CONCRETE. RAW MATERIALS ppt

CHAPTER 1 CONCRETE. RAW MATERIALS L. Dvorkin and O.Dvorkin Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com 22 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. Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com 23 Concrete classification Classificat ion indicat ion Types of concrete Types of binders Cement, Gypsum, Lime, Slag-alkaline, Polymer, Polymer- cement Density Normal-weight, High-weight, Light-weight Types of aggregat es Normal-weight, Heavy-weight, Light-weight, Inorganic, Organic Size of aggregat es Coarse, Fine Workability of concret e mixtures Stiff and Plastic consistency Porosity of concrete High-density, Low-density, Cellular Typical properties High-strength, Resistance to action of acids or alkalis, Sulfate resistance, Rapid hardening, Decorat iveness Exploitat ion purpose Structural concrete, Concrete for road and hydrotechnical construction, Concrete for thermal isolation, Radiation- protective concrete, White and Coloured concrete Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com 24 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 Pastes Molten materials, solders Binding and production of composite materials Fig.1.1. Types of adhesives Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com 25 Periodicity of chemical compounds binding properties Oxide Oxide of chemical element Al 2 O 3 SiO 2 Fe 2 O 3 Cr 2 O 3 Mn 2 O 3 GeO 2 SnO 2 BeO - - - - - MgO - - - - CaO ++ ++ ++ ++ ++ ++ ++ ZnO - - - SrO ++ ++ ++ + + + + CdO - - - - - BaO ++ ++ ++ ++ ++ ++ ++ Note: fixed (++) and predicted (+) existence of binding properties; fixed ( ) and foreseen (-) absence of binding properties. Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com 26 1.3. Portland cement and its types Chemical composition of portland cement clinker is as a rule within following range, %: СаО- 63 66 MgO- 0.5 5 SiO 2 - 22 24 SO 3 - 0.3 1 Al 2 O 3 - 4 8 Na 2 O+K 2 O- 0.4 1 Fe 2 O 3 - 2 4 TiO 2 +Cr 2 O 3 - 0.2 0.5 Fig. 1.2. Crystals of alite Fig. 1.3. Crystals of belite Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com 27 Fig. 1.4. Rate of cement paste hardening under using cements with different grain sizes: 1– <3 µm; 2 – 3…9 µm; 3 – 9…25 µm; 4 – 25…50 µm Compressive strength, МPа Age of hardening, days Fig. 1.5. Relationship between amount of alite and compressive strength o f cement Amount of alite, % Compressive strength, МPа 3 days 28 days Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com 28 1.4. Hydraulic non portland cement binders Lime binders Hydraulic lime binders contain materials produced by grinding or blending of lime with active mineral admixtures (pozzolans) — natural materials and industrial byproducts. At mixing of active mineral admixtures in pulverized form with hydrated lime and water, a paste which hardened can be obtained. Typical hydraulic lime binders are lime-ash binders. Slag binders Slag binders are products of fine grinding blast-furnace slag which contains activation hardening admixtures. Activation admixtures must be blended with slag at their grinding (sulfate – slag and lime – slag binders) or mixing with water solutions (slag - alkaline binders). Activation admixtures are alkaline compounds or sulfates which contain ions Са 2+ , (ОН) - and (SO 4 ) 2- . Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com 29 Calcium - aluminate (high-alumina) cements Calcium - aluminate (high-alumina) cements are quickly hardening hydraulic binders. They are produced by pulverizing clinker consisting essentially of calcium aluminates. Fig. 1.6. Typical curves of cement strength increase: 1 - calcium - aluminate cement; 2 – high-early strength portland cement; 3 – ordinary portland cement Strength, percent of 28 day strength Age, days Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com 30 1.5. Concrete aggregates Classification of aggregates for concrete Classification indication Kind of aggregat es Characteristics of classificat ion indicat ion Fine aggregates ≤5 mm Grain size Coarse aggregates >5 mm Gravel Smooth particles Part icle shape Crushed stone Angular particles Heavy ρ 0 >1100 kg/m 3 Bulk density (ρ 0 ) Light ρ 0 ≤1100 kg/m 3 Normal and high - density P≤10% Porosit y (P) Low - densit y P>10% Exploitation purpose Normal, high and low – density concrete, Concrete for hydrotechnical, road and other kinds of construction Propert ies of aggregat es must conform to the concrete properties Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com [...]... amorphous silica which quantity usually exceeds 85 and reaches 98 % 36 Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Mineral admixtures Mineral admixtures are finely divided mineral materials added into concrete mixes in quantity usually more than 5 % for improvement or achievement certain properties of concrete As a basis of classification of the mineral admixtures accepted in the . CHAPTER 1 CONCRETE. RAW MATERIALS L. Dvorkin and O.Dvorkin Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com 22 1.1. Concrete. General Concrete can be classified. ion purpose Structural concrete, Concrete for road and hydrotechnical construction, Concrete for thermal isolation, Radiation- protective concrete, White and Coloured concrete Simpo PDF Merge. Normal, high and low – density concrete, Concrete for hydrotechnical, road and other kinds of construction Propert ies of aggregat es must conform to the concrete properties Simpo PDF