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ROOFPLAST SP 35
- Early strength in concrete
- Admixture for precast elements
- Pumped concrete workability
- Flowing concrete mixes
ROOFPLAST SP 35 is a high-performance super plasticiser and water reducing admixture based on specially formulated organic polymers, compliant with IS 9103-99. It disperses cement particles effectively in all concrete mixes, increasing ultimate strength and producing high workability and pumpability without slump loss. Delivers 40–50% early strength gain when water reduction is used, and up to 20% improvement in strength at constant slump. Chloride-free, non-flammable and safe for prestressed concrete. Approved and used across CPWD, State PWDs and major government infrastructure projects.
Specifications
Figures are controlled laboratory results. Actual site performance varies with substrate, temperature, humidity, application method and workmanship — please confirm the current product datasheet before specification.
Where to use ROOFPLAST SP 35: superplasticizer for high early strength concrete
ROOFPLAST SP 35 is a superplasticizer for high early strength concrete, a single component water reducing admixture based on specially formulated organic polymers. It disperses cement particles in the mix, giving high workability and pumpability without slump loss. This chloride free superplasticizer is safe for prestressed concrete and is added to the concrete mix, not to dry cement.
High Workability Concrete
Disperses cement particles to give high workability without slump loss.
Pumped Concrete
Improves pumpability of the mix without loss of slump.
Prestressed & Precast Concrete
Chloride-free and safe for prestressed work, with early strength gain.
Flowing Concrete
Adjust the mix design to prevent bleeding and segregation.
High-Strength Structural Concrete
Water reduction of 10–20% for high early compressive strength.
Highway & Pavement Concrete
Workable concrete with reduced permeability and improved surface finish.
Mass Concrete
Setting is retarded by 1–2 hours at normal dosage.
Large-Section Pours
At higher dosage, expect 2–3 hours of setting time retardation.
If you want to know how to get early strength in concrete, dose 250–600 g per 50 kg bag of cement. Early strength gain is 40–50% when water reduction is used, or up to 20% at constant slump. It complies with IS 9103-99, has nil chloride and a shelf life of 2 years. As a superplasticizer for precast concrete it is not compatible with High Alumina cement. Cure with water after placement, or use ROOFEXCURE WB/WX curing membrane if water curing is not possible.
Armstrong Chemicals supplies ROOFPLAST SP 35 to sites across Telangana, Andhra Pradesh, Karnataka, Kerala and Tamil Nadu, including Hyderabad, Vijayawada, Bengaluru, Kochi and Chennai.
40–50% Early Strength Gain. Real Trial Data. Site Advisory Included.
A chloride-free super plasticiser that disperses cement particles effectively in all concrete mixes — delivering 40–50% early strength gain with water reduction, or up to 160mm slump at constant W/C, backed by real trial test data and Armstrong's on-site mix design advisory service.
Get a QuoteThe Workability-Strength Compromise in Structural Concrete
High-grade concrete needs a low water-cement ratio for strength and impermeability — but reducing water reduces workability, making pumping harder and risking honeycombing. Adding more water for workability weakens the concrete.
The ROOFPLAST SP 35 Advantage
Disperses cement particles uniformly so you gain workability and strength from the same mix — trial data shows 160mm slump and 60 N/mm² at 28 days when W/C is reduced to 0.30, versus 52mm slump and 50 N/mm² for reference concrete.
40–50% Early Strength Gain — Proven in Trial Data
Early compressive strength increases 40–50% when water reduction is applied. At W/C 0.30 with 0.4L dosage, 7-day strength reached 55 N/mm² against 41 N/mm² for control concrete — enabling earlier formwork stripping and faster construction cycles.
On-Site Mix Design Advisory
Armstrong provides a technical advisory service for on-site mix design assistance — particularly for producing high workability concrete without segregation. Included when ordering ROOFPLAST SP 35 for major projects.
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Trial Test Performance Results
Results obtained from actual concrete trials: OPC 350 kg/m³, Sand 730 kg, Coarse aggregates 990 kg.
| Mix | Dosage / 50kg | W/C | Slump | 3-Day | 7-Day | 28-Day |
|---|---|---|---|---|---|---|
| Control (no admixture) | Nil | 0.35 | 52mm | 29 N/mm² | 41 N/mm² | 50 N/mm² |
| Workability Increased | 0.4L (~460–480g) | 0.35 | 150mm | 31 N/mm² | 50 N/mm² | 56 N/mm² |
| Strength Increased | 0.4L (~460–480g) | 0.30 | 160mm | 33 N/mm² | 55 N/mm² | 60 N/mm² |
Note: The trial table lists dosage in litres; 0.4L equals approximately 460–480g at the product's specific gravity of 1.15–1.20.
Dosage Guidance
High Alumina cement incompatibility: ROOFPLAST SP 35 is compatible with all Portland and slab cements except High Alumina cement. Confirm cement type before use.
- 1
Determine dosage: 250–600g per 50kg bag of cement — establish optimum by site trial
- 2
Add ROOFPLAST SP 35 to the concrete mix; do not add directly to dry cement
- 3
⚠️ Not compatible with High Alumina cement — confirm cement type before use
- 4
At normal dosage expect 1–2 hours setting time retardation; at higher dosage, 2–3 hours
- 5
For minor adjustments in flowing concrete, modify mix design to prevent bleeding and segregation
- 6
Apply normal water curing after placement — water pouring, spray or wet hessian. Where water curing is not possible, use ROOFEXCURE WB / WX spray-applied curing membrane.
- 7
For site-specific mix design assistance, contact Armstrong's on-site technical advisory service
Built for High Workability, High-Grade Concrete
Chloride-free organic polymer performance — real trial data, on-site advisory support.
40–50% Early Strength Gain
Early compressive strength increases 40–50% with water reduction — and up to 20% strength improvement at constant slump — through effective cement particle dispersion that increases cement utilisation.
IS 9103-99 Compliant, NIL Chloride
IS 9103-99 certified, chloride-free and non-flammable — safe for prestressed and reinforced concrete with no risk of reinforcement corrosion.
Pumping & Cohesion Improved
Lubricates cement particles to reduce line friction for pumped concrete, while minimising segregation and bleeding — producing improved surface finish and reduced porosity.
2-Year Shelf Life
The longest shelf life of any Armstrong super-plasticiser — 2 years from manufacture in cool, dry storage. No minimum temperature constraint unlike other admixtures in the range.
Which plasticiser for your concrete grade
Armstrong admixture selection guide
Applicable Areas
Packing & Shelf Life
Available in 1kg, 5kg, 20kg and 225kg barrels. Shelf life of 2 years from manufacture date — the longest in the Armstrong super-plasticiser range. Store in a cool, dry place.
Key Constraints
⚠️ Not compatible with High Alumina cement — confirm cement type before use. At higher dosage levels, retardation increases to 2–3 hours — factor into pour scheduling. Minor mix design adjustments may be needed for flowing concrete to prevent bleeding.
Curing & Mix Design Support
Normal water curing (pouring, spray or wet hessian) after placement. If water curing is not possible, use ROOFEXCURE WB / WX spray curing membrane. Armstrong provides on-site technical advisory service for mix design — contact technical support for site-specific guidance.
Product Brochure
Download Technical Datasheet
Full specifications, application systems, layering guides, and coverage tables.
Frequently Asked Questions
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