Mechanical properties and corrosion resistance of recycled aggregate concrete exposed to accelerated and natural marine environment

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This paper presents the effect of long-term exposure (simulated and natural) on the mechanical and durability characteristics of ordinary Portland cement concrete (OPCC) with and without recycled concrete aggregate (RCA) prepared using two water-cement (w/c) ratios. Each of the four concrete mixes (i.e. 0.40-R0, 0.40-R30, 0.43-R0 and 0.43-R30) was exposed to the simulated ((i.e. Fog apparatus/chamber as per provisions of ASTM B117) and two natural marine environments (on a water jetty and submerged in the seawater) for a period of 90, 180 and 365 days. To observe the long-term effect of the simulated and natural environment exposure, the exposed specimens were tested for compressive strength, splitting tensile strength, pull-out strength, and half-cell potential test as per the standard testing provisions of ASTM C39, ASTMC496, ASTMC900, and ASTMC876, respectively. The comparison of the results showed that the concrete specimens exposed to the natural marine environment submerged in the seawater resulted in reduced compressive and pull-out strengths, high and increased split tensile strength, and poor resistivity to corrosion as compared to the one placed on a deck of water jetty and simulated marine environment. The concrete prepared by using 30% RCA was significantly affected by the exposures as compared to the natural environment and a difference of nearly 30% in results of compressive strength, split tensile strength, and pull-out strength and a difference of 40% was found in resistivity to corrosion. Similarly, the high w/c ratio also affected the compressive strength, split tensile strength, pull-out strength, and resistivity to corrosion of concrete. The results of microstructure also confirmed that the concrete exposed to a harsh environment underwent severe deterioration, which led to the lessening of the mechanical properties.