STP ShaliPlast IW CI
A dual-action liquid admixture from STP Limited that waterproofs RCC from within and lays a passive protective film over reinforcement — one dose at the mixer, two protections for the life of the structure.
What is it?
A brownish liquid integral waterproofing-cum-corrosion inhibiting admixture for reinforced concrete, built on STP’s bi-polar chemistry. It conforms to IS 2645:2003, IS 9103 and ASTM C1582/C1582M-11.
Where is it used?
Bridges, marine and coastal RCC, floors, walls and slabs, mass concrete pours such as dyke walls, and deck or pavement areas exposed to deicing salts.
Why use it?
A single dose cuts water permeability to below half that of control concrete and passivates the rebar against chloride attack — with compressive strength staying equal to control.
How is it applied?
Dosed at 200–600 ml per 50 kg bag of cement into the final portion of mixing water at the batching stage. A trial mix establishes the optimum dose for the RCC grade.
About STP ShaliPlast IW CI
ShaliPlast IW CI answers a question every structural consultant working near water eventually asks: if moisture and chlorides travel through the same capillary network, why treat them separately? STP Limited’s answer is a liquid admixture that does both jobs in one dose. Blended from surface-active agents, plasticiser, polymer additives and a corrosion inhibitor, it makes fresh concrete more cohesive, shrinks the capillary voids that let water through, and — its distinguishing trick — releases a bi-polar compound that migrates through the concrete during curing and deposits a passive layer directly onto the reinforcement bars. The result is RCC that resists water ingress from within and steel that stays protected even when chlorides eventually reach it. Compliance with IS 2645:2003, IS 9103 and ASTM C1582/C1582M-11 makes it straightforward to accommodate in tender specifications.
Space Arc Engineering supplies genuine STP material as an authorised distributor and applicator, serving Delhi NCR from local stock and project sites pan-India. For bridge, marine and infrastructure work we can assist with dosage trial mixes, compatibility checks against your existing admixture package, and manufacturer TDS documentation for consultant approval — before the first transit mixer is ever batched.
The technical insight
The working principle is a bi-polar molecule: one end is hydrophobic and acts within the cement matrix, plugging and lining the capillaries so water permeability drops to below 50% of control concrete. The other end has an affinity for steel — carried by the mixing water during curing, it migrates through the pore network and adsorbs onto the rebar surface as a passive film, interrupting the electrochemical cell that chloride-induced corrosion needs to start. Two details make the chemistry credible. First, the admixture’s own chloride content is below 0.02%, so it adds practically nothing to the chloride budget of the mix it is protecting. Second, compressive strength remains equal to control concrete, meaning the impermeability is not being bought at the cost of structural capacity — a trade-off some older waterproofing compounds quietly imposed.
Where it is used
- Bridge decks, piers and approach structures exposed to spray and salt-laden runoff
- Marine and coastal RCC — jetties, wharves and seafront structures
- RCC floors and pavements where low water permeability is specified
- RCC walls and slabs across residential, commercial and industrial frames
- Mass concrete casting, including dyke and embankment walls
- Deck and pavement areas subject to deicing salt exposure
- Chloride-prone RCC where rebar protection must be built into the mix itself
Key advantages
- Dual action — integral waterproofing plus rebar corrosion inhibition from a single admixture
- Reduces water permeability to below 50% of control concrete
- No strength penalty: compressive strength stays equal to control
- Chloride content under 0.02%, so the admixture never feeds the corrosion it is meant to prevent
- Improves workability and mix cohesion while reducing shrinkage-crack development
- Disperses easily and suits all Portland cements, including sulphate-resisting cement (SRC)
- Specification-ready: conforms to IS 2645:2003, IS 9103 and ASTM C1582/C1582M-11
Limitations & considerations
- Not compatible with high-alumina cement
- Behaves as a set retarder — setting time can range from 40 to 550 minutes with dose, and overdosing extends it excessively
- No universal dosage exists across RCC grades; a site trial mix is needed to fix the optimum dose
- Amplifies the effect of air-entraining agents, so a pre-blend trial is mandatory when the two are combined
- It is an integral admixture, not a membrane — it cannot bridge structural cracks, cold joints or honeycombing, and severe hydrostatic conditions still warrant a surface waterproofing system
- 12-month shelf life in unopened containers; store cool, dry and under shed
Selection & best practice
Batching sequence matters more than most sites assume. Dry-mix the cement, sand and aggregate in the mixer for two minutes, then add 75–80% of the design mixing water and mix for a further three minutes. Dissolve the measured dose of ShaliPlast IW CI — 200 ml minimum to 600 ml maximum per 50 kg bag of cement (0.42–1.27% by weight of cement) — into the remaining water, add it, and wet-mix for two more minutes before placing. Cure the RCC as per normal good practice. Always run a pre-trial: the optimum dose depends on the concrete grade and on how much set retardation the pour can tolerate, and a trial is equally essential when the mix already carries a superplasticiser or other admixtures. Never eyeball the dose upward for extra protection — overdosing buys you an excessively delayed set, not better waterproofing. Handle with gloves and eye protection, and keep containers sealed until use.
