PCC The Plain cement concrete consists of cement, sand and acoarse aggregate mixed itin suitable proportions in addition to water.
PCC IS MAINLY USED FOR FOLLOWINGPURPOSESIt is used as a protective layer for the RCC above so that water from the RCC is not absorbed by the earth below.Provides a base for the concrete and also helps workers to set out the structure above in a easier wayAct as a cover to reinforced cement concrete i.e. Resist corrosion of steel bars in footingsMoisture available in soil should not absorbed by R.C.C footings which causes corrosion of reinforcement
0 the aggregate size is 40mm down size0 the concrete should be mixed in the top & placed it where we want it may be machine mixed or manual
0 The depth of PCC depends on SBC of soil0 In our site they provided 150mm thick cement concrete bed0 In the ratio of 1:4:8 i.e., 1 part of cement, 4 parts of fine aggregates and 8 parts of coarse aggregates by volume were used in it.
FOOTINGS0 Footings are pads or strips that support columns and spread their load directly to the soil.0 At our site, spread footing and one combined footing are provided0 Spread footing are provided to support an individual column, it is called isolated footing0 Depending on the size and configuration of the building, spread footers can be buried just below ground level or several feet below the surface
0 This type of footer design is highly beneficial to builders and homeowners0 This design helps to minimize cracks and other signs of damage that occur as a building settles over time0 There are 44 footings and dimension of 2400 x 2000 x 600mm0 At our site we learnt how the centering for footing been done. First applying oil and checking for all tight joints at the corners.
0 Combined footing are provided when the two columns are so close to each other that their individual footings would overlap.0 A combined footing is also provided when the property line is so close to one column that a spread footing would be eccentrically loaded when kept entirely within the property line. By combining it with that of an interior column, the load is evenly distributed.0 A combine footing may be rectangular or trapezoidal in plan.0 Trapezoidal footing is provided when the load on one of the columns is larger than the other column.
0 The use of combined footings helps spread out the loads out to the adjacent footings in order to minimize stresses in the footings and reduce the differential settlement between them.
COLUMN0 Columns are vertical members that support loads from the beam or slabs. They may be subjected to axial loads or moments0 In our site they provided rectangular and circular columns0 The sides of rectangular column varies from 230mm to 600mm.0 The diameter of circular column is 450mm.
SSM- SIZE STONE MASONARY0 The SSM is a substructure is the lower portion of the building, which transmits the load of the superstructure to the subsoil0 SSM distributes the loads of the super structure, to a larger area so that intensity of load at its base does not exceed the SBC of the subsoil
0 SSM provide levelled and hard surface over which super structure can be built0 The stability of the building ,against sliding and overturning ,due to horizontal forces such as wind earthquake etc. Is increased due to SSM0 The ratio of cement mortar is 1:6 i.e., 1 part of cement and 6 parts of fine aggregates(sand)0 Stepped SSM are provided in our site.0 In our site undressed stones are used.0 The grade of concrete used in SSM is M100 In SSM as per code(IS1597 PART 1:1992) we have to provide break @every 1m or 2m
PLINTH BEAM0 Its the sheer wall load that needs to be transferred to the foundation; as such, 4” thick plinth concrete is adequate0 In RCC frame structure, plinth acts as a tie, as a beam at ground level itself. More recently, after few disasters we have faced, RCC plinth beams are being recommended for their earthquake-resistant properties.0 In our site they used plinth beam of size 230 x 530mm