CONCRETE. RAW MATERIALS

CHAPTER 1 CONCRETE. RAW MATERIALS L. Dvorkin and O.Dvorkin 1.1. Concrete. General Concrete can be classified as composite material and that is a combination of different components which improve their performance properties. In general case binder component which can be in hard crystalline or amorphous state is considered as the matrix of composite material. In concrete matrix phase the grains of aggregates (dispersed phase) are uniformly distributed. 22 Concrete classification Classification indication Types of binders Density Types of aggregates Size of aggregates Workability of concrete mixtures Porosity of concrete Typical properties Exploitation purpose Types of concrete Cement, Gypsum, Lime, Slag-alkaline, Polymer, Polymer-cement Normal-weight, High-weight, Light-weight Normal-weight, Heavy-weight, Light-weight,Inorganic, Organic Coarse, Fine Stiff and Plastic consistency High-density, Low-density, Cellular High-strength, Resistance to action of acids or alkalis, Sulfate resistance, Rapid hardening, Decorativeness Structural concrete, Concrete for road and hydrotechnical construction, Concrete for thermal isolation, Radiation- protective concrete, White and Coloured concrete 23 1.2. Binders. Classification. Nature of binding properties Concrete can be produced on the basis of all types of glues which have adhesion to the aggregates and ability for hardening and strength development. Organic glues Organic – mineral glues Inorganic glues Solutions, pastes Pastes Solutions, bond Molten Pastes materials, solders Binding and production of composite materials Fig.1.1. Types of adhesives 24 Periodicity of chemical compounds binding properties Oxide of chemical element BeO MgO CaO ZnO SrO CdO BaO Al2O3 SiO2 -- ---- -- ++ ++ -- --++ ++ -- -- ++ ++ Oxide Fe2O3 Cr2O3 Mn2O3 GeO2 SnO2 - - - - --- - - - - ++ ++ ++ ++ ++ -- -- - - - ++ + + + + - - - - - ++ ++ ++ ++ ++ Note: fixed (++) and predicted (+) existence of binding properties; fixed (--) and foreseen (-) absence of binding properties. 25 ... - tailieumienphi.vn