About Fosroc Conplast Crystalline

Fosroc Conplast Crystalline is an integral crystalline waterproofing admixture engineered to make concrete water-resistant from the inside out. Supplied as a grey powder, it is a blend of Portland cement with other crystalline-active ingredients that is added to the concrete mix during batching. Once in the concrete, the crystalline chemicals react with moisture and react throughout the pores and capillary tracks to form insoluble crystal structures, permanently blocking the pathways through which water would otherwise travel. This is a fundamentally different approach from surface-applied membranes or liquid densifiers: the waterproofing is built into the body of the concrete, so it cannot be punctured, peeled, or left behind during backfilling.

For Indian construction, where monsoon loading, high water tables, and aggressive ground conditions routinely challenge below-ground and water-retaining concrete, Conplast Crystalline offers a durable, integral solution. As an authorised Fosroc distributor and applicator serving Delhi NCR and projects Pan-India, Space Arc Engineering supplies genuine Conplast Crystalline along with application guidance to ensure correct dosing and mix compatibility on site.

A defining benefit of crystalline technology is its self-sealing behaviour. Where fine cracks develop over the life of the structure and moisture finds its way in, the unreacted crystalline chemistry reactivates and grows fresh crystals to re-seal the gap. Per the current Fosroc TDS, this self-sealing ability addresses cracks up to 0.5 mm in width over time. The product is compatible with all cements, including pozzolanic and sulphate-resisting cements, and with supplementary cementitious replacement materials such as PFA, GGBFS and microsilica.

The technical insight

Conplast Crystalline works by crystalline growth, not by densification. The crystalline-active ingredients in the grey powder react with the moisture present in fresh and hardened concrete and grow insoluble crystal structures throughout the pores and capillary tracks of the concrete matrix. Because the reaction is moisture-driven, the chemistry remains dormant when dry and reactivates whenever water is reintroduced, which is what gives the concrete its long-term self-sealing capability for cracks up to 0.5 mm wide (an earlier 2022 TDS stated 0.4 mm). The recommended dosage is 0.8% by weight of total cementitious content, with the optimum determined by laboratory or batch trials for the specific mix design. Setting time conforms to IS 2645-2003 for both initial and final set. The product carries a grey-powder appearance, specific gravity of 2.02 ± 5% (IS 4031-11), tapped bulk density of 1.01 ± 5% gm/cc, and a pH of 12.0 ± 1.0. It is supplied in 30 kg bags with a 12-month shelf life from date of manufacture when stored between 5 degrees C and 50 degrees C in sealed bags.

Where it is used

• Below-ground concrete foundations and basements subject to water ingress
• Water reservoirs, water tanks and swimming pools
• Tunnel concreting and underground works
• Retaining walls and subways
• Bridge deck, plinth and intermediate slabs
• Precast concrete units requiring integral waterproofing

Key advantages

• Waterproofs concrete integrally from within, with no external membrane to puncture, peel or be damaged during backfill
• Self-seals fine cracks up to 0.5 mm in width over time as the crystalline chemistry reactivates with moisture
• Crystalline structures are insoluble and permanent within the concrete matrix
• Compatible with all cements including pozzolanic and SRC, and with PFA, GGBFS and microsilica replacement materials
• Compatible with Fosroc water-reducing admixtures (added separately) for mix optimisation
• Added during batching, so there is no separate waterproofing trade or curing membrane on the critical path

Limitations & considerations

• Optimum dosage must be confirmed by laboratory or batch trials for the specific mix; the 0.8% figure is the recommended starting point
• Self-sealing is limited to fine cracks up to 0.5 mm width and is not a substitute for correct structural crack control
• Requires moisture to activate, so the crystalline reaction depends on water being present in the concrete
• Supplied only in 30 kg bags, which must be stored sealed between 5 degrees C and 50 degrees C
• Shelf life is 12 months from date of manufacture; older stock should be checked before use

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Conplast Crystalline

Fosroc Conplast Crystalline is positioned as a premium integral crystalline waterproofing admixture for water-retaining and below-ground concrete. Within the crystalline category it competes with brands such as Xypex Admix, Penetron Admix, Kryton KIM and Sika WT-200 P, but is favoured on Indian projects where Fosroc’s TDS compliance and Space Arc’s authorised distribution and applicator support are decisive. It is distinct from liquid densifiers and surface membranes, offering built-in, permanent, self-sealing waterproofing.

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