Maawa World

Cement Cement is a commonly used binding material in the construction. The cement is obtained by burning amixture of calcarious (calcium) and argillaceous (clay) material at a very high temperature and then grinding the clinker so produced to a fine powder. It was first produced by a mason Joseph Aspdin in England in 1924. He patented it as portland cement. Types of Cement In addition to ordinary portland cement there are many varieties of cement. Important varieties are briefly explained below: (i) White Cement: The cement when made free from colouring oxides of iron, maganese and chlorium results into white cement. In the manufacture of this cement, the oil fuel is used instead of coal for burning. White cement is used for the floor finishes, plastering, ornamental works etc. In swimming pools white cement is used to replace glazed tiles. It is used for fixing marbles and glazed tiles. (ii) Coloured Cement: The cements of desired colours are produced by intimately mixi...

LIME It is an important binding material used in building construction. Lime has been used as the material of construction from ancient time. When it is mixed with sand it provides lime mortar and when mixed with sand and coarse aggregate, it forms lime concrete. Types of Limes and their Properties The limes are classified as fat lime, hydraulic lime and poor lime: (i) Fat lime: It is composed of 95 percentage of calcium oxide. When water is added, it slakes vigorously and its volume increases to 2 to 2 1/2 times. It is white in colour. Its properties are: (a) hardens slowly (b) has high degree of plasticity (c) sets slowly in the presence of air (d) white in colour (e) slakes vigorously. (ii) Hydraulic lime: It contains clay and ferrous oxide. Depending upon the percentage of clay present, the hydraulic lime is divided into the following three types: (a) Feebly hydraulic lime (5 to 10% clay content) (b) Moderately hydraulic lime (11 to 20% clay content) (c) Emin...

ATTERBERG LIMITS The Atterberg limits are water contents which define the limits of various stages of consistency for fine-grained soils. The liquid limit (LL) and the plastic limit (PL) define the upper and lower limits, respectively, of the plastic range of a soil; the numerical difference between these two limits expresses the plasticity of a soil and is termed the plasticity index (PI). Liquid Limit The liquid limit of a soil is the water content, expressed as a percentage of the weight of oven-dried soil at which two halves of a soil pat separated by a groove of standard dimensions will close at the bottom of the groove along a distance of 1/2 in. under the impact of 25 blows in a standard liquid limit device. Plastic Limit The plastic limit of a soil is the water content, expressed as a percentage of the weight of oven dried soil at which the soil just begins to crumble into short pieces when rolled into a thread 1/8 in.  in diameter. P...