ABSTRACT
It was shown in Chapter 4 that although the cracking caused in concrete by AAR may be visually alarming, there is strong evidence that the effects of the deterioration may be less serious in terms of structural safety than appearances might suggest. This is at least partly because most structural loading codes are almost unrealistically conservative. Thus building and highway structures are hardly ever required to carry more than a small proportion of their design loads during service, and actual service stresses are generally low. The latter statement has also been demonstrated by measuring dynamic strains in a bridge pier under real service loading (Section 4.4.1). Visually the pier had deteriorated severely as a result of AAR. However, the actual service live load compressive stresses in the concrete amounted to a maximum of only 0.5 MPa. As the minimum strength measured for cores taken from the pier was 28 MPa it was most unlikely that there could be an immediate safety problem. Fullscale load tests on structures showing AAR deterioration have been carried out in many countries, where a range of climates is experienced. In some cases these tests have been repeated over a number of years. In all cases the structures were found to behave predictably with little loss in serviceability as a result of the deterioration by AAR.
