Field Investigation into Abrasion of Concrete at a Coastal Stepped Revetment: A U.K. Case Study

Abstract

Although concrete abrasion damage is a major maintenance challenge for coastal structures fronted by beaches with hard coarse sediments, there are no readily available field studies that have measured abrasion damage of known concrete mixtures under defined exposure conditions. The objective of this investigation is to evaluate the abrasive exposure conditions of the concrete revetment armour units at Cleveleys on the Fylde coast of the U.K. and examine the feasibility of using terrestrial laser scanning (TLS) to measure concrete abrasion damage in field conditions. It was found that the concrete elements at Cleveleys are exposed to a macro-tidal environment, which experiences significant wave heights that vary from 0.42 to 1.92 m, whilst the peak wave periods range from 3.7 to 6.5 s. The beach sediments have a mean size of 26 mm and are moderately sorted. TLS provides a dense point cloud of abraded surfaces suitable for quantitative assessment of concrete abrasion in the field. Based on the measured abrasion depths and exposure durations, the peak concrete abrasion rates at the site varied from 3.5 to 4.5 mm/year, and severe abrasion was concentrated in the region between mean high-water springs and mean high-water neaps, wherein the highest beach levels were also found during the survey. Finally, the abraded surfaces exhibited a polished texture with no visible craters; thus, the mechanism of concrete material loss was by grinding/polishing due to rolling/sliding sediments.