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Coconut products such as oil, milk powder, activated carbon, and desiccated coconut are increasingly in demand, leading to higher coconut production and a surplus of coconut fibers. Despite their excellent physical and mechanical properties, these fibers are often discarded or burned due to limited research into alternative uses, contributing to environmental pollution. This study evaluates the potential of coconut fibers in hot mix asphalt (HMA) to reduce waste and enhance their mechanical performance. Central composite design (CCD) was adopted to optimize fiber-modified HMA mixes using response surface methodology (RSM) based on Marshall testing. Sixty Marshall samples with varying fiber content, bitumen content, and fiber length were prepared to develop the RSM model based on 20 runs. Fiber content (%), fiber length (mm), and bitumen content (%) were considered as factors, while marshall stability (KN) and flow (mm) were taken as responses. The optimized mix, containing 0.28% coconut fibers (approximately 13 mm in length) and 4. 16% bitumen, achieved a marshall stability of 18. 02 kN and a flow of 3.12 mm. Validation of the optimized solution with the experimental trials showed an error of 7.05% for marshall stability and 6. 11% for marshall flow. Indirect tensile strength testing showed a 5% higher tensile strength for the optimized dry mix compared to the 1.29 KN observed for control samples. Furthermore, the tensile strength ratio between dry and wet samples was recorded to be higher than the threshold of 80% for both control and optimized HMA mixes. Moreover, the indirect tensile stiffness modulus (ITSM) for control samples recorded at 5 °C was higher than the optimized mix. However, the optimized HMA mixes resulted in around 13%, 6%, and 2.16% higher ITSM at 15 °C, 20 °C, and 25 °C, respectively, in reference to the control mix. Furthermore, the indirect tensile fatigue testing revealed that the control mix performed better than the optimized mix. Nonetheless, the optimized mix showed steady behavior against stress variation as compared to the control mix. Overall, this study demonstrates the effective use of RSM to optimize the Marshall mix design, reducing laboratory testing. Additionally, it was observed that optimized fiber-modified HMA mixes exhibit superior mechanical properties compared to control samples, paving the roads for sustainable and efficient asphalt technologies.

This paper summarizes a theoretical study undertaken to provide a better understanding of the consequences of poor bond on flexible pavement performance. The main objective of this paper is to investigate the influence of bond on the performance of Malaysian road. The pavement structure of Malaysian road was analyzed using a layered linear elastic program, BISAR 3.0 taking into account different state of the bond at the interfaces of the pavement layers and a static horizontal load in addition to the standard vertical dual load. The results indicate that the condition of the bond between the wearing and binder course can reduce the life of the pavement by up to 64%. On the other hand, the results also indicate that the condition of the bond between the binder and road base course, which was made up from asphaltic materials can reduce the life of the pavement by up to 68%.

Moisture damage in hot mix asphalt pavements is a periodic but persistent problem nowadays, even though laboratory testing is performed to identify different moisture-susceptible mixtures. In this study, a Hamburg Wheel Tracking device (HWTD) was used for rutting tests which were conducted on control and a high percentage of recycled asphalt pavement (RAP), i.e., 30%, 50% and 100% of virgin mixtures, under air dry and water-immersed conditions. Similarly, the extracted bitumen from RAP was tested for binder physical properties. Results showed that the asphalt mixtures containing RAP have less rut depth as compared to the control mix both in air dry and immersion conditions and hence showed better anti-rutting properties and moisture stability. Stripping performance of control and RAP containing mixtures was also checked, concluding that the RAP mixture was greatly dependent on the interaction between the binder (virgin plus aged) and aggregates.

Due to increased traffic and environmental concerns, this study addresses challenges in conventional asphalt concrete. Our focus is on enhancing the water resistance of asphalt mixes through the optimization of both the asphalt binder and the biochar-based geopolymer composite. We employ experiments and response surface methodology to assess their impact on volume, Marshall parameters, and water resistance. Asphalt binders were evaluated within the range of 4–6%, while biochar-based geopolymer composite levels varied from 0 to 4%. According to the findings, the incorporation of the biochar-based geopolymer composite improves asphalt properties, stiffness, and temperature sensitivity. Response surface methodology (RSM) was utilized to construct robust mathematical models with high R 2 values (90%) and low p -values. Multi-objective optimization indicated that optimal content levels were 4.56% for the binder and 2.71% for the biochar-based geopolymer composite. Model accuracy was confirmed with less than a 5% error in validation tests. The research also identified structural changes in the asphalt binder caused by the BGC Si–O phase. Additionally, the leaching value for both BGC and BGC-MAB asphalt concrete was found to be substantially below the regulatory limit, demonstrating the environmental safety of incorporating BGC into the asphalt sector.

Peat is formed by the degradation of plants and animals in the lack of oxygen and is widely known for its very weak geotechnical characteristics. This is the reason to be considered as an unsuitable foundation soil for construction activities. Several attempts have been made to characterize and stabilize peat soil to make construction viable. This study encapsulates an extensive literature review of the available published data for Atterberg limits, consolidation, and stabilization of peat soil using traditional additives, especially cement and lime. Moreover, peat formation and distribution around the world are also discussed. The analysis of the gathered data shows that peat soils having a high amount of fibers may suffer a large amount of secondary consolidation when the load is applied. Besides, the compressibility factors vary for Malaysian peat due to different water and organic contents. The improvement of peat soil is challenging and expensive, requiring an extra amount of stabilizer for the initiation of the stabilization process. However, the optimum and threshold stabilizer’s dosage for peat is also a challenging task to predict due to several factors affecting the stabilization process. Lastly, the study concludes with recommendations on the implication of the fall cone and thread rolling tests for the determination of Atterberg limits of fibrous peat, effective consolidometer for peat, and utilization of traditional additives for peat soil stabilization.

