HOW TO GET GOOD CONCRETE

CONCRETE OF RELIABLY HIGH QUALITY IS NEEDED FOR ADEQUATE PERFORMANCE IN STRUCTURES. THE PRODUCER OF READY-MIXED CONCRETE MUST BE HELD RESPONSIBLE TO SPECIFICATIONS FOR' INGREDIENTS, PROPERTIES OF THE FRESH CONCRETE, PROPERTIES OF THE HARD-CONCRETE, AND ENFORCEMENT. THE CONTROL OF SLUMP AND BATCH PROPORTIONS WILL PROVIDE A MIXTURE THAT WILL ACHIEVE GOOD APPEARANCE IF PROPERLY PLACED, FINISHED AND CURED. THE GUARANTEE OF STRENGTH IN TERMS OF STANDARD TESTS OF THE DELIVERED PRODUCT HAS BECOME ALMOST UNIFORM FOR STRUCTURE CONCRETE. REAL VARIATIONS IN STRENGTH CAN BE ATTRIBUTED TO DIFFERENCES IN THE INGREDIENTS AND DIFFERENCES IN PRODUCTION CONDITIONS. VARIATIONS IN THE CEMENT SOURCE AND PRODUCTION ARE DISCUSSED. INGREDIENTS, BATCHING, MIXING AND DELIVERY SHOULD BE REGULATED BY STATISTICAL TECHNIQUES APPLIED TO STRENGTH TESTS. SEVERAL CONTROL CHARTS ARE PRESENTED. STRENGTH TESTS ANALYZED STATISTICALLY ARE VERY USEFUL FOR KEEPING TRACK OF CONCRETE PRODUCTION CONTROL.