Strong structures using hollow blocks

Benders’ hollow blocks make it easy to build walls that withstand large stresses. The blocks simply stack on top of each other with no mortar. As the wall rises, reinforcement is added, both horizontally and vertically, course by course. The bricks are then filled with a concrete of suitable quality. This gives you a very strong, reinforced wall without any of the bother of formwork. Hollow blocks are also very suitable if, for example, you are building a pool, retaining wall, bunker silo or manure (slurry) pit. They can also be used in making foundations for machine halls and many other things.

The blocks are available in widths of 150, 190 and 250 mm. They are all 200 mm high and 500 mm long. For the 190 and 250 formats, there are also termination blocks. These have a closed end so that it is easy to build an attractive gable termination or corner.

Format, w x l x h Weight per unit Concrete consumption per m2 10 mm horizontal reinforcement per m2 12 mm vertical reinforcement per m2
150 x 200 x 500 19 kg 60 litres 5 m 5 m
190 x 200 x 500 21 kg 90 litres 10 m 10 m
250 x 200 x 500 23 kg 140 litres 10 m  10 m

10 mm rebars are used as horizontal reinforcement. These are laid in each layer, 1 for the 150 mm width and 2 for the two wider formats. All joins in the reinforcement should have an at least 500 mm overlap. Pouring is most easily carried out 400 mm at a time (2 layers – these are to be carefully compacted together). Two new courses are then stacked, filled with concrete and compacted together. This is repeated until you reach the desired height. Blocks must be stacked with a stretcher (running) bond. If the structure is to be subjected to especially large stresses, the first course of blocks should be laid in the not yet set concrete slab. The vertical reinforcement (12 mm) should also be fitted in the slab with a centre to centre distance of 250 mm. For extra strength, it can also be lashed to the slab’s reinforcement. With the 190 and 250 mm blocks, double vertical rebars must be used.

Benders’ hollow blocks

NB! This information is for guidance only. Owing to geological variations in site and ground conditions, further technical factors may have to be taken into consideration. Benders’ information is free and is not to be regarded in the same way as, for example, an authoritative construction drawing. Nonetheless, the information is of great use in all relevant building projects.