Utilization of Straw Ash as a Partial Substitute for Ordinary Portland Cement in Concrete

Abstract

The disposal of agricultural waste ash is a great ecological challenge. This study analyzed the basic properties of corn straw ash and soybean straw ash, encompassing the identification of key oxides, the assessment of particle size distribution, and the performance of thermogravimetric analysis. This study also evaluated the potential of corn straw ash and soybean straw ash to replace cement in mortar and concrete through laboratory tests. The findings indicated that the strength activity index of corn straw ash was higher than soybean straw ash. Furthermore, when these ashes were used as cement replacements, the compressive strength of concrete decreased. Notably, concrete containing corn straw ash exhibited greater strength than concrete with the same substitution amount of soybean straw ash. Specifically, at a 5% substitution level, the compressive strengths of corn straw ash concrete and soybean straw ash concrete were 31.5 and 30.5 MPa, respectively. Additionally, soybean straw ash concrete demonstrated superior resistance to water penetration compared to corn straw ash concrete. Both corn straw ash and soybean straw ash exhibited the potential to enhance the early crack resistance of concrete.

Keywords

• straw ash
• concrete
• unconfined compressive strength
• resistance of concrete water penetration
• cracking resistance