The utilization of a large amount of waste in concrete production is considered the best alternative for solving the issues associated with improper disposal. Plastic waste is considered as one of such waste and could be utilized in several applications. The drawback associated with the utilization of a large amount of plastic waste is the decrease in the mechanical properties of the mortar or concrete as the case may be. This paper presents a detailed review about waste recycled plastics and research published on the effect of non-irradiated recycled plastic on the mechanical properties of cement mortar and cement concretes as either fillers or aggregates and the application of gamma radiation on the recycled plastic waste. The effect of recycled waste plastic on compressive strength, flexural strength and splitting tensile strength is discussed in this paper.

Due to the visco-elastic nature, the performance of flexible pavements depends on temperature and loading conditions. This study investigates the influence of different speeds of vehicle and binder type on stiffness modulus and the corresponding pavement life. The filed data was collected from the pavement section at Bukit Mertajam, Penang, Malaysia. The data were used to determine the stiffness of binder and corresponding stiffness of wearing and binder courses at different vehicle speeds (30, 50, 70 and 80 km/h) using analytical equations. The data of layer properties (stiffness and poison’s ratio) and axle loading (wheel load, tyre configuration) were incorporated in BISAR software to determine the horizontal tensile strain at bottom of binder layer and vertical compressive strain at top of subgrade. The strains were then used to predict pavement life passed on fatigue and rutting failure criteria. It was concluded that increasing the speed of the vehicle (from 30 km/h to 80 km/h) causes about 24% increase in stiffness modulus of wearing course. Similarly, asphalt mixture with Pen 80/100 grade bitumen has a lower stiffness modulus than Pen 60/70 grade bitumen. Furthermore, reducing vehicle speed (i.e., increasing loading time) causes a reduction in fatigue and rutting life of the pavement. Therefore, it is required to consider the speed of the vehicle while designing flexible pavement in addition to other mixed design considerations.

Pavement industry is placing more emphasis on incorporating the sustainability in road construction. The construction of road contributes to global warming in terms of greenhouse gas emissions. Generally, the construction of roads adopt hot mix asphalt (HMA) that requires high energy consumption and also lead to environmental pollution. Since last decade, warm mix asphalt (WMA) technology is an attempt to address the aforementioned energy and environmental problems by reducing the harmful emissions and energy consumption. This study investigates the effect of organic foaming agent zeolite on the rheological properties, mixing temperature and compaction temperature of bitumen used in WMA. Dynamic shear rheometer (DSR) characterization is performed to determine the effect of zeolite on complex modulus (G*), phase angle (δ) and Superpave rutting parameter (G*/sirδ) of bitumen. In addition to that, viscosity characterization using Brookfield rotational viscometer is conducted to determine the mixing and compaction temperature. Rheological characterization of binder containing zeolite shows the improvement of elastic segment and short-term ageing resistance. Viscosity characterization reveals that the addition of zeolite in bitumen offers significant reduction in mixing and compaction temperature. Based on the findings of this study, 3 % zeolite can be added to WMA technology as optimum additive content in order to reduce the energy consumption and improve the workability of road construction thereby promoting sustainability in pavement industry.

Maturity models (MMs) have witnessed exponential increase due to their successful application in several domains. However, there is an absence of review that guides researchers in developing, applying and validating Public-Private Partnership maturity models (PPPMMs). This study examines PPPMMs, provides guidance on the topic and highlights gaps in the literature. A literature search on selected electronic databases was conducted, and the study adopted the widely accepted Preferred Reporting Items for Systematic Review and Meta-analysis statement (PRISMA). The study identified a total of four thousand six hundred and eighteen (4,618) studies, and twenty-one studies (21Nr) were rigorously selected. The results revealed PPPMMs as an emerging area of research with a low number -21 publications since its deployment for about two (2) decades. Similarly, the findings unveiled a lack of uniformity in conceptualising the terms, dimensions used, and methodology adopted. This finding is attributed mainly to the limited use of the theoretical lens, which considerably weakens the model's theoretical foundation and limits its potential to guide improvement. Additionally, there are more efforts in developing MMs than applying and validating them. Furthermore, there is an unbalanced focus on descriptive models over prescriptive and comparative models, which inhibit the model's potential to guide improvement. Future work should provide a solid ground to the field using a theoretical lens and focus on prescriptive models with a strong emphasis on application and validation. This research is the first of its kind that synthesises and brings together available PPPMMs literature into one place. It also contributes to the body of knowledge by highlighting areas of research that require immediate attention to enhance the much-needed success of PPP in the post-COVID-19 era.

This paper scrutinizes bending performance of light weight half-slab mortar against bending and punching load. To produce the slab, 30 % round bud Styrofoam was used as fine aggregate substitution. Besides, glazed nylon fiber was applied to increase its tension strength and cavities at tension area of slab were also created. This method results in the significant reduction of self-weight of half-slab, while the cavities do not affect its bending performance and the fiber increases its ductility. Furthermore, the lower result of punching test should not to be a disadvantage as the slab is primarily to be used as a formwork.