Page - 1505 - in Book of Full Papers - Symposium Hydro Engineering

The Quality Control system for RCC dams comprised the following main activities: • Control of production process by inspection of the equipment and material • Control by testing and inspection of the properties of the RCC constituents • Control of fresh RCC sampling and testing • Control of hardened concrete by testing samples and statistical conformity analysis This paper is concerned with the relationship between the specification of RCC, construction procedures, the properties of RCC and how quality control is used in RCC dams during construction. 2. QUALITY CONTROL OF MATERIALS [1, 2, 3] The primary objectives of performing RCC mix designs for a dam project are to evaluate the uniformity, compactability, workability, and economic issues of the likely RCC mix components and proportions. These objectives are evaluated relative to the RCC unit weight and strength requirements. Commonly, RCC mix design is comprised of four main components: aggregate, cementitious materials (pozzolan and cement), water and admixture. The selection, proportioning, and quality of each of these components effect on the RCC quality. Key aspects of each of these components on the quality of the final concrete product are discussed below. 2.1. AGGREGATE The selection of an appropriate aggregate for RCC production is probably the single most important factor in any RCC project. Aggregate is the one component in RCC that potentially has the greatest variability and impact on quality. Ideally, a suitable RCC aggregate will have the following characteristics: • Compactable to high density • High specific gravity • High Strength • Suitable gradation to prevent segregation • Excellent durability/soundness Aggregate is normally derived from local sources to avoid the considerable cost attached to transport. Some sources will yield aggregate of high quality, which conforms to national or international standards. Specification of processes and RCC mixtures can overcome such defects and produce adequate RCC. Where the aggregate source is known to be of good quality, the specification can be based on published standards such as ACI 221 or ASTM C-33. Table 1 and 1505