Influence of High Volume Bottom Ash as a Pozzolan on Compressive Strength, Water Absorption, and MgSO4 Resistance of Concrete

Abstract

This article presents the effect of high-volume bottom ash to be used as Pozzolan on compressive strength, percentage compressive strength loss due to immersion in magnesium sulfate (MgSO₄) solution, and water absorption of concrete. The bottom ash used in this research was ground until the particles were retained on a No.325 sieve less than 5% by weight. After that, the bottom ash was used to replace Portland cement at the rates of 10, 20, 30, 50, and 70% by weight of the binder. The water to binder ratio was constant at 0.45. Compressive strength, the percentage loss of compressive strength due to immersion in 5% MgSO₄ solution, and water absorption of concrete were investigated. The results found that concrete containing bottom ash in the mixture as 10% by weight gave higher compressive strength than control concrete and the others bottom ash concrete mixture. The loss of compressive strength due to immersion in MgSO₄ solution was increased when the age of concrete increased. The losses of compressive strength due to immersion in MgSO₄ solution in the percentage of concrete containing bottom ash at the rates of 50 and 70% by weight of binder were higher than the others bottom ash concrete. For another result, the water absorption of concrete was increased by enhancing the bottom ash level in the concrete mixture. Additionally, the result also found that the percentage loss of compressive strength due to immersion in MgSO₄ solution rapidly raised when the concrete had water absorption higher than 3.10%. This research indicated that, although the use of high-volume bottom ash in the concrete mixture affected the decreasing of compressive strength, their compressive strength could meet the requirement of concrete exposed in a sulfate environment in accordance with ACI 318-14.