Chapter 3: Physical deterioration mechanisms

This chapter reviews the range of mechanisms that result in the physical degradation of concrete. Conventional abrasion and cavitation occur where concrete surfaces are subject to traffic or where large hydrostatic pressures arise when moisture is compressed in defects. Some physical degradation mechanisms involve the expansion of material within the pores nearest to the surface. This imparts an indirect tensile stress on the concrete, which can cause the surface to scale off. Finally, fire, and the subsequent firefighting, can damage concrete. Typically, the simplest way of avoiding degradation is to gain a full understanding of the working performance required of the concrete and then selecting the right material. Choosing the right mix is only the start of the process, as installation and curing are of equal if not greater importance, since all the physical degradation mechanisms start at the surface of the concrete, and it is the surface that is most vulnerable to placing and curing effects.