Types of Cement

Cements – adhesive substances that unite masses of solid mater into compact whole. - Contains compounds of lime (principal constituents) mixed with water forming paste. Cements = calcareous cements TYPES OF CEMENT 1. PORTLAND CEMENT • American Society for Testing and Materials (ASTM) - defines this product as a hydraulic cement produced by pulverizing Portlandcement clinker, and usually containing calcium sulfate. HISTORY Prehistoric and Ancient Times Egyptians developed – mortar from gypsum for building the Great Pyramid Roman times – introduction of lime cement Greek and Roman Innovations - Pioneered the use of volcanic deposits (Santornin earth) mixed with lime and sand Romans – utilized powdered tiles or pottery. The term “cement” originated from this materials. Middle Ages The term “cement,” continued to be used variously. 18th and 19th Century James Parker – “Roman Cement,” 1796 – quick setting and useful for hydraulic work Joseph Aspdin – “Portland Cement” 1824 – resemblance for Portland stone and foundation for modern cement. 1914 Ynchausti Business in Binangonan Rizal – first cement plant 1969 13 cements plants were established – 85 million bags annually 2024 Challenges include increasing imports mostly from Vietnam – “Buy Local, Build Lokal,” program by Cement Manufacturers Association of the Philippines and DTI. a. Type I. Regular Portland Cement – used for concrete construction. - Types: white (contains less ferric oxide), oilwell cement, and quick-setting cement. b. Type II. Moderate-heat-of-hardening Portland cement – used when moderate heat of hydration is required and/or for general concrete construction when exposed to moderate sulfate activity. - Heat should not exceed 295 and 335 J/g after 7 to 28 days, respectively. c. Type III. High-early-strength (HES) cement – made from raw materials with a lime-to-silica ratio higher than Type I. - Ground finer than cements - Higher concentrations of tricalcium cilicate d. Type IV. Low-heat Portland cement – lower percentage and tricalcium silicate and tricalcium aluminate - High percentage of tetracalcium aluminoferrite and dicalcium silicate. - Heat evolution is lower. e. Type V. Sulfate-resisting Portland cement – resist sulfates better than others. - Used when high sulfate resistance is required, contains lower concentrations of tricalcium aluminate. - Possesses higher content of tetracalcium aluminoferrite. 2. Portland Pozzolana Cement (PPC) • Cement not cementitious alone; becomes one when mixed with lime. • Volcanic tuffs – natural • Burnt clays and shales – artificial • Mixture of Type I Portland Cement with pozzolanic materials (fly ash, volcanic ash, silicia fumes) • • Contains high amounts of silica that reacts with calcium hydroxide to form calcium silicate hydrate. Used in general construction projects, improves durability and resistance to chemical attacks (sulfate and chloride resistance) 3. Calcium Aluminate Cement • High-alumina Cement • High proportions of calcium aluminates (CA, C12A7, CA2) • Key reactive components – alumina and lime • Very rapid rate of development of strength and superior resistance to sea water and sulfate-bearing water. • Used when rapid strength gain is required. PORTLAND CEMENT - 4. Special or Corrosion-Resisting Cements • Designed to withstand chemical attacks that ordinary Portland cement cannot resist. • Modifications a. Low in tricalcium aluminate (ettringite) b. Higher levels of alumina (resistant to acidic environment) c. Incorporation of Ground Granulated Blast Furnace Slag (GGBFS) Main Compounds of Portland Cement • • MANUFACTURING COMPANIES Most common type of cement Primary ingredient is concrete Heated in a kiln Grinding the resultant clinker into a fine powder. “Portland” comes from Portland Stone, a type of building stone in England. • • Tricalcium and Dicalcium Silicate – most important because they are responsible for the strength of hydrated cement paste. Tricalcium Aluminate – undesirable because it lacks contribution. C3A forms to become Calcium Sulfoaluminate (ettringite) Only benefit is it facilitates the combination of lime and silica Tetracalcium Aluminoferrite – does not affect the cement significantly. If reacts to gypsum, accelerates the hydration of the silicates. The Alkalis – oxides of sodium and potassium. RAW MATERIALS - Mixing of materials containing calcium carbonate and clay in proper rations. 1. Limestone – Calcium Carbonate - Undergoes Calcination - 2. 3. 4. 