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Trinic LS Lockup is a single component ready to use water based lithium and siliconate based solution designed to densify and add waterproofing characteristics to cement and concrete substrates. Please contact me with any questions, thanks.
Mark Celebuski - E: firstname.lastname@example.org P: 717.823.7408
Very few projects are going to specify a minimum compressive strength of 5,500 PSI just so the floor can be polished without using a densifier. Some overlay products made does not contain Portland cement. With the increasing use of pozzolans in concrete there is less reactive free lime for conventional densifiers to work with on “standard” concrete. There are also very weak floors (some almost hard sand like in their density) being rescued by floor polishing. The answer is all densifiers work, some work better than other in different situations.
Pozzolans and densifiers do similar things internally verses externally. The majority of products added to mixes or used as densifiers are silica based (or course there are exceptions). Pozzolans have a silica component, Slag is about 40% silica (varies with source), Silica Fume about 95% silica. The smaller the particles are the faster they react, in many cases getting small enough to actually act as accelerators rather than retarding the set.
Many polished concrete products are also silica based: it started with sodium silicates, then potassium silicates, now on to lithium silicates and colloidal silica. The first three have a metallic salt component, that’s why they can cause efflorescence (less so with Lithium Silicate – Trinic LS Lockup) if over applied. Why did this floor white out when the last did not even though I applied the densifier the same way? – The answer may have been differing porosity and free lime available in the floors.
If your floor is dense (PSI wise) and has enough free lime to work with, lithium silicates (Trinic LS Lockup) or colloidal silicas (Trinic CS Densifier) generally work fine. If your floor contains very little free lime (was cast with a very high pozzolan dosage) or is weak (PSI wise), or very young, you may need to look for alternatives or in many cases a combination of alternatives.
Dense, high strength concrete requires just a little help from surface densifiers to polish compared to problem floors. When concrete is cast with high degrees of excess water, the water evaporates out of the concrete leaving channels behind. The more excess water in the mix, the larger and more frequent the channels and the weaker the mix (less ability to hold the aggregate so the polishing machine can shave it rather than pulling it out). This is the main reason most polishing concrete contractors stay away from the residential market, less quality control with the concrete. You don’t know what you’re walking into or how much it will cost to get it polished if it will polish at all.
You will need to start with the largest particle required to fill the pores and work your way smaller to fill the voids, densify, and provide a uniform plain for polishing. Sometimes this can be accomplished in one densification step; other floors will require more or different densification steps.
Very weak porous concrete may require a very large particle in the form of cementitious slurry prior to any attempt at densification. The concrete may be so porous that any densifier will simply absorb into the matrix without benefit to the surface. A neat (no sand or aggregate in the mix) reactive slurry will close the very large voids. This may need to be ground off before going to the next step. The next step would be larger particle (lithium silicate) mixed with smaller particles (colloidal silica). A final step (if needed) would be colloidal silica; this would bond to any silica particles present and fill any microscopic low spots readying the concrete for finale polishing. Obviously product and machine usage will be much higher than polishing dense concrete often making this option more expensive than coating the floor with a film type product.
There are ways to evaluate a floor for polishing before quoting it. You will need to develop benchmarks (test floors you’re currently polishing) before you can accurately predict how a future floor will polish and what densifier to use on the floor.
The first tool I would recommend every polishing contractor obtain is a Schmidt Hammer also known as a Swiss Hammer. It’s a simple non-destructive test device that will give you instant data about concrete strength and thus polishability. Once you gain an understanding of the correlation between PSI and polishability you can gain a sense of how (or if) a floor will polish and to some extent material costs to polish; Low PSI floor = more densifier required, high PSI floor = more diamond usage especially if aggregate exposure is required.
Another simple test you can perform is an acid resistance test. The higher the pozzolan load in the floor the lower the amount of free lime available, the more acid resistant the concrete will be. Acid staining contractors quickly develop a feel for how different floors take acid stain, due in part to differing free lime content, polishing contractors can evaluate free lime in a similar way.
You’ll have to develop benchmarks for acid resistance. This will help guide your choice of densifiers or a blend of densifiers; the denser and more acid resistant the concrete is the more I’d be inclined to lean towards colloidal silica vs. a lithium silicate, if the acid foams green on contact you know you’ve got plenty of free lime for lithium silicates to work with. This test will also reveal any polymer concrete or Portland cement free concrete you may encounter.
Will a little science and testing some of the unknowns of floor polishing can become knows, leading to more and more profitable polished floor projects.