Factors affecting the quality of vertical cast-in-place concrete include design and construction practices, concrete properties, formwork, and vibration. Cold joints, bugholes, and honeycombs, are best prevented before concrete is placed and hardens. Repairs after the fact can be expensive and unsatisfactory. The most critical element is proper vibration of the fresh concrete. Next in importance to vibration technique is having the right concrete mix. Finally, plan ahead. Cold joints can occur when placement is delayed until the lower concrete cannot be vibrated successfully. To reduce the occurrence of bugholes, avoid concrete mixes with high air contents, sands with a low fineness modulus, high sand contents, or high paste contents. Honeycombs can occur in narrow sections, where reinforcement is placed close to the forms, and where there is internal interference with flow and consolidation of concrete.