Activated Glass Additive Mitigates Alkali-Aggregate Reaction in Cement
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Solution Overview
Problem
The use of glass as a mineral additive in cement is problematic due to the risk of alkali-aggregate reaction (AAR), which can lead to structural degradation and cracking, as it involves the release of alkalis that react with silica-containing aggregates, causing expansion and damage to cement structures.
Innovation Solution
The use of ground glass as a mineral additive, which is subjected to grinding and subsequent washing with water to increase its reactive silica content and pozzolanic activity, thereby reducing its reactivity with alkalis and mitigating the AAR through improved fineness, surface area, and particle distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ground glass is used as a mineral additive in cement, then the pozzolanic activity and reactive silica content are improved, but the risk of alkali-aggregate reaction increases
Solution Approach 1:
The glass is pre-ground to a fine granulometry (mean diameter 10-200 microns) before being incorporated into the cement mixture. This preliminary size reduction increases the surface area and reactive silica availability, enhancing pozzolanic activity while the fine distribution helps mitigate AAR by reducing localized alkali concentration
Solution Approach 2:
The invention changes the physical parameters of the glass additive by controlling its granulometry (mean diameter 10-200 microns) and chemical composition (specific silica and alkali content ratios). These parameter modifications optimize the balance between pozzolanic reactivity and AAR resistance, allowing the glass to contribute beneficially to cement performance
2Strength
If glass content is increased to improve mechanical resistance, then the durability is enhanced, but the expansion phenomena and structural degradation worsen
Solution Approach 1:
The invention specifies precise compositional parameters for the glass additive, including silica content, alkali content, and mean particle diameter (10-200 microns). By controlling these parameters, the glass provides mechanical strength enhancement through pozzolanic reactions while maintaining structural stability by preventing excessive alkali release that would cause expansion and cracking
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The activated glass additive effectively reduces the expansion caused by AAR, enhancing the durability and mechanical resistance of cement structures by distributing alkali attack and inhibiting the reaction mechanism, as demonstrated by reduced deformation in mortar and cement test pieces.
Implementation Method 1
ground glass as a mineral additive, which is subjected to grinding and subsequent washing with water to increase its reactive silica content and pozzolanic activity, thereby reducing its reactivity with alkalis
Implementation Method 2
increase its reactive silica content and pozzolanic activity, thereby reducing its reactivity with alkalis
Data Source
AI summary
The present invention relates to a cementitious composition adapted to form mortars or cements comprising glass as an additive having reduced tendency to reaction with alkali, characterized in that said glass is obtained by grinding and subsequent washing with water.