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  Characteristics of aggregate  Aggregate must be clean, hard ,strong , properly shaped and well graded. The aggregate must possess chemical stability, resistance to abrasion and to freezing and thawing.they should not contain deleterious material which may causes physical ir chemical changes . The properties of aggregate for concerete are discussed under the following heads   1) Particles size and shape   2) Surface texture   3) specific gravity   4) Bulk density   5) Voids   6) Water absorption   7) surface moisture   8) Bulking of sand    9) Deleterious material in the aggregate    1) Particles size and shape The size and shape of aggregate significantly influence the mobility i.e.. the workability fresh concerete and the bond between the aggregate and the mortar phase .The rounded aggregates are available in the form of river or seashore gravel which are fully waterworm or compeletly shaped by attrition, where irr...

  Agrregates   These are chemically inert material which are bounded by cement paste form concerete . Aggregate is  derived from igneous, sedimentary and metamorphic rocks . Aggregate are generally cheaper than cement and impart greater volume stability and durability to concerete. The aggregate provide about 75% of the body of concerete and hence its influence is extremely important.  Classification of aggregate   1- Classification of Aggregates According to source. 2- Classification of Aggregate According to size  3- Classification of Aggregate According to shape  4- Classification of Aggregate According to unit weight.  1- Classification of Aggregates According to source.  According to sources, the aggregate are classified into two categories:  1) Natural Aggregate  2) Artificial Aggregate.  1) Natural Aggregate   These aggregate are generally obtained from natural deposition of sand and gravel or from quarries by cutti...

  कंक्रीट के संघटक   कंक्रीट सीमेंट,  बालू ,  गिट्टी और जल  से मिलकर बनती है। यही कंक्रीट के संघटक होते है।  सीमेंट  सीमेंट एक बंधक पदार्थ है जिसका प्रयोग कंक्रीट के संघटको को आपस में एक दूसरे से बांधने के लिए किया जाता है।  सीमेंट के संघटक  सीमेंट निम्न घटकों से मिलकर बना होता है।  Lime   60-67%  Silica - 17-24%  Alumina -3-8%  Magnisum oxide 0.5-3%  Iron oxide 1-3%  Gypsum - 3-5%  SO3  चुना (lime)  चुने का प्रयोग सीमेंट में बंधक पदार्थ के रूप में किया जाता है।चुना सीमेंट को सामर्थ्य प्रदान करता है। इसकी मात्रा अधिक होने पर सीमेंट में प्रसार होने लगता है। और मात्रा कम होने पर सीमेंट की सामर्थ्य में कमी आ जाती है।  सिलिका   सिलिका का प्रयोग सीमेंट में सामर्थ्य प्रदान करने के लिए  होता है। अधिक होने पर- सीमेंट जल्दी कठोर हो जाता है। कम होने पर सामर्थ्य में कमी। एल्यूमिना Alumina   Alumina का प्रयोग सीमेंट में सीमेंट को जमाने के लिए प्रयोग किया जाता है।इसकी मात्रा अधिक ह...

  Notes for competitive exam Who wrote the book ‘Discovery of India’? – Pt. Jawaharlal Nehru Who discovered the ‘Gravitational’? – Newton Who is the first Indian to receive Nobel Prize? – Ravinder Nath Tagore What is the Dronacharya Award related to? – Best Coach in Sports/Games Khajuraho is situated in-? – Madhya Pradesh Does earth have one large natural satellite, known as? – Moon Who played Gandhi’s role in the film ‘Gandhi’? – Ben Kingsley Teachers’ Day is celebrated? – 5 September When was the nuclear bomb dropped on Japan? – 1945 On which river is the clumsy Nangal dam? – Sutlej India’s national flower? – Lotus Dhanraj Pillai is related to which game? – hockey In United Nations Organization (U.N.O), How many permanent members are in the Security Council? – 5 Which Indus Civilization is now in Pakistan? – Harappan Which types of taxes were collected in South India, particularly the Maratha Empire during medieval times? – Chauth and Sardeshmukhi Who introduced English education...