Saudi Arabia routinely experiences extreme summer temperatures—often exceeding 45 °C. Under such conditions, proper concrete curing becomes critical to achieving long-term strength, durability, and structural performance. Without the right precautions, heat can significantly undermine concrete integrity.

Why Hot Weather Poses Risks

Rapid Moisture Loss and Plastic Shrinkage Cracks

High ambient temperatures accelerate evaporation from fresh concrete surfaces, leading to plastic shrinkage cracks. These superficial flaws reduce durability and weaken the bond within the concrete layers. Rapid water loss also prevents proper hydration, hampering strength development.

Temperature Gradients and Thermal Cracking

Direct solar exposure heats the concrete surface much faster than its core. Such temperature differentials (ideally kept under 25 °C between surface and interior, and under 20 °C between interior and ambient) create internal stresses that lead to cracking, especially in thick structural members.

Accelerated Hydration and Reduced Strength

High temperatures promote fast hydration, causing early stiffening. This means reduced finishing time, poor compaction, and ultimately a more brittle matrix with lower long-term strength, even if early strength appears adequate.

Dust Contamination and Wind Exposure

Desert winds often carry dust and sand that settle on uncured surfaces, leading to weak top layers, uneven finishes, and increased risk of scaling or delamination.

Surface Defects: Crazing and Scaling

Ultrafast drying often causes fine surface cracks (crazing) or peeling of the top layer (scaling). These cosmetic flaws often signal deeper strength issues and elevated permeability.

Expanded Risks of Inadequate Curing

• Significant reduction in 28-day strength and durability
  
  

• Increased susceptibility to reinforcement corrosion
  
  

• Higher permeability, increasing chemical attack and moisture penetration
  
  

• Poor finish quality and long-term performance degradation

Proven Strategies for Hot-Weather Curing

Optimal Timing: Early Morning or Night Pouring

Scheduling pours during early morning or night hours minimizes peak heat exposure. Early scheduling also helps ensure longer workability windows and safer moisture retention.

Moisture Retention Techniques

Maintaining continuous moisture is essential:

• Use fogging systems or sprinklers shortly after finishing
  
  

• Lay wet burlap or absorbent covers, kept consistently damp
  
  

• Seal moisture in using plastic sheeting or membrane-forming compounds
  
  

Continuous curing for at least 3 to 7 days is advised to maximize hydration.

Shading and Wind Control

Install temporary shades, reflective blankets, or sun tarps over fresh concrete and use windbreaks to reduce wind-driven evaporation. These measures help stabilize thermal and moisture conditions.

Cooling Ingredients and Mix Preparation

Pre-cool mixing water, aggregates, and cement using chilled water, ice, or other cooling techniques. Even a temperature reduction of 5 to 10 °C can significantly slow hydration, reduce cracking risk, and preserve workability.

Adjusted Mix Design

Engineered mix designs help counter heat effects:

• Use low-heat cement or supplementary cementitious materials (e.g., fly ash, slag)
  
  

• Add chemical retarders to extend setting time
  
  

• Employ low water–cement ratios supported by superplasticizers
  
  

• Include shrinkage-reducing admixtures where needed
  
  

Site Preparation and Placement Speed

Before pouring, dampen subgrade and formwork to prevent premature water absorption. Fast placement and finishing are essential; delays increase risk of early setting in transit or on-site.

Quality Assurance: Monitoring and Testing

Incorporate temperature and humidity sensors to monitor curing conditions in real time. Use maturity indexing, penetration resistance, or pull-out testing to verify in-place strength before formwork removal or load application. Adhering to standards ensures temperature differentials and curing duration remain within safe limits.

Additional Insights: Real-World Guidance

From on-site practitioner's advice:

“Ideally ... lay the slab in the evening and let it cure overnight at 70… keeping it wet is the right idea, but in that heat the concrete could get hot enough to boil the water out…”
“We usually don’t start until 12 a.m.… iced mix, early morning pour, early saw cutting, burlap and misters/sprinkles.”

These reflections reinforce the importance of timing, controlled moisture application, and mix cooling.

Long-Term Impact of Failures

Poor curing often leads to:

• Premature structural degradation
  
  

• Reduced service life and increased maintenance costs
  
  

• Cracks, spalling, and compromised fire resistance
  
  

• Weak pores that accelerate chemical or chloride intrusion

Final Recommendations

A robust hot-weather concrete strategy combines:

• Thoughtful scheduling (cool time pours)
  
  

• Continuous moisture retention (spraying, wet coverings)
  
  

• Ingredient cooling and mix optimization
  
  

• Shading, wind control, and accelerated placement
  
  

• Real-time monitoring and adherence to quality standards
  
  

These interventions ensure that concrete placed in Saudi Arabia’s harsh heat gains its full strength, avoids cracking, and will stand the test of time—delivering long-lasting, resilient construction outcomes.