Synergistical influence of internal expansion and external constraint on demolition efficiency of soundless chemical demolition method for concrete structures

Soundless chemical demolition (SCD) holds significant promise in building demolition engineering due to its safety, eco-friendliness, and flexibility, while insufficient understanding of the damage to concrete structure using this method hinders its application, which requires further research. This study investigated the damage of concrete structure caused by the soundless chemical demolition agent from the perspective of internal expansion and external constraint. The two parameters were controlled by adjusting the hole diameter, spacing and specimen size in the experiment and finite element simulation. Experiment results showed that the cracking time of concrete blocks shortened with increased internal expansion or decreased external constraint. The damage of blocks varied between the double-hole, unidirectional single-hole and multidirectional single-hole pattern with the increase of inter-hole constraint. Further, the damage range and level of blocks damaged in the unidirectional single-hole pattern were almost 45 % and 50 % lower than those of blocks damaged in other patterns, respectively, indicating that enhancing the synergy of adjacent holes or weakening the around-hole constraint can significantly improve the damage of concrete blocks. For the blocks damaged in the same pattern, internal expansion played a significant role in the damage range and level, while the effect of external constraint was not obvious. In addition, a hole parameter design method was established based on the comprehensive analysis of the synergy between external constraint and internal expansion, which was verified by the experiment of concrete shear walls. This work provides a new solution for the efficient demolition of concrete structure based on SCD.