Thermal Cracking in Concrete: Causes, Prevention, and Repair Methods

Thermal cracking is a critical issue in concrete structures, causing breakdowns and threatening overall stability. Understanding its causes, prevention strategies, and repair methods is essential for engineers, builders, and construction professionals aiming to create durable structures. This guide also highlights the role of concrete hardeners, particularly the best options available in India, along with insights on bulk buying, suppliers, and pricing.

Introduction to Thermal Cracking in Concrete

Thermal cracking occurs when temperature-induced stresses exceed the tensile strength of concrete. Unlike cracks caused by loads or shrinkage, these are due to temperature gradients within the concrete mass or differences between the structure and its environment.

• What is Thermal Cracking? During cement hydration, heat builds up—especially in mass concrete pours—causing the core to expand more than the cooler surface, generating cracks.
• Why it Matters: Thermal cracks weaken concrete, lower load-bearing capacity, and reduce durability.

Causes of Thermal Cracking in Concrete

1. Heat of Hydration: Excessive heat buildup in thick pours leads to surface tension and cracks.
2. Temperature Differentials: Rapid cooling or uneven temperatures between core and surface cause stress.
3. Poor Curing Practices: Inadequate curing accelerates moisture loss and temperature fluctuations.
4. Environmental Factors: Sun, wind, cold nights, or sudden cooling affect thermal balance.
5. Improper Mix Design & Placement: High cement content, poor substitutes, and thick slabs increase crack risk.

Prevention of Thermal Cracking

1. Proper Mix Design with Admixtures: Use water reducers, supplementary materials (fly ash, slag), and chemical hardeners to reduce heat generation and boost durability.
2. Cooling Techniques: Pre-cooling aggregates, chilled water, or embedded cooling pipes regulate temperature.
3. Controlled Placement & Thickness: Pour concrete in thinner layers or add construction joints to minimize heat buildup.
4. Proper Curing: Maintain surface moisture through wet coverings, spraying, or curing compounds.
5. Use of Concrete Hardeners: Floor and surface hardeners strengthen the concrete skin, making it less porous and more resistant to crack propagation.

Benefits of Concrete Hardeners

• Increase surface durability and reduce fissures.
• Boost resistance to chemicals and moisture ingress.
• Control wear in industrial and factory floors.

Popular Types of Hardeners

• Dry metallic and non-metallic shake hardeners
• Silicate-based liquid density hardeners
• Concrete hardeners for paver blocks—strengthening blocks while reducing thermal cracks

Repair Methods for Thermal Cracking

1. Injection Techniques: Epoxy for strength, polyurethane for flexibility.
2. Surface Sealers & Overlays: Elastomeric sealers or fiber-reinforced overlays prevent further cracking.
3. Routing & Sealing: Cracks are widened and sealed with flexible fillers to accommodate movement.
4. Grinding & Polishing with Hardeners: Restores factory floors, reduces dusting, and strengthens cracked surfaces.

Key Considerations for Selecting Concrete Hardeners

• Compatibility: Ensure the hardener matches your concrete mix and project type.
• Application Method: Choose powder, liquid, shake-on, or admixture forms based on scale.
• Supplier Reliability: Work with trusted suppliers offering technical support.
• Price & Availability: Compare costs and consider bulk buying for savings.

Concrete Hardener Pricing and Bulk Buying

• Prices vary by type, size, and brand.
• Industrial-grade hardeners typically cost INR 10–50 per kg.
• Bulk buying ensures better rates and consistent supply.
• Purchasing from trusted manufacturers guarantees timely delivery and quality.

Why Use Floor Hardener Chemicals for Factories?

• Enhance abrasion resistance against machinery and forklifts.
• Improve chemical resistance to spills and industrial cleaners.
• Seal pores, reducing dusting and crack formation risks.