Densify Concrete with Colloidal Silica? - Vlog  

Thank you for answering the question. I get that colloidal silica iis a good additive in aerated concrete. When we used the interlocking blocks 110mm x 450mm x900 mm as wall material reinforced with layers of angle iron hooked into concrete pillars the blocks weigh 55kg each, more than a bag of cement. After the third row the building becomes backbreaking, hence the idea to use a lighter material. The blocks don't need to float, though it would not hurt, but if they are lighter all costs go down, labour, transport and even cement. So the intended purpose is not mechanical abrasion resistance, as in polished concrete flooring. The idea is to develop a building block that can have a texture printed on the outside, and a different texture such as a polished surface on the inside, such as where the room is a bathroom, toilet or kitchen or any room that would usually be tiled. So instead of investing in tiles on one side and paint or facebrick on the other, one spends more effort on the finishes during block manufacturing. Then once the structure is built, and we built a two room 42square meter structure on a previously cured raft foundation routinely in 5 hours with 5 unskilled labourers, there would be no need to paint or tile. What we did was to roughcast the outside after spattering with plaster, using a hessian bag, and drywalling and then painting or tiling the interior. Polishing the concrete of the raft foundation is better than tiling, I see some contractors even print 3D photographs on the floor. So the floor is finished before building the walls starts. The problem with the blocks made in a 50 ton horizontal mould press using a dry mix was that the blocks were so hard after curing that fitting fixtures required much more effort to drill or cut than fired clay bricks. The graal would be to have a good recipe, cast huge blocks, say 5metre by 1 metre by 1 metre like they do in Siberia, then saw and router or shape the building blocks from this monolith, blocks with the same shape and size than those made in the block machine. Once they have been cut to a shape and size, they could be treated on one side maybe with an epoxy to achieve the required aesthetic effect. But of course as you point out, aerated concrete would probably not make a strong enough floor. You referred to something where we also used on another site the hydraform system, where the soil excavated on the site was mixed with 10% portland cement and pressed into interlocking bricks, which were used for dry stacked walls. But labourers need a higher level of skill than the other system where it is impossible to mess things up. The angle irons hooked into the pillars are precut to multiples of 900mm, the right size for a door frame, so the resulting structure is always square and if the foundation is level, the walls are level. Once the foundation is cured, you take the blocks, beams, pillars, wiring harnass, doors and windows in frames and roof sheets etc. to the site, and before the sun sets the structure is finished and can be locked up. (SOUTH AFRICA) You also don't need to crack another bag of cement on site, so there is no theft of materials and no left overs, and the site is clean when you finish. Unless you have to tile, paint or drywall. You see the cost saving if the level of finish of the block can be improved. So far nobody that I know of has cracked this.

AFIK, densification is the primary use of CS. For example, Sherwin Williams' flagship densifier is a 10% solids CS. Millions of pounds of CS are put down as densifier for polished concrete.

What's a good formula for white cement based artificial marble or granite, that can be polished nicely? Can you please make a video on concrete formulations for decorative and architectural mouldings?