Experimental Investigation on Mechanical and Demolition Properties of High-Performance Phase Change Aggregate Concrete

A high-performance phase change aggregate concrete (PCAC) is proposed for the postpouring area of demountable prefabricated structural components. The variation in compressive strength of PCAC with the volume fraction of phase change aggregate (PCA) was studied at both room temperature (20°C) and elevated temperatures (from 40°C to 200°C). Specific chiseling work tests of PCAC were conducted over a temperature range of 40°C to 200°C. By incorporating compressive strength data, the demolishability was quantified, leading to the establishment of an optimal formulation for high-performance PCAC. Additionally, a study on the basic performance of the optimal formulation at room temperature was conducted. The results indicated that the compressive strength of the concrete decreased with an increase in the volume fraction of PCA at room temperature. At the phase change temperature of 200°C, the compressive strength of the concrete sharply decreased with an increase in the volume fraction of PCA. The compressive strength of the concrete with a PCA content of 15% decreased from 76.4 MPa to 5.7 MPa after phase change. Compared with the concrete mixture without PCA, concrete with 15% PCA content exhibited good workability, a relatively low elastic modulus, and an ascending branch of the stress-strain curve that approached linear elasticity at room temperature. Based on the compressive strength, specific chiseling work, and scanning electron microscopy inspection at both room temperature and phase change temperature, it was evident that high-performance concrete with PCA maintains stable strength at room temperature and exhibited excellent demolishability at the phase change temperature.