Warm mix asphalt (WMA) is a high-speed emerging technology of producing asphalt mixture at lower temperature with equivalent performance of hot mix asphalt (HMA). It offers benefits such as energy savings, compaction aid for stiffer mixes, reduces emission, and reduces asphalt binder aging during production. This paper is an overview of mix design concept, mix design properties and mechanical properties (moisture-induced damage, rutting resistance and fatigue life) of WMA and same was compared with the properties of control HMA mixtures. Review indicates that mix design concept of WMA is similar to that of control HMA and possesses better mix design properties. Regarding mechanical properties, WMA mixtures were found more prone to moisture-induced damage, rutting and fatigue than control HMA mixtures due to lower production temperature but similar or better resistance were noticed with the use of modified and higher grade binders, addition of anti-stripping agents (ASA) and hydrated lime (HL), use of open graded mix and inclusion of recycled asphalt pavement (RAP). Further, the effect of nominal maximum aggregate size (NMAS) and design gyration (N_design) on mix design, NMAS and aggregate type and its water absorption on moisture-induced damage, NMAS, wheel load, test temperature, air voids, and binder grade on rutting, and NMAS, air voids, and stress or strain levels on fatigue properties of asphalt mixtures were analysed. Results indicated that NMAS had the significant effect on moisture-induced damage, rutting resistance and fatigue life of WMA mixtures. WMA mixtures made with aggregates of higher water absorption values were more prone to moisture-induced damage and even fail to meet minimum (tensile strength ratio) TSR requirements. Results also indicated that WMA mixtures made with modified and higher grade binder grade were high rut resistant. WMA mixtures tested at high stress or strain levels shows higher fatigue damage compared to WMA mixtures tested at lower stress or strain levels.

This study hybridized the ensemble and weight optimization approaches with an artificial neural network (ANN) algorithm to forecast the dynamic modulus (E*) of asphalt concrete. For input selection, this study employed the random forest technique and tested various techniques, including evolutionary, backward, forward, and brute force, to be hybridized with random forest. The evolutionary-random forest technique was used as the best input-selection method. The ρ200, V_beff, binder G* (dynamic shear modulus), and binder φ (phase angle) were selected as the most important variables for developing the ANN models. The findings of this research indicated that the artificial neural network-particle swarm optimisation (ANNPSO) model performed better than the other models. Also, the weight optimization techniques were more efficient than the ensemble techniques to improve the predictive power of ANN to forecast the dynamic modulus of asphalt concrete.

This article investigates the potential usage of eggshell powder as a bio-modifier for asphalt binder and mixture with the consideration of workability and mechanical properties. The effects of varying dosages (3%, 6%, 9%, and 12%) of eggshell powder on workability, rutting, and moisture damage of asphalt binder and mixture were investigated. Viscosity, multiple stress creep recovery, and bitumen bond strength tests were performed on asphalt binders. Subsequently, Superpave gyratory densification indices (Locking point method), wheel tracking, and indirect tensile strength (Modified Lottman) tests were performed on asphalt mixtures. Results show that incorporation of eggshell powder makes asphalt binder stiffer, increases moisture susceptibility, and reduces pumping ability irrespective of dosage rate. Furthermore, the incorporation of eggshell powder reduces workability but increases resistance to rutting and moisture damage properties of asphalt mixtures irrespective of dosage rate.

This research explores the utilization of wheat straw ash (WSA), an agricultural by-product enriched with amorphous silica, as a partial cement replacement in concrete production. The WSA content ranged from 4% to 16% by mass, with water-to-cement (w/c) ratios varying between 0.4 and 0.6. Using response surface methodology (RSM) combined with central composite design, this study optimized mix designs and developed predictive models for key performance indicators, including workability and mechanical properties of concrete. The results demonstrate that an optimal balance of the WSA and a reduced w/c ratio significantly enhance both the workability and mechanical performance of concrete. The pozzolanic reaction between WSA and calcium hydroxide promotes the formation of calcium silicate hydrate (C-S-H) gel. The optimal mix composition, comprising 10.12% w(WSA) with a w/c ratio of 0.45, achieved a desirability score of 71.83%. This ground-breaking research underscores the viability of WSA as a supplementary cementitious material, offering a sustainable solution for concrete production while simultaneously enhancing its workability and mechanical properties.