Concrete PDF

TOPIC: CONCRETE (CEMENT + WATER) + (SAND + STONES) = CONCRETE Cement/water paste + aggregates = concrete · Cement is a substance that binds aggregates together into a very dense material that possesses great compressive strength. ·...

TOPIC: CONCRETE (CEMENT + WATER) + (SAND + STONES) = CONCRETE Cement/water paste + aggregates = concrete · Cement is a substance that binds aggregates together into a very dense material that possesses great compressive strength. · Manufacturing of OPC Portland Cement Portland cement is used in the manufacturing of concrete and mortar. It may also be used as a bed for clay and cement tiles. Step 1: Ordinary Portland Cement is made by mixing limestone and clay with water to form a semi-liquid mixture, or slurry. Step 2: The slurry is screened and is passed into a storage tank where it is kept agitated in preparation for passage into a kiln, Step 3: The slurry is fed into the upper end of the kiln and flows down to the direction of the heat. As the kiln revolves, it dries the slurry. Water evaporates under this intense temperature heat fusing the materials into a clinker or cement noodles. Step 4: The clinker is cooled and ground to a fine powder. A small amount of gypsum is added to retard the setting time of the cement. Aggregates: These are broad categories of coarse- to medium-grained particulate material used in construction, including sand, gravel, crushed stone, etc. Characteristics of Aggregates Aggregates generally make up the bulk of the concrete. These are available in fine and coarse grades. For mortar the size of aggregates is very small ranging from 0-4mm, and for general concrete work the size varies from 5-20mm. Requirements of Aggregates All aggregates should be: clean free from sediments sound strong – not easily crushed well graded well shaped