Testing methods for concrete durability

Experimental techniques for measuring progressive deterioration of concrete were investigated. Specimens of pastes, mortars, and concretes were subjected to alternate wetting and drying in sodium sulfate solutions and plain water as well as freezing and thawing. The methods used to assess the effects included: changes in weight, length, and flexural strength, changes in ultrasonic pulse time, quantitative and qualitative optical microscopy, scanning electron microscopy, and energy dispersive X-ray analysis. The results of the study show that the ultrasonic pulse method can be used to detect local cracking at an early stage of formation. Of the different testing methods employed, the progressive deterioration was best reflected by the measurements of pulse time. Measurements of flexural strength also adequately reflected the state of corrosion. Measurements of weight did not consistently indicate damage, while those of length were not always reliable.