Coal fly ash (CFA) is a coal ignition buildup at thermal power plants, which has been viewed as a hazardous waste globally. The major problems with CFA are the large volume of land needed for its disposal and poisonous weighty metal sifted to groundwater. CFA has been considered a waste and water pollutant until recently; however, CFA is a helpful material and has shown its useful value, especially in the construction industry. This review paper aims to evaluate CFA properties and validate its utilization in the construction industry to save the planet from damages associated with its disposal. The current paper surveys the potential uses of CFA as a crude material in the construction industry in catalysis, soil stabilization and replacement, brick production, cement replacement highway embankment, bricks construction, material for soil replacement and stabilization, and dams, asphalt pavement, and road construction. This review was conducted through systematic consultation of mostly recent relevant literature with a few old publications to evaluate the efficiency of CFA utilization in the construction industry. Moreover, all the literature rated CFA as a suitable material for use in the construction industry. A major drawback of CFA usage in concrete is the slow early strength development. However, this can be taken care of by accelerating the admixtures in the concrete mix. Future research tends towards production of CFA with more improved features suitable for advanced construction technology as in 3D printing construction. Conclusively, CFA is recommended for use in the construction industry based on its performance success recorded from the research findings reviewed in this paper.

Roller compacted concrete (RCC) pavement is subjected to continues traffic loading from vehicular activities which can results to fatigue cracking. Fatigue is one of the commonest defects affecting pavement which affect the cost of maintenance, and shortens pavement design life. To carter for these factors, higher deformation resistant pavements with longer design life need to be designed. Therefore, in this study, crumb rubber was used as a partial replacement to fine aggregate in RCC pavement to improve its fatigue life. Five mixtures were considered; one control mixture, two mixtures with fine aggregate replaced using crumb rubber at 10 and 20% by volume; one mixture containing 20% crumb rubber as partial replacement to fine aggregate 1% nano silica added by weight of cementitious materials. Lastly, one high volumefly ash (HVFA) RCC pavement mixture where 50% cement was replaced with fly ash, and 20% fine aggregate replaced with crumb rubber. The results showed that both crumb rubber and nano silica increases the bending resistance and fatigue life of RCC pavement. While HVFA decreases both flexural strength and fatigue performance of RCC pavement. The double logarithmic-equation can best be used to determine the stress level–number of cycles (S–N) fatigue behavior and relation for RCC pavement mixtures.

Roller compacted concrete (RCC) pavement usage is limited to low-speed roads due to its low skid resistance, caused by the smooth surface texture that makes it unsuitable for use in high-speed traffic pavements. If used in high-speed roadways will lead to increased skid related accidents. In this study, crumb rubber was used as partially replaced with fine aggregate at levels 10, 20, and 30% by volumeto produce roller compacted rubbercrete (RCR) so as to improve the skid resistance of RCC pavement, and nano silica was added at 0, 1, 2 and 3% by weight of cementitious materials to mitigate loss of strength with incorporation of crumb rubber. The British Pendulum Number (BPN) was used to measure the skid resistance. Incorporating up to 20% crumb rubber and 2% nano silica increases both skid and impact resistance. The findings showed that RCR with 20% CR and 2% NS can be used for motorways, trunk, and class 1 roads. Finally, response surface methodology was used to develop the relationship between BPN in wet/dry conditions and crumb rubber/nano-silica. The analysis of variance for response surface methodology analysis shows that the quadratic models developed has a very good degree of correlation, and can be used to predict the skid resistance of RCR. The results of multi-objective optimization showed that an optimum mixture can be achieved with a 17.20% volumereplacement of fine aggregate and 1.87% nano silica addition by weight of cementitious materials to have the highest skid resistance RCR for pavement applications.

The world is now focusing on a sustainable environment and reducing the effects of global warming. One way to achieve such targets is to properly utilize waste and reduce greenhouse CO₂ emissions. The cement industry is responsible for almost 10% of global CO₂ emission due to the high demand for cement in the construction industry. One of the ways to minimize this effect is the partial replacement of cement by other materials in concrete. Therefore, in this study, calcium carbide residue (CCR), which is highly rich in calcium oxide, partially replaced cement for waste management. Waste tires were grinded to fine sizes in crumb rubber (CR) and partially replaced the fine aggregate. Therefore, this paper investigared the influence of CR and CCR on the durability properties and heat/temperature resistance of self-compacting concrete (SCC). The experiment was designed using response surface methodology to investigate the effects of CR and CCR on SCC properties, design models for properties of the SCC, and optimize the mixes to achieve the best results. The properties considered were the durability of acid attack resistance (H₂SO₄ attack), salt attack resistance (MgSO₄ attack), and water absorption. The heat resistance considered was weight reduction and residual compressive strength after heating the samples at a 200 °C and 400 °C. The results findings showed that CR and CCR negatively affect the acid and salt resistance of the SCC. Furthermore, CR negatively affects the heat resistance of the SCC, while CCR slightly improved it at 200 °C. The models developed using RSM were significant with high degrees of correlation and predictability. The optimum properties achieved 2.9% CR as a fine aggregate replacement and 5.5% CCR as a cement replacement. The developed models can predict the durability performance of SCC mixes in terms of acid and salt attack resistance and the effects of elevated temperatures using CR, CCR, and fly ash as the variables. This will reduce the need for carrying out experimental work, thereby reducing cost and time.