Sika 1
Integral Waterproofing and Permeability-Reducing Admixture for Cement Mortar and Concrete
Authorized Project Distributor — Sika India | Space Arc Engineering, Ghaziabad
Product Overview
Sika 1 is a liquid integral waterproofing admixture from Sika that is added to the gauging water of cement mortar or the mix water of concrete during batching to significantly reduce the water permeability of the hardened cementitious material. The waterproofing mechanism of Sika 1 operates through two pathways: a reactive component that reacts with cement hydration products to form insoluble calcium compounds in the capillary pore system of the mortar or concrete, progressively blocking the pore network and increasing resistance to water penetration over time; and a plasticizing component that reduces the water-to-cement ratio achievable at the same workability, producing a denser, lower-porosity cementitious matrix from the outset. Sika 1 is particularly valuable for water-retaining and water-excluding construction in India where mortar and render-based waterproofing systems are commonly used: water storage tanks (overhead and underground), swimming pool render coats, roof screed waterproofing over flat concrete roof slabs, basement wall render coats, and plinth-level mortar bed waterproofing. The dosage of Sika 1 at 0.3 to 0.5 litres per 50 kg bag of cement (for mortar) and 1 to 2 litres per m3 of concrete transforms ordinary cement mortar into an integral waterproofing mortar without requiring a separate membrane system for mild waterproofing duty. Sika 1 is most effective in dense, well-compacted mortar or concrete with a low w/c ratio — it does not compensate for poor workmanship, excessive water addition, or inadequate compaction, all of which create macropores and cracks that Sika 1 cannot seal. For the most important and demanding waterproofing applications in Delhi NCR — basements under active hydrostatic pressure, water treatment plant tanks, and large underground water reservoirs — Sika 1 should be used as part of a complete waterproofing system (Sika 1 modified mortar render plus SikaTop 107 Seal crystalline coating) rather than as the sole waterproofing measure. Space Arc Engineering supplies Sika 1 for waterproofing projects throughout Delhi NCR, Ghaziabad, and Northern India.
Applications
- Overhead and underground water storage tank construction — integral waterproofing mortar render
- Swimming pool render — Sika 1 modified cement render as waterproof base coat
- Flat roof screed — waterproof screed over concrete roof slab before floor finish
- Basement wall render coat — integral waterproofing mortar on concrete or brick walls
- Retaining wall render waterproofing — below grade external face
- Plinth-level mortar bed waterproofing — damp-proof course area mortar modification
Key Advantages
- Integral waterproofing — treats the entire mortar or concrete mass, not just the surface
- Dual action — pore blocking crystalline reaction PLUS water-to-cement ratio reduction
- Simple dosage — liquid admixture added to gauging water during normal mortar mixing
- Suitable for mortars, screeds, renders, and concrete in one product
- Cost-effective — converts standard mortar into waterproof mortar at low cost per m2
- Complements SikaTop 107 Seal for a multi-layer high-performance waterproofing system
Technical Data
| Type | Liquid integral waterproofing and permeability-reducing admixture |
| Dosage (Mortar) | 0.3 to 0.5 litres per 50 kg cement |
| Dosage (Concrete) | 1 to 2 litres per m3 |
| Water Reduction (Plasticizing Effect) | 3 to 6 per cent |
| Chloride Content | Chloride-free |
| Pack Sizes | 1 litre, 5 litre, 20 litre containers |
Get a Quote
+91 9999155255 | info@space-arc.com | Space Arc Engineering, Sahibabad, Ghaziabad
Frequently Asked Questions
Can Sika 1 alone provide sufficient waterproofing for an underground water storage sump of 50,000 litre capacity at 4 metre depth in Ghaziabad?