Specifications
| Form / Colour | Brownish liquid |
| Specific gravity | 1.06 ± 0.01 |
| pH | 8 – 13 |
| Non-volatile content | 17 ± 1% |
| Chloride content | < 0.02% |
| Dosage | 200 – 600 ml per 50 kg cement (0.42 – 1.27% by weight of cement) |
| Water permeability | < 50% of control concrete |
| Standards compliance | IS 2645:2003, IS 9103, ASTM C1582/C1582M-11 |
| Packing / shelf life | 1 L, 20 L and 200 L containers; 12 months unopened |
Industry use cases
Bridges & Highways
Decks, piers and crash-barrier upstands take spray, monsoon runoff and — on hill routes — deicing salts. Dosing IW CI at the batching plant cuts permeability and passivates rebar in every cubic metre placed, instead of relying solely on surface protection applied later.
Ports & Marine
Jetties, wharves and seafront RCC live in a chloride-saturated environment where corrosion, not load, usually ends service life. The passive film over reinforcement delays corrosion initiation while the densified matrix slows chloride ingress itself.
Buildings & Real Estate
For RCC floors, walls and roof slabs, the same dose that waterproofs also improves workability and reduces shrinkage-crack development — useful on large pours where curing discipline varies between contractors.
Mass Concrete & Embankments
Dyke walls and long continuous pours benefit from the improved cohesion and the wide, controllable setting window, which can be tuned through dosage within the 40–550 minute range.
Cold-Region Infrastructure
Pavement and deck areas treated with deicing salts face the harshest chloride cycling in Indian infrastructure. IW CI is explicitly recommended by STP for deicing-exposed RCC.
Frequently asked questions
What is the dosage of ShaliPlast IW CI per bag of cement?
How is it different from an ordinary integral waterproofing compound?
Will it delay the setting of my concrete?
Is it compatible with superplasticisers and other admixtures?
Does it reduce concrete strength?
Can it replace membrane waterproofing in basements or on roofs?
How we position STP ShaliPlast IW CI
Within the STP family, ShaliPlast IW CI sits between two simpler products: plain ShaliPlast IW covers integral waterproofing where rebar corrosion is not a design concern, while ShaliPlast CI addresses corrosion inhibition alone; IW CI is the pick when a single admixture must do both, as on coastal and bridge work. For waterproofing existing structures rather than fresh pours, STP’s ShaliCrystal surface-applied crystalline treatment is the complementary route. Across our other brands, Dr. Fixit Pidiproof LW+ remains the familiar choice for smaller residential integral waterproofing, and Fosroc’s Conplast range serves projects already specified around Fosroc systems. Space Arc stocks all three families, so we can supply to the specification you have rather than the brand we prefer.
Fosroc Conplast X421IC — Specifiers standardised on Fosroc systems can achieve IS 2645-compliant integral waterproofing with Conplast X421IC, adding a dedicated corrosion inhibitor separately where rebar protection is also required.
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Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.