5. - 6. CaO reacts with other materials, they form the four main compounds known as – clinker. Cement Rock – naturally occurring sedimentary rocks. Blend of limestone and clay Clay and Shale – contains silica, alumina, and iron oxides. Gypsum – soft sulfate mineral composed of calcium sulfate dihydrate (CaSO4 * 2H2O ) Used in final grinding stage of clinker Acts as a cement retarding agent/ prevent the premature hardening of the cement. “Flash Set” – cement harden immediately when mixed with water. Blast-Furnace Slag – by-product from the iron making process May be used as Supplementary Cementitious Material (SCM) – reduce the amount of clinker and lower carbon emissions. Possess latent hydraulic properties – presence of activator (Calcium hydroxide) Sources is iron, ore, coke and flux. Sand and Sandstone – composed of silicon dioxide to form quartz. - Source of silica for the formation of silicate phases. - React with calcium oxide to form silicate phases. 7. Marl – sedimentary rock containing mixtures of clay and calcium carbonate. - Natural blend of limestone and clay. - Single raw material source - Found near bodies of water because of very-fine grained particles. 8. Iron Materials – natural sources for the formation of C4AF (iron ore, mill scale, or iron oxides) - C4AF – fluxing agent that reduces the melting temperature in the Klin. DETAILED MANUFACTURING PROCESS 1. Preparation of Raw Materials and Handling • Calcium, the element of highest concentration in Portland cement, - gathered from a variety of calcareous raw materials (e.g., limestone, chalk, marl, seashells, etc) -After the raw materials are quarried, they must undergo the next steps: crushing, blending, grinding, and storage - Initially, the raw materials are crushed using a cement crusher - Crushing method (i.e., extrusion, cutting, impact). - To further pulverize the materials, the grinding mill is used. - The products are then stored in large silos for additional processing. 2. Calcination of Clinker - most important stage in the entire Portland cement manufacturing process • Pretreatment for the pyro-processing stage, there are two ways: the dry method, and the wet method. Difference: form of kiln feed. : raw material vs with water - a. Dry Process ~ Most efficient - utilizing hot exit gases from the pyro-processing system. - Other sources - - • • • of thermal energy for drying includes exhaust gases, direct-fired coal, oil, and gas burners. - The dry materials are transported in silos using conveying systems (e.g., screw conveyors, belt conveyors, drag conveyors, bucket elevators, etc.). b) Wet Process - mixed with water -produces pumpable slurry ~ Pyro-processing system - heart of Portland manufacturing process – Clinkers—these are gray, glass-hard, spherically shaped nodules that range from 0.32 to 5.1 cm in diameter. 4 stages of transformation to clinker 1 Evaporation of uncombined water from raw materials 2.Dehydration 3. Calcination 4. Reaction of the oxides Rotary kilns are elongated, cylindrical furnaces with a slight incline, lined with refractory material to safeguard the steel structure and maintain heat inside. As the materials progress through the kiln, they transform into cementitious or hydraulic minerals due to the rising temperatures. 2. Anhydride - anhydrous calcium sulfate Product uses: Lime -medicinal purposes Gypsum -widely used industrial and building material • • • • Building Gypsum – building mold ash, all kinds of gypsum products. Model Gypsum – less impurities, white color, used for ceramic culture. Floor Gypsum – mold ash engineering, plasterboard Whitewash Gypsum – made of cementing material with appropriate amount of retarder. • Formed in the sea basins and lake basins formed by evaporation of brine or hydration of anhydrite. - The gypsum in oxidation zone of sulfide deposits is by sulfides. DETAILED MANUFACTURING PROCESS LIME 3. Blending and Grinding of Finished Portland • Cement - Clinker will be grinded • Gypsum and other raw materials is added Then, the finish milling is completed almost exclusively in ball or tube mills. Lime and Gypsum Lime Lime is sold as a high-calcium quicklime containing not less than 90% of calcium oxide and from 0 to 5% of magnesia with small percentage of calcium carbonate, silica, alumina, and ferric oxide present as impurities. • Carbonates of calcium or magnesium are obtained from naturally occurring deposits. Gypsum: 1. Raw Material - calcium sulfate dihydrate ((Ca (SO4) 2H2O), also known as gypsum dihydrate 1. Quarrying raw limestone 2. Preparing limestone for kilns by crushing and sizing 3. Calcining limestone 4. Processing the lime further by hydrating 5. Miscellaneous transfer, storage, and handling operations. Kiln – heart of the lime plant - - long, cylindrical, slightly inclined, refractorylined furnace, through which the limestone and hot combustion gases pass countercurrently. Coal, oil, natural gas – fired in rotary kilns. Vertical or Shaft Kiln – upright heavy steel cylinder with refractory material. Higher average fuel efficiency. Relatively low production rates Coal cannot be used