In this experimental study, compressive strength and resistance to sodium sulphate attack of concrete incorporating recycled ceramic tiles (RCT) as fine aggregate were investigated. RCT was used as partial replacement for river sand at four levels (0%, 33%, 66%, 100%). Samples for sulphate resistance tests were immersed in 5% Na2SO4 solution for 180 days after they had been cured under water for 28 days, and were monitored for change in physical appearance, mass change and loss of compressive strength. From experimental results, RCT was found to be capable of producing light weight concrete compared to river sand. The results showed increase in compressive strength as the level of RCT content increased. On resistance to sulphate attack, sodium sulphate seems not to attack C-S-H bond which is produced in excess in RCT concrete, rather it attacks calcium hydroxide and calcium aluminate which are produced in equal amounts for both RCT and control samples. Hence, RCT might not play much direct role in concrete’s resistance to strength loss due to sulphate attack. However, the residual compressive strength of the RCT samples after the attack was seen to be much higher than that of the control samples because of their initial higher strength before the attack. This shows that RCT can improve the properties of concrete when incorporated as fine aggregates.

At present, the large quantity of wastes generated by the ceramic industry is not reused in any significant quantity. Research has shown the feasibility of incorporating these wastes into concrete production. This will benefit both the ceramic and concrete industries. However, not much research data is available on the use of ceramic wastes as fine aggregate material compared to their use as coarse aggregate material. Moreover, there are presently no models for predicting the properties of ceramic waste aggregate concretes. In this study, a modified regression theory based on Taylor’s series was adopted to formulate mathematical model for predicting compressive strength of concrete into which Recycled Ceramic Tile (RCT) is incorporated as fine aggregate. Preliminary tests on RCT indicate that it is a suitable fine aggregate material for concrete production. It has also been established that addition of RCT improves compressive strength of concrete and reduces concrete’s workability. The formulated model is a function of the mix proportions of its constituents and its predicted responses are in good agreement with experimentally observed data. The model has been tested using student’s t-test and analysis of variance and has been confirmed to be adequate and hence is validated.

This study investigated the effects of incorporating rice husk ash (RHA) as a partial replacement for cement on the properties of concrete. To determine the optimal replacement level, RHA was used to replace cement in varying proportions, ranging from 0% to 25% in 5% increments. The mix with 0% RHA served as the control. The properties evaluated included setting time, density, and compressive strength. The results revealed that blending RHA with cement increased the initial setting time. This was attributed to the lower calcium oxide (CaO) content of RHA, which slows early-age hydration reactions. Conversely, the final setting time was reduced due to the pozzolanic activity of RHA, which enhances later-stage reactions. Additionally, the inclusion of RHA resulted in a decrease in concrete density, owing to its lower specific gravity and bulk density compared to Portland cement. Despite this, RHA-modified specimens exhibited higher compressive strengths than the control specimens. This strength enhancement was linked to the formation of additional calcium–silicate–hydrate (C-S-H) gel due to the pozzolanic reaction between amorphous silica in RHA and calcium hydroxide (Ca(OH)₂) from hydration reaction. The gel fills concrete voids at the microstructural level, producing a denser and more compact concrete matrix. Based on the balance between strength and durability, the optimal RHA replacement level was identified as 10%.

The mechanical properties of most asphalt binders may not be sufficient to withstand the increased load requirements experienced by flexible pavement in practice, especially in regions notorious for severe climatic conditions. This necessitated the need to often enhance the properties of asphalt binder so that it can counteract most pavement distresses, such as rutting and moisture susceptibility. In this study, economical industrial waste plastic dust (IWPD) from high-density polyethylene (HDPE) origin was used to modify base bitumen with a penetration grade of 60/70, and its effect on the moisture susceptibility and rutting potential of hot-mix asphalt (HMA) was investigated thereafter. The IWPD was added at varying percentages (3%, 6%, and 9%) to the base bitumen by weight of the optimum bitumen content. Afterward, Marshall stability and indirect tensile strength ratio were performed on HMA samples produced with the IWPD-modified bitumen blends to evaluate, respectively, its rutting and moisture susceptibility. Based on the results obtained from the analysis, it was found that the modified blends of bitumen enhance the properties of the conventional bitumen. More importantly, the modified blend of bitumen with 6% IWPD content gave optimal results in terms of the increment of rutting resistance and improvement of moisture susceptibility of HMA.