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ROOFPLAST SP 25
- Increase slump without extra water
- Pumpable concrete mix
- Bleeding and segregation
- Ready-mix concrete workability
ROOFPLAST SP 25 is a super plasticiser and water reducing admixture based on specially formulated organic polymers, compliant with IS 9103-99. At just 100–150g per 50kg bag of cement, it disperses cement particles uniformly and effectively — improving slump from 50mm to 148mm in workability trials, reducing bleeding and segregation, and improving pumpability and surface finish. Chloride-free, non-toxic, 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 25: low dosage superplasticizer for structural concrete
ROOFPLAST SP 25 is a low dosage superplasticizer and water reducing admixture based on specially formulated organic polymers. At 100–150 g per 50 kg bag of cement it disperses cement particles uniformly, reducing bleeding and segregation and improving surface finish. As an admixture for pumpable concrete it is added to the concrete mix, never directly to dry cement.
High Workability Concrete
Improved slump from 50 mm to 148 mm in workability trials.
Pumped Concrete
Improves pumpability and reduces bleeding and segregation.
Flowing Concrete (No Compaction)
Modify the mix design to prevent bleeding and segregation.
Prestressed & Precast Concrete
Chloride-free and safe for prestressed concrete.
Standard Grade Structural Concrete
A dose of 100–150 g per bag improves workability.
Highway & Pavement Concrete
Uniformly dispersed cement and an improved surface finish.
Ready-Mix Concrete
Raises slump for ready-mix loads without changing the water content.
If you are looking at how to increase concrete slump without adding water, the dosage is 100–150 g per 50 kg bag of cement, set by site trial. In workability trials slump rose from 50 mm to 148 mm at constant W/C. This IS 9103 superplasticizer complies with IS 9103-99, has nil chloride and keeps for 2 years in a cool and dry place. Expect 1–2 hours of setting time retardation at normal dosage. Confirm the cement type first, as it is not compatible with High Alumina cement.
Armstrong Chemicals supplies ROOFPLAST SP 25 to sites across Telangana, Andhra Pradesh, Karnataka, Kerala and Tamil Nadu, including Hyderabad, Vijayawada, Bengaluru, Kochi and Chennai.
Three Times the Slump. One-Tenth the Dosage.
At just 0.1 litre per 50kg bag of cement, ROOFPLAST SP 25 increases slump from 50mm to 148mm — improving workability, reducing bleeding and segregation, and making concrete easier to pump and place, without adding water or losing strength.
Get a QuoteWhy Conventional Concrete Mixes Struggle in the Field
Low workability concrete is difficult to pump, hard to place evenly in formwork, and risks honeycombing at exactly the areas where bond strength matters most — all from a mix that's technically correct on paper but impractical on site.
The ROOFPLAST SP 25 Advantage
At 0.1L per 50kg bag, slump increases from 50mm to 148mm — nearly tripling workability — without adding water, without increasing cement content, and without sacrificing the water-cement ratio that determines long-term strength.
Nearly 3× Slump Improvement at Minimal Dosage
Trial data: 0.1L dosage at W/C 0.35 increased slump from 50mm to 148mm. At W/C 0.30, slump reached 158mm and 28-day strength was 51 N/mm² — demonstrating workability and strength gain from the same minimal dose.
On-Site Mix Design Advisory
Armstrong provides a technical advisory service for on-site mix design assistance — particularly valuable for producing high workability concrete without segregation when site conditions or cement sources vary.
Trusted on India's Toughest Infrastructure
Trial Test Performance Results
Results obtained from actual concrete trials: OPC 320 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 | 50mm | 25 N/mm² | 36 N/mm² | 48 N/mm² |
| Workability Increased | 0.1L (~115–120g) | 0.35 | 148mm | 29 N/mm² | 38 N/mm² | 50 N/mm² |
| Strength Increased | 0.1L (~115–120g) | 0.30 | 158mm | 32 N/mm² | 40 N/mm² | 51 N/mm² |
Note: The trial table lists dosage in litres; 0.1L equals approximately 115–120g at the product's specific gravity of 1.15–1.20. The 40–50% early strength gain quoted in the brochure is a potential when water reduction is fully utilised — trial data at 28 days shows a ~6% improvement in this OPC 320 mix.
Dosage Guidance
High Alumina cement incompatibility: ROOFPLAST SP 25 is compatible with all Portland and slab cements except High Alumina cement. Confirm cement type before use.
- 1
Determine dosage: 100–150g per 50kg bag of cement — establish optimum by site trial
- 2
Add ROOFPLAST SP 25 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 Workability at Minimal Dosage
Maximum slump improvement from the smallest dosage in the Armstrong super-plasticiser range.
Nearly 3× Slump at 0.1L Dosage
Trial data: 0.1L per 50kg cement increased slump from 50mm to 148mm at constant W/C — and to 158mm at W/C 0.30 — improving workability, pumpability and placing without adding water.
Lowest Dosage in the Range
At 100–150g per 50kg bag, ROOFPLAST SP 25 requires the smallest quantity of any Armstrong super-plasticiser — economical to use across standard concrete grades and ready-mix operations.
IS 9103-99 Compliant, NIL Chloride
Certified to IS 9103-99, chloride-free and safe for prestressed concrete — with no risk of reinforcement corrosion in any concrete type except High Alumina cement.
2-Year Shelf Life, 6 Pack Sizes
2 years from manufacture — the longest shelf life in the ROOFPLAST range. Available in 1, 5, 10, 20, 30 and 225 Kg packs — more sizing options than any other product in the series.
Which plasticiser for your concrete grade
Armstrong admixture selection guide
Applicable Areas
Packing & Shelf Life
Available in 1, 5, 10, 20, 30 & 225 Kg packs — the widest packing range in the ROOFPLAST super-plasticiser series, including 10kg and 30kg sizes for mid-scale project ordering. Shelf life of 2 years from manufacture. Store in a cool, dry place.
Key Constraints
⚠️ Not compatible with High Alumina cement. 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 and segregation.
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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