Chargement…
Chargement…
by Dakhla Aménagement Team
A waterproof mortar is one whose formulation cuts water absorption sharply — by 70 to 90 % — thanks to specific additives. The short answer: it belongs in basement tanking, damp-room screeds, pools and tanks where moisture wicks through by capillarity; it does not replace a waterproofing system under water pressure. And to be clear: DAM does not produce waterproofed cement — we make the standard CPJ 45/CPJ 55 for your structures.
Two complementary mechanisms. The capillary one: silicate-based additives react with the cement's free lime to form insoluble gels that plug the mortar's capillaries. The hydrophobic one: mass water-repellents (fatty acids, stearates, resins) coat the pore walls and repel water by surface tension — water beads off instead of soaking in. The mortar keeps its mechanical strength and keeps "breathing": water vapour passes, liquid water does not.
| Structure | Exposure | Right answer |
|---|---|---|
| Basement in damp ground | Capillary rise | Waterproof mortar tanking + perimeter drainage |
| Damp-room screed | Rising damp | Waterproofed mortar or waterproofing screed |
| Pool, tank | Water under head | Sound structure + dedicated waterproofing system |
| Rain-lashed facade | Run-off water | Hydrophobic finishing render |
The dividing line is pressure: against capillary damp, a well-dosed waterproof mortar does the job; against a column of water, you need a true system (membrane, waterproof coating) installed per the rules.
The additive cannot rescue a bad mix. Three conditions remain decisive: a sufficient cement dosage (≥ 350 kg/m³), a controlled water/cement ratio (≤ 0.5) and careful compaction — the water-repellent fills the capillaries of a dense mortar, not the voids of a badly placed one. Construction joints and internal corners stay the sensitive points to treat specifically.
Factory-waterproofed CPJ 45 trades about 10 to 20 % above standard cement: at a notable premium over standard bulk cement. The small-site alternative: a liquid admixture added to standard CPJ 45 at mixing, about 80-150 DH per litre, dosed at 1-2 litres per m³ of mortar. Our grey CPJ 45 is quoted personally, delivered to Dakhla sites.
Unsure about your structure's waterproofing strategy? Our "cement and waterproofing" guide details what cement can and cannot do — and the team answers technical questions.
Capillary damp or water under pressure? Exposure dictates the system — not the other way round.
Waterproof mortar tanking against capillarity; dedicated system (membrane) under pressure.
Dosage ≥ 350 kg/m³, W/C ≤ 0.5, careful compaction: the additive cannot rescue a bad mix.
Coats onto a clean, damp substrate, with extra care at internal corners and joints.
Let it dry per the data sheet and inspect weak points before backfilling or filling with water.
Fireplaces, ovens and flues destroy ordinary mortar. Aluminous-cement refractory mortar holds up to 1,500 °C and beyond: grades, uses and prices — with DAM's honest framing.
Read article
Densities, lightweight aggregates, foamed concrete, blocks: when and why to lighten a concrete, what you gain and lose, and how to run the pour.
Read articleA 30-tonne minimum, tanker truck, 30-45 minutes of pumping, a 30 to 200 T silo (rental available): the bulk-cement playbook, and when to prefer big bags or bags.
Read articleOur team responds within 24h. CPJ 45 on request, CPJ 55 on request. Delivery within Dakhla included.