concrete notes and dictionary

concrete notes and dictionary - TERMS Accelerator An...

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TERMS Accelerator An admixture which, when added to concrete, mortar, or grout, increases the rate of hydration of the hydraulic cement, shortens the time of set and increases the rate of hardening or strength development Air Entraining Agent An addition for hydraulic cement, or an admixture for concrete or mortar which entrains air in the form of minute bubbles in the concrete or mortar during mixing. Concrete A composite material which consists essentially of a binding medium, within which are embedded particles or fragments of a relative inert filler in portland cement concrete, the binder is a mixture of portland cement, possibly additional cementitious materials such as fly ash and water; the filler may be any of a wide variety of natural or artificial, fine and coarse aggregates; and in some instances, an admixture. Entrained Air (See air entrainment) Microscopic air bubbles intentionally incorporated in mortar or concrete, to improve workability and durability (usually imparting a higher degree of resistance to freezing and thawing). Plasticizer A material that increases the workability or consistency of a concrete mixture, mortar or cement paste Pozzolan (ASTM C 618) A siliceous, or siliceous and aluminous material, which in itself possesses little or no cementitious value but will, in a finely divided form, such as a powder or liquid and in the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures to form permanent, insoluble compounds possessing cementitious properties. Retardation Delaying the hardening or strength gain of fresh concrete, mortar or grout. Retarder An admixture which extends the setting time of cement paste, and therefore of mixtures such as concrete, mortar, or grout. Plastic A condition of freshly mixed concrete. mortar or cement -paste indicating that it is workable and readily re-moldable, is cohesive, and has an ample content of fines and cement but is not over wet. Plastic Consistency Condition in which concrete, mortar, or cement paste will sustain deformation continuously in any direction without rupture. Plasticity Property of freshly mixed concrete, cement paste or mortar which determines its ease of molding or resistance to deformation. Plastic – capable of being molded or modeled. Capable of adapting to varying conditions. Capable of being deformed continuously and permanently in any direction without rupture. Applies to substances soft enough to be molded yet capable of hardening into the desired fixed form Cement - a substance used to adhere material together. In concrete, the dry powder that when combined with the water chemically cements all the particles together. Heat of Hydration – thermal energy given off by concrete or gypsum as it cures Portland Cement – a combination of lime, iron, silica, and alumina. Lime comes from limestone, marble, marl or seashells, Iron, silica, and alumina can be found in clay or shale Cement types Type I - Normal, used most Type IA- Normal, Air Entraining – contains ingredients that cause microscopic air bubbles
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concrete notes and dictionary - TERMS Accelerator An...

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