Interlocking Stabilised Soil Bricks [ISSB]
In January 2010, the Henry van Straubenzee Memorial Fund purchased a brick making machine from the Haileybury Youth Trust (HYT). Our decision was principally made for economic and environmental reasons. The traditional method of making “mud bricks” has remained unchanged for hundreds of years. Now, the majority of building bricks are simple locally produced fired bricks. The major environmental issue with this type of brick is their production requires the use of small home-made kilns. The villagers require wood for burning, so local forests are cut down. This is unsustainable as there is no afforestation programme in most areas of Uganda. Locally produced fired building bricks, have to be fired for 24 to 48hrs, with the resultant carbon emission and wood usage. The size and shape of these bricks are never uniform, which means extra cement is necessary.
With cement in Uganda demanding a premium price, buildings become unnecessarily expensive too. The ISSB is made by compressing a mixture of the local Murram soil with a small amount of cement and water, to make a uniform size block. The brick needs no firing and is ready for use in 6 hours. Our machine can produce 300-400 bricks per day on site, saving transport costs. Each brick is uniformly shaped and is interlocking, thereby requiring a fraction of the amount of cement required with burnt bricks.
In theory, we should replace locally produced burnt bricks for all our building construction, with the exception of the water tanks. However, there are limitations. Firstly, village communities rely on selling their bricks to us. It is a major factor in local economy. More importantly, a burnt brick is stronger than an ISSB, which is prone to crumble when exposed to the intense heat and rain of Uganda. Added to this, not all of our schools are situated on pure Murram land, thus negating the claim that transport costs will reduce.
In 2014, the charity purchased a second ISSB machine which makes curved bricks to build water tanks. In the early days, the charity embarked on a programme of providing 20,000 litre water tanks to its supported schools. These curved bricks were designed to ensure no leakage and produce a vandal proof tank to harvest the plentiful rainwater off the roofs of our school buildings. In total we have supplied 48 ISSB 20,000 litre water tanks to various HvSMF schools. A completed 20,000 litre ISSB water tank costs the same as a plastic 10,000 litre tank but is a more efficient, economic and eco-friendly product, as well as keeping the water cool. However, since 2015, we have embarked on a programme to provide bore holes at all our schools, which ensures a plentiful supply of clean water all the year round and therefore less water tanks are required.
The ISSB machines are transportable and require no power apart from builder’s muscle. The technology is not new but there are only a few of these machines in Uganda. In summary, the ISSB machines are a useful back up for our construction programmes and provide the environmental benefits of not burning large quantities of wood from the forests.
Muguluka Primary School water tank made from ISSB bricks
Muguluka Primary School children enjoying the water
Nalango children in front of tank, (with Alex holding Ugandan walking stick)
Magogo Secondary tank, plus guttering attached to a girls’ dorm
Busuuli Brick making machine
ISSB Bricks at Kisadhaki
Interlocking Stabilised Soil Bricks