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Multilayer Casting of Eco-Efficient Self-Compacting Concrete with Reduced Binder Content
Piotr Dybeł1, Milena Kucharska1
1Faculty of Civil Engineering and Resource Management, AGH University of Science and Technology, 30-059 Cracow, Poland.
Materials (Basel, Switzerland)
|October 13, 2021
Summary
Eco-efficient self-compacting concrete (SCC) can be multilayer cast, but delays reduce interlayer bond strength. Mechanical surface disturbance mitigates this bond strength loss, especially in reduced binder content concrete.
Area of Science:
- Civil Engineering
- Materials Science
- Sustainable Construction
Background:
- Eco-efficient concrete mixes with reduced binder content and supplementary cementitious materials are gaining traction.
- Self-compacting concrete (SCC) is typically poured in a single, uninterrupted layer.
- Construction delays can necessitate multilayer casting, potentially creating cold joints and compromising structural integrity.
Purpose of the Study:
- To evaluate the suitability of eco-efficient SCC for multilayer casting.
- To analyze the impact of delay times and surface preparation on interlayer bond strength in multilayer SCC.
- To provide recommendations for improved guidelines on multilayer SCC casting.
Main Methods:
- Two eco-efficient SCC mixtures with reduced binder content were tested.
- Multilayer casting was performed using two variants: pouring onto a fresh layer and pouring onto a mechanically disturbed layer.
- Delay times of 15, 30, 45, and 60 minutes were investigated.
- Splitting tensile strength tests were conducted on cubic elements to assess interlayer bond strength.
Main Results:
- Interlayer bond strength decreased significantly with increased delay times between layers, irrespective of the casting variant.
- Mechanical disturbance of the underlying layer surface reduced the negative impact of delay times on bond strength.
- Concrete with reduced binder content exhibited a less pronounced drop in bond strength compared to standard mixes.
- The casting variant and delay time significantly influenced the load-bearing capacity of the joint.
Conclusions:
- Eco-efficient SCC can be used for multilayer casting, but careful consideration of delay times is crucial.
- Mechanical surface preparation is recommended to maintain interlayer bond strength when delays occur.
- Existing guidelines for multilayer SCC casting need refinement regarding acceptable time delays between layers.
- Failure to manage interlayer bonding in multilayer SCC can lead to cold joints and reduced structural capacity.
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