含飛灰混凝土之孔隙與強度關係

Abstract

摘 要 本文旨在探討掺加飛灰的混凝土孔隙結構，及其與抗壓強度的關係。研究上採用三種水膠比0.35、0.50、0.70，三種飛灰對水泥取代量10％、20％、30％製作混凝土試體，於六個齡期（0~91天）進行 強度試驗和MIP孔隙測定。結果發現，飛灰混凝土在早齡期（7天以前）時，其內部孔隙仍以孔徑大於0.05um的微孔隙佔較大比例，但長齡期（28天）後該0.05um微孔隙明顯減少，印證飛灰的卜作嵐反應可填充微孔隙，有利於提升混凝土的晚期強度。另外發現，飛灰混凝土的毛細孔隙體積與強度的關係最為密切，並研提兩者的關係式，可用以推估混凝土抗壓強度。

Abstract The object of the research is to investigative the pore structure of fly ash concrete and the relations between porosity and compressive strength. Three water to binder ratios (0.35, 0.50, 0.70) and three substitute ratios of cement with fly ash (10％,20％,30％)were selected for preparing concrete samples. They were tested at 6 ages (0~91 days)for compressive strength and MIP porosity measurement. Test results show that the fly ash concrete consisted of more micropores of under 0.05μm at early age(7 day), but this portion of micropore evidently decreased after 28days. It is attributed to the pozzolanic reaction of fly ash at later age, the C-S/A-H gel will fill the micropore and enhance the strength of concrete. It was also found that the capillary pore volume had most intimate relation with the strength of fly ash concrete. A relation equation was proposed for the prediction of strength.