Structural and environmental impacts of concrete quality a comparative life cycle assessment

Two concrete residential buildings built in Tehran that had the same structural system and differed only in the strength of the concrete were studied. The first building had a concrete strength of 25 MPa. In the second building, the inappropriate quality of the concrete, which is related to the water-to-cement (w/c) ratio caused a decrease in the concrete strength to 20 MPa. The lateral bearing capacity of the two buildings was calculated using non-linear static pushover analysis. ISO standards and SimaPro9.1.1.7 software were used to assess the potential damage, environmental pollution produced, and construction energy used by the two concrete structures. The life cycle assessment (LCA) method was applied using a cradle-to-gate approach. The results indicated that to reach a single structural performance level, the concrete with 20 MPa strength caused 31.8% more damage and environmental pollution than the concrete with 25 MPa strength. Also, 31.8% more energy was consumed to produce the 20-MPa concrete. Pushover analysis indicated that the 25-MPa concrete structure had 20-29% greater elastic strength and almost 16% greater inelastic strength compared to the structure built with 20-MPa concrete. The building with 20 MPa concrete strength experienced a 34.8% greater displacement than the building with 25 MPa strength under shear loading. These results confirm that the structure with 20 MPa concrete strength was more vulnerable than 25 MPa concrete strength.