THE ADVANCES AND BARRIERS IN APPLICATION OF NEW CONCRETE TECHNOLOGY

摘要

Numerous advances in all areas of concrete technology including materials, mixture proportioning, recycling, structural design, durability requirements, testing and specifications have been made. Throughout the world some progress has been made in utilizing these innovations but largely these remain outside routine practice. The high performance concrete (HPC) for transportation structures, e.g., bridges and pavements, is gaining wider acceptability in routine practice. HPC provides enhanced strength and durability properties and contributes towards long lasting structures and pavements. The constructability can also be enhanced by proper mixture proportioning and testing. Most HPC mixture include recycled materials e.g. Fly ash, ground granulated blast furnace slag (GGBFS) or silica fume. The use of recycled materials in construction is an issue of great importance in this century. Utilization of fly ash and GGBFS in concrete addresses this issue. The replacement of portland cement by fly ash or GGBFS reduces the volumes of portland cement used is a major benefit. The reduction of portland cement production will reduce carbon dioxide (CO2) emissions, reduce energy consumption and reduce the rate of global warming. Utilization of fly ash and GGBFS usually provides cost savings as well as improved concrete properties. The case histories discussed demonstrate the practical uses of supplementary cementitious materials—e.g., fly ash, GGBFS, and silica fume—for various types of bridges and pavements in wide ranging environmental conditions. The successful utilization of supplementary cementitious materials requires proper mixture proportioning, testing, placement and curing. Lack of widespread transfer of developed and available new concrete technology is a major problem in most countries.