Bottom ash as an Alternative Pozzolanic Material to Produce Eco-Friendly, High-Quality Chloride-Resistant Concrete

This study presents a high-quality chloride-resistant concrete containing pozzolan from bottom ash (BA). A new method of improving the quality of BA to be used as a pozzolan is also presented. The effects of particle size and replacement levels of BA on the compressive strength and chloride ion penetration were investigated. Additionally, the influence of concrete containing the original BA passed through sieve No.30 before grinding was studied. Although the concrete containing the finest particles of ground bottom ash (GBA) at a 15% replacement level had the highest compressive strength (51.7 MPa at 90 days), this concrete had moderate and low chloride ion penetration according to ASTM C1202. The coarser GBA tended to decrease the compressive strength. However, the concrete containing the coarsest GBA in this study (32.44% of the weight retained on a No. 325 sieve) at a 25% replacement level had low and very low strengths (29.7 and 34.5 MPa at 28 and 90 days, respectively). When the non-improved BA (only ground) and improved BA with similar particle size and replacement level were compared, the improved BA concrete improved the compressive strength by approximately 34% and 26% at 7 and 28 days, respectively. Using improved BA in the concrete mixture at a 35% replacement level could reduce ordinary Portland cement (OPC) by as much as 135 kg/m³. Nevertheless, it had a compressive strength of 44.6 MPa at 28 days and a very low chloride ion penetration after 28 days.