For companies and craftspeople that need rapid results. Choose the concrete mix formulated to have your slabs and posts set into place in as little as 20 minutes. Each 50-lb. bag of mix yields approximately 0.375 cu ft of mixed concrete. Poured concrete will reach a compressive strength of 4000 PSI within 28 days. For best results with fast-setting mix, do not overwork the mix and ensure proper curing in the hours immediately following use, such as with plastic covering. Meets ASTM C39, ASTM C191, and ASTM C387 Standards. Find more general purpose and pre-blended mixture concrete, as well as top-quality masonry tools, at 95TSS.