What causes the internal pressure that produces popouts? What is the remedy if this happens on a warehouse floor, and how can popouts be avoided?
Popouts are generally due to physically unsound materials contained in the coarse aggregate. Materials such as shales, clayey rocks and cherts deteriorate through absorption of moisture. Moisture absorption causes them to swell and to produce internal pressures which rupture the concrete. Popping and spalling can also arise from slow hydration of hard burnt lime, dolomite or gypsum contained in the aggregate. To correct, remove unsound aggregate particles from the floor concrete then patch the affected areas. Popouts can be avoided by using sound, clean aggregate conforming to ASTM specifications.