Magnesium Oxide Expansive Agent is a additive primarily composed of active magnesium oxide (MgO), appearing as a greyish-white or white powder.
It produces stable and controllable volume expansion through a unique hydration reaction, primarily used to compensate for the shrinkage of cement-based materials during the hardening process.
Its core value lies in effectively preventing concrete cracking, significantly enhancing the structure’s durability, impermeability, and integrity.
The resulting Magnesium Hydroxide crystals (Brucite) occupy a larger volume, thereby generating gentle expansion pressure from within the concrete.
This expansion pressure precisely offsets the tensile stress generated by concrete due to temperature drop (thermal contraction) and moisture loss (drying shrinkage), fundamentally preventing the formation of shrinkage cracks.
Product Parameters
| project | ||||
| R-type | M-type | S-type | ||
| MgO content/% ≥ | 80.0 | |||
| Loss on ignition/% ≤ | 4.0 | |||
| Moisture content/% ≤ | 0.3 | |||
| Reaction time/s | <100 | ≥100&<200 | ≥200&<300 | |
| Fineness/% | 80 μm Square hole sieve residue ≤ | 5.0 | ||
| 1.18 μm Square hole sieve residue ≤ | 0.5 | |||
| restrained expansive rate/% | 7d in 20℃ water ≥ | 0.020 | 0.015 | 0.015 |
| 20℃ water,Δε ≥ | 0.020 | 0.015 | 0.010 | |
| 7d in 40℃ water ≥ | 0.040 | 0.030 | 0.020 | |
| 40℃ water,Δε ≥ | 0.020 | 0.030 | 0.040 | |
| Setting time | Initial Setting | 45 | ||
| Final Setting | 600 | |||
| Compressive strength/MPa | 7d ≥ | 22.5 | ||
| 28d ≥ | 42.5 | |||
Product Advantages
High-Efficiency Crack Control: Remarkably compensates for shrinkage, greatly reducing the risk of concrete cracking.
Controllable Expansion:The expansion rate can be tailored by modifying the reactivity of MgO , ensuring perfect synchronization with the concrete’s shrinkage profile.
Enhanced Durability:Results in a denser concrete structure, effectively blocking the ingress of harmful substances like chlorides and moisture, thereby extending the service life of the structure.
Strength Contribution:The optimized internal micro structure contributes to the long-term strength development of concrete.
Easy Application:A powdered material that is easy to use and can be directly added to the mixer along with other dry ingredients.
Application range
