Binary and Ternary Blended Portland Cements Containing Different Types of Rice Husk Ash

Area of Science:

• Materials Science
• Civil Engineering
• Sustainable Construction

Background:

• Rice husk ash (RHA) is a silica-rich agricultural waste with proven pozzolanic properties.
• Current standards limit RHA use in concrete and mortars, particularly in countries with high RHA production like Spain.
• The cement industry faces pressure to reduce energy consumption and CO2 emissions, increasing interest in mineral admixtures.

Purpose of the Study:

• To evaluate the impact of different RHA types on blended Portland cement properties.
• To determine optimal replacement levels for RHA in cement formulations.
• To explore the potential for designing new blended cement standards incorporating RHA.

Main Methods:

• Characterization of various RHA types for pozzolanic activity (specific surface area, amorphous silica content).
• Experimental preparation of binary and ternary blended cements using RHA and fly ash.
• Assessment of workability and 28-day mechanical performance of blended cements.

Main Results:

• Highly reactive RHA (high surface area, amorphous silica) is limited to 10% cement replacement due to workability issues.
• Less reactive RHA or fly ash can be combined with reactive RHA in blended cements.
• Cements like CEM II/A-H, CEM II/A-(H-V), and CEM II/B-(H-V) can be designed.

Conclusions:

• Blended cements with up to 30% RHA can achieve comparable 28-day mechanical performance to traditional Portland cement.
• The study demonstrates the technical feasibility of incorporating RHA into standardized cement types.
• Optimizing RHA reactivity and blending strategies is key to maximizing its use in sustainable construction.