Retarded-Set Cement in Morocco — Concrete Pouring

Retarded-set cement: the solution for difficult pours

Retarded-set cement is a Portland cement (CPJ 45 or CPJ 55) whose formulation incorporates a setting retarder. This retarder slows the hydration of the clinker — mainly tricalcium aluminate (C3A) and tricalcium silicate (C3S) — to push the initial setting time to 2, 4 or even 6 hours depending on dosage. The objective: extend the workability time of fresh concrete to secure long pours, distant transport and hot-weather pours, without compromising the final 28-day strength.

In Morocco, particularly in the Southern regions (Dakhla), summer temperatures frequently exceed 35 °C from May to September. At 35 °C, a standard CPJ 45-based concrete begins to set in less than an hour, making pours of more than 50 m³ difficult, even impossible without pour resumption. Retarded-set cement, combined with other precautions (cold water, aggregates stored in the shade, early morning pouring, wet curing), allows these critical pours to be completed. It is also essential for ready-mix transport over long distances — for example from Dakhla to inland sites or to Mauritania.

Mechanism and setting time

The setting retarder (sodium gluconate, lignosulfonate, sugar, citric acid) acts by complexing the calcium ions released during the first hydration of C3A, thus slowing the crystallization of ettringite. The initial set typically shifts from 45-90 min (standard CPJ 45) to 2-4 hours depending on the retarder dosage (0.1 to 0.5% of cement weight). Beyond 6 hours, a degradation of the 1-3 day strength and a risk of segregation are observed. The final set is also shifted proportionally, but the final 28-day strength is preserved or even slightly improved thanks to more complete hydration.

When to choose retarded-set cement?

• Hot-weather pouring (> 30 °C), common in Southern Morocco from May to September
• Large-volume pouring (> 100 m³): rafts, industrial slabs, massive foundations
• Ready-mix transport over more than 60-90 min of travel
• Continuous pours without pour resumption (watertight, massive structures)
• Night or off-peak pouring to avoid heat peaks
• Concrete export to Mauritania (long distance)

Retarded cement vs retarding admixture

Two approaches are possible: (1) use a retarded-set cement formulated at the plant — advantage: perfect homogeneity, reproducibility, traceability; disadvantage: production lead time (5-10 days); (2) use a standard CPJ 45 or CPJ 55 cement and add a retarding admixture at mixing — advantage: flexibility, adjustment of retardation according to the day's weather; disadvantage: risk of dosage error, heterogeneity if poorly mixed. In practice, the admixture is preferred for occasional or adjustable pours, retarded cement for reproducible industrial production. For large volumes and consistent quality, we recommend DAM retarded-set cement.

Price and availability

Retarded-set cement is sold on request in bulk (tanker truck, minimum 30T), tarif sur devis in 50kg bags (1T pallet) and tarif sur devis in 1T big bag — a 5-8% surcharge over standard CPJ 45. Prices are volume-degressive and depend on the delivery zone. As production is planned to order, allow 5 to 10 working days. To compare with our standard cements, see our CPJ 45, CPJ 55 pages and the complete cement price guide. Request a free quote via our dedicated form for a custom delivered-to-site price.