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The general safety measures taken during civil engineering construction.

The following safety measures are taken during civil engineering construction. (i) Suitable scaffolds should be provided for workmen. (ii) When ladder are used, it should be provided with foot holds and hand holds and inclination of one is to four (1 horizontal : 4 vertical) be provided. (iii) The scaffolding should be properly supported and shall have a guard rail property attached to it. (iv) Every opening in floor of a building should be provided with suitable means to prevent the fall of persons or materials. (v) Fencing and lights shall be provided to protect the public from accident. (vi) The excavated material shall not be placed within 1.5m of the edge of the trench or half the depth whichever is more to avoid collapse of sides due to surcharge. (vii) No undermining or undercutting shall be allowed. (viii) All roads and open areas adjacent to any side where demolition is to be carried out, must be closed or suitably protected. (ix) No electrical cable etc. shall remain electric...
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The function and uses of various admixtures used in concrete.

Admixture is a material other than water, aggregates and hydraulic cement abd additives like pozzolana or slag and fibre reinforcement used as an ingredient of concrete or mortar and added to the batch immediately before or during its mixing to modify one or more of the different types of admixtures are as follows:

(a) Accelerating Admixtures or Accelerators: An admixture when added to concrete, mortar or grout. increases the rate of hydration of a hydraulic cement, shortens the time to set, or increase the rate of hardening or strength development.

(b) Retarding Admixture or Retarder: An admixture which delays the setting of cement paste, and hence of mixtures, such as mortar or concrete containing cement.

(c) Water Reducing Admixture or Workability Aid: An admixture which either increases workability of freshly mixed mortar or concrete without increasing water content or maintain workability with reduced amount of water.

(d) Air-Entraining Admixtures: An admixture for concrete or mortar which causes air to be incorporated in the form of minute bubbles in the concrete or mortar during mixing, usually to increase workability and resistance to freezing and thawing and disruptive action of de-icing salts.

(e) Superplasticizing Admixtures: An admixture for mortar or concrete which imparts very high workability or allows a large decrease in water content for a given workability.

(f) Retarding Supreplasticizing admixture: Retarding Superplasticizing admixture imparts prolonged workability retention and retards setting.

 

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