【Daily Topic】【Civil Engineering Version 20160522】

A. Fluidity B. Cohesiveness D. Water retention

USA~~~~~~~~

The workability of fresh concrete, also known as its handling properties, refers to a comprehensive technical characteristic that enables the mixture to be easily mixed, transported, poured, and shaped, resulting in concrete with uniform and dense quality. It is usually expressed in terms of three parameters: fluidity, cohesion, and water retention. Fluidity – refers to the property of concrete mixtures that enables them to flow easily under the effect of their own weight or mechanical vibration, allowing for easy transportation and filling of concrete formwork. Cohesiveness – the ability of concrete mix to remain uniform as a whole during construction. Good cohesion ensures that the concrete mixture does not separate or stratify during transportation, pouring, and shaping, thereby guaranteeing a uniform internal structure in the hardened concrete. Water retention – the ability of concrete mix to retain moisture during construction. Its good water retention ensures that the concrete mixture does not experience significant or severe bleeding during transportation, shaping, and setting. This prevents the formation of numerous interconnected capillary pores caused by bleeding, as well as interface bonding defects resulting from the accumulation of water beneath the coarse aggregates and rebar. Water retention has a significant impact on the strength and durability of concrete. Generally, the greater the fluidity of concrete mix, the worse its water retention and cohesion, and vice versa; there is a certain contradiction between these properties. Concrete with good workability refers to concrete that possesses the fluidity required for construction, as well as good cohesion and water retention. Therefore, concrete with high fluidity cannot simply be considered to have good workability, nor can a decrease in fluidity be taken to mean that the workability has deteriorated. Good workability is not only a requirement for construction but also a fundamental guarantee for obtaining concrete with uniform and dense quality.