Phase transformation on old hardened concrete cement paste

Abstract

Analogous with most modern cities, waste disposal is a pressing issue due to limited landfill and public filling (land reclamation) areas in Hong Kong in which construction and demolition (C&D) waste forms the major source. Concrete, apportioning the largest portion of C&D wastes, has the greatest potential for recycling. However, the knowledge on micro-structural behavior of concrete waste is immature to give adequate details on the macro-behavior of concrete waste. This paper attempts to examine the problems of recycling old concrete by investigating the phase transformation of the concrete samples collected from buildings with 46 years of services. From the results of FT-IR examination, it is found that the carbonation over the hardened cement paste (HCP) is high.