NANTAI NVERSTES BUILDING MATERIALS CHAPTER 10 CONCRETE Mhendislik

NİŞANTAŞI ÜNİVERSİTESİ BUILDING MATERIALS CHAPTER 10 -CONCRETE Mühendislik Mimarlık Fakültesi mmf. nisantasi. edu. tr NİŞANTAŞI ÜNİVERS İTESİ ©

CONCRETE Concrete a composite man-made material, is the most widely used building material in the construction industry. It consists of a rationally chosen mixture of binding material such as lime or cement, well graded fine and coarse aggregates, water and admixtures (to produce concrete with special properties). In a concrete mix, cement and water form a paste or matrix which in addition to filling the voids of the fine aggregate, coats the surface of fine and coarse aggregates and binds them together. NİŞANTAŞI ÜNİVERSİTESİ ©

LIME CONCRETE, GYPSUM CONCRETE AND CEMENT CONCRETE The stages of concrete production: 1. Batching or measurement of materials 2. Mixing 3. Transporting 4. Placing 5. Compacting 6. Curing 7. Finishing A typical vertical batching mixing plant for large size work NİŞANTAŞI ÜNİVERSİTESİ ©

COMPACTION After concrete is placed at the desired location, the next step in the process of concrete production is its compaction. Compaction consolidates fresh concrete within the moulds or frameworks and around embedded parts and reinforcement steel. Considerable quantity of air is entrapped in concrete during its production and there is possible partial segregation also. Both of these adversely affect the quality of concrete. Compaction of the concrete is the process to get rid of the entrapped air and voids, elimination of segregation occurred and to form a homogeneous dense mass. NİŞANTAŞI ÜNİVERSİTESİ ©

COMPACTION BY VIBRATION The vibrations imparted to the fresh concrete reduce the internal friction between the particles of concrete by setting the particles in motion and thus produce a dense and compact mass. On vibration, the concrete mix gets fluidized and the internal friction between the aggregate particles reduces, resulting in entrapped air to rise to the surface. On losing entrapped air the concrete gets denser. For proper compaction in a heaped concrete the poker position should be changed gradually from the side of the heap and moving away from the heap all around. NİŞANTAŞI ÜNİVERSİTESİ ©

CURING Cement gains strength and hardness because of the chemical action between cement and water. This chemical reaction requires moisture, favourable temperature and time referred to as the curing period. The variation of compressive strength with curing period. NİŞANTAŞI ÜNİVERSİTESİ ©