ABSTRACT

Deterioration of structural concrete may be caused either by chemical and physical environmental effects upon the concrete itself, or by damage resulting from the corrosion of embedded steel. It is very likely that reinforcement corrosion in one form or another will form part of the problem experienced by an Engineer requiring a survey of a structure. The tests described in this chapter are concerned primarily with the assessment of material characteristics which are likely to influence the resistance to such deterioration, and to assist identification of the cause and extent if it should occur. These tests have been summarized in Table 1.3, although those involving chemical or petrographic analysis (including carbonation depth, and sulfate and chloride content) are considered in detail in Chapter 9. Other relevant tests relating to structural integrity and performance are described in Chapter 8, and test selection is discussed in Section 1.4.3. The principal causes of degradation of the concrete are sulfate attack,

alkali-aggregate reaction, freeze-thaw damage, abrasion and fire. The presence of moisture and its ability to enter and move through the concrete are critical features since both sulfates and chlorides require moisture for mobility and alkali-aggregate reactions cannot occur in dry concrete. Carbonation rates depend on gas permeability and are also influenced by moisture levels. Tests which assess water and gas absorption or permeability, and moisture content, are thus of great importance with respect to durability. Planning and interpretation of a typical corrosion-related investigation are outlined in Appendix A7.