Abstract
In order to enhance both durability and early age strength, improved early age strength development of fly ash cement (AF) was studied with increasing the amount of alite, f.CaO content and Blaine surface area compared to Ordinary Portland Cement (OPC). In this paper, the early age strength under steam curing condition of AF as precast concrete product was studied. The long-term hydration by selective dissolution method, Quantitative X-Ray Diffraction, and SEM-EDS was investigated. The experimental results showed that the
compressive strength of AF just after demolding was about 4N/mm2 higher than OPC under the same curing conditions. The reaction of clinker and fly ash were enhanced under steam curing conditions compared to sealed ones at long-term ages. Therefore, it seems that AF shows not only higher early age strength compared to OPC and common fly ash cement but also the resistance to alkali silica reaction about the same as the common fly ash cement under air curing which is the practical use as precast concrete product. Moreover, it was found that Ca/(Si+Al) ratio of C-S-H was similar in both the AF paste and fly ash cement containing OPC paste at 182 days and was about 1.4.
