Chemical Admixtures for Use in Producing Flowing Concrete

This specification covers chemical admixtures to be added to hydraulic cement concrete mixtures for use in producing flowing concrete. The two types of chemical admixtures are: Type I–plasticizing; and Type II–plasticizing and retarding. Tests of the chemical admixtures with reference concreting materials or with concrete-making materials proposed for specific work are specified. Three levels of testing are discussed: Level 1, Level 2, and Level 3. Types of admixtures shall conform to the physical requirements: time of setting, increase in slump, compressive strength, flexural strength, length of change after days of drying, and relative durability factor. Uniformity and equivalence shall be established by the following requirements: infrared analysis, residue by oven drying (liquid and nonliquid admixtures), and specific gravity (liquid admixtures). Tests for quality, uniformity, and equivalence shall be made. Samples of freshly mixed concrete shall be tested according to slump, air content, time of setting, and water content and unit weight. Hardened concrete shall be tested according to the following: compressive strength, flexural strength, resistance to freezing and thawing, and length change.