Changing urban cement metabolism under rapid urbanization – A flow and stock perspective

Abstract

China's rapid urbanization is characterized by large-scale construction activities which require enormous amounts of construction materials and induce a series of resource and environmental problems. However, few studies have paid serious attention to construction material metabolism within urban ecosystems in the Chinese urbanization hotspot. This study focuses on changes in cement metabolism in Xiamen from 2002 to 2012 and aims to elucidate its metabolic characteristics and mechanisms. The results show that, (1) residential buildings account for 1/3 of total cement use, with more and more accumulating as unused stock; (2) decoration is the second largest cement consumer after building and should be paid more attention in metabolism analyses; (3) road transport infrastructure is expected to maintain its growing potential for cement use; (4) increasing amounts of construction and demolition waste are hardly reused or recycled. To mitigate ecological pressures resulting from urban cement metabolism and foster sustainable construction, a multidimensional policy portfolio is proposed including development of improved real estate policies, optimization of urban spatial patterns, popularization of decoration-binding residential buildings and premixed mortar usage, establishment of a waste recycling system, industrialization of the construction industry and the promotion of sustainable consumption. This empirical research provides a reference template for future sustainable construction material management studies in rapidly urbanizing areas elsewhere.