Pouring concrete in a Riyadh summer is a different job from pouring it in mild weather. High temperatures, direct sun and dry wind strip water from fresh concrete quickly, causing surface cracks and lower final strength – damage that may only show years later. This guide covers what to prepare before a pour, what to watch during it, and how to cure the concrete afterwards so it reaches the strength the engineer designed for.
Why heat is the enemy of fresh concrete
Concrete does not gain strength by drying out. It hardens through a chemical reaction between cement and water (hydration), which needs water inside the concrete for days and weeks. In hot weather two things happen at once:
- Faster setting – a hot mix loses workability quickly, making it hard to place, vibrate and finish before it starts to set, and raising the risk of cold joints between batches.
- Surface evaporation – when water leaves the surface faster than it rises from below, the surface shrinks and plastic shrinkage cracks appear: the fine cracks you sometimes see on slabs a few hours after a pour.
The result is a weak, porous surface that lets moisture and salts reach the steel over time, and structural elements below their intended strength.
Before the pour: preparation starts the day before
Coordinate with the ready-mix plant
- Confirm the mix design and strength approved by the engineer.
- Discuss set-retarding and workability admixtures, with the engineer’s approval, to allow enough time for placing and finishing.
- Ask how the plant cools the mix, for example chilled water or crushed ice in place of part of the mixing water. Many specifications cap the concrete temperature at placement, often around 32–35 °C; the project specification is the reference.
- Schedule truck arrivals so trucks do not wait in the sun and the pour does not stall between loads.
Pick the right time
In summer, pour at dawn or early morning, or at night on larger jobs with proper lighting. A midday pour means hotter concrete, faster evaporation and exhausted crews – a recipe for workmanship errors.
Prepare the site
- Inspect formwork and steel – reinforcement to the drawing, spacers in place, formwork tight and braced. See column formwork quality.
- Dampen formwork and surfaces that will touch the concrete, without leaving standing water.
- Windbreaks and shade where possible, especially on large exposed slabs.
- Curing materials on site before the pour starts – hessian, polythene, hoses or an approved curing compound.
- Backup equipment – a spare vibrator and a standby pump, because a breakdown mid-pour can leave a cold joint in the wrong place.
During the pour: organised speed, not rushing
Each truck’s delivery ticket is checked for the mix and batching time. A slump test confirms consistency, and cube samples are taken for the lab as the engineer directs. If a truck is badly delayed or the mix is wrong, the engineer decides – not the driver or the crew.
The most common mistake we see is adding water because the mix feels stiff. Extra water raises the water–cement ratio, making the concrete weaker, more porous and more prone to shrinkage. Consistency is adjusted at the plant with approved admixtures, not with a hose on site.
- Place in even layers and vibrate each one before it begins to set so it knits with the layer below.
- Avoid long gaps between adjacent batches.
- If a construction joint is unavoidable, the engineer chooses where it goes – not wherever the last truck ran out.
- Finish quickly without overworking the surface, which draws water and fines to the top and weakens it.
After the pour: curing is half the job
Curing means keeping the concrete moist and at a suitable temperature in its early days so hydration continues. In Riyadh it is not optional. Protect the surface as soon as finishing is done – cover it or apply a fine mist that does not wash out the paste – then start full wet curing once the surface is firm enough.
| Method | How it works | Notes |
|---|---|---|
| Water spraying | Regular spraying through the day | Effective only if the surface never dries between sprays |
| Wet hessian | Surface covered with hessian kept wet | Excellent for slabs and columns; needs attention |
| Polythene sheets | Laid over the dampened surface, edges weighted | Traps moisture and blocks wind |
| Curing compound | Sprayed membrane that limits evaporation | With engineer approval; may affect later bonding |
| Ponding | Small bunds holding water on the surface | Suits some horizontal slabs |
The engineer sets the curing period; at least seven days is common in normal conditions and more may be required in extreme heat or with certain cements. The first three days matter most. Columns and concrete walls need curing too – wrap them in wet hessian or polythene once the formwork is struck.
Samples and tests: the written proof of quality
Cubes or cylinders taken during the pour are crushed in an accredited lab at ages set by the engineer, most often 7 and 28 days. Ask for a copy of the results and keep it in your project file – it is part of the building’s record when you sell or extend.
Common summer mistakes
- Pouring at midday because trucks arrived late.
- Adding water to ease pumping or finishing.
- Covering the slab only after everything else is done.
- Stopping curing after a day or two because the surface “looks hard”.
- Stacking blocks and materials on a new slab before the engineer allows it.
- Removing props before the period the engineer sets.
How Marafi pours and cures
At Marafi each pour is treated as its own stage with preparation and follow-up. We inspect steel and formwork beforehand, fix column formwork precisely and check it for plumb before and after the pour, and follow the engineering drawings and approved mixes. A team of labourers, technicians, supervisors and engineers works with modern equipment, and pour timing and curing materials are planned in advance under strict safety standards. Owners receive photos at each key stage. See Reinforced Concrete Works, Structural Skeleton Works and How we build. If you are still choosing a slab type, read hollow-block vs solid slabs.
Summer pour checklist
- Approved mix, placement temperature within the specification.
- Pour at dawn or early morning with coordinated trucks.
- Steel and formwork inspected; surfaces dampened.
- Curing materials ready before starting.
- Slump test and samples for every pour.
- No water added on site.
- Cover immediately; cure for the full period the engineer sets.
- Cure columns and walls as well as slabs.
Have a project in Riyadh and want pours managed this way? Contact us to arrange a site visit and drawing review, and we will send an itemised proposal by stage.
Frequently asked questions
What is the best time to pour concrete in a Riyadh summer?
Dawn or early morning, or at night when needed, is far better than midday. Heat and direct sun speed up evaporation and setting before placing and finishing are complete.
How many days should concrete be cured?
The engineer sets the period based on cement type, element and weather. At least seven days is common in normal conditions, and longer may be required in extreme heat or with some cements.
Can water be added to concrete on site if it stiffens?
It is not recommended: extra water weakens the concrete and increases shrinkage and cracking. If the mix is unsuitable, the engineer decides – approved admixtures from the plant or rejecting the load.
Why do surface cracks appear on a slab a few hours after pouring?
Usually because water evaporates from the surface faster than it rises from within, driven by heat, wind and sun. Early covering, misting and windbreaks reduce these cracks considerably.
