About Fosroc Conplast WL

Space Arc Engineering supplies Fosroc Conplast WL as the integral-waterproofing member of the Conplast admixture range — a dark brown, lignosulphonate-based liquid formulated to IS:2645-2003, the Indian Standard governing integral waterproofing compounds for concrete and mortar. The product was previously sold under the name Conplast X421IC. Rather than shedding water at the surface the way a hydrophobic coating would, it works from inside the mix: the lignosulphonate chemistry cuts the water demand of the concrete or mortar and densifies the resulting matrix, leaving it less permeable and more durable.

That densifying action is well matched to the conditions Indian sites face every monsoon — rising damp, water ingress through roof slabs, and structures built to hold water outright — which is why it is routinely specified on basements, plastering and water-retaining elements. Because a lower water-cement ratio can be held at the same workability, the capillary pore network that water would otherwise travel through once the concrete hardens ends up narrower. Measured against a control sample, treated concrete comes in under 15% water permeability, well inside the 50% ceiling IS:2645 allows.

As an authorised Fosroc distributor and applicator, Space Arc Engineering supplies and applies Conplast WL across Delhi NCR and Pan-India, in pack sizes from pouches up to 200-litre containers. Being a single-component integral admixture, it is dosed at the batching or mixing stage rather than applied as a site coating — straightforward to specify on both RMC and site-batched work. Teams comparing integral waterproofing admixtures typically weigh it against Sika WT-200 P / Sika-1, Dr. Fixit Pidiproof LW+ and BASF MasterLife-type waterproofers; Space Arc can advise on the right Fosroc fit for the application.

The technical insight

Conplast WL is built on a lignosulphonate base, which gives it a dual water-reducing and waterproofing action. The waterproofing does not come from a hydrophobic or water-repellent additive; instead, the lignosulphonate disperses cement particles, allowing the same workability to be achieved at a lower water content. Utilising this water-reduction potential (as much as 15% or more) lowers the water-cement ratio, reduces capillary porosity and densifies the hardened matrix. The denser, pore-filled microstructure is what restricts water passage, achieving less than 15% permeability against the IS:2645 control. Importantly, Conplast WL has no significant effect on the setting time of concrete or mortar, so it is not a set-retarding admixture. Compressive strength is maintained equal to a control mix and can be improved if the water-reduction potential is exploited. Chloride content is controlled as per IS 2645-2003. The admixture is compatible with all cements, including pozzolanic (PPC) types, but must not be used with High Alumina Cement.

Where it is used

• Waterproofing roof slabs and cement screeds against monsoon ingress
• Integral waterproofing of basement concrete and retaining structures
• External cement plastering exposed to driving rain
• Bathroom and toilet floor concrete and screeds
• Concrete and mortar for water tanks and storage sumps
• Drains and water-conveyance channels requiring low permeability

Key advantages

• Conforms to IS:2645-2003 for integral waterproofing compounds
• Reduces water permeability to less than 15% against the 50% IS:2645 maximum
• Reduces water demand by as much as 15% or more for the same workability
• No significant effect on setting time of concrete or mortar
• Maintains compressive strength equal to control; can improve it when water reduction is utilised
• Compatible with all cements including pozzolanic (PPC) types
• Single-component liquid dosed easily during batching
• Long shelf life of minimum 12 months in unopened containers

Limitations & considerations

• Not compatible with High Alumina Cement (HAC)
• Functions as a densifying integral admixture, not a surface waterproof coating, so it does not bridge existing cracks
• Performance depends on correct dosing within the 125-200 ml per 50 kg cement range
• Full waterproofing benefit relies on utilising the water-reduction potential at the maximum dose
• Must be stored in a dry store in unopened containers to achieve the stated 12-month shelf life
• Not a substitute for proper concrete design, compaction and curing

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Conplast WL

Positioned as a standards-compliant integral waterproofing admixture for the Indian market, Fosroc Conplast WL competes with integral waterproofers such as Sika WT-200 P / Sika-1, Dr. Fixit Pidiproof LW+ and BASF MasterLife-type products. Its differentiator is the dual lignosulphonate water-reducing and densifying action conforming to IS:2645-2003, delivering sub-15% permeability without affecting set time. Space Arc Engineering leads with Fosroc as an authorised distributor and applicator across Delhi NCR and Pan-India, advising specifiers on the right product per application.

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