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Time-Dependent Transition in the Re-Tempering Behavior of Cement Mortar
1Department of Architecture, Seowon University, Cheongju 28674, Republic of Korea.
Materials (Basel, Switzerland)
|August 13, 2026
Summary
Re-tempering cement mortar with extra water restores workability but weakens hardened properties. The Workability-Strength Trade-off Ratio (WSTR) shows benefits diminish significantly after 30 minutes of waiting time.
Area of Science:
- Civil Engineering
- Materials Science
- Construction Management
Background:
- Construction delays often necessitate re-tempering cement mortar with additional water to maintain workability.
- Re-tempering can negatively impact the hardened properties of cement mortar, despite improving fresh-state fluidity.
Purpose of the Study:
- To investigate the effects of waiting time and additional water on cement mortar re-tempering.
- To quantify the trade-off between workability recovery and strength deterioration during re-tempering.
Main Methods:
- Controlled laboratory experiments evaluated mortar flow, compressive strength, and water absorption.
- A dimensionless Workability-Strength Trade-off Ratio (WSTR) was developed to assess re-tempering efficiency.
Main Results:
- Re-tempering improved workability, but recovery efficiency decreased with longer waiting times.
- Compressive strength decreased and water absorption increased with both increased waiting time and water content.
- WSTR showed a marked decline after approximately 30 minutes of waiting, indicating reduced engineering benefits.
Conclusions:
- The primary impact of re-tempering shifts from workability enhancement to hardened property degradation as hydration progresses.
- A quantitative framework (WSTR) is provided for evaluating re-tempering under construction delays.
- Further research is needed for different mortar compositions and material systems.
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