Concrete is an artificial stone material. Concrete is the result of consolidation of rationally selected, thoroughly mixed and compacted blend of a particular mineral binding material, water, aggregate, and, if necessary, special additives. Before this blend is hardened it is called concrete mix which is divided to various compositions. Water and binder are the main and active components of concrete. As a result of their chemical interaction a new compound is formed. The compound is sticky dough (cement dough, cement milk) that covers grains of fine and coarse aggregate with thin layer. Eventually, this compound hardens, binds the aggregates, and turn concrete mix into strong monolith stone – concrete. Aggregates (sand, scalping, crushed stone, gravel and etc.) make up 80-85% of concrete volume. Aggregates form rough skeleton of concrete. Aggregates having various features make different sorts of concrete. They differ by physical and mechanical indicators; for example, they can be light, heavy, heat-resistant and so on. Thus, before consolidation the concrete is a concrete mix consisting of rationally selected and thoroughly mixed binders (cement), water, aggregates and, in necessary cases, additives like various plasticizers and hardening agents. As any other material, concrete mix has different chemical, physical and mechanical features that predetermine the quality and characteristics of concrete formed from a mix. Vibro-compaction is a method of compacting semi-dry (rough) concrete mix: concrete mix placed to the mould is exposed to vibrating power from below and simultaneous pressure from top. This method is quite high-producing. It involves increased level of automation and provides an opportunity to use rough concrete mix what ensures high durability and frost-resistance of concrete products. |