CHARACTERIZATION OF DETERIORATION ON THE SHOTCRETE LINING IMMERSED IN VARIOUS SULFATE SOLUTIONS

摘要

This study is to evaluate the characterization of shotcrete exposed to sulfate solution on long-term. Surface examination, compressive strength test, adhesive strength test and micro-structural analysis were performed to analyze the deterioration of shotcrete specimens, which were cored at cast-in-place shotcrete lining. The shotcrete specimens were immersed in 1, 2, and 5% of sodium sulfate solutions upto 35-weeks. From the test results, the compressive strength and adhesive strength of shotcrete specimen increased up to 56 days of immersion period. The reason was that the cement matrix was densified in filling the pore of shotcrete with cement hydrate products in the early age of immersion period. After 56 days of immersion period, the compressive strength and adhesive strength decreased with increasing immersion period of shotcrete specimens in sodium sulfate solutions. The deterioration of shotcrete was caused by the gypsum, ettringite, and thaumasite formation in the shotcrete specimens. These results were confirmed by XRD, SEM and EDS analyses.