mohammed sadeq - Academia.edu (original) (raw)

Papers by mohammed sadeq

Case Studies in Construction Materials

The dynamic modulus (|E * |) of asphalt mixtures is one of the most important inputs in Mechanist... more The dynamic modulus (|E * |) of asphalt mixtures is one of the most important inputs in Mechanistic-Empirical (ME) pavement analysis and design. Several models have been developed to predict the dynamic modulus based on mixture volumetrics and material properties. This study aimed to calibrate and validate two commonly used models (i.e., Hirsch model and Alkhateeb model) for predicting the dynamic modulus of asphalt mixtures in Qatar. Based on the study outcomes, the Hirsch model was found to have a high prediction performance of asphalt mixture moduli before calibration with a coefficient of determination (R 2) of 87.2 % between predicted and measured values. This R 2 value improved slightly after calibration to 89.2 %, Alkhateeb model, on the other hand, had a coefficient of determination of 70.8 % before calibration, which also improved to 89.2 % after calibration. The moduli predicted by the Hirsch model before and after calibration were employed in this study to perform a mechanistic-empirical analysis of the performance of various typical pavement sections in Qatar. According to the findings, the percentage change in the predicted fatigue damage due to the use of the calibrated Hirsch model reached more than 50 % with an average value of 17.33 %, while the percent change in rutting reached 14 % with an average value of 3.65 %. These results highlight the importance of using locally calibrated models for the dynamic modulus in order to improve performance predictions.

Proceedings of the Eighth International Conference on Maintenance and Rehabilitation of Pavements, 2016

Upon the design of any pavement structure, three fundamental external design parameters have to b... more Upon the design of any pavement structure, three fundamental external design parameters have to be considered throughout the design process: the characteristics of the subgrade, traffic loads, and environmental conditions. This paper focuses on the main challenges being faced to estimate site-specific traffic loading for a pavement design due to the lack of accurate and recent traffic data. A case study for a pavement structural design process for an actual expressway project in the State of Qatar is discussed in this paper. This case study goes through traffic loading calculations inputs; the Average Daily Traffic (ADT), Truck Factor (TF), as well as Heavy Good Vehicle Percentage (HGV%). The challenges of calculating these site-specific traffic loading inputs are discussed through investigation of the accuracy in traffic loading estimation using Qatar Strategic Transport Model (QSTM), and how the model can be incorporated in the design. Besides, limited available Wight-In-Motion (WIM) surveys have been discussed and the paper ends with the conclusion that rich availability of traffic data enhances the accuracy of the pavement structural design. It affects significantly the value engineering practice, and results in sustainable pavement sections.

This paper introduces the constructability and economic feasibility study of using one of the pro... more This paper introduces the constructability and economic feasibility study of using one of the proposed two types of permanent shoring system for a highway project in Qatar. The cast-in-situ cantilever retaining wall and the contiguous piles wall were suggested and designed to be used as a permanent retaining system at a multi-level intersection. In this study, the construction complexities of using the cantilever retaining wall system are illustrated and compared to the contiguous piles wall. Besides, the impact on the Right-of-Way (ROW) of the road, excavation process, traffic circulation, and existing utilities are discussed. The paper summarizes the difference in the required construction materials and excavation quantity for the proposed shoring systems at the same retained elevation. Furthermore, the design of both systems is performed based on the local and international guidelines and regulations of the shoring system design in Qatar. The study has shown that both suggested systems are providing the same finishing quality while the contiguous piles system is more effective in minimizing economic and site preparation challenges. It also provides safer utilities handling and faster construction sequencing without cost increases.

