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The slump test measures the consistency of fresh concrete before it sets. It is performed to check the workability of freshly made concrete, and therefore the ease with which concrete flows How is slump measured? Simply defined,  slump  is a  measure  of the consistency of fresh concrete. The  slump  test is a very simple test. The  slump  cone is a right circular cone that is 12 inches high. The base of the cone is 8 inches in diameter and the top of the cone is 4 inches in diameter. Concrete Slump Test Procedure Firstly, the internal surface of the mould is cleaned carefully. Oil can be applied on the surface. The mould is then placed on a base plate. The base plate should be clean, smooth, horizontal and non-porous. The mould is filled with fresh concrete in three layers. Each layer is tamped 25 times with a steel rod. The diameter of this steel rod is  5 ⁄ 8 inch. The rod is rounded at the ends. The tamping should be done u...

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HOW TO MINIMISE THE DEFECTS IN PLASTERING WORK? HOW TO MINIMISE THE DEFECTS IN PLASTERING WORK? MINIMISING DEFECTS IN PLASTERING WORK Defects in plastering work can be minimised by following the below mentioned techniques. The brick and plastering work should be carried out by skilled masons in the best workmanship manner. Bond of brick work should be properly maintained. Efflorescence is removed by rubbing brushes on the damaged surface. A solution of one part of hydrochloric acid or sulphuric acid and five parts of clean water is prepared and it is applied with the help of brushes on the affected area. The surface is then washed with clean water. It should, however be remembered that it is desirable to prevent efflorescence than to cure it. Building material should be selected of superior quality and suitable methods of construction should be employed. Water should not be used to wash the surface so as to remove efflorescence. In that case, soluble salts will be partl...

4 PRIMARY CEMENT COMPOUNDS & THEIR ROLES COMPOUNDS OF CEMENT   cement compounds About 90-95% of a Portland cement is comprised of the four main cement minerals, which are  C 3 S ,  C 2 S ,  C 3 A , and  C 4 AF , with the remainder consisting of calcium sulphate, alkali sulphates, unreacted (free) CaO, MgO, and other minor constituents left over from the clinkering and grinding steps. The four cement minerals play very different roles in the hydration process that converts the dry cement into hardened cement paste.  The C 3 S and the C 2 S contribute virtually all of the beneficial properties by generating the main hydration product, C-S-H gel.  However, the  C 3 S hydrates much more quickly than the C 2 S   and thus is responsible for the early strength development .  The C 3 A and C 4 AF minerals also hydrate, but the products that are formed contribute little to the properties of the cement paste.  These minerals a...