Concrete admixture

VF21 EXPANSION AGENT

Sulfoaluminate-calcium type; effectively compensates shrinkage and improves concrete density, impermeability, and crack resistance.

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Category Concrete admixture

Concrete Expansion Agent for Shrinkage-Compensating Concrete

VF-21 Expansion Agent is a new-generation sulfoaluminate-calcium concrete expansion agent developed by Luka Chemicals for modern construction chemical supplies and high-performance concrete production. It is engineered to deliver coordinated expansion, stable strength development, and reliable long-term expansion performance, helping reduce shrinkage-related cracking while improving the durability of concrete structures. As a trusted solution in chemical admixtures for concrete, VF-21 Expansion Agent is suitable for manufacturers, contractors, importers, and distributors looking for dependable chemical admixtures concrete solutions from a professional concrete admixture factory. It is designed for use in shrinkage-compensating concrete, waterproof mass concrete, and other demanding applications where structural integrity and crack control are critical. The product complies with the Chinese standard GB23439-2009 “Concrete Expansion Agent.” It offers safe performance, reliable application, and reduced dependence on water replenishment during later curing stages, making it a practical choice for large-scale infrastructure and engineered concrete systems.

Uses

VF-21 Expansion Agent is widely used across a broad range of engineering and infrastructure projects, including: Underground Structures: High-rise basements, subways, underground parking lots, warehouses, tunnels, mines, civil air defense projects, pedestrian underpasses, and large foundation slabs. Water Storage: Pools, water towers, storage tanks, reservoirs, and mountain cave depots. Mass Structures: Mass concrete structures, ultra-long slab extension shrinkage seams, and seamless construction projects. Infrastructure: Large frame structures, seamless floor systems, airport runways, highway pavements, bridge decks, marine engineering, hydraulic structures, seaports, wharves, dams, and spillways. Specialty Concrete: High-performance concrete, steel tube concrete, impact-resistant concrete, and large-scale backfill concrete.

Characteristics / Advantages

High Efficiency: Provides strong expansion efficiency with low alkali content, supporting safer and more stable concrete performance. Improved Density: Helps optimize concrete microstructure, increasing density and improving overall material quality. Better Durability: Enhances impermeability, frost resistance, and long-term service life of concrete structures. Crack Resistance: Effectively compensates for shrinkage during hardening and drying, reducing the risk of cracking. Steel Reinforcement Protection: Non-corrosive to steel reinforcement and helps prevent alkali-aggregate reactions, supporting durable structural performance.

Main Technical Indicators

The following data represents the typical characteristics of the product:

Test Item	Standard Index (GB23439-2009)	Test Result
Magnesium Oxide (%)	≤ 5	3.2
Alkali Content (%)	≤ 0.75	0.45
Fineness: Specific Surface Area (m²/kg)	≥ 200	410
Fineness: 1.18mm Sieve Residue (%)	< 0.5	0.1
Restricted Expansion Rate (%): 7d in Water	0.025	0.029
Restricted Expansion Rate (%): 21d in Air	-0.02	-0.011
Compressive Strength (MPa): 7d	≥ 20	22.5
Compressive Strength (MPa): 28d	≥ 40	43.7

Conclusion: The tested items comply with the requirements of GB23439-2009 “Concrete Expansion Agent.”

Application Information

Trial Mixes

Because the compatibility between VF-21 , cement, admixtures, and water reducers may vary, laboratory trial mixes are recommended before full-scale production. This helps determine the best dosage and performance balance for your specific concrete mix design.

Recommended Dosage

General shrinkage-compensating concrete: 6–10% of the cementitious material mass
Mass expansion shrinkage-compensating concrete such as strengthening bands or self-stressing concrete: 8–12%

Dosage may be adjusted according to project specifications, cement type, and performance requirements.

Mixing Time

Ready-mixed concrete: Mixing time is the same as ordinary concrete
On-site mixing: Extend mixing time by 60 seconds to ensure uniform dispersion

Vibration

Concrete should be fully vibrated during construction. Avoid under-vibration, over-vibration, and missed areas to maintain density and structural quality.

Curing

Poured concrete should be cured for at least 14 days. During winter construction, thermal insulation measures should be used when the ambient temperature is below 5°C.

Temperature Limit

Use with caution in environments where the long-term working temperature exceeds 80°C.

Standards

Refer to the Technical Specification for Application of Shrinkage-Compensating Concrete when necessary for project guidance and design alignment.

Packaging, Storage & Transportation

Packaging: Available in 50kg or 25kg moisture-proof bags. Custom packaging weight is available upon request. Storage: Store in a ventilated, dry place. Protect from moisture and physical damage. Do not use if caking occurs. Shelf Life: 12 months. Safety Information and Transportation: Non-toxic, non-flammable, and suitable for transportation as general goods.

Why Choose Luka Chemicals?