Construction and Building Materials, 2021

Abstract Pavement industry concerns have been increasing in the past decades towards fatigue crac... more Abstract Pavement industry concerns have been increasing in the past decades towards fatigue cracking due to its negative impact on asphalt pavement performance. Therefore, several studies were conducted to model and characterize asphalt mixture fatigue life and number of cycles to failure ( N f ) to achieve the designer’s goal ensuring the asphalt pavement serviceability, durability and to reduce the cost. Viscoelastic Continuum Damage (VECD) approach with incorporating probabilistic analysis (P-VECD) was proposed by several researchers to characterize the fatigue cracking of asphalt mixtures reliably. Although the probabilistic VECD studies attract great attention for characterizing the fatigue crack of asphalt mixtures, the VECD- N f model random variables (RVs) are defined by using many arbitrary assumptions. Furthermore, the proposed approaches are very complicated, which added computation complexity to the VECD mode. Therefore, the prediction of asphalt mixtures’ fatigue life is needed in a reliable and simple process. This study focuses on developing a user-friendly analysis tool that determines the Nf following the VECD approach with incorporating probabilistic analysis. To achieve this goal, the proper distribution function for each RV in the VECD- N f model is defined, a simple analysis tool is developed using MATLAB App Designer, and previous studies data for Hot-Mix Asphalt (HMA) and Fine Warm-Mix Asphalt (F-WMA) mixtures are re-analyzed using the developed P-VECD analysis tool. By using the P-VECD analysis tool, deterministic VECD analysis, probabilistic VECD analysis, and the prediction of the fatigue life of asphalt mixtures will be possible for technicians and engineers in the asphalt community.

Advances in Materials and Pavement Performance Prediction, 2018

This work was made possible by the NPRP award [NPRP 5-506-2-203] from the Qatar National Research... more This work was made possible by the NPRP award [NPRP 5-506-2-203] from the Qatar National Research Fund (a member of Qatar Foundation).

Road Materials and Pavement Design, 2020

This study presents two approaches for evaluating damage and recovery characteristics of asphalt ... more This study presents two approaches for evaluating damage and recovery characteristics of asphalt mixtures. The first approach focuses on determining damage by extracting recoverable viscoelastic strain that has no damage and comparing it with the strain response of a material that has damage. The second approach is based on identifying the capacity of asphalt mixtures to recover some of the damage that may occur during creep loading. The advantage of these approaches is that they utilise experimental data to extract damage and recovery responses, without detailed mathematical modelling of material behaviour. The developed approaches are used to analyse the behaviours of fine aggregate mixtures (FAM) incorporating warm mix additives. The results show that these mixtures vary in their damage and recovery characteristics. For example, Sasobit FAM experienced the highest damage among mixtures, but it also had the highest recovery. Ageing was found to reduce the differences among mixtures in terms of resistance to damage, but it had less effect on the differences in their healing potential.

Road Materials and Pavement Design, 2019

The goal of this study is to model the creep and recovery response of fine asphalt mixtures using... more The goal of this study is to model the creep and recovery response of fine asphalt mixtures using a thermodynamically consistent nonlinear viscoelastic model. The model considers asphalt mixture to consist of two constituents: aggregate structure incorporating the asphaltaggregate interface and asphalt binder. The efficacy of the model is evaluated using the response of warm fine aggregate mixtures (WFAM). These materials were produced using a polymer-modified binder of PG 76-22 and three warm mix additives (Sasobit, Advera and Rediset). Unaged and aged samples were subjected to creep stress levels of 75 and 400 kPa followed by rest periods. The model was quite successful in capturing the material behaviour as a single set of parameters were derived from the prediction of shear and normal stress responses for both 75 and 400 kPa stress levels. The presented model offers a unique feature in modelling the energy storage and dissipation of each of the two constituents. As such, one can examine the effect of changes in individual material properties on the material response and performance.

