Guniting or Shotcrete or Shot Concrete

Guniting or Shotcrete Guniting or Shotcrete: An intimate mixture of cement, sand (or fine aggregate) and water is forced or ejected through a cement-gun and shot into place by means of compressed air. The usual equipment consists of a compressor, spray nozzle and flexible hose pi...

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Geological Classification of Rocks

Geological Classification of Rocks It is estimated that three-fourth of the land area of the globe is underlain by sedimentary rocks and the other fourth by igneous and metamorphic rocks. Main three geological classification of rocks are, : Igneous rocks: Are of volcanic origin, ...

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Cement Mortar – Preparation of Cement Mortar

Cement Mortar The unit of measurement for cement is a bag of cement weighing 50 kg and this is taken as 0.035 cu. m. Sand is measured in boxes of size 25x35x40 cm on the basis of its dry volume. Cement mortar shall be used as soon as possible after mixing and before it has [&hell...

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Cold Weather Concreting- Concreting in Cold Weather

Cold Weather Concreting During Cold weather concreting, the rate of hardening and setting of concrete is very much retarded when the temperature falls below 21 deg. C. (70 deg. F.). At about 10 deg. C. (50 deg. F.) the action of setting slows down to about one-half of what it is ...

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Hot Weather Concreting – Concreting in Hot Weather

Hot Weather Concreting Hot Weather Concreting in tropical countries, such as India, air temperatures may rise up to 40-50 deg. C. during summer months. Such temperatures combined with high wind velocity and/or low humidity enhance the rate of evaporation of the water, increase th...

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Efflorescence in Brick Work

Efflorescence in Brick Work When soluble salts are present in huge quantities in the bricks or in the mortar, they absorb moisture from air or during construction progress and are brought to the surface in solution and deposited in concentrated patches either in the form of white...

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Quick Sand Formation/Condition

Quick Sand Formation/Condition Quick sand formation/condition is not a soil type. Quick sand formation/condition is created in saturated thick layers of loose fine sandy soils when disturbed either due to vibration such as from pile driving in the near by locality or due to the p...

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Foundations in Black Cotton Soils

Foundations in Black Cotton Soils: The following methods are generally adopted to meet the characteristics of foundations in black cotton soils,   (1) Foundation loads are limited to 5 tonnes/sq.m if water finds access to the foundations, otherwise it may be about 10 tonnes/...

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Test for Sand – Fine Aggregate

Test for Sand – Fine Aggregate The required test for sand are as follows, 1. Take a glass of water and add some quantity of sand in it. Then it is vigorously shaken and allowed to settle. If clay is present in sand,its distinct layer is formed at top of sand. 2. For detect...

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Concrete Shrinkage – Shrinkage of Concrete

Concrete Shrinkage – Shrinkage of Concrete Concrete shrinks during setting and drying due to hydration of cement and produces shrinkage cracks. The drying shrinkage increases with an increase in cement content or an increase in water content. Shrinkage is greater with riche...

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