interlocking concrete hollow plastic block molds

plastic stumble blocks moulds was invented to give anyone with limited skills and limited means the opportunity to build their own home in a cost effective way.
The interlocking building blocks are made with the unique and innovative Stumbelbloc plastic moulds, which are filled with a concrete mix and left to dry.

When removed from the mould, a very accurate hollow core block is created. The unique interlocking shape allows building with great ease and,

in conjunction with the glue i.e. thin bed mortar and render (NHBRC approved building method), a very strong, fast and cheap construction method is created.

1.Block manufacturing should be done in some form of shade and not in direct sunlight. Direct sunlight and extreme variations of temperatures may cause the blocks to crack before they are properly cured.
2.Lubricate the entire inner surface of the mould's two halves using cooking oil or similar. A heavier oil e.g. gearbox oil SAE 80W90 is used for the first usage as recommendation to compensate for oils release from plastic. Method of applying lubrication can be by painting with paint brush, spraying with compressed air, or dipping the mould in its entire into a drum containing the lubrication oil. This step is vital to ensure easy de-moulding. Make sure that ALL internal surfaces and edges of the moulds are coated! Improper coating will result in difficulty to de-mould blocks from moulds.

3.Mould to stand up with open side at top.

4.Use the bolts, washers, and wing nuts provided to join the two halves (Yellow and Red) of mould together. Ensure that the washers provided are used on both sides to spread the load. Slide the aluminium strips/rails down each side of the joined mould.

1.How strong is the block?
The strength of the finished block is determined by the mixture. The recommended mix is 2,5 level wheelbarrows of sand, 1 x 50kg bag of 42 MPa cement and 2,5 level wheelbarrows of chipped stone (Not larger than 13mm stone), gives a block of roughly 5,2 MPa strength. The required strength in most countries for a concrete block (Reference B-Block) is 3,5 MPa. The block can be strengthened to any level by simply adding more cement. The above mixture makes 32 large blocks.

2.Can other fillings be used?
The blocks can be made with any material that can bond with cement. As stated previous, the strength of the finished block will depend on the material used. For example, volcanic sand/any crushed rock material is ideal when mixed with cement. Please note: ORGANIC material is not suitable for making the blocks and should not be used.

3.Can any sort of sand be used?

Yes, any sort of concrete or plaster sand may be used but the finer the sand the weaker the finished block will be. Sand containing any organic material or salt should not be used. River sand is preferred. Sand with best properties comprise of particulars that has a variation of fine to coarse sand grains and must have no clay form.