Magnesium Oxide (MgO) Shrinkage Reducing Admixture is a high-performance concrete expansive agent utilizing adjustable activity of lightly calcined MgO to precisely match the released expansion energy and timing with the shrinkage of concrete structures, generating post-pour crystals for effective compensation, micro-expansion or zero-shrinkage states, and crack-free durability in waterproof and large-scale projects.
Post-Pour Expansion Crystals
Zero-Shrinkage Compensation
Crack Prevention Durability
Waterproof Structure Integrity
Product Introduction
Magnesium Oxide (MgO) Shrinkage Reducing Admixture is a high-performance concrete admixture designed primarily around post-pour temperature dynamics. It generates expansion crystals through specialized chemical reactions at various stages after pouring, effectively compensating for concrete shrinkage to achieve micro-expansion or zero-shrinkage states. This targeted MgO expansive admixture resolves cracking issues caused by shrinkage, enhancing durability and structural integrity in waterproof and large-scale applications.
Key applications include underground parking garages, subway tunnels, basements, large-volume structures, and waterproof engineering. Compliant with CBMF 19-2017, available in R, M, S types with dosages of 6-10%.
Product Parameters
| Test item | Indicator Requirements | |||
| Type R | Type M | Type S | ||
| MgO content (%) | ≥80.0 | |||
| Loss on burnout (%) | ≤4.0 | |||
| Moisture content/% | 0.3 | |||
| Reaction time (s) | <100 | ≥100 and <200 | ≥200 and <300 | |
| Fineness (%) | 80 μm square hole sieve 1.18 mm square hole sieve | 5.0 0.5 | ||
| Restriction on expansion (%) | 20℃ water 7d 20℃ water Δε 40℃ water 7d 40℃ water Δε | ≥0.020 ≥0.020 ≥0.040 ≥0.020 | 0.015 0.015 0.030 0.030 | 0.015 0.010 0.020 0.040 |
| Setting time (min) | Initial coagulation Final coagulation | ≥ ≤ | 45 600 | |
| Compressive strength (MPa) | 7d 28d | ≥ ≤ | 22.5 42.5 | 22.5 42.5 |
Product Usage
Magnesium Oxide (MgO) Shrinkage Reducing Admixture is perfect for concrete shrinkage compensation in waterproof and large-scale projects. Applications include underground parking, subway tunnels, civil defense, basements, large-volume pours, ultra-long structures, and special waterproof engineering.
Usage Guidelines:
Mix at 6-10% of binder weight (≤9% max); select R/M/S type and test for specifics.
Ensure even mixing for optimal magnesium oxide expansive agent performance.
Cure for ≥7 days with moisture to activate crystals.
Key Benefits: Achieves micro-expansion, prevents cracks, supports hydration and expansion in concrete. Follow CBMF 19-2017.
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