USING DURABILITY TO ENHANCE CONCRETE SUSTAINABILITY

INTRODUCTION

The sustainability of concrete buildings and infrastructure must be considered both in terms of its benefits to society and the environmental impact associated with its use in construction. Production of Portland cement (PC), in particular, is energy intensive and generates a significant amount of carbon dioxide. Cement is, however, only a relatively small component of concrete and overall the material is resource efficient and has moderate embodied energy and carbon dioxide footprint. Concrete is widely used due to its low cost, ease of use, good track record, versatility, local availability, thermal benefits, acoustic dampening, and durability.

Durability performance of construction materials is important, and concrete is often considered to be inherently durable due to its chemical and physical resistance to various environments and dimensional stability. Concrete structures are assumed to be largely maintenance-free and to provide long service lives. Figure 1 shows an 80-yearold concrete bridge in South Africa that is still providing good performance under severe weather conditions. This assumption is not true in all environments and service conditions unless special attention is given to ensuring a high level of durability performance.

With an understanding of concrete microstructure and potential deterioration mechanisms, it is possible to engineer almost any level of durability performance. Increasing the service life of buildings and infrastructure through improved durability has clear advantages in terms of optimizing resources and reducing waste, thus enhancing efficiency. Other advantages associated with improved durability that enhance the sustainability of concrete include improved structural performance, reduced labour, and improved understanding of concrete materials, which will assist in development of new technologies.