Early Attempts of Prestressing

Prestressing of structures was introduced in late nineteenth century. The following sketch explains the application of prestress.     Mild steel rods are stretched and concrete is poured around them. After hardening of concrete, the tension in the rods is released. The rods will try to regain their original length, but …

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Pre-tensioning the spokes in a bicycle wheel

The pre-tension of a spoke in a bicycle wheel is applied to such an extent that there will always be a residual tension in the spoke. For concrete, internal stresses are induced (usually, by means of tensioned steel) for the following reasons…… • The tensile strength of concrete is only …

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Prestressed Concrete Structures

prestressed concrete structure is different from a conventional reinforced concrete structure due to the application of an initial load on the structure prior to its use. The initial load or ‘prestress’ is applied to enable the structure to counteract the stresses arising during its service period. The prestressing of a structure is …

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Water impermeable expanding cement

Water impermeable expanding cement is a quick-setting and quick hardening hydraulic cementing material obtained by grinding or mixing finely ground aluminous cement, gypsum and high basicity calcium aluminate in a ball mill. Calcium aluminate of high basicity (4CaO.Al2O3.12H2O) is obtained by hydrothermal curing over a period of 5 to 6 hours …

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Expanding Cement

This group of binding material encompasses cements that show a slight increase in volume in the course of hardening under moist conditions, or that do not shrink when hardened in the air. Two kinds of expanding cements are available the water-impermeable and gypsum-aluminous varieties.

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Acid resistant cement

Acid-resistant cements consist of an aqueous solution of sodium silicate (soluble glass), an acid-resistant aggregate and an additive (hardening accelerant). The micro aggregates are quartz, quartzites, andesite, diabase and other acid-resistant materials; the hardening accelerant is sodium fluosilicate. The binding material in the acid-resistant cement is soluble glass—a water solution of sodium silicate …

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 Mortar classification

Mortars are classified on the basis of their bulk density, kind of binding material, applications and ,physical and mechanical properties. On the basis of bulk density :  Type of Mortar       Bulk Density (kg/m3)          Aggregate Heavy weight               …

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Building Mortar

Building mortars are mixtures used for the jointing of bricks, stones, blocks, etc. Mortar may be defined as a paste (capable of setting and hardening) obtained by adding water to a mixture of fine aggregates such as sand and binding material, e.g., clay, gypsum, lime or cement or their combinations. The …

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TYPE OF FOUNDATION

Foundation Broadly can be classified into two type :  shallow foundation Deep foundation Shallow Foundation :  A shallow foundation is that which transmits the load to the strata at a shallow depth shallow foundation is laid at a depth equal to or less than it’s width called shallow foundation.  

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