Engineering Science Around Us

O verhead water tanks serve purpose due to its elevation, and the potential energy generated due to the height results in more water pressure, without need of electricity for outflow.  I n combination with the underground water tank which shall be of relatively higher size, overhead tank provides more pressure in the plumbing pipes. W e shall be selective of the location we choose for the placement of water tank on the roof. As a rule, we shall avoid concentration of higher loads at a specific location, hence provision of 500litre tanks well connected, rather than a large tank will be sufficient. Tank location  - On beam Ideal location for water tanks, is on beams, near to column so the load flow will be clear from the slab - beam - column - footings. -On slab- If there are no grids of beams in the vicinity then water tank shall be located away from the center of slab. To avoid concentration of loads, a frame can be prepared from steel sections made up of angles or wide flange sections

C oncrete is a composite material consisting of cement, sand, aggregates and water. There are various mixes preferred based on the underground or above the ground  structures. F or underground structures higher strength concrete is selected to resist the alkali and sulphate attacks from the chemicals present in the soil or ground water.  F or over the ground structures mix of M20 or higher is selected having higher strength, based on the type and importance of the structure. C oncrete Mixing on site can be manual or by using a mixer machine. For smaller quantities and for places far from the city, manual mix is allowed under supervision of engineer in charge. For larger quantity of concrete machine mix is preferred to maintain the uniform quality of concrete. Nominal and Design mix Design Mix If there are variation in the raw materials regarding, size, shape, porosity etc then each material is tested and mix is designed after trail and error method for the selection of the best proport

S tructures are designed to withstand natures forces but throughout the life-span of a structure regular maintenance is necessary to strengthen the durability factor. V arious seasons like summer, winter and monsoon impose thermal, compressive and tensile stresses in the form of wind and rain to make structures weak every passing year causing depreciation and reduced functionality. R egular maintenance would strengthen and increase the life of a structure. Below mentioned forces act on the structure, 1. Wind forces- Periodic checking to notice any building vibrations. 2. Thermal forces- Observe closely all the surface cracks and their pattern. 3. Rain-Water and humidity cause corrosion- Proper storm water drainage system is essential, also no water shall be allowed to stagnate on members like roof etc. 4. Vibrations- Lack of stiffness causes vibrations, to counter vibrations, stiffness of members shall be increased. 5. Insects causing structural member damages- Observe the effects.

B uilding elevation looks elegant when it is provided with projections in combination with the contrast wall color combinations. M any owners just can not make decisions to keep balance between the cost of elevation and effects it will have on the functionality of the building. I think functionality shall be given more importance than the elevations, and the cost of elevation shall not be more than 50% of the ordinary wall construction cost.

Plain cement concrete(PCC)- As the name suggests there is no rebar in the Plain Cement Concrete. Where it is used? -To prepare a bed level for foundations. -For repair works of plaster, and Concrete surfaces. Reinforced Cement Concrete (RCC) - Concrete is strong in compression and weak in tension, therefore to provide tensile properties it is reinforced with steel rebars. In combination with the concrete, the steel rebars form a composite member having both tensile and compressive properties.      

 Buildings consist of a frame which carries the structural load and the partition walls to separate the rooms. Column positioning is important because it fixes the layout by controlling the design concepts. In order to mark columns on a site, Cartesian coordinate system is followed. All the column centers are provided with coordinates for marking on the site.   There are 2 methods to mark the centerline on site, 1) Fence by using bambu stics - In this the building area is provided with horizontal planks fixed in vertical posts. The column centerline is marked on planks by using nails and annotations are marked by paint. 2) By masonry pillars for each grid. In this method, each grid coverting horizontal and vertical is marked slightly away from the excavation areas. The advantage of this method is that, the posts cannot be damaged or destroyed during the excavation works.

  -Introduction- Slump test is the most basic test, which is easy to conduct on the site. It is important to know the workability or flowability of concrete, which reduces the air voids and amount of compaction required for concrete. -Apparatus- Slump test requires slump cone, tamping rod, plate platform, Pan, and twovel. When the concrete is ready to be poured, a random sample is selected and taken in a pan. -Before the test starts-   Test Procedure- 1. The steel platform is placed on a horizontal plain surface, it shall be clean from any foreign objects. 2.  Concrete sample is collected in a pan and placed by each layer in the slump cone. 3.Each layer shall be well tamped by using the tamping rod. Usually 3 layers are selected for filling the cone.  4.As the cone is completely filled with the concrete layers, the top portion is scraped to get an even surface. Any fallen concrete in the tray shall be removed. 5. Lift the cone upward, and allow the concrete to freely slide in the tray

C onstruction material constitute about 60% of the material cost of construction. And to control the cost of construction, both sourcing the material when the market cost is lower for the same is important and also it shall be delivered on time.  B ased on the seasons, the cost of material varies and hence procuring the material earlier, can save huge amount. A lso delay in delivery of the material on site, may incur cost to owner, hence more emphasis is made to procure the materials and manage the delivery based on the site conditions.   A s we have understood the importance of early procurement and the consequences of late arrival of materials on site, let us know about the quantities of materials to be procured. There are two types of estimates. 1. Rough Estimates - This is when the drawings and specifications of the construction is not yet finalized. But roughly we know the major items like the units to be constructed or the plinth area of the plot to be construction. Based on thes

C ement is a binding material, and as soon as water is added to it, chemical reaction known as Hydration starts. When concrete is prepared on the site, and placing to the final position is near, the time of transit usually is less, but still concrete test for temperature shall be initiated by selecting a random sample from the batch and checking the concrete temperature by using a thermometer.    -Nominal Mix on Site by Concrete Mixer- A s the hydration process continues up to the final setting time of concrete, temperature rises. In order to reduce the  temperatures, cold water or ice shall be added to maintain a constant temperature. D uring summer season, the ambient temperature is higher, and hence cold water shall be used for mixing, to compensate for the higher atmospheric temperatures.   -Ready Mix Concrete from a Batching plant- W hen concrete batching plant is available near the construction site, it is preferable to order the concrete from the nearest plant. Quality factor is