Development of sustainable interlocking concrete paving blocks using bamboo leaf ash and metakaolin.

Eco-friendly interlocking concrete pavement block was developed using the admixture of bamboo leaf ash and metakaolin. This was done to develop an eco-friendly interlocking paving block for sustainable pavement construction. Bamboo leaf ash and metakaolin were added as a supplementary cementitious material. The supplementary cementitious material (bamboo leaf ash and metakaolin) were admixed and added at 0, 5, 10, 15, 20, 25 and 30 % replacement of cement. The workability of the fresh concrete (slump) at the varied percentage additions, and the mechanical properties of the concrete at 7, 14, 28, and 56 days of curing were assessed, including their microstructural characteristics. The outcome of the research showed that increasing the percentage of (bamboo leaf ash + metakaolin) reduces the workability of the concrete. With a 20 % addition of this cementitious material, the developed fresh concrete became unworkable. In addition, replacing up to 10 % of the concrete in the pavement with bamboo leaf ash and metakaolin increased the mechanical strength of the concrete by 28.7 %. At 30 % a percentage increase of 3.6 % was recorded. However, the strength at 5 % was still adequate for pavement construction with a 13.62 % increase in mechanical strength. The compressive strength at 5 % and 10 % addition of the supplementary cementitious material at maturity met the criteria for constructing a semi-rigid pavement, using IRC standards. The microstructural assessment showed that the number of pores in the mature concrete samples decreased at 10 % addition of bamboo leaf ash and metakaolin. The research data provides construction workers, researchers, and highway engineers with vital information regarding the viability of these sustainable materials for pavement improvement.