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 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 the concrete cracks.
2. Embedding Grouting Pipes: Place grouting pipes approximately every 500mm along the length of the crack.
3. Sealing the Crack: 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 observe whether the sealing is dense. Keep the concrete crack surface moist but without standing water inside the crack.
5. Mixing: The mass ratio of 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, and use after thorough mixing. The mixed slurry should have uniform color, no powder lumps, sedimentation, uneven coloring, or bleeding, and its fluidity should meet the grouting consistency requirements. The mixed grout should be used immediately to avoid 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 grouting nozzle at a time, and seal each filled nozzle immediately. During grouting, ensure that air is expelled from the crack. The last grouting pipe serves as an exhaust vent and should not be blocked to avoid hindering air discharge.
