Application of depth-sensing microindentation testing to study of interfacial transition zone in reinforced concrete

A new method, the depth-sensing microindentation technique, was successfully used to study the elastic modulus and micro-strength of the interfacial transition zone (ITZ) around steel reinforcement in practical reinforced concrete. A normal concrete mix and a special self-compacting concrete (SCC) mix, both produced commercially, were used in the study. It was found that the elastic modulus and microstrength in the ITZ were significantly lower on the bottom side of a horizontal steel reinforcement than on the top side. The difference was particularly pronounced in the 10-30 mum distance from the actual interface. The method showed clear advantages over the conventional Vickers microhardness test. (C) 2000 Elsevier Science Ltd. All rights reserved.