The Effect on the Compressive Strength of Concrete Produced by the Incorporation of Boiler-Calcined Biomass Ash into Sand from the Maule River, Chile

Abstract

The pulp industry generates large amounts of wood biomass ash (WBA) as waste, which causes economic and environmental problems. However, WBA has pozzolanic and cementing properties that can complement cement in concrete production. Many studies have been published on the replacement of cement by WBA, but few discuss the replacement of other concrete components such as sand. The objective of this research is to determine the effect of volume replacement of sand with ash on the mechanical resistance of concrete. A reference concrete was made with a specified strength of 30 MPa at 28 days. Samples with 5%, 10%, 13%, 15% and 20% WBA were compared. A water-cement ratio of 0.49 was maintained, plasticizer was added to maintain an acceptable workability, and compression tests were conducted at 7, 28 and 63 days. The results indicate that WBA decreases the workability of the fresh concrete mixture. However, the compressive strength increases in most cases, thus demonstrating the possibility of using WBA as an addition to the concrete to improve its mechanical properties, and at the same time reduce the environmental impact of this waste material.