Evaluation and Testing of Carbonation Behavior of Sprayed Concrete with Different Liquid Accelerators

Abstract

This article mainly tested and evaluated the carbonation resistance of sprayed concrete mixed with different liquid accelerators, and thus attempted to establish a prediction model for the carbonation depth of sprayed concrete. Firstly, the influence of alkaline liquid accelerator based on sodium aluminate (AR), alkaline-free liquid accelerator based on aluminum sulfate (AS), and alkali-free liquid accelerator based on fluoroaluminate (AF) on carbonation resistance of sprayed concrete was explored. In addition, the porosity and pore structure distribution of ordinary sprayed concrete (OSC), sprayed concrete with AR (SC-AR), sprayed concrete with AS (SC-AS), and sprayed concrete with AF (SC-AF) were analyzed by the mercury intrusion porosimetry. The carbonation depth and compressive and splitting tensile strength also were tested. Furthermore, the scanning electron microscopy was employed to observe the micromorphology of hydration products. The experimental results indicated that the carbonation depth order of sprayed concrete was as follows: SC-AR > SC-AF > SC-AS > OSC. After analyzing the disparity of SC-AR, SC-AS, and SC-AF carbonation depth caused by AR, AS, and AF dosage, the influence coefficients of sprayed concrete carbonation depth were introduced. Finally, the carbonation depth prediction models of SC-AR, SC-AS, and SC-AF were preliminarily established.