Engineering key Point

REINFORCED BRICK CONCRETE (RBC) It is the combination of reinforcement, brick and concrete. It is well known fact that concrete is very weak in tension. Hence in the slabs, lintels and beams the concrete in the portion below the neutral axis do not participate in resisting the load. It acts as a filler material only. Hence to achieve economy the concrete in tensile zone may be replaced by bricks or tiles. Dense cement mortar is used to embed the reinforcement. The reinforcement may be steel bars, expanded mesh etc. PRESTRESSED CONCRETE (PSC) Strength of concrete in tension is very low and hence it is ignored in R.C.C. design. Concrete in tension is acting as a cover to steel and helping to keep steel at desired distance. Thus in R.C.C. lot of concrete is not properly utilized. Prestressing the concrete is one of the method of utilizing entire concrete. The principle of prestressed concrete is to introduce calculated compressive stresses in the zones wherever tensile stres

CAUSES OF DAMPNESS Dampness may be caused by: (a) Ground water (b) Rainwater and (c) Leakages from pipes. (a) Dampness due to Ground Water:  All buildings are founded on soils. Soil holds water for along time. Sometimes water level may rise and come in contact with foundation. Due to capillary action moisture from ground rises into foundation, floor and even in wall. (b) RainWater:  May enter the building components due to various reasons. (i) From wall top: If top of wall is not protected with impervious course like concrete, water can enter the wall and keep it damp for a long time. (ii) From face of external walls: Splashing of outer wall by rain results into moisture entering the wall. Poor plaster coat is the main source of this type of dampness. (iii) Improper fixing of downtake pipes: Ifdowntake pipes from roof are not properly fixed, a thin layer of water stagnates near the mouth of downtake pipes. This results into entry of rain water into roof and wa

Prestressed Concrete Beam Load Test to Failure The determining of the load capacity for any structure, is in these days of paramount importance, none more so, than for those involving concrete. Major building structures such as bridges rely on tests involvingprestressed concrete beam load test to failure. Introduction For enabling concrete to support a greater load capacity, or to span a greater distance than ordinary reinforced concrete, a French engineer named Eugéne Fressenet devised a process. This was during the early part of the twentieth century and was the introduction of prestressing. How It's Done and Benefits ofPrestressed Concrete The process involves the reinforcing of concrete, using pre-tensioning or post-tensioning and the result of thisprestressing process places a concrete section in compression. The compressive stresses, have the effect of counteracting the tensile bending stresses of an applied load. However, it still has to be determined if it w

Reinforced Rigid pavement with dam prove (nylon) Home is a basic need of human kind. If water seep in it, it distract the owner of that home and frustration levels get increased due to it. Why water leaks *Because during rain water may getting accumulated on roof and the accumulated water is finding its way to get down. Water always flow in the direction of gravity and erode everything in its way including hard rock, erosion depends on its intensity and the quality of material. *Another possibility is leakage in the water line concealed in wall, which is dampening the walls and floors. How to do conventional waterproofing Chip out any access dead mortar from the surface of concrete . First check for any water leakages in base surface. Open the cracks on surface from top by making 'V' groove, fill it with cement mortar including integral waterproofing compound and place the spouts in between. In case dampness is seen, place the spout in weak areas. Do pres

Properties of Ordinary Portland Cement (i) Chemical properties: Portland cement consists of the following chemical compounds: (a) Tricalcium silicate 3 CaO.SiO2 (C3S) 40% (b) Dicalcium silicate 2CaO.SiO2 (C2S) 30% (c) Tricalcium aluminate 3CaO.Al2O3 (C3A) 11% (d) Tetracalcium aluminate 4CaO.Al2O3.Fe2O3 (C3AF) 11% There may be small quantities of impurities present such as calcium oxide (CaO) and magnesium oxide (MgO). When water is added to cement, C3A is the first to react and cause initial set. It generates great amount of heat. C3S hydrates early and develops strength in the first 28 days. It also generates heat. C2S is the next to hydrate. It hydrates slowly and is responsible for increase in ultimate strength. C4AF is comparatively inactive compound. (ii) Physical properties:  The following physical properties should be checked before selecting a portland cement for the civil engineering works. IS 269–1967 specifies the method of testing and prescribes the

R.C.C Foundation FOOTINGS There are mainly two types of R.C.C. footings: 1. One way reinforced footings. 2. Two way reinforced footings. 1. One Way Reinforced Footing:  These footings are for the walls. In these footings main reinforcements are in the transverse direction of wall. In longitudinal directions there will be only nominal reinforcement. 2. Two Way Reinforced Footings:  For columns two way reinforced footings are provided. The following types of the footings are common: (i) Isolated Column Footings:  If separate footings are provided for each column, it is called isolated column footing. Figure 7.3 shows a typical isolated column footing. The size of footing is based on the area required to distribute the load of the columns safely over the soil . These footings are provided over a 100 to 150 mm bed concrete. Required reinforcements and thickness of footing are found by the design engineers. Thickness may be uniform or varying. (ii) Combined Footings:  Co