Bonding between Aggregates and Cement Pastes in Concrete

Abstract

This investigation was carried out to study the effect of aggregate roughness on ITZ (interfacial transition zone) at same water/cement ratio and the influence of silica fume on the bond strength. On the experimental side, two types of aggregates (limestone and granite) were used, which were prepared with broken surface. Cement (Type I) was used with same w/c ratio for all batches. In order to study the effect of silica fume on the bond, the same mixes were produced with 8% silica fume. Three different tests were performed: "pull a part", Brazilian test and compressive strength test. The specimens for Brazilian and compressive strength were tested after 28 days, while the "pull a part" specimens were tested after 29 days. The result showed that the bond strength is influenced by the surface roughness of aggregate. For the same mix, limestone recorded higher bond strength than granite. Moreover, the bond strength is increased by adding the silica fume.