Cellular or aerated concrete

Cellular or aerated concrete :- It is prepared by mixing aluminium in the cement concrete. It is light in weight and spongy in structure. It is used for roof slab and precast unit in partition for heat and sound insulation. It also called air-entrained concrete.

Ø Advantages:-

a) Workability of concrete increases.

b) Use of air entraining agent reduces the effect of freezing and thawing.

c) Bleeding, segregation and laitance in concrete reduces.

d) Entrained air improves the sulphate resisting capacity of concrete.

e) Reduces the possibility of shrinkage and crack formation in the concrete surface.

Ø Disadvantages:-

a) The strength of concrete decreases.

b) The use of air entraining agent increases the porosity of concrete thereby reducing the unit weight.

c) Air-entrainment in concrete must not be done if the site control is not good. This is due to the fact that the air entrained in a concrete varies with the change in sand grading, errors in proportioning and workability of the mix and temperatures.

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Composition of Cement Clinker

The various constituents combine in burning and form cement clinker. The compounds formed in the burning process have the properties of setting and hardening in the presence of water. They are known as Bogue compounds after the name of Bogue who identified them. Le-Chatelier and Tornebohm have referred these compounds as Alite (C3S), Belite (C2S), Celite (C3A) and Felite (C4AF). The following Bogue compounds are formed during clinkering process. The properties of Portland cement varies markedly with the proportions of the above four compounds, reflecting substantial difference between their individual behaviour. Tricalcium Silicate :- It is supposed to be the best cementing material and is well burnt cement. It is about 25-50% (normally about 40 per cent) of cement. It renders the clinker easier to grind, increases resistance to freezing and thawing, hydrates rapidly generating high heat and develops an early ha...

Types of bonds generally used in brick masonry.

Brick masonry is built with bricks bonded together with mortar. For temporary sheds mud mortar may be used but for all permanent buildings lime or cement mortars are used. The various types of bonds generally used in brick masonry are 1. Stretcher bond 2. Header bond 3. English bond and 4. Flemish bond. Stretcher Bond: A stretcher is the longer face of the brick as seen in the elevation. In the brick of size 190 mm × 90 mm × 90 mm, 190 mm × 90 mm face is the stretcher. However care should be taken to break vertical joints. This type of construction is useful for the construction half brick thick partition wall.This bond is sometimes known as running bond. This bond is the simplest bond that is used today, this bond is not suitable as a stand alone structural wall and a structural wall built directly behind it, fixed with wall ties would be needed. Header Bond A header is the shorter face of the brick as seen in the elevation. In a standard...

1cum 250mm THICK BRICK WORK CALCULATION

1cum 250mm THICK BRICK WORK CALCULATION Brick size with mortar :- 250mm*125mm*75mm Volume of 1 brick with mortar:- 0.250*0.125*0.075 = 0.00234cum. Brick size with out mortar :- 240mm*115mm*65mm Volume of 1brick without mortar :- 0.240*0.115*0.065 = 0.00179. Nos of brick in 1cum with mortar:- 1/0.00234 = 427.4 = 427 Volume of 427nos brick without mortar:- 427*0.00179 = 0.76 cum Required of cement mortar :- 1-0.76 = 0.24cum. Now Dry volume of mortar :- 0.24*1.33 = 0.32 cum We know the mortar ratio :- 1:6 So, Cement :- 0.32*1/7*1440 kg = 65.8 = 66 kg Sand :- 0.32*6/7 cum = 0.27 cum.

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