Polymer cement grout is a cement-based grouting material primarily composed of high-strength cement, polycarboxylate superplasticizers, and multi-mineral materials as the main modifying components. It features good fluidity, micro-expansion, certain toughness, strong bonding strength with concrete, and corrosion resistance and durability. It is suitable for grouting repair of concrete structure cracks with widths greater than 3mm and for external steel reinforcement.
| II. Performance Indicators |
Table 1 Performance Indicators of Polymer Cement Grout
| No. | Test Item | Performance Indicator |
| 1 | Vertical Expansion Rate (%) | 3h | ≥0.10 |
| Difference between 4h and 3h | ≥0.020 |
| 2 | Fluidity (mm) | Initial Value | ≥380 |
| 30min Retention Value (%) | ≥90 |
| 3 | Compressive Strength (MPa) | 3d | ≥25 |
| 7d | ≥35 |
| 28d | ≥55 |
| 4 | Flexural Strength (MPa) | 7d | ≥5 |
| 28d | ≥8 |
| 5 | Splitting Tensile Strength (MPa) | 7d | ≥3 |
| 28d | ≥4 |
| 6 | Bleeding Rate (%) | 0 |
| 7 | Normal Tensile Bond Strength with Concrete (MPa) | 28d | ≥1.5, and cohesive failure in concrete |
| III. Construction Process |
1. Pretreatment: Use compressed air to blow out dust and contaminants from concrete cracks.
2. Embedding Grouting Pipes: Place a grouting pipe every approximately 500mm along the length of the crack.
3. Sealing Cracks: Seal the entire surface of the crack using inorganic rapid-setting materials.
4. Pressure Test: Seal the grouting pipes and conduct a water or air pressure test at 0.2~0.3MPa to check the sealing integrity. Ensure the concrete crack surface remains moist but without standing water inside the crack.
5. Mixing: The mass ratio for CBGM polymer cement grout is: polymer cement grout∶water = 10∶(2.5~2.8). Use a forced-action mixer or a modified impact drill for mixing. After thorough mixing, the grout should have a uniform color, no powder clumps, sedimentation, streaking, or bleeding, and its fluidity should meet the grouting consistency requirements. The mixed grout should be used immediately to prevent setting.
6. Grouting: Load the mixed grout into a specialized pressure grouting tank and inject it continuously into the crack at a pressure of about 0.3MPa. For vertical cracks, grout from the bottom up one nozzle at a time, sealing each nozzle immediately after filling. During grouting, ensure air is expelled from the crack. The last grouting pipe serves as an exhaust vent and must not be blocked to avoid hindering air escape.
7. Curing: After grouting, maintain water curing at the grouted area for more than 7 days.
