Construction Field series Episode 3 – R.C.C Basement bed
In this episode our technical staff will explain proceedings after following steps discussed in last episode:
-Marking for excavation
-Basement Bed P.C.C (Plain cement concrete)
Step 7 to be discussed: R.C.C Basement bed which will include brief tutorials about:
-Toe wall for holding R.C.C bed concrete
It is a temporary wall which is made by using bricks or concrete blocks for holding the concrete of R.C.C bed, other than bricks, shuttering material such as steel plates, wood planks and palai sheets can also be used to hold concrete together.
-Vapour barrier for seepage protection
This step is carried out after making P.C.C bed and above discussed toe wall. As the name suggests, it serves the purpose of protecting basement from seepage especially in areas where water level is very close to ground. Most reliable method for vapour barrier is using PVC membrane sheets, however due to higher cost, alternate and economical method has been discussed in this video in which bitumen and polythene sheet is used as vapour barriers.
Reinforcement is carried out as per structural drawings for basement R.C.C bed provided by the structural engineer. There should be no compromise in reinforcement of R.C.C bed as it has to hold the weight of whole retaining walls.
-Water stopper PVC for joint protection
PVC water stoppers are placed at joint of R.C.C bed and R.C.C retaining walls. It is mostly available in width of 9 inches and is placed such that it suppresses half (4.5 inches) inside R.C.C bed during pouring and remaining half in R.C.C retaining walls, hence making a barrier and joint protection.
-Concrete pouring 1:2:4 M15
M15 concrete pouring is composed of 1 ratio of cement to 2 ratio of sand to 4 ratio of crush aggregate and mixed with 24 to 25 litres water. Bed concrete should always be vibrated using a vibrator so that the mixture blends together. Better blending means more strength. After concrete pouring, it should be cured for at least 10 days to gain comprehensive strength.
RCC(Reinforced cement concrete) structure have a higher cost, and basements are constructed in RCC structures. Financially it is out of budget for most of us to afford basements. However it has many benefits e.g. extra living space, controlled temperatures in summers and winters both, safe from outside pollutions such as noise and dust etc. Basements can be designed for complete and partial accommodations. A complete accommodation includes master bedrooms with washrooms along with other divisions such as living area, store, servant room etc., whereas partial accommodation only includes later divisions. Partial accommodations are recommended more since it does not have wet areas such as washrooms & kitchens hence not requiring installation and maintenance of septic/liquid waste disposal systems.
Field series Episode 3