Standard Methods used to Measure Drying Shrinkage of Concrete Nathaniel R. Gant ABSTRACT: Concrete is one of the most common materials used in construction today. When engineers design a structure, they must consider properties of different types of concrete batches including drying shrinkage. In order to measure drying shrinkage of concrete, technicians use length comparators according to ASTM C596. An alternate method using DEMEC gauges has been devised to measure the shrinkage of four sides of standard shrinkage bars. The newly devised method and the ASTM were compared on three concrete mixes: grout, standard concrete, and lightweight concrete. This report contains the results of an experiment performed to reveal if the alternate method of measuring shrinkage yields similar results. Keywords: Concrete, drying shrinkage, ASTM C596, DEMEC
INTRODUCTION Many man-made structures in the world are made of concrete. It is widely used for making architectural structures, foundations, brick/block walls, pavements, bridges, roads, runways, parking structures, dams, pools/reservoirs, pipes, footings for gates, fences, poles, and even boats. Composite steel and concrete beams have been used in the United States for more than 100 years (Subcommittee 2002). Concrete is composed of water, cement, and aggregate. Aggregate is generally coarse gravel or crushed rocks such as limestone or granite, and finer materials such as sand. Cement is composed of a combination of calcium, silicon, aluminum, iron and small amounts of other materials; gypsum is added to regulate the setting time of the concrete (Portland Cement 2013). Lime and silica make up about 85% of the mass of cement. Portland cement is the most common type of cement used for concrete construction today. When the correct ratio of cement, water, and aggregates are blended together, a chemical reaction