Influence of coal bottom ash and copper slag as a fine aggregate substitute on the characteristics of mortar

Abstract

In recent decades, the global demand for sand has increased dramatically, and further increases are anticipated. Natural sand of acceptable quality is in short supply and diminishing at an alarming rate. It is essential that we find safe waste disposal methods and make prudent use of the available natural resources. The findings of this study shed light on the performance of mortar mixtures containing coal bottom ash (CBA) and copper slag (CS) as complete replacements for natural river sand. This study investigated the variations in compressive strength, flexural strength, abrasion resistance, the volume of permeable pore voids, and water absorption of mortar containing coal bottom ash and copper slag as fine aggregate. Flow values vary significantly among mixes, with the mix containing 70% copper slag and 30% coal bottom ash (RC7B3) exhibiting the highest flow by 43.5% compared to the Normal Mortar mix (NM). RC7B3 has the greatest density. Testing for compressive strength reveals that all mixtures gain strength at comparable rates. Additionally, flexural strength attainment rates are consistent. Notably, all mixtures experience negligible strength gains after 56 days. Mix RC7B3 absorbs much less water than Mix NM. Additionally, the volume of permeable voids is diminished. Abrasion tests reveal that the wear depths of all mixtures are less than 1 mm. The study concludes that it is feasible to use a mixture of 70% CS and 30% CBA as a replacement for natural sand, with compressive and flexural strengths that are acceptable. RC7B3 is characterised by its exceptional strength, low water absorption, and permeable voids. These results highlight the need for innovative technological approaches to incorporate industrial waste materials into modern mortar and concrete practises, indicating the potential of the investigated mixes for a variety of applications in the construction industry.