Fosroc Conplast P505
Chloride-free water-reducing and retarding admixture based on sugar-reduced lignosulphonate, supplied and supported by Space Arc Engineering across Delhi NCR and Pan-India.
What is it?
A chloride-free, water-reducing admixture (plasticiser / water-reducing retarder) based on selected sugar-reduced lignosulphonate materials, conforming to ASTM C494 Type B & D, BS 5075 and BS EN 934-2.
Where is it used?
General structural and ready-mix concrete across India where water reduction, improved workability and reduced permeability are required, on projects supplied by Space Arc Engineering in Delhi NCR and Pan-India.
Why use it?
It disperses fine cement particles to cut mixing water and improve workability while retarding initial set, helping placement in hot conditions and reducing permeability and water penetration at higher dosages.
How is it applied?
Dispensed with the mixing water at 0.4 to 1.2 litres per 100 kg of cementitious material via a recommended dispenser; the brown liquid disperses instantly in water.
About Fosroc Conplast P505
Fosroc Conplast P505 is a chloride-free water-reducing admixture, classed as a plasticiser and water-reducing retarder, based on selected sugar-reduced lignosulphonate materials. It is supplied as a brown liquid that instantly disperses in water and is added with the concrete mixing water using a recommended dispenser. The admixture works by dispersing the fine cement particles in the mix, which releases trapped water and allows either a reduction in water content at the same workability, or improved workability at the same water content.
It is important to understand what Conplast P505 is and is not. It is a water-reducing and retarding admixture, conforming to ASTM C494 as a Type B (retarding) and Type D (water-reducing-and-retarding) admixture depending on the dosage used. It is not an accelerator, and it does not promote rapid or early setting; at normal and higher dosages it retards the initial set of concrete, and overdosing will tend to increase that retardation. Any description of P505 as an accelerator, or as a product for rapid-set, cold-weather or sprayed-concrete applications, does not reflect the genuine product.
The admixture is chloride-free to BS 5075 and BS EN 934, making it suitable for reinforced and prestressed concrete where chloride-induced corrosion of steel must be avoided. It is compatible with a wide range of cementitious systems including Ordinary Portland Cement (OPC), Pulverised Fuel Ash (PFA), Ground Granulated Blast-furnace Slag (GGBFS), Sulphate Resisting Cement (SRC) and microsilica blends, which suits the cement-replacement mixes increasingly common on Indian infrastructure and building projects.
As an authorised Fosroc distributor and applicator, Space Arc Engineering supplies genuine Conplast P505 with batch documentation and technical support across Delhi NCR and Pan-India. Where a project specification calls for a comparable water-reducing or retarding admixture, recognised alternatives in the Indian market include BASF MasterPozzolith, Sika Plastiment and Chryso Plast ranges; our team can advise on the correct Fosroc grade and dosage for your mix design.
The technical insight
Conplast P505 functions by adsorbing onto cement grains and dispersing flocculated fine particles, which frees the water otherwise trapped within those flocs. This dispersion gives the water-reducing effect, while the sugar-reduced lignosulphonate chemistry simultaneously delays the early hydration reactions, producing controlled retardation (ASTM C494 Type B and, with water reduction, Type D). At normal dosage air entrainment is low, but overdosing can cause increased air entrainment and increased retardation, so dosage should be confirmed by trial mix. With a specific gravity of 1.18 at 25°C and a normal dosage of 0.4 to 1.2 litres per 100 kg of cementitious material, P505 is added through the mixing water using a recommended dispenser rather than dosed at any nozzle. At the upper end of the dosage range the reduced water-cement ratio and denser paste structure help lower concrete permeability and resistance to water penetration.
Where it is used
- Water reduction in structural and ready-mix concrete to lower the water-cement ratio at constant workability
- Improving workability of concrete at constant water content for easier placement and compaction
- Retarding the initial set of concrete to extend working time, useful in hot-weather concreting common across India
- Reducing concrete permeability and resistance to water penetration when used at higher dosages within the recommended range
- Concrete using cement-replacement materials such as PFA, GGBFS, SRC and microsilica, where