>>>> Kavuma makes hydra form block machines   By John Kasozi          Tonnet Agro-Engineering Company is one the leading local firms that manufacture agro-processing machinery, spare parts and general fabrications. The firm, located at Kyebando on Gayaza Road, makes simple manual hydraform block machines.   Its proprietor, Joseph Kavuma, is the winner of the first presidential science innovative award. The tough steel machines are operated by two people and withstand pressure to make about 500 blocks per day. The block size is 10x3x5 inches. The machine costs sh700,000.Kavuma says the walls built with hydraform blocks are strong, adding that that is why they have become popular. Background The Hydraform Group was established in South Africa in 1988. They manufacture a range of construction machinery marketed in over 50 countries. Hydraform walls have been built in Angola, Sudan, South Africa, Mozambique, Uganda and Nigeria.The hydraform building system consists of two technologies; the compressed soil-cement block technology, which compresses soil mixed with cement into a block. The other is dry-stacking, where the shape of the blocks achieves block interlocking. Making hydraform blocks The blocks are made by mixing cement with soil and water. Sieve the soil, at least two days before. There must be a water source near the area of operation. Mixing by hand is done two times. The second mix is the most crucial one. The yard for drying the blocks should be set out properly with sufficient space. No soil-cement mixture should stay unused overnight. Different mix designs are possible depending upon the quality of the raw materials and strength required.   It is important to check the soil composition for contents like clay, silt and fine and coarse sand. Normally sandy loam soils are better suited. However, other soils can be worked upon to get the right mix and strength. Black cotton soils are not suitable. The block strength is determined by soil, fly ash type, quantity of cement used and other materials used and the extent of curing after manufacturing the block. Kavuma urges that the machine should be firm on the ground to minimise loss of force.   Kavuma testing a manual hydraform block making machine “If you follow the rules, you get good quality blocks,” Kavuma says. He adds that he plans to start making motorised machines that will produce hollow blocks and those for making high-value cassava flour.   Advantages of using hydraform blocks Since the hydraform system uses inter-locking soil-cement dry-stacking blocks, it is better than the conventional way of building with brick and mortar.The hydraform system is an eco-friendly building system because the bricks do not need burning, thus saving fuel. It is cost-effective, labour-intensive and ideal for use in both remote rural areas and high-density urban areas.It is cheaper to use the interlocking blocks than bricks because the blocks do not need mortar and plaster. One can save up to 40% on cement and labour when using the interlocking blocks compared to when using ordinary bricks.   Hydraform walls contain up to 50% less cement than conventional cement brick walls.The hydraform block is 10 times stronger than a brick and is bullet-proof. This makes them ideal for security boundary walling.   Hydraform interlocking block masonry can be effectively used in earthquake resistant constructions incorporating necessary structural design and reinforcements.   More so, the hydraform block making machine is portable. Thus it reduces the transport cost of building materials because blocks can be made on the building site. Training of workers can also take place on the job. All window, door, slab and roofing systems that are used with conventional systems can also be used with hydraform blocks.   Several new motorised hydraform block-making machines have been donated to the youth in northern Uganda.   About 100 youths were selected and trained on how to use the hydraform machines. Each motorised machine can produce about 3,000 blocks per day. In two days, the youth can produce enough blocks to build a simple three-bedroom house.