Abstract

CRUZ H, Ricardo A; ZAPATA O, Luis E; QUINTERO O, Luz A  and  HERRERA, Julián O. Ultrasonic pulse velocity for monitoring the susceptibility of concrete to sodium sulphate and wetting-drying cycles. Rev. LatinAm. Metal. Mater. [online]. 2016, vol.36, n.2, pp.155-163. ISSN 0255-6952.

The external sulphate attack of concrete is related to the formation of expansive sulphate-containing compounds in the hardened state of the concrete samples. The aim of this research is to study the use of the technique of ultrasonic pulse velocity (UPV) to estimate the mechanical and physical changes during an accelerated attack of sodium sulphate combined with wetting-drying cycles. Each cycle consisted in wetting, drying in oven and cooling. This combination tries to replicate field conditions for concrete samples in sulphate-rich environments under climatic changes (wetting/drying). The experimental program consisted of visual inspection, development of cooling curves, X-ray diffraction analysis, UPV measurements, mass and volume changes as well as compressive strength of concrete specimens. Standard concrete cylinders of 100 x 200 mm were used and the accelerated attack was monitored each 15 cycles with a total of 120 cycles. The results showed that both density (physical) and compressive strength (mechanical) measurements agreed with the UPV behavior registered through the external sulphate attack. In addition, mathematical models relating the compression analysis and the density values with the UPV measures were constructed. Finally, the X-ray diffraction results were successfully correlated with the developed mathematical models.

Keywords : sulphate attack; concrete; compressive strength; ultrasonic pulse velocity.

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