Effect of curing, finishing and loading rate on the bond strength of fiber reinforced SCC layer with normal concrete by pull-off method

Expansion and damage due to the alkaline reaction of aggregates in various concrete structures as one of the major concerns in the durability of concrete structures have attracted the attention of many researchers to identify and study this importance. Aggregates containing active ingredients can cause destructive expansions even when they are small in weight. This reaction occurs between some materials in aggregates with alkaline hydroxide in the concrete pores resulting in a water-absorbing gel. This phenomenon usually causes the concrete to expand and crack through internal changes by creating changes in the boundaries between the aggregate and the cement paste. On the other hand, due to limited credit resources and the importance of environmental issues in most countries, using recycled and unused materials in the concrete industry has flourished. Therefore, in the present study, with the approach of using dredging materials and potentials in the Caspian Sea coast, in the first step, by performing lithographic experiments (microscopic observations) according to ASTM C295 standard, minerals with alkali-siliceous and carbonate reaction potentials have been identified. Then, the reactivity of the materials was studied by making concrete and mortar prisms containing these aggregates in both short-term and long-term states, and finally, by performing chemical experiments, the potential of alkaline-carbonate activity of carbonate aggregates was evaluated. Based on the results obtained from these experiments, the quality of dredged materials from the sea was suitable for making concrete.