Cemforce's Ingredients

Well, to my perhaps more-than-slight disappointment, the ingredients Cemforce used were different to what I was using. For a start, they are using a Cement:Sand ratio of 1:1, whilst I was using 3:1, which means they are using 3 times more cement in their mix than I was. Like me they add a plasticizer to the mix to reduce the water content, whilst at the same time making the concrete runny enough to spray it into the mould, but they also add an accelerator, which allows the concrete to cure faster.

For the reinforcement, they use alkali-resistant glass fibre rather than polypropylene, as they found that the polypropylene tended to stretch before reaching its full tensile capacity, during which time the concrete began to crack (I have some glass fibre mesh, but haven’t got round to testing it yet). The fibres are chopped, rather than woven, cos its cheaper that way, and they can be sprayed into the mould, rather than having to be placed by hand (see the the video below).