Developed method for measuring flexural strength and modulus of elasticity of micro-regions in normal and recycled aggregate concretes

摘要

Concrete as a material is a heterogeneous system formed by mixing cement, water, aggregate and some admixtures. Each region in concrete has its own distinct properties and structural behaviour. For instance, the interfacial transition zone (ITZ) is considered to be the weakest region of concrete, and its mechanical properties relate to the mechanical properties of concrete. Similarly, the surface layer of concrete is a weak region due to a bleeding of mix water; consequently, the transport of various aggressive substances into concrete depends on the quality of surface layer. Therefore, it is of paramount concern to characterise the properties of concrete in the micro-regions in order to fully understand its complex structure. This research was conducted to evaluate the flexural strength and the modulus of elasticity of the micro-regions in real concrete. By so doing, we would be able to establish quantitatively the strength and performance of concrete. To accomplish this, a newly developed method called the micro-bending method is used in performing the laboratory experiments. This method is specially designed to measure the mechanical properties of concrete specimens located in micro-regions. Moreover, this new method can be applied to characterise and compare the mechanical properties between normal and recycled aggregate concrete.