Cement and concrete in hot, desert climates: a practical guide

In intense heat, concrete behaves like a material in a hurry: water evaporates faster, setting accelerates and plastic-shrinkage cracks threaten the surface right after casting. Beyond roughly 30 °C for fresh concrete, these effects call for specific precautions — even more so in the arid regions of southern Morocco, where heat, dry wind and direct sun combine. Concreting in hot weather is not forbidden; it is a matter of organisation.

What happens physically

Heat accelerates cement hydration: the concrete gains early strength but loses workability, becomes harder to place and sees its working window shorten. At the same time, surface evaporation — aggravated by wind and direct sun — dries the surface before setting has consolidated it: that is plastic shrinkage, cracking the skin of the concrete in characteristic chevron patterns. And mix water added to compensate dilutes the paste and lowers final strength: restoring workability by adding water is the worst possible answer.

Organise the site around the heat

• Cast early morning or in the evening: target the coolest windows and avoid midday.
• Shade the aggregates and keep mixing water cool: every degree gained on the constituents delays rapid setting.
• Cut the delays between mixing, transport and placing: concrete does not wait in 35 °C heat.
• Vibrate effectively and quickly, layer by layer, before plasticity vanishes.

Adjust the mix, with due care

Formulation tools exist and work: set retarders dosed per the concrete mix design, a strictly controlled water/cement ratio (counted to the litre, never by eye), possibly a plasticising admixture to hold workability without adding water. Those adjustments belong to the concrete designer or the ready-mix supplier — not to improvisation on site. The principle stands: heat means steering the set, not enduring it.

Curing: the anti-cracking key

In an arid climate, curing is not a finishing option — it is the structural gesture of the pour. As soon as placing ends — immediately, not "after the break" — the surface must be protected from evaporation: regular spraying, polythene film, damp geotextile or a curing compound. That protection is kept up for several days. Well-cured concrete in heat develops its strength without cracks; the same concrete abandoned in the sun cracks on the surface and loses part of its durability, especially against sulphates and salts.

The Dakhla context: constraint becomes advantage

The Dakhla region stacks the demanding factors — heat, wind, salty air — but also a practical reality: a local cement producer shortens the time between plant exit and casting, with delivery included in the city, timelines confirmed in your quote. A fresh binder, short logistics and teams organised around thermal windows: that is the equation for concreting with confidence in the Deep South.