To achieve sustainable development goals (SDGs), corporate activities considering social and environmental aspects are required and life cycle assessment (LCA) is conducted in many companies. However, the LCA includes only environmental aspects in many cases, and evaluation using economic indicators is also necessary for decision-making in corporate activities. Recently life-cycle cost (LCC) attracts attention as an evaluation of economic aspects and it is important to comprehensively evaluate LCA and LCC in order to achieve SDGs.
The authors have so far developed a waste indicator that can evaluate the use of recyclable resources (wastes and byproducts) in cement manufacture and also an integration method for comprehensive evaluation of wastes, byproducts, and CO2 emissions. In addition, the LCA of a concrete structure was conducted considering cement manufacture to the demolition and disposal of the structure as its life cycle. An integrated evaluation including economic indicators was also carried out by using the integration coefficients of the Life-cycle Impact Assessment Method Based on Endpoint Modeling (LIME3), which has been developed in Japan. The results showed that the evaluation value for ordinary portland cement was higher than that for portland blast-furnace slag cement type B.
In the present study, the environmental impact assessment of cement and concrete was performed considering economic aspects and full cost which is the sum of LCA cost and LCC was calculated. The relationship between the LCA cost and LCC was then discussed.
The LCA costs of cement and concrete were calculated from the integration of the waste indicator and global warming indicator by using the integration coefficients of LIME3 as an economic indicator. In the calculation of the LCC, market prices were used for cement, concrete constituents, and intermediate processing and disposal of demolished concrete. Construction and demolition costs were based on the estimation standard. The full cost was calculated as the sum of the LCA cost and LCC.
As a result, for both cement and concrete, the full cost for ordinary portland cement was lower than that for portland blast-furnace slag cement type B. The LCA cost was significantly lower than the LCC for concrete. Besides, for concrete using portland blast-furnace slag cement, the increase in the ground granulated blast-furnace slag content increased the full cost of the cement.
