The Study on the Early Age Cracking due to the Addition of Silica Fume into Concrete and the Trouble-shooting Strategy

摘要

This study is mainly to investigate the early age cracking due to the addition of silica fume (SF) into concrete and to propose Densified Mixture Design Algorithm (DMDA) method as a trouble-shooting strategy. Specimens with different water-to-binder ratio (W/B) and silica fume content were prepared with ACI concrete (W/B ＝ 0.23, 0.35 and 0.47; SF content ＝ 0%, 10%, 20% and 30%) and DMDA concrete (W/B ＝ 0.23, 0.35 and 0.47; coating paste thickness t ＝ 5, 15 and 25 μm). Adding silica fume to the concrete system to replace part of cement may increase the crack intensity, and the rate of water absorption; but reduce the heat of hydration. DMDA method as a problem-shooting technique shows to have a better performance in reducing the crack intensities up to 41% with W/B ＝ 0.23 and the better durability index than that of ACI method.