Construction Chemicals Sand

Choosing the Fraction by Product Type

There is no single "sand" in construction chemicals; the application thickness and the surface expectation of the product decide the fraction. In thin-layer products such as tile adhesive and joint filler the 100-300 micron range is preferred; coarse grain spoils the notch pattern and leaves a rough surface in narrow joints. In plaster and dry mortar the 100-500 and 300-700 micron grades are usually used together — the fine part provides filling and workability, the coarse part volume and strength. For thick-layer repair mortars the 500-1000 micron grade may be used. In self-levelling screeds, fine sand works together with micronized quartz filler: the micronized part provides flow and surface closure, while the sand limits settlement and shrinkage of the layer.

→ How to read a sieve analysis

Why Is Moisture Critical in Dry Mix Products?

In bagged dry mix products the moisture of the sand directly determines shelf life. If the sand is damp, the cement begins to hydrate inside the bag; the product cakes, its setting behaviour changes and the expected performance is not achieved on site. Moisture also upsets dosing accuracy: in a mix batched by weight, water enters the system as part of the sand weight and shifts the water/cement balance of the formulation. In plants fed from silos, damp sand loses its flowability, bridges and interrupts the feed. This is why our sand goes through fluid-bed drying and moisture is measured separately, batch by batch, before shipment.

Whiteness and Colour Consistency Between Batches

In white cement based products — joint filler, decorative render, moulding mortar — the final colour is largely determined by the whiteness of the sand. The component that lowers whiteness is iron oxide (Fe₂O₃); a difference of a few parts per thousand turns into a visible yellowish tone in the product. For a manufacturer the real risk is not the colour of a single batch but the difference between batches: the same product code looking different across shipments shows up on site as patch marks. In our low-iron products the whiteness value is 92% and above, and every batch goes through chemical analysis.

→ Why does Fe₂O₃ matter?