Engineering key Point

Physical Tests on Cement (a) Soundness Test: It is conducted by sieve analysis. 100 gms of cement is taken and sieved through IS sieve No. 9 for fifteen minutes. Residue on the sieve is weighed. This should not exceed 10 per cent by weight of sample taken. (b) Setting Time: Initial setting time and final setting time are the two important physical properties of cement. Initial setting time is the time taken by the cement from adding of water to the starting of losing its plasticity. Final setting time is the time lapsed from adding of the water to complete loss of plasticity. Vicat apparatus is used for finding the setting timesVicat apparatus consists of a movable rod to which any one of the three needles shown in figure can be attached. An indicator is attached to the movable rod. A vicat mould is associated with this apparatus which is in the form of split cylinder. Before finding initial and final setting time it is necessary to determine...

Chapter one INTRODUCTION Curves are provided whenever a road changes its direction from right to S (vice versa) or change sits alignment from up to down (vice versa). Curves are a critical element in the pavement design. They are provided with a maximum speed limit that should lie followed very strictly. Following the speed limit becomes essential as the exceed in speed may lead to the chances of the vehicle becoming out of control while negotiating a turn and thus increase the odds of fatal accidents. Also, it is very necessary that appropriate safety measures be adopted at all horizontal and vertical curves to make the infrastructure road user friendly and decrease the risks of hazardous circumstances. The center lines of highways and railroads consist of a series of straight lines connected by curves. The curves of fast traffic are normally circular, although spiral curves may be used to provide gradual transitions to or from the circular cur...

Details of structures or building can be drawn out with AutoCAD software clearly, for the engineer or builder for easy understanding. Sections

Causes Of Global Warming The  greenhouse effect The average surface temperature of  Earth  is maintained by a balance of various forms of solar and terrestrial radiation.  Solar radiation  is often called “shortwave” radiation because the frequencies of the radiation are relatively high and the wavelengths relatively short—close to the visible portion of the  electromagnetic spectrum . Terrestrial radiation, on the other hand, is often called “longwave” radiation because the frequencies are relatively low and the wavelengths relatively long—somewhere in the  infrared  part of the spectrum. Downward-moving  solar energy  is typically measured in  watts  per square metre. The energy of the total incoming  solar radiation  at the top of Earth’s  atmosphere  (the so-called “ solar constant ”) amounts roughly to 1,366 watts per square metre annually. Adjusting for the fact that only one-half of the plane...

ASBESTOS Asbestos is a general name for several varieties of fibrous minerals which are available in nature. But presently, most of the commercial asbestos produced is ‘chriotile’ [Mg6SiO11(OH)6.H2O]. Properties of Asbestos 1. It is flexible, soft and non-porous. 2. It is fireproof and acid proof material. 3. It is a good insulator of heat and electricity. 4. When it is mixed with cement and water, it retains shape firmly. 5. Its colour is brown or grey. 6. It can be cut into pieces or can be drilled. 7. It possesses high tensile strength in the direction of its fibres. 8. Its specific gravity is 3.10. Uses of Asbestos 1. Asbestos cement sheets are the cheapest roofing materials. 2. Asbestos cement pipes are used as down take pipes of rain water from the roof. 3. With bitumen it forms good damp proof layer. 4. It is used for preparing fire proof ropes and clothes. 5. It is used as covering material for fuse and electric switch boxes. 6. It is...

BITUMEN Ashalt, bitumen and tar are referred as bituminous materials, which are essentially hydrocarbon materials.The asphalt is a mixture of inert mineral matter lime alumina, lime, silica etc. and a hydrocarbon known as asphaltic bitumen. In some places like Trinidad and Bermudez, asphalt is available in nature at a depth of 3 to 60 metres. It is known as natural asphalt.  Common variety used all over the world is residual asphalt, which is obtained by fractional distillation of crude petroleum oil. Bitumen is the binding material which is present in asphalt. It is a hydrocarbon.  It is obtained by partial distillation of crude oil. It contains 87 per cent carbon, 11 per cent hydrogen and 2 per cent oxygen.Tar is obtained in the distructive distillation of coal, wood or other organic materials. When coal or wood is heated to redness in an closed chamber, it yields volatile product and residue coke. After separating and coo...

DISTEMPERS Distempers are the cheaper variety of paints in which chalk is used as base and water is used as a carrier.The emulsifying agent which is commonly used is glue or casein. Distempers are available in powder form or in the form of paste.  They are to be mixed with hot water before use.The surface to be distempered should be thoroughly rubbed and cleaned. The cracks, if anyshould be filled by lime putty. The surface should be kept dry for about two months before applying distemper. Thus a primary coat is applied and is allowed to dry. Distemper is usually applied in two coats. Properties of Distemper 1. They are generally light in colour. 2. The coatings are generally thick. 3. They give reflective coating. 4. They are less durable than oil paints but are cheaper.