Feasibility of Using Biomass Fly and Bottom Ashes to Produce RCC and PCC

Abstract

Roller-compacted concrete (RCC) and paver-compacted concrete (PCC) are widely used in mass concrete and pavement. Alternative supplementary cementitious materials (ASCM) can be used in RCC production for rheological, mechanical, and environmental improvement. This paper presents optimization of biomass fly ash (BFA) as ASCM and biomass bottom ash (BBA) as an alternative sand for RCC production. This optimization was carried out on RCC with a water-to-binder ratio (w/b) from 0.32 to 0.37. The BFA was used to replace up to 30% of cement and the BBA was employed to totally replace sand. The optimal replacement rates when combining the BFA and BBA was also carried out. The fresh (Vebe time and unit weight), mechanical (compressive and flexural strengths), and transport (water absorption, air voids, and electrical resistivity) properties up to 91 days were determined for all concrete mixtures. The results of concrete mixtures made with 10 and 20% BFA with 50% BBA showed 23 and 29% higher flexural strength than the limits required for practical use of RCC, respectively. These mixtures also exhibited very low permeability, which can be considered an indication for durable in situ behavior.