Application of Microscopic Techniques for Studying Microstructure of Concrete Containing Lightweight Aggregate

Abstract

The reason for failure in engineering component can be attributed to design deficiencies, poor selection of materials, manufacturing defects, exceeding design limits and overloading, and inadequate maintenance. The behaviour of material depends on the chemical, physical, mineralogical, microstructure characteristics and the interaction between them in the concrete. The aim of this research is to investigate some of the properties on the concrete that is containing the lightweight expanded clay aggregates (LECA). Study the microstructure of concrete be able to understand the relationship between structure and behaviour of concrete. Interaction inside the phase of concrete such as dislocations, grain boundaries, phase interfaces, pores and crack can be identified by a microstructure of concrete. Therefore, a microstructure of concrete has been studied under a digital microscope. The properties of LECA were investigated in order to relate the behaviour of aggregate in the concrete. LECA were used in the production of lightweight aggregate concrete (LWAC) with the size 50 mm × 50 mm × 50 mm. The results show that LECA has several improvements when compared with normal crushed aggregate. The density of LECA was 520 kg/m3 and its characteristics were round, rough and porous. Besides that, the LWAC shows an excellent strength development, 29.41 MPa compared than normal weight concrete (NWC), 25.57 MPa. The surface of LWAC was darker than NWC due to LWAC experience more hydration of ferrite compound. In addition, the microstructure investigation of the LWAC shows a good bonding between aggregate and mortar at the interface transition zone (ITZ).