modeling Technique

Journal of Civil Engineering and Construction

This paper presents the use of Agent Based Modeling (ABM) technique as a tool for optimum resour... more This paper presents the use of Agent Based Modeling (ABM) technique as a tool for optimum resource constrained scheduling. The model added two features to the standard resource scheduling applications. It allowed activity interruptions when necessary and the impact of the quality of the predecessors on the successors’ duration. An illustrative example is offered to demonstrate the performance of the proposed model. ABM technique was confirmed to be a valid approach for seeking alternative solutions in resource constrained schedules. The model proved advantageous to resource-constrained schedules. It illustrated additional flexibility to the standard techniques for resource-constrained problems. The model was proven successful in minimizing the project duration under preset priority rules.

Research paper thumbnail of A Multi Objective Scheduling Model for Minimization of Construction Project Duration, Total Cost and Environmental Impact

Proceedings of the Creative Construction Conference 2019, 2019

The performance of construction projects has traditionally been measured based on cost, time, and... more The performance of construction projects has traditionally been measured based on cost, time, and quality. Recently, the environment impact has been introduced as a fourth criterion for the assessment of project performance. Significant research advancements have been made in the area of optimizing resource utilization to minimize the total cost, duration, and quality for construction projects. A number of models have been developed using a variety of methods, including heuristics methods, mathematical programming, genetic algorithms, ant colony, and particle swarm optimization. However, there has been little or no reported research focusing on studying and optimizing the collective impact of resource utilization decisions on construction cost, duration, and environmental impact. The objective of this paper is to present the development of a multi-objective optimization model for optimizing resource utilization and scheduling of projects. The model provides construction planners and decision makers with new and important capabilities, including: (1) evaluating the combined impact of multiple resource utilization decisions on construction cost, duration, and environmental impact and (2) generating and visualizing optimal/near-optimal resource utilization and scheduling plans that provide optimal trade-offs between the project cost, duration, and environmental impact. The model is developed in two stages: (1) model formulation to identify the decision variables and optimization objectives for the construction optimization problem and (2) model implementation to perform the optimization computations using three modules that compute project duration, total cost, and environmental impact, respectively.

Research paper thumbnail of Reliability Assessment Model for Water Distribution Networks

Journal of Pipeline Systems Engineering and Practice

AbstractThe aging water distribution networks in the US are approaching the end of their useful l... more AbstractThe aging water distribution networks in the US are approaching the end of their useful life, and more than 240,000 pipeline breaks are estimated to occur every year, which corresponds to a...

Research paper thumbnail of Proposed Formulas for Estimating Splitting Tensile, Shear and Flexural Strengths, and Long Term Deflection Assessment of Self-Compacting Concrete Elements

Science of Advanced Materials

Research paper thumbnail of Characterisation of self-healing efficiency of calcium nitrate microcapsules for concrete applications

International Journal of Microstructure and Materials Properties

This study presents characterisation of concrete samples containing 0.75% by cement weight of mod... more This study presents characterisation of concrete samples containing 0.75% by cement weight of modified calcium nitrate self-healing microcapsules. The phased array ultrasonic testing method was used to investigate the healing efficiency of calcium nitrate microcapsules in concrete. The method is a novel non-destructive testing technique that is commonly used for detecting the defects in welding. Concrete beams were prepared from the control mix (without microcapsules) and mixes containing 0.75% by weight of cement of calcium nitrate microcapsules. After 28 days of moist curing, the phased array ultrasonic images of all beams were captured before loading, after applying 60% of the ultimate flexural load, and after 3 and 7 days of accelerated healing. Moreover, scanning electron microscopy images taken from fractured surfaces of the beams that were loaded up to failure before healing were compared to those of the beams that were healed for 7 days and loaded up to failure.

