Water tanks are a common household feature of many homes across the African continent. During periods of drought, or in the event of a water cut, it is important to have a store of water available in the home. Household water tanks can range in volume between 1000 and 20 000 litres.
This means that a strong concrete base is needed to support the weight of the full water tank. The base needs to be perfectly level and capable of supporting up to 20 tonnes of water. Here are the materials and steps needed to make a concrete slab for a water tank.
Materials needed to build concrete base
- Tembo SupaSet 42.5 cement
- River sand
- Crushed stone
- Steel rebar and binding wire
- Hammer, nails and pegs
- Wooden float
- Spirit level
Steps to build a concrete base for a water tank
- Use the timber, hammer and nails to build a wooden frame. This will act as the concrete formwork to support the wet concrete above the ground level. The frame needs to be wider than the water tank.
- Place the frame on the ground where the concrete slab will be laid. Mark out the outline of the frame on the ground and start digging out the ground for the foundations, using the spade. The hole should be about 10 to 20 cm deep.
- Put the wooden frame back at the top of the hole and use pegs to hold it in place. Make sure that the top of the frame is level and sticks up about 10 cm above the ground.
- Place a 5 cm layer of crushed stone at the base of the hole and tamp flat.
- Mix your concrete according to the instructions on the bag, using the Tembo cement, river sand, crushed stone and water. The concrete can be mixed in the wheelbarrow. Pour a 10 cm layer of concrete over the stone bedding.
- Cut the steel rebar to size and create a grid on top of the concrete layer. Use binding wire to hold the rebar grid in shape.
- Pour another layer of concrete on top of the steel rebar, filling the wooden formwork up to the top. Tap the sides of the formwork to remove any trapped air bubbles within the concrete.
- Use the wooden float to scrape the excess concrete off the top of the wooden formwork. Move the float is a side-to-side manner across the top of the formwork to make the surface of the concrete smooth.
- Let the concrete set for 48 hours before removing the wooden formwork. Then, allow the concrete to cure for two weeks before placing the water tank on top.
LafargeHolcim is a leading building materials and solutions company that has been operating in international markets for decades. We produce cement and aggregates for construction projects, ranging from small affordable housing developments to large-scale infrastructure projects such as high-rise buildings, dams and bridges.
LafargeHolcim Tanzania has been supplying the country and neighbouring countries with our world-class Tembo cement brand for over 30 years. Our head office and fully-integrated plant are located in the Mbeya Region in Southwest Tanzania.
At LafargeHolcim Tanzania, we believe customers come first. We listen to your specific requirements to supply and develop the best solutions for your needs. As the new leader in building materials, you can also rely on our cutting-edge research and development capabilities that have resulted in the finest materials for your construction projects, whether large or small.