JOURNAL OF EDUCATION AND SCIENCE, 2007

Seeds of green fuzz mutant of cotton Gossypium hirsutum L. (Coker-31 0) which produced from mosai... more Seeds of green fuzz mutant of cotton Gossypium hirsutum L. (Coker-31 0) which produced from mosaic leaves mutant (MC3) were used. The study was carried out according to complete randomize design (CRD) with three replicates. The results showed a depreciation in morphological and production properties of green fuzz mutant in comparison with white fuzz plants. The depreciation was also noticed in qualitative characters of lint. ~I l 2•, •a Gossypium hirsutum L. ~\ u~ .J.J~ ~\.).)]\ o~ ~ ~~\ .~_r.J\ 0\.J 3~\ L.J\j MC3 t>y_bj\ u-a ~ ~\ 3 ~\ ~j L.J\j (Coker-310)

JOURNAL OF EDUCATION AND SCIENCE, 2006

Journal of Transportation Engineering, Part B: Pavements, 2019

AbstractFatigue damage is one of the major distress modes that have a critical impact on the perf... more AbstractFatigue damage is one of the major distress modes that have a critical impact on the performance and serviceability of asphalt pavements. High variability in testing results poses a challen...

International Journal of Pavement Engineering, 2016

ABSTRACT Warm-Mix Asphalt (WMA) is a widely used product, which proved a contribution to the redu... more ABSTRACT Warm-Mix Asphalt (WMA) is a widely used product, which proved a contribution to the reduction in asphalt mixing and compaction temperatures. This reduction leads to lower fuel consumption and smoke emission in asphalt plants. Most of the characterisation of binders used in WMA has focused in the past on measuring linear viscoelastic properties and associated Superpave parameters. Several studies have shown that the average stresses and strains of the asphalt mixture remain mostly within the linear viscoelastic response. However, localised strains in the binder phase of the mixture could reach values high enough to induce nonlinear viscoelastic and viscoplastic deformations. Therefore, this study focuses on an experimental and analytical evaluation of linear, nonlinear viscoelastic and viscoplastic responses of selected binders modified for use in WMA. The first part of the paper analyses the linear viscoelastic material properties and their ability to evaluate permanent deformation resistance. Then, the non-recoverable creep compliance parameter obtained from the Multiple Stress Creep Recovery (MSCR) test is analysed to assess the nonlinear response and permanent deformation of asphalt binders. The paper utilises a nonlinear plasto-viscoelastic (NPVE) approach to assess and quantify the nonlinear plasto-viscoelastic response of binders by separating the recoverable and irrecoverable strains measured in the MSCR test. Two WMA additives were included in this study by mixing them with polymer-modified and unmodified asphalt binders. Analysis of results showed that the NPVE approach captured a higher percentage of recovery than the NLVE approach. However, binder’s performance evaluation and ranking did not change by adopting the NPVE approach. The nonlinear viscoelastic parameters provided insight on the behaviour of asphalt binders mixed with WMA additives during loading cycles. Sasobit showed higher influence than Advera on binders in resisting permanent deformation by increasing the recoverable strain during the unloading phase.

Construction and Building Materials, 2016

Abstract Fatigue cracking is one of the crucial distresses in asphalt pavements that affect its s... more Abstract Fatigue cracking is one of the crucial distresses in asphalt pavements that affect its service life and rehabilitation process. The resistance of asphalt mixtures to fatigue failure in the laboratory experiments is influenced by several factors such as temperature, loading frequency, loading mode, sample type and geometry. This study focused on the evaluation of fatigue performance of different types of warm mix asphalt (WMA) mixture and comparing them with a hot asphalt mixture (control mixture). Warm fine aggregate mixtures (W-FAM) were fabricated using three different WMA additives: Advera, Sasobit, and Rediset which were short-term aged in the laboratory. Then, the W-FAM specimens were exposed to shear stress oscillation test by applying damaging stress level in the dynamic mechanical analyser (DMA) to examine the material fatigue resistance. The test results were analysed using the viscoelastic continuum damage (VECD) approach. The W-FAM exhibited lower dissipated pseudo-strain energy (DPSE) than the control mixture. However, there was no statistical significant difference between the W-FAM and control mix in terms of the number of cycles to failure resulted from the VECD analysis.

