Properties of Self-Compacting Concrete (SCC) Prepared with Binary and Ternary Blended Calcined Clay and Steel Slag

Abstract

Key Answers

What materials can be used to create sustainable self-compacting concrete?

This study found that self-compacting concrete (SCC) can effectively incorporate steel slag and calcined clay as partial replacements for traditional Portland cement. These materials improve sustainability by reducing reliance on cement, which in turn lowers carbon emissions and decreases environmental impact.

How do steel slag and calcined clay affect the compressive strength of SCC?

Adding 10% steel slag and up to 20% calcined clay improved the 28-day compressive strength of SCC, with mixes achieving 6.2% higher strength compared to traditional cement-based SCC. However, higher replacement levels led to a decline in strength, indicating an optimal range for these materials.

What is the impact of calcined clay on the fluidity of SCC?

Calcined clay decreases SCC fluidity, shown by reduced slump flow and increased viscosity. Adding steel slag compensates for this effect, maintaining flowability and cohesion, making it feasible to use calcined clay in SCC without significantly compromising workability.

How does the ternary blend of steel slag and calcined clay affect SCC's durability?

The ternary blend of steel slag and calcined clay improved SCC’s resistance to chloride permeability and sulphate attacks. This enhanced durability is attributed to a denser microstructure and refined pore distribution, which limit ion ingress and increase resilience to environmental stressors.

Can steel slag and calcined clay be used to improve environmental performance in construction materials?

Yes, using steel slag and calcined clay as supplementary cementitious materials in SCC aligns with sustainable construction practices. This approach minimizes waste, decreases cement usage, and enhances the environmental footprint of concrete production.

Key Points

Environmental Sustainability

Using steel slag and calcined clay as partial substitutes for Portland cement can reduce environmental impact, leveraging materials traditionally considered waste for sustainable concrete production.

Improved Workability in Concrete

Incorporating 10% steel slag with calcined clay enhances the workability and consistency of self-compacting concrete (SCC), achieving optimal results at 10-15% calcined clay substitution.

Strength and Durability

The ternary blend of SCC with 10% steel slag and 10-20% calcined clay produced compressive strengths up to 6.2% higher than the control, demonstrating durability and increased resistance to sulphate and chloride attacks.

Enhanced Microstructure

XRD analysis shows reduced portlandite peaks in SCC samples containing steel slag and calcined clay, indicating a refined concrete matrix that promotes strength development and decreases permeability.

Application Potential

The study supports the use of a calcined clay-steel slag blend as a sustainable binder in SCC, maintaining mechanical properties without compromising durability, even in challenging environments.

Abstract