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Comparative Evaluation of Packing Models for Mix Design and Performance Optimization of Ceramsite-Modified
Wanqing Zhou1, Liangcheng Wang1, Mengjie Jiang1
1College of Civil Engineering and Architecture, China Three Gorges University, Yichang 443002, China.
Materials (Basel, Switzerland)
|June 12, 2026
Summary
This study introduces a new mix design for lightweight ultra-high-performance concrete (LUHPC) using ceramsite sand. The compressible packing model (CPM) offers superior mechanical properties and lower density compared to the modified Andreasen packing model (APM).
Area of Science:
- Materials Science
- Civil Engineering
- Concrete Technology
Background:
- Lightweight aggregates (LWAs) like ceramsite sand have porous structures and high water absorption, challenging conventional mix design for lightweight ultra-high-performance concrete (LUHPC).
- Existing methods may underestimate powder content, affecting the accuracy of LUHPC mix design.
- Need for optimized mix design strategies for ceramsite-sand-based LUHPC.
Purpose of the Study:
- To develop and evaluate a suitable mix design method for ceramsite-sand-based LUHPC.
- To compare the effectiveness of the modified Andreasen packing model (APM) and the compressible packing model (CPM) for LUHPC mix design.
- To investigate the influence of steel fiber content on the properties of ceramsite-sand-based LUHPC.
Main Methods:
- Utilized ceramsite sand as the lightweight aggregate.
- Combined excess paste theory with particle packing methods (APM and CPM) for mix design.
- Optimized particle size distribution of ceramsite sand and binder composition.
- Systematically investigated workability, apparent density, mechanical properties, elastic modulus, and shrinkage with varying steel fiber content.
Main Results:
- CPM resulted in a denser aggregate skeleton with approximately 3.5% lower skeleton packing volume than APM.
- CPM-designed LUHPC exhibited superior mechanical properties (compressive, tensile, flexural, shear strength) compared to APM-designed mixtures.
- CPM-2.0 LUHPC achieved 124.6 MPa compressive strength at 1982 kg/m³ density; CPM-3.0 reached 131.7 MPa.
- Increased steel fiber content (1.5% to 3.0%) improved mechanical properties and slightly increased elastic modulus, while decreasing workability and showing diminishing returns for shrinkage restraint.
Conclusions:
- The compressible packing model (CPM) is more suitable than the modified Andreasen packing model (APM) for designing ceramsite-sand-based LUHPC.
- A steel fiber content of approximately 2.0% is recommended for balancing mechanical performance, shrinkage control, and material economy in ceramsite-sand-based LUHPC.
- The developed mix design method provides guidance for optimizing LUHPC performance.
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