Redispersible Polymer Powder (RDP) Modified Mortar Performance Study

Empirical Breakthroughs in VAE/SA Systems for Engineering Applications 

Experimental Design

Base System  

- Cement: P·O 42.5 (GB 175-2020)  

- Aggregate: Medium-fine sand (fineness modulus 2.3–3.0)  

- Control Groups: RDP dosages of 0%, 2%, 5%, 8% (fixed water-cement ratio = 0.5, sand-binder ratio = 3:1)  

Performance Evaluation Matrix  

| Evaluation Criteria       | Test Standard           | Key Metrics                  |  

|--------------------------|-------------------------|------------------------------|  

| Workability               | JGJ/T 70-2009           | Consistency loss rate (120 min) |  

| Mechanical Properties     | GB/T 17671-2021         | Flexural-to-compressive strength ratio (28d) |  

| Durability                | JGJ/T 193-2009          | Mass loss after 50 freeze-thaw cycles |  

| Interfacial Bonding       | JC/T 547-2017           | Tensile bond strength (MPa)  |  

Key Findings  

1. Bonding Performance  

- 8% RDP dosage: Tensile bond strength reaches 1.8 MPa(240% increase vs. control group).  

- Failure mode shifts from *interface debonding to cohesive substrate failure.  

2. Mechanical Balance  

| RDP Dosage | Flexural Strength (MPa) | Compressive Strength (MPa) | Flexural-to-Compressive Ratio |  

|------------|-------------------------|----------------------------|-------------------------------|  

| 0%         | 6.2                     | 32.5                       | 0.19                          |  

| 8%         | 8.7 (+40%)          | 28.1 (-14%)            | 0.31(+63%)           |  

3. Durability Enhancement  

- Water absorption decreases from 9.8% → 5.2% (8% dosage).  

- Freeze-thaw mass loss improves from 2.1% → 0.7%.  

Engineering Value

1. Thin-Layer Construction 

- With ≥5% RDP, open time extends to 45 min, meeting thin-layer external wall insulation requirements.  

2. Dynamic Stress Applications

- 63% higher flexural-to-compressive ratio enables seismic deformation compensation in earthquake-prone zones.  

3. Humid/Tropical Environments  

- Chloride ion diffusion coefficient reduced by two orders of magnitude, extending service life of coastal structures by **30%**.  

Cost-Benefit Analysis 

Case Study: High-Rise Curtain Wall Project  

- RDP dosage increased from 3% → 6%.  

- Bonding layer thickness reduced from 15 mm → 8 mm.  

- Material cost increases by ¥8.5/m², but 12% reduction in hollowing defects lowers total costs by 23%.  

Conclusion 

An RDP dosage of 5–6% achieves Pareto optimization between mechanical performance and cost efficiency. This aligns with China’s *GB55015-2021: General Code for Building Energy Efficiency and Renewable Energy Utilization*, offering critical technical support for sustainable construction practices.