Strength, shrinkage, heat evolution, and microstructure of high performance concrete containing high proportions of ground bottom ash blended with fly ash

Abstract

This study examines the use of ground bottom ash incorporating fly ash in high performance concrete. A self-compacting concrete was considered in this study as to maximize the properties of high performance concrete. Bottom ash was processed to a fine consistency by oven-drying, sieving, and grinding. Ordinary Portland cement (OPC), sieved and ground bottom ash (GBA), and fly ash (FA) were used for producing high performance concrete at a W/B ratio of 0.27. Replacement of 50% cement by GBA produced 101.0 MPa concrete at 28 days: 21.6% stronger than OPC concrete. The 50% GBA mixture needed a greater quantity of superplasticizer to satisfy slump flow requirements for self-compacting concrete, but that dosage was reduced with a partial replacement of GBA by FA. Elastic moduli of all blended concretes matched OPC concrete. However, the blended concretes experienced much less autogenous shrinkage. Pastes containing GBA and FA have less portlandite than OPC paste. In addition, replacing OPC by GBA–FA substantially reduced cumulative heat evolution.