EQUILIBRIUM POINT OF CO2 EMISSION AND MATERIAL REUSABILITY IN CONCRETE INDUSTRY AT THE CASE OF REPLACING READY-MIXED CONCRETE DEMANDS TO PRE CAST CONCRETE PRODUCTS

摘要

A large proportion of the environmental loads in Japan in recent years is caused by the construction industry, which accounts for approximately 40% of the total industrial emissions of CO2. The concrete industry is being required to reduce its own CO2 emissions. This may necessitate, in particular, effective use of precast concrete (PCa) in place of ready-mix concrete (RMC) because of its potential for minimizing wasted resources at its dedicated production facilities through standardization and utilization of materials and means. The purpose of the research is to compare performance of ready-mixed concrete and pre-cast concrete in aspect of CO2 emission and find the optimal demand balance of ready-mixed concrete and pre-cast concrete introduced in Tokyo metropolitan area through the regional resource flow simulation system named ecoMA. This can evaluate not only CO2 emission in production but in transportation, therefore, total CO2 emission in an industry are comprehensively evaluated and contributes to awareness of the optimal material balance. Conclusively, total CO2 emission required in pre-cast concretes are always more than that of ready-mixed concrete because energy consumption cannot defeat CO2 reduction by saving unit cement volume. The energy saving improvement in curing process will be indispensable in the near future.