Sika 1 as a sole waterproofing measure is NOT sufficient for an underground water storage sump of 50,000 litre capacity at 4 metre depth in Ghaziabad. An underground sump at 4 metre depth in the Gangetic alluvial plain (where the groundwater table is typically 2 to 4 metres below surface) is subject to hydrostatic water pressure from both sides: internally from the stored water and externally from groundwater. The hydrostatic head at 4 metre depth is up to 4 metres, equivalent to 0.04 MPa or 400 mm water column pressure. While Sika 1 modified mortar render reduces permeability by approximately 50 to 70 per cent compared to unmodified mortar, a well-built Sika 1 modified render on a well-constructed RCC structure can resist 1 to 2 metres of hydrostatic head but will not reliably seal against 3 to 4 metres of sustained hydrostatic pressure, particularly if the RCC structure has any construction joint leaks, tie-bolt holes, or minor honeycombing. For a 50,000 litre capacity sump at 4 metre depth, the correct waterproofing specification is: RCC structure with Sika Waterbar at all construction joints + all concrete tie-bolt holes sealed with non-shrink grout + minimum two coats SikaTop 107 Seal crystalline coating on the internal face + Sika 1 modified mortar render on the external face. Sika 1 plays a useful supporting role in this multi-barrier system but cannot be the primary waterproofing element.
What is the correct mortar mix ratio for Sika 1 waterproof mortar for a water tank render coat and how thick should each coat be?
For water tank waterproof render using Sika 1 modified mortar, the standard mix is 1 part OPC : 2 parts clean washed river sand or M-sand (by volume) with Sika 1 added at 0.4 litres per 50 kg bag of OPC used. For a 1:2 mix using one 50 kg bag of OPC: weigh out 100 kg of clean sand (approximately 2 bags of river sand); dissolve 0.4 litres of Sika 1 in the total gauging water required (typically 10 to 12 litres for a 1:2 mortar at workable consistency); mix OPC and sand dry until uniform, then add the Sika 1 admixed water gradually and mix until uniform, smooth, and workable. Do not add extra water beyond the design quantity — adding excess water defeats the purpose of the integral waterproofing admixture by raising the w/c ratio and increasing permeability. Apply the waterproof mortar render on the prepared (clean, damp, laitance-free) concrete substrate in two coats: Scratch coat (6 to 8 mm): applied and scratched with a notched rake immediately after application to provide a mechanical key for the second coat. Allow to firm up for 12 to 24 hours, keep damp. Finishing coat (10 to 15 mm): applied onto the damp scratch coat and finished flush with a wooden float. Do not use a steel trowel for final finishing — a steel-burnished surface creates a thin weak zone prone to delamination and also seals the surface against moisture exchange, causing blistering. Total render thickness: 20 to 25 mm (two coats) for water tank internal render.
Can Sika 1 be added to ready-mixed concrete (RMC) at the RMC plant for waterproofing a basement raft slab and what dosage is required?
Yes — Sika 1 can be incorporated into RMC at the plant as an integral concrete admixture for basement raft slabs and basement wall concrete. The dosage for concrete (as opposed to mortar) is 1 to 2 litres of Sika 1 per m3 of concrete. For a typical basement raft using M30 concrete with 350 kg OPC per m3, the dosage is 1.4 to 1.8 litres per m3 (approximately 4 litres per 50 kg OPC). Adding Sika 1 to the concrete does reduce the effective water content slightly (3 to 6 per cent water reduction plasticizing effect), which slightly reduces the w/c ratio and improves the baseline permeability of the concrete before the crystalline reaction further reduces pore permeability over 28 to 90 days. However, note two important limitations of Sika 1 in RMC for basement slabs: First, RMC plant dosing requires the Sika 1 to be dissolved in the mix water before addition to the mixer — this requires the plant to have a separate Sika 1 admixture tank and dosing system, or the product can be hand-poured into the drum before filling. Second, and more importantly, for basement concrete under active groundwater hydrostatic pressure in Delhi NCR, Sika 1 in the concrete body is a permeability-reducing measure but NOT a complete waterproofing system — it must be combined with crystalline render or coating on the positive face (SikaTop 107 Seal), Sika Waterbar at all construction joints, and proper surface preparation and curing for the system to deliver long-term water-tightness. Contact Space Arc Engineering for a complete basement waterproofing specification for your project.
Source Sika 1 for Your Project
Space Arc Engineering is an Authorized Project Distributor for Sika India serving Delhi NCR, Ghaziabad, Noida and Uttar Pradesh.
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