Cement properties & Types
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Cement is a binding material that provides strength to concrete through a process called hydration. It consists of calcium, silica, alumina, and other ingredients. The main ingredients are hydrated lime, silica, alumina, iron oxide, and sulfates. There are different types of cement classified based on composition and used for various applications like general construction, structures exposed to sulfate ions, rapid construction projects, and structures requiring high sulfate resistance. Cement is tested for fineness, consistency, setting time, soundness, compression and tensile strength. Ordinary Portland cement gains 112.7 kg/m^2 compression strength at 3 days and 176 kg/m^2 at 7 days, while rapid hardening cement
Cement properties & Types
- 1. Cement • Binding Material • Provide strength to concrete with a process called Hydration • The ready mix of cement consist of silicate and aluminate of lime. • Consist of seven major ingredients:- A.) Hydrated Lime (60%-67%) CaO:- Provide strength and responsible for hydration B.) Silica (17%-25%) SiO2:- Provide Strength to cement due to formation of dicalcium Silicate & tricalcium Silicate C.)Alumina (3%-8%)Al2O3:- Resistance against high temperature/control of temperature. D.) Magnesia(0.1%-4%)MgO:- Responsible of Hardness E.) Iron Oxide (0.5%-6%)FE2O3:-Responsible for Strength and Color of Cement F.) Sulpher Trioxide (1%-2.25%)SO3:- Responsible of Setting time of Cement G.) Alkalies (Soda and Potash):- 0.1% to 1%
- 2. Types of Cement Type Classification Characteristics Applications Type I OPC BS EN-197-1:2000 ASTM C-150-94 Fairly high C3S content for good early strength development Not more then 10% by weight particles will retain on BS Sieve No.170 Chemical composition: C3S-tricalcium silicate=50% (Responsible for Finial setting time, produce heat) C2S-dicalcium silicate=25% (Responsible for final setting time) C3A-tricalcium aluminate=12% (Responsible for initial setting time and quick setting time, produce heat) C4AF-tetracalcium aluminoferrite=8% (Responsible for initial setting time and quick setting time) General construction (most buildings, bridges, pavements, precast units, etc) Type II Moderate sulfate resistance BS EN-197-1:2000 ASTM C-150 Low C3A content (<8%) Chemical composition: C3S=46% C2S=29% C3A=6% C4AF=12% Structures exposed to soil or water containing sulfate ions Type III Rapid Hardening Cement BS EN -197-1 Grind more finely, provide more heated with high temperature in factory may have slightly more C3S Not more then 5% by weight particles will retain on BS Sieve No.170 Chemical composition: C3S=60% C2S=12% C3A=12% C4AF=8% Rapid construction, cold weather concreting Type IV Low heat of hydration (slow reacting) BS 1370-1979 Low content of C3S (<50%) and C3A=5% More amount of C2S Chemical composition: C3S=30% C2S=46% C3A=5% C4AF=12% Massive structures such as dams. Now rare. Type V High sulfate resistance BS-4027-1996 Very low C3A content (<5%) Chemical composition: C3S=43% C2S=36% C3A=4% C4AF=12% Structures exposed to high levels of sulfate ions White White color No C4AF, low MgO Decorative (otherwise has properties similar to Type I)
- 3. Tests of Cement A.) Fineness Test:- to check the particles grinding Equipment used: BS Sieve No.170 B.) Consistency Test: To Check the %age of water required for Cement Paste Equipment Used: Vicat Apparatus C.) Setting Time Test: to check Initial and Final setting time of Cement Equipment Used:- Vicat Apparatus D.) Soundness Test: to check the changes in volume of cement paste after setting time. Equipment Used: Le Chateller Apparatus E.)Compression Test F.) Tensile Test
- 4. Values for Compression strength of Cement • Ordinary Portland Cement 3 Days= 112.7 kg/m^2 7 Days=176 kg/m^2 • Rapid Hardening Cement 3 Days= 211.3 kg/m^2 7 Days=264.1 kg/m^2
- 5. Values for Tensile strength of Cement • Ordinary Portland Cement 3 Days= 21 kg/m^2 7 Days=26 kg/m^2 • Rapid Hardening Cement 3 Days= 21 kg/m^2 7 Days=32 kg/m^2