Influence of the concrete strength class and the span/depth ratio on the sustainability of reinforced concrete beam slabs

Abstract

Slabs form a significant part of the mass of reinforced concrete structures in buildings. Therefore, their sustainable design is crucial for the overall sustainability of the structure. A critical factor for the sustainability of slabs is their depth. The initial choice is usually based on conservative span/depth ratios or span/effective depth ratios, found in literature. However, thinner slabs may often be designed at the expense of greater reinforcement ratios and/or greater concrete strength class. This paper seeks to find the most effective choice of span/depth ratio of beam slabs for different concrete strength classes in terms of their sustainability. Quantitative assessment of the slab’s embodied energy per m2 and embodied CO2 per m2 is made for slabs with different static schemes and with different variable loads. Only the cradle-to-gate embodied energy and CO2 of the concrete and the reinforcement steel of the slab itself are considered. Other aspects of the sustainability of slabs, such as their influence on other structural elements, insulation properties, etc., are shortly discussed. Based on the analysis of the obtained results, some general conclusions are made and recommendations for the optimal choice in terms of sustainability of concrete strength class and span/depth ratio are given.