CONCRETE – is defined as the mixture of water, cement, aggregates and admixture. - - The name concrete comes from the latin word “Concretuse” (meaning compact or condensed). Process known HYDRATION solidifies and hardens the concrete after mixing and chemical. TYPES OF CONCRETE a) BASED IN WEIGHT, CONCRETE CAN BE CLASSIFIED INTO FOUR CATEGORIES: - ULTRA-LIGHT WEIGHT CONCRETE (1200 kg/m^3) LIGHT WEIGHT CONCRETE (<1800 kg/m^3) NORMAL WEIGHT CONCRETE (2400 kg/m^3) HEAVY WEIGHT CONCRETE (>3200 kg/m^3) b) BASED ON STRENGTH, CONCRETE CAN ALSO BE CLASSIFIED INTO FOUR CATEGORIES: - - - - LOW STRENGTH CONCRETE (< 20 MPA COMPRESSIVE STRENTH) MODERATE – STRENGTH CONRETE (20 – 50 MPA COMPRESSIVE STRENGTH) HIGH STRENGTH CONCRETE (50-200 MPA COMPRESSIVE STRENGTH) ULTRE HIGH STRENGTH CONCRETE (>200 MPA COMPRESSIVE STRENGTH) USES OF CONCRETE 1) CONCRETE DAMS – used to store water and produce electricity. The loads imposed on the dam due to water pressure are very intense which makes concrete as a suitable material for dam construction. 2) RESIDENTIAL BUILDINGS – the construction of small buildings, villas, and even high-rise buildings are done using concrete with traditional or modern formwork. 3) COMMERCIAL BUILDINGS – the use of concrete in commercial buildings makes it safe than using most other construction materials. 4) ROADS OR DRIVEWAYS – concrete streets, pavement, and driveways are more durable and stronger than asphalt roadways. 5) MARINE CONSTRUCTION – concrete has had extensive use as a construction material for seawalls, jetties, groins, breakwaters, bulkheads, and other structures exposed to seawater. 6) CULVERTS AND SEWERS – Sewers and underground construction works need strong and durable building materials and concrete is the ideal one. 7) FOUNDATIONS – the foundations of high-rise or lowrise buildings is usually constructed using reinforced cement concrete, as it is durable and has a huge load-carrying capacity. 8) FENCES – the development in the precast concrete industry has improved the industry has improved the industry of concrete fences. 9) CONCRETE BRIDGES – reinforced concrete strength, durability, ductility, weather resistance, fire resistance and long-lasting life cycle makes the concrete the best solution for constructing bridges. FACTORS AFFECTING CONCRETE STRENGTH 1) WATER/CEMENT RATIO 2) AGE AND CURING CONDITIONS 3) AGGREGATES 4) ADMIXTURES