Luka Chemicals supplies construction chemical solutions for global buyers who need stable product quality, technical consistency, and reliable manufacturing support. As one of the suppliers serving the china concrete admixtures market, we support B2B buyers who are sourcing professional concrete admixture manufacturers with strong production capability and application knowledge. VF-21 Expansion Agent is suitable for buyers seeking:

Reliable performance in large-scale concrete projects
Consistent quality from a professional concrete admixture factory
Technical support for shrinkage-compensating and waterproof concrete systems
Export-ready packaging and B2B supply capability
A dependable source for construction chemical supplies and concrete additive solutions

Legal Notes

The information provided in this document is given in good faith based on our current knowledge and experience of the product when properly stored, handled, and applied under normal conditions. However, due to variations in materials, substrates, and site conditions, no warranty regarding fitness for a particular purpose or merchantability is implied. The user is responsible for testing the product’s suitability for their specific applications. We reserve the right to change the properties of our products. All orders are accepted subject to our current terms of sale and delivery. Users should always refer to the most recent Product Data Sheet for this product, available upon request. FAQs

What is VF-21 Expansion Agent used for? VF-21 Expansion Agent is used in shrinkage-compensating concrete, mass concrete, waterproof concrete, and large infrastructure projects where crack resistance and long-term durability are required.
Is VF-21 Expansion Agent suitable for mass concrete? Yes, it is suitable for mass concrete structures, including foundations, slabs, tunnels, dams, and other large-scale engineering projects.
What is the recommended dosage of VF-21 Expansion Agent? The dosage is typically 6–10% for general shrinkage-compensating concrete and 8–12% for mass expansion shrinkage-compensating concrete, depending on project requirements.
Does VF-21 Expansion Agent comply with any standard? Yes, it complies with GB23439-2009 “Concrete Expansion Agent.”
How should VF-21 be stored? Store it in a dry, ventilated place and protect it from moisture and damage. Do not use the product if caking occurs.
Can VF-21 Expansion Agent be used in waterproof concrete? Yes, it is suitable for waterproof and impermeability-focused concrete applications, especially in underground and water-retaining structures.
What packaging options are available? It is available in 25kg or 50kg moisture-proof bags, and custom packaging is available on request.
Is trial mixing necessary before use? Yes, laboratory trial mixes are recommended to confirm compatibility with cement, admixtures, and water reducers.

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Flexible Payment & Global Delivery Solutions

Backed by large-scale production capacity and strong technical strength, Sichuan Lujia Sitong Technology Development Co., Ltd. ensures stable supply and efficient delivery to customers worldwide.

We support multiple international trade terms and flexible payment methods to meet diverse procurement needs.

Payment Options:

T/T, L/C, OA, and other negotiated methods

Shipping Coverage:

Worldwide

Transportation Terms:

Sea freight by CIF, FOB, CFR, and other Incoterms

Lead Time:

7–14 days depending on order volume and specifications

Packaging:

• 25kg moisture-proof bags • 500kg / 600kg palletized packaging • Customized packaging available

Minimum Order Quantity (MOQ):

500kg

Request Your Free Product Sample

To help you better evaluate our product quality and performance, we are pleased to offer free samples of our construction chemical solutions. Experience real results before placing bulk orders — with worldwide delivery available.

What You Will Receive:

✔ Product Technical Data Sheet (TDS) & brochure
✔ 200–600g sample (depending on product type)
✔ Fast global shipping via DHL or FedEx
✔ Technical consultation & formulation support
✔ Zero sample cost (shipping may vary by region)

Why Try Our Samples?

• Verify performance in real applications
• Test compatibility with your materials
• Reduce procurement risk
• Get expert technical guidance

Frequently Asked Questions

1. What are concrete admixtures used for?

Concrete admixtures are added to concrete mixes to improve performance such as strength, workability, waterproofing, durability, setting time, and crack resistance. They help achieve better construction quality and efficiency under different project conditions.

2. Can your admixtures be used with standard concrete materials?

Yes. Our products are compatible with most types of cement, aggregates, and conventional concrete mix designs. Technical support is available to ensure optimal performance for your specific application.

3. Do you provide technical data sheets (TDS)?

Yes. Each product is supplied with a detailed Technical Data Sheet including dosage, application guidelines, storage conditions, and safety information.

4. Can I request samples before placing a bulk order?

Absolutely. We offer free product samples for testing and evaluation. Samples are typically 200–600g depending on the product type.

5. What is the typical dosage of your admixtures?

Dosage varies depending on the product and application, usually ranging from 0.5% to 2% by cement weight. Exact recommendations are provided in the product TDS.

6. Do you offer customized formulations?

Yes. Our technical team can adjust formulations based on your project requirements, climate conditions, and performance goals.

7. What packaging options are available?

Standard packaging is 25kg bags, with palletized options (500kg–600kg) and customized packaging available upon request.

8. How long is the shelf life?

Most products have a shelf life of 12 months when stored in a dry, cool, and sealed environment.