Skip to main content

Cement

Chemical Composition:-
Ordinary cement contains two basic ingredients, namely, argillaceous and calcareous. In argillaceous materials,
clay predominates and in calcareous calcium carbonate predominates.
Broadly, the raw materials used for manufacture of cement consist mainly of lime, silica, alumina and iron oxide. These oxides interact with one another at high temperature and form more complex compounds. The relative proportions of these oxide compounds are responsible for
influencing the various properties of cement, in addition to rate of cooling and fineness of grinding.

Functions Of Cement Ingredients
1. Lime (CaO): Excess lime makes the cement unsound and causes the cement to expand and disintegrate.
Deficiency in lime makes loss of strength and makes cement to set quickly.
2. Silica (SiO2): SiO2 imparts the strength to cement by forming the di-calcium and tri-calcium silicates.
Excess silica makes the strength of cement increases,but prolongs the setting time.
3. Alumina (Al2O3): Al2O3 imparts quick setting property to the cement. It acts as a flux and lowers the clinkering temperature. Excess alumina makes cement weaker.
4. Calcium Sulphate (CaSO4): It is in the form of gypsum and increases the initial setting time of cement.
5. Iron Oxide (Fe2O3): Fe2O3 imparts colour, hardness and strength to cement.
6. Magnesia (MgO): MgO imparts hardness and colour, if present in small amount. Excess MgO makes cement unsound.
7. Sulphur (S): It is useful in making sound cement.
8. Alkalis: Most of the alkalis present in raw materials are carried away by the flue gases during heating process. Presence of alkalis causes problems such as alkali-aggregate reaction, efflorescence and staining, etc.
Labels:

Popular posts from this blog

Stone masonry

The construction of stones bonded together with mortar is termed as stone masonry where the stones are available in a abundance in nature, on cutting and dressing to the proper shape, they  provide an economical material for the construction of various building components such as walls, columns, footings, arches, lintels, beams etc. Uses of stone masonry: Stone masonry construction is used in (i) Building foundations, dams,monumental structures.  (ii) Building walls, piers, columns, pillars, light houses and architectural works.   (iii) Arches, domes, lintels and beams (iv) Roofs, flems, paving jobs (v) Railway, bullest, black boards and electrical switch boards.    Selection of stone for stone masonry:  The selection of stones for stone masonry depends upon a. Availability b. Ease of working c. Appearance d. Strength and stability e. Polishing characteristics f. Economy g. Durability General pri...
Read more

Formwork

             Formwork is the term used for the process of creating a temporary mould into which concrete is poured and formed. formwork it is a temporary support. 1)This is temporary casing is known formwork or forms or shuttering. 2) It becomes sufficiently strong to support its own weight. 3) Traditional formwork is fabricated using timber, but it can be also constructed from Steel, glass fibre, reinforced plastics and other material. specification:- 1. Capable of resisting hydrostatic pressure of the wet concrete. 2. Join should prevent leakage of cement grout. 3. High quality workmanship and inspection necessary. 4. As light weight has possible. 5. Material used be suitable for reuse. 6.Formwork base or soffit must be capable of resisting the initial dead load of wet concrete. 7.Strong enough to withstand dead and live loads. 8.Capable of retaining its shape by being efficiently propped and braced horizontally and vertically...
Read more

Types of brick bonds

Bonding is a process of arranging bricks and mortars to tie them together in a mass of brickwork. It should have a minimum of vertical joints in any part of the work. Characteristics of brick bond or rules for bonding: 1. The brick masonry should have bricks of uniform shape and size. 2. For satisfactory bondage the lap should be one-fourth of the brick along the length of the wall and half brick across thickness of the  wall.  3. The brick bats use should be discouraged. 4. The vertical joints in the alternate courses should coincides with the centre line of the stretcher.   5. The alternate courses the centre line of header should coincide with the centre line of stretcher, in course below or above it.   6. The stretcher should be used only in the facing while hearting should be done in the headers only. Classifications of bonds: The bonds can be classified as follows: (i) Stretcher bond (ii) Header bond (iii) English bon...
Read more