Chargement…
Chargement…
by Dakhla Aménagement Team
Five mistakes recur on almost every site where cement underperforms: they do not show on pouring day, but they are paid for in cracks, missed strengths and re-work. Here they are, with the numbers that make you think — and the simple reflexes that avoid them.
Under-dosing reduces mechanical strength and durability; over-dosing wastes cement and drives shrinkage cracking and heat of hydration. The benchmarks: 300 to 350 kg/m³ for standard concrete, 400 and above for demanding work — and always the structural note's prescription when there is one. The site calculator converts your volumes into tonnes and packagings, with the 5-10 % waste margin.
The most common end-of-day mistake: the mixer runs stiff, so in goes a litre of water "to get through". Every surplus litre costs about 2 to 3 MPa of final strength; the water/cement ratio must never exceed 0.50 for reinforced work. If workability is short, the answer is a plasticiser — not water. A stiff, well-vibrated concrete always beats a liquid one.
Cement is a live product: left on the ground, exposed to damp or weather, it cakes and loses a significant share of its activity. The rules: bags on pallets, never in ground contact; a covered, ventilated room; consumption within 3 months of production — and always the packing date printed on the bag as the starting point, not the purchase date. Cement that crumbles grudgingly under your fingers has already aged.
Concrete gains its strength in moisture: without water retention in the early days, hydration stalls at the surface. Poor curing can cost 30 to 50 % of the 28-day strength — and more still in hot, dry climates like southern Morocco. The means are cheap: regular watering, polythene sheeting, damp geotextile, curing compound. Seven days minimum, straight after placing.
Young concrete looks like hard concrete — until it is loaded. Side forms: 24 to 48 h; beams and short-span slabs (≤ 6 m): about 7 days (70 % of target strength); long spans: 21 to 28 days. The calendar bends to the strength actually reached, not to the site's administrative schedule.
| Mistake | Typical consequence | Correct reflex |
|---|---|---|
| Rough dosage | Missed strengths, cracking | 300-350 standard, 400+ demanding, per the note |
| Extra water | −2 to 3 MPa per litre/m³, shrinkage | W/C ≤ 0.50, plasticiser if needed |
| Careless storage | Caking, lost activity | Pallets, dry room, 3 months max |
| Skipped curing | −30 to 50 % at 28 days | 7 days minimum, immediate protection |
| Early striking | Deflection, cracks, collapse risk | 24-48 h / 7 d / 21-28 d per element |
These five reflexes cost almost nothing to apply and change the service life of the structure. Our storage, shelf-life and blinding-concrete articles go deeper on each point — and the technical team answers your site questions.
Mistake 1: rough dosage. 300-350 kg/m³ standard, 400+ demanding — and always the structural note.
Mistake 2: every surplus litre costs 2 to 3 MPa. W/C ≤ 0.50, plasticiser if needed.
Mistake 3: no bags on the ground. Pallets, covered ventilated room, use within 3 months.
Mistake 4: without 7 days minimum of curing, 28-day strength drops 30 to 50 %.
Mistake 5: sides 24-48 h, beams/slabs ≤ 6 m about 7 days, long spans 21-28 days.
Our free calculator gives you the exact cement quantity, cost estimate and suggested packaging.
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