Abstract: When curing time of rapid-hardening backfill materials is up to 60 days,the weathering of the materials will begin and at 90 days the weathering becomes more severe. The reasons of weathering happening are that the ettrin-gite in the backfill body is destroied by the erosion of CO₂ in air, and the free water in the backfill body is dried out. An approch to keep the rapid-hardening backfill materials from weathering is to have a environment of unchanging temperature and unchanging moisture.