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A higher ratio gives a too fluid concrete mix resulting in a too porous hardened concrete of poor quality. Often, the concept also refers to the ratio of water to cementitious materials, w/cm. Cementitious materials include cement and supplementary cementitious materials such as ground granulated blast-furnace slag (GGBFS), fly ash (FA), silica ...
A gypsum block is made of gypsum plaster and water. The manufacturing process [1] is automated at production plants where raw gypsum (CaSO 4 ·2H 2 O) is ground and dried, then heated to remove three-quarters of the bound water and thus transformed into calcium sulfate hemihydrate (CaSO 4 ·½H 2 O), also known as gypsum plaster, stucco, calcined gypsum or plaster of Paris.
Cement render or cement plaster is the application of a mortar mix of sand and cement, (optionally lime) and water to brick, concrete, stone, or mud brick. It is often textured, colored, or painted after application. It is generally used on exterior walls but can be used to feature an interior wall. [1]
The mix is prepared on site using a specialized truck. The truck contains a tank for water, a mixing tank, a holding tank, a pump, and a conveyor for the sand and calcined gypsum. A hopper for the sand and gypsum is mounted externally on the vehicle. [8] To prepare the mix, the sand and calcined gypsum are added to the hopper and mixed.
This is of considerable economic value, particularly in a precast factory as the forms can be reused at frequent intervals. The bond strength of vacuum concrete is about 20% higher. The surface of vacuum concrete is entirely free from pitting and the uppermost 1/16 inch is highly resistant to abrasion.
Traditionally, a render would be manufactured on site by a plasterer mixing sand, cement and sometimes lime material together with water to produce his render. This would then be applied to the walls, usually in either two or three coats. [6] When painting, there is usually a primer, an undercoat and a topcoat.
The wall should be sufficiently rough to form a key and well wetted to prevent the moisture being absorbed from the plaster. Rough stucco is used to imitate stonework. It is worked with a hand float covered with rough felt (a stiff bristled brush can also be used), which forms a sand surface on the plaster.
Precast concrete is a construction product produced by casting concrete in a reusable mold or "form" which is then cured in a controlled environment, transported to the construction site and maneuvered into place; examples include precast beams, and wall panels, floors, roofs, and piles.