Use of impact-echo technique for detection of distributed damage in concrete due to alkali-silica reactivity: Fid-Bau Portal

Use of impact-echo technique for detection of distributed damage in concrete due to alkali-silica reactivity

Tajari, M. / Shekarchi, M. / Sadri, A.

Alkali-silica reactivity (ASR) can cause distributed cracking and premature deterioration in concrete structures. It is highly desirable to determine whether impact-echo testing may be applied to detect and quantify the amount of ASR damage in concrete specimens. To address this issue, all efforts were concentrated on monitoring the evolution of ASR damage in concrete using transient stress waves. Impact-echo testing was applied on concrete specimens affected by ASR and the corresponding results were analyzed to test the parameters sensitive to ASR. In this study two sets of experiments were used to accelerate ASR in concrete. First, three reactive concrete mixtures were cast using different percentages of silicate aggregates. Concrete specimens were kept at 80 °C (353.15 K) in a 1 mol^-1 sodium hydroxide (NaOH) solution. The results were obtained through consequent tests over eight months. In addition, other experiments were performed for three different mixtures, which were synthesized by using different types of silicate aggregates, as well as one mixture including non-reactive aggregates. All these mixtures were investigated six months after fabrication, and these specimens were kept at 38 °C (311.15 K) in a 1 mol^-1 NaOH solution. The applied technique, which is classified as a nondestructive testing (NDT) technique based on the impact-echo technique, may have the capability to inspect the development of ASR in concrete structures. Based on the observations in this study, petrographic inspection confirms that the damage was associated with ASR.