Mineral Addition and Mixing Methods Effect on Recycled Aggregate Concrete

Area of Science:

• Civil Engineering
• Materials Science

Background:

• Recycled aggregate concrete (RAC) offers a sustainable alternative to natural aggregate concrete (NAC).
• Optimizing RAC design requires effective methods to ensure desired mechanical properties.
• Treatment and mixing techniques significantly influence concrete performance.

Purpose of the Study:

• To evaluate the influence of different design methods and silica fume (SF) on recycled aggregate concrete (RAC).
• To compare the performance of RAC designed using Absolute Volume Method (AVM) and Equivalent Mortar Volume (EMV).
• To determine the effectiveness of SF as a mineral admixture in RAC.

Main Methods:

• Four concrete groups were produced: NAC (AVM), control RAC (AVM), treated RAC (AVM with SF), and treated RAC (EMV).
• Concrete properties were tested at 28 days.
• Statistical analysis, including multiple comparison, was performed on the test results.

Main Results:

• Both EMV and SF incorporation led to increased compressive strength in RAC, elevating its strength class.
• A significant statistical difference was observed among the different concrete types.
• Multiple comparison analysis revealed a significant relationship between NAC, control RAC, and RAC-EMV.

Conclusions:

• The Equivalent Mortar Volume (EMV) method and the addition of 5% silica fume (SF) are effective in improving RAC properties.
• These methods, combined with AVM, are recommended for designing RAC to meet target strength classes, such as C30/37.
• RAC designed with EMV or AVM incorporating SF shows superior performance compared to RAC designed solely with AVM.