RILEM Bookseries, 2015

Warm-mix asphalt (WMA) additives are environmentally friendly and cost-effective products that lo... more Warm-mix asphalt (WMA) additives are environmentally friendly and cost-effective products that lower the viscosity of bituminous binders to allow reduction of mixing and compaction temperatures in asphalt mix production. In this study, two WMA additives were used; Sasobit® and Advera®. Both were mixed in the lab with unmodified 60/70 Pen and modified PG 76-22 binders. Strain oscillation and viscosity measurement tests were performed to determine the rheological properties of the binder with and without WMA additives. Different ageing processes were performed in this study; half and full short-term ageing using the Rolling Thin Film Oven (RTFO) procedure, and long-term ageing using the Pressurized Ageing Vessel (PAV) procedure. Test results have shown that the addition of Sasobit® increased the stiffness of both binders and changed PG grade by one unit up (6 °C PG grade). Also, Sasobit® presented better rutting resistance in modified and unmodified binders than Advera®, while both WMA additives decreased the fatigue cracking resistance. Multiple Stress Creep Recovery (MSCR) test was also conducted on both unaged and RTFO aged binders. Modified binder with Sasobit® and Advera® exhibited the same performance of the original binder after complete short-term ageing. However, Sasobit® increased the potential of rutting resistance in the unmodified binder more than Advera® did. The viscosity measurements revealed that adding Sasobit® to modified or unmodified binders lowered the viscosity more than Advera® did. These measures were considered as preliminary data required for further studies on the effect of WMA additives on the resistance of bituminous binders to fatigue cracking.

Bituminous Mixtures and Pavements VI, 2015

Warm-Mix Asphalt (WMA) technology is widely used in the paving industry due to its impact on redu... more Warm-Mix Asphalt (WMA) technology is widely used in the paving industry due to its impact on reduction of asphalt mixing and compaction temperatures. Characterisation of WMA in the past had focused on evaluating the linear viscoelastic properties and associated Superpave specifications. In this study, evaluating the nonlinear viscoelastic responses of different WMA technologies is introduced. A comparison was made to show the difference in permanent deformation resistance of each binder type. Two WMA additives were tested after mixing them with modified and unmodified binders. The tests were conducted using a Dynamic Shear Rheometer to perform oscillatory and multiple stress creep recovery (MSCR) tests. Resistance to permanent deformation was evaluated using the rutting factor and irrecoverable creep compliance. The results showed that Sasobit stiffened the asphalt binder and increased its resistance against permanent deformation. On the other hand, Advera's effect was almost negligible on both binder types.

International Journal of Pavement Engineering, 2013

The State of Qatar is experiencing tremendous growth in infrastructure including road network and... more The State of Qatar is experiencing tremendous growth in infrastructure including road network and highways. The current methods used in design of asphalt pavements in the State of Qatar are empirical and might not be suitable for the design of long-lasting pavements. Given the significant increase in traffic, road authorities in the State of Qatar have been considering the use of mechanistic-empirical methods in the design and analysis of asphalt pavements. This study documents the results of a study in which the mechanistic-empirical pavement design guide (M-E PDG) software was used in the design of asphalt pavements with input parameters that were carefully selected to reresent local materials and climatic conditions. The selection of material properties was based primarily on specifications and design guides in the State of Qatar and on published literature about these materials. The mechanistic-empirical method was also used to assess the benefits of adopting the concepts of perpetual pavement design and also to compare the performance of pavement structures in which various bitumen grades, granular bases and chemically stabilised sub-base were used. A life-cycle cost analysis was carried out to determine the design with the highest net present value among the various options investigated. It is expected that the outcomes of this study would promote the use of mechanistic-empirical methods in the State of Qatar and the region. Inevitably, this will require significant efforts to calibrate material and damage prediction models used in the M-E PDG for more accurate representation of material properties and measured pavements performance.Qatar National Research Fund (QNRF) through the National Priority Research Program project [NPRP 08-310-2-110].Scopu