Research paper thumbnail of Simulation-based deterioration patterns of water pipelines

Structure and Infrastructure Engineering

Abstract Water pipelines deteriorate overtime due to several distressing factors. To keep water p... more Abstract Water pipelines deteriorate overtime due to several distressing factors. To keep water pipelines in good condition, municipalities need to use reliable and credible deterioration models and inspection plans to better manage their rehabilitation and maintenance. Thus, this paper presents the development of deterioration models and patterns of water pipelines. The deterioration models consider different water pipe sizes and materials as well as different surrounding environmental conditions which affect their deterioration rates. As a prerequisite to the development of such deterioration models, a condition assessment model for water pipelines was first developed. Questionnaires were distributed among experts to determine the weights of the factors affecting water pipeline conditions using the fuzzy analytic network process. Monte-Carlo simulation was used to account for the large uncertainties of the calculated weights in the development of the condition assessment model. The validation of the model, which was performed using historical data, yielded an average validity percentage of 93.59%. The developed models are expected to help municipalities and decision makers to accurately plan for future water pipelines maintenance and rehabilitation activities based on their different deterioration patterns. It takes into consideration both the uncertainties at the initial stage and those accumulated during the calculation process.

Research paper thumbnail of Using Aerosol OT in Hexane Solution to Synthesize Calcium Nitrate Self-Healing Refined Microcapsules for Construction Applications

Buildings

The micro-encapsulation procedure of calcium nitrate in urea-formaldehyde shell is well known. Th... more The micro-encapsulation procedure of calcium nitrate in urea-formaldehyde shell is well known. The most recent developed method for the synthesis of the calcium nitrate self-healing micro-capsules was based on the in-situ polymerization using water-in-oil emulsion. Although the microcapsules’ yield was significantly improved using this approach, incorporating the micro-capsules into concrete mixes has been found to reduce strength. One potential strength reduction cause might be the presence of sulfonic acid as a component in the continuous (oil) phase. As the anionic surfactant, Aerosol OT (AOT) has been widely used to prepare water-in-oil emulsions and to form aggregates in non-polar solvents; submicron calcium nitrate refined microcapsules were synthesized using AOT in hexane solution. While the aqueous phase in the original encapsulation procedure has not been altered, the continuous organic phase was prepared by dissolving AOT in hexane. The prepared microcapsules were characte...

Research paper thumbnail of Current Supply Chain Management in Construction Industry

Proceedings of the Creative Construction Conference 2019, 2019

Supply Chain Management (SCM) in construction industry is a developing field of study. This paper... more Supply Chain Management (SCM) in construction industry is a developing field of study. This paper analyses the results of a questionnaire survey on supply chain management in top US construction industries. A survey was sent out via online tool to more than 100 contracting companies in the US, mapping the relationship between contractors and suppliers, the tools and methods employed in executing the supply chain practices. The survey results indicated that SCM in the construction industry is still in its developing state. They also indicated that the construction industry has been relatively slow in adopting SCM as a tactic due to its complexity and uniqueness. The study recommends several solutions to overcome the above mentioned problems and improve the efficiency of the SCM in the construction industry.

Research paper thumbnail of Current Supply Chain Management in Construction Industry

Proceedings of the Creative Construction Conference 2019, 2019

Research paper thumbnail of Safety Improvement on Building Construction Sites in Qatar

Procedia Engineering, 2015

The construction industry is an essential national backbone, especially for developing countries.... more The construction industry is an essential national backbone, especially for developing countries. Poor project performance and lack of construction control could have long-reaching detrimental effects on slowing down the country's development pace and on impacting the prosperity of its citizens. The State of Qatar is currently experiencing an unprecedented rate of economic growth and urban development. As the host of the FIFA World Cup in 2022, Qatar plans to invest over $40 billion in infrastructure projects in preparation of such a significant event. The plan includes a new airport, metro system, high-speed rail, and addition of 40,000 hotel rooms. Such an explosive boom has raised concerns about the construction industry, especially regarding its health and safety problems. Qatar National Provisional Safety Committee prepared a safety guide for construction work. The aim of the guide is to ensure worker safety and mandates that contractors, owners, and consultants abide by the established safety rules. The purpose of this study is to: 1) identify safety issues in Qatari jobsites, and 2) use risk management techniques to minimize the impacts of the risk factors. The risk management process consists of risk identification, risk assessment, risk response and risk control. In risk identification, 38 safety risk factors related to Qatari building construction sites were compiled based on an extensive literature review and recommendations of safety experts. The risk assessment was addressed through safety questionnaires to rank the risk factors in order to guide the application of risk management. Safety personnel were included in the data collection. After analyzing the questionnaires, the risk factors were ranked as low, moderate, and sever based on their degree potential impact. To address the risk response, interviews with safety experts were conducted to determine mitigation measures. These measures include: 1) developing comprehensive safety plans, 2) clearly defining the role of managers, supervisors, and employees in safety implementation and 3) teaming up managers and workers to accomplish the safety objectives.

Research paper thumbnail of Safety Improvement on Building Construction Sites in Qatar

Procedia Engineering, 2015

The construction industry is an essential national backbone, especially for developing countries.... more The construction industry is an essential national backbone, especially for developing countries. Poor project performance and lack of construction control could have long-reaching detrimental effects on slowing down the country's development pace and on impacting the prosperity of its citizens. The State of Qatar is currently experiencing an unprecedented rate of economic growth and urban development. As the host of the FIFA World Cup in 2022, Qatar plans to invest over $40 billion in infrastructure projects in preparation of such a significant event. The plan includes a new airport, metro system, high-speed rail, and addition of 40,000 hotel rooms. Such an explosive boom has raised concerns about the construction industry, especially regarding its health and safety problems. Qatar National Provisional Safety Committee prepared a safety guide for construction work. The aim of the guide is to ensure worker safety and mandates that contractors, owners, and consultants abide by the established safety rules. The purpose of this study is to: 1) identify safety issues in Qatari jobsites, and 2) use risk management techniques to minimize the impacts of the risk factors. The risk management process consists of risk identification, risk assessment, risk response and risk control. In risk identification, 38 safety risk factors related to Qatari building construction sites were compiled based on an extensive literature review and recommendations of safety experts. The risk assessment was addressed through safety questionnaires to rank the risk factors in order to guide the application of risk management. Safety personnel were included in the data collection. After analyzing the questionnaires, the risk factors were ranked as low, moderate, and sever based on their degree potential impact. To address the risk response, interviews with safety experts were conducted to determine mitigation measures. These measures include: 1) developing comprehensive safety plans, 2) clearly defining the role of managers, supervisors, and employees in safety implementation and 3) teaming up managers and workers to accomplish the safety objectives.

Research paper thumbnail of Compressed Earth Blocks Using Sediments and Alkali-Activated Byproducts

Sustainability

Sediment dredging is necessary and vital to preserve maritime activities and prevent floods. The ... more Sediment dredging is necessary and vital to preserve maritime activities and prevent floods. The management of these sediments represent an environmental challenge for many countries all over the world. This study focuses on evaluating the feasibility of using dredged sediments for the manufacturing of compressed earth blocks (CEB). The alternative construction material has the potential of reducing the need for dredged sediment onshore storage or ocean dumping. Several experimental tests have been conducted on two geopolymer types, which were obtained by mixing sediments from the northern region of France, fly ash (FA), and grounded blast furnace slag (GBFS). The geopolymers, which were activated using an eight-molar concentrated sodium hydroxide solution (NH), were cured at a temperature of 50 °C. The results have shown that a geopolymer content of 36% of FA and 10% of GBFS along with (NH) alkaline solution has significantly improved the mechanical properties of CEBs, which have o...

Research paper thumbnail of Optimum Dispersion Parameters of Carbon Nanotubes: Concrete Strength by Response Surface Methodologies

Proceedings of the International Conference on Civil Infrastructure and Construction (CIC 2020)

This paper implements Response Surface Methodologies (RSM) techniques to illustrate the maximum c... more This paper implements Response Surface Methodologies (RSM) techniques to illustrate the maximum carbon nanotubes (CNTs)-concrete mechanical properties responses to the length, weight fraction and treatment variables. Mixes with different CNTs' content were prepared and tested for flexure, compression and tension. RSM analysis showed that the highest effect on the strengths was due to the CNTs' content variable. The analysis showed that a weight fraction of 0.3 wt.% of non-treated CNTs is required to achieve the maximum flexural, compressive and tensile strengths in a batch as per the predicted model. RSM analysis also showed that maximum flexural strength will be obtained by using 0.2 wt. % non-treated long CNTs, 0.25 wt. % non-treated short CNTs and 0.03 wt. % treated long CNTs, respectively.

Research paper thumbnail of Potential use and benefits of automation for traffic control in roadway construction

This paper addresses the impact of using automated flagging devices in road construction instead ... more This paper addresses the impact of using automated flagging devices in road construction instead of using construction workers. To examine the efficacy of automating this construction activity, a group of drivers with diverse characteristics/demographics was involved in the study. The diverse characteristics included gender, age, years of driving experience, and level of formal education (e.g., high school, college, and graduate degrees). Each participant was requested to view road construction scenarios involving the use of traffic control means/devices. The participants were requested to complete a questionnaire after viewing the scenarios to determine the drivers’ perceptions (that is, comfort/discomfort) in each scenario. The scenarios were displayed on a computer, and an eye-tracking software was used to determine where drivers focused their attention as they approached the road construction zones. During the viewing of the scenarios, the eye-tracking software recorded the driv...

Research paper thumbnail of Observations on Rubberized Concrete Behavior

Cement, Concrete, and Aggregates

... The paper uses a mathematical model to quantitate the effects of rubber aggregates on thecomp... more ... The paper uses a mathematical model to quantitate the effects of rubber aggregates on thecompressive and splitting tensile strength reduction of concrete. Files: HRIS. Pagination: p. 74-84. Authors: Eldin, NN. Senouci, AB. Publication Date: 1993. Serial: ...

Research paper thumbnail of Performance of Concrete Mixes Containing TBM Muck as Partial Coarse Aggregate Replacements

Materials

This study investigated the potential utilization of the TBM muck obtained from the Gold Line of ... more This study investigated the potential utilization of the TBM muck obtained from the Gold Line of the Doha Metro Project as a partial replacement of coarse aggregates in concrete mixes. First, the TBM muck particles were screened to coarse aggregate standard sizes. Then, concrete mixes were prepared using 0%, 25%, 50%, and 75% TBM muck replacement of coarse aggregates. The compressive and flexural strengths were determined for all mixes at 28 and 56 days. Moreover, the results obtained were validated using EDX analysis and SEM images. A t-statistical analysis did not show a significant impact of TBM muck usage on the compressive strength results of the concrete mixes. However, another t-statistical analysis showed that TBM muck replacement of coarse aggregates had adversely affected the flexural strength results. The EDX analysis indicated the presence of Na+ ions, which can replace the Ca2+ ions in the C-S-H gel, cause discontinuities of it, and hence reduce the strength at later ag...

Research paper thumbnail of Safety Performance in Industrial Construction: A Case Study

Journal of Civil Engineering and Construction

This paper presents a case study of a safety training program developed by an international leadi... more This paper presents a case study of a safety training program developed by an international leading construction firm. The study was prompted by the continuing challenge of work- related accidents in the construction industry. Even with the measurable safety improvements in the last several decades, the construction industry still exhibits high rate of occupational fatal injuries compared to other industries. A linear regression model was developed using Microsoft Excel to determine the level of impact of the number of training hours on the resulting safety performance. The analysis confirmed that the number of training hours had a strong impact on reducing safety incidents. The coefficient of determination (R2) demonstrated that the number of training hours accounted for 81% of the variance in the incidents rate. The study results should assist in quantifying the cost-benefits of implementing safety programs, and in justifying the mandating of a certain number of training hours.

Research paper thumbnail of Optimization of an Eco-Friendly Hydraulic Road Binders Comprising Clayey Dam Sediments and Ground Granulated Blast-Furnace Slag

Buildings

This study investigated the potential use of Zerdezas dam Calcined Sediments (CS) and El-Hadjar B... more This study investigated the potential use of Zerdezas dam Calcined Sediments (CS) and El-Hadjar Blast Furnace Slag (GGBS) from northern Algeria as a partial replacement of cement (C) in normal hardening hydraulic road binders. Two binder mix designs were optimized using a Response Surface Methodology (RSM). The first mix, 50C35GGBS15CS, consisted of 50% cement, 35% blast furnace slag, and 15% calcined sediment. The second mix, 80C10GGBS10CS, consisted of 80% cement, 10% blast furnace slag, and 10% calcined sediments. The tests of workability, setting time, volume expansion, compressive and flexural strengths, porosity, and SEM were conducted to ensure that both mixes meet the standard requirements for road construction binders. The two proposed mixes were qualified as normal hardening hydraulic road binder. The reuse of the sediments will contribute to a better disposal of dam sediments and steel industry waste and to preserve natural resources that are used for manufacturing cement...

Research paper thumbnail of Impact of weather conditions on construction labour productivity in Qatar

Middle East J. of Management

Qatari construction projects frequently encounter significant delays. One of the major causes of ... more Qatari construction projects frequently encounter significant delays. One of the major causes of these delays is ignoring Qatar's extreme weather conditions on labour productivity. This paper studies the impact of temperature, humidity, and wind on labour productivity in Qatar for four construction trades, namely, formwork, masonry, plaster, and ceramic tiles. These trades were chosen because they are time-consuming and commonly found in most construction projects. Weather and trade labour productivity data were recorded between July 2013 and February 2014. The results showed that weather conditions have a high impact on trade labour productivity. They also showed that the labour productivity in the summer can be as low as half of that in the winter. Linear regression models were developed to predict trade productivity on a given day of the year.

Research paper thumbnail of Characterization of TBM Muck for Construction Applications

Applied Sciences

This paper investigates the potential utilization of the Tunnel Boring Machine (TBM) muck generat... more This paper investigates the potential utilization of the Tunnel Boring Machine (TBM) muck generated from Doha’s Metro Gold Line in different construction applications. The properties of the raw TBM muck were studied, and the results were compared to the specifications of Qatari Construction Standards (QCS 2014) of concrete aggregates, fill material under buildings and road subgrades. Compared to the requirements of concrete aggregates, the results indicated that the gradation of the raw TBM muck does not comply with the QCS 2014 requirements, and hence, sieving and screening may be essential. Moreover, the tests’ results showed that the properties of the muck meet the requirements of the concrete coarse aggregates, except for the water absorption, loss by magnesium sulphate soundness, loss by Los Angeles abrasion and the acid-soluble sulphate. As fill material under buildings or road subgrades, the gradation of the TBM muck complies with the QCS 2014 requirements, while the liquid l...

Research paper thumbnail of Resource-Constrained Construction Scheduling Using Agent Based Modeling Technique

Journal of Civil Engineering and Construction

This paper presents the use of Agent Based Modeling (ABM) technique as a tool for optimum resour... more This paper presents the use of Agent Based Modeling (ABM) technique as a tool for optimum resource constrained scheduling. The model added two features to the standard resource scheduling applications. It allowed activity interruptions when necessary and the impact of the quality of the predecessors on the successors’ duration. An illustrative example is offered to demonstrate the performance of the proposed model. ABM technique was confirmed to be a valid approach for seeking alternative solutions in resource constrained schedules. The model proved advantageous to resource-constrained schedules. It illustrated additional flexibility to the standard techniques for resource-constrained problems. The model was proven successful in minimizing the project duration under preset priority rules.

Research paper thumbnail of A Multi Objective Scheduling Model for Minimization of Construction Project Duration, Total Cost and Environmental Impact

Proceedings of the Creative Construction Conference 2019, 2019

The performance of construction projects has traditionally been measured based on cost, time, and... more The performance of construction projects has traditionally been measured based on cost, time, and quality. Recently, the environment impact has been introduced as a fourth criterion for the assessment of project performance. Significant research advancements have been made in the area of optimizing resource utilization to minimize the total cost, duration, and quality for construction projects. A number of models have been developed using a variety of methods, including heuristics methods, mathematical programming, genetic algorithms, ant colony, and particle swarm optimization. However, there has been little or no reported research focusing on studying and optimizing the collective impact of resource utilization decisions on construction cost, duration, and environmental impact. The objective of this paper is to present the development of a multi-objective optimization model for optimizing resource utilization and scheduling of projects. The model provides construction planners and decision makers with new and important capabilities, including: (1) evaluating the combined impact of multiple resource utilization decisions on construction cost, duration, and environmental impact and (2) generating and visualizing optimal/near-optimal resource utilization and scheduling plans that provide optimal trade-offs between the project cost, duration, and environmental impact. The model is developed in two stages: (1) model formulation to identify the decision variables and optimization objectives for the construction optimization problem and (2) model implementation to perform the optimization computations using three modules that compute project duration, total cost, and environmental impact, respectively.

Research paper thumbnail of Reliability Assessment Model for Water Distribution Networks

Journal of Pipeline Systems Engineering and Practice

AbstractThe aging water distribution networks in the US are approaching the end of their useful l... more AbstractThe aging water distribution networks in the US are approaching the end of their useful life, and more than 240,000 pipeline breaks are estimated to occur every year, which corresponds to a...

Research paper thumbnail of Proposed Formulas for Estimating Splitting Tensile, Shear and Flexural Strengths, and Long Term Deflection Assessment of Self-Compacting Concrete Elements

Science of Advanced Materials

Research paper thumbnail of Characterisation of self-healing efficiency of calcium nitrate microcapsules for concrete applications

International Journal of Microstructure and Materials Properties

This study presents characterisation of concrete samples containing 0.75% by cement weight of mod... more This study presents characterisation of concrete samples containing 0.75% by cement weight of modified calcium nitrate self-healing microcapsules. The phased array ultrasonic testing method was used to investigate the healing efficiency of calcium nitrate microcapsules in concrete. The method is a novel non-destructive testing technique that is commonly used for detecting the defects in welding. Concrete beams were prepared from the control mix (without microcapsules) and mixes containing 0.75% by weight of cement of calcium nitrate microcapsules. After 28 days of moist curing, the phased array ultrasonic images of all beams were captured before loading, after applying 60% of the ultimate flexural load, and after 3 and 7 days of accelerated healing. Moreover, scanning electron microscopy images taken from fractured surfaces of the beams that were loaded up to failure before healing were compared to those of the beams that were healed for 7 days and loaded up to failure.

Research paper thumbnail of Simulation-based deterioration patterns of water pipelines

Structure and Infrastructure Engineering

Abstract Water pipelines deteriorate overtime due to several distressing factors. To keep water p... more Abstract Water pipelines deteriorate overtime due to several distressing factors. To keep water pipelines in good condition, municipalities need to use reliable and credible deterioration models and inspection plans to better manage their rehabilitation and maintenance. Thus, this paper presents the development of deterioration models and patterns of water pipelines. The deterioration models consider different water pipe sizes and materials as well as different surrounding environmental conditions which affect their deterioration rates. As a prerequisite to the development of such deterioration models, a condition assessment model for water pipelines was first developed. Questionnaires were distributed among experts to determine the weights of the factors affecting water pipeline conditions using the fuzzy analytic network process. Monte-Carlo simulation was used to account for the large uncertainties of the calculated weights in the development of the condition assessment model. The validation of the model, which was performed using historical data, yielded an average validity percentage of 93.59%. The developed models are expected to help municipalities and decision makers to accurately plan for future water pipelines maintenance and rehabilitation activities based on their different deterioration patterns. It takes into consideration both the uncertainties at the initial stage and those accumulated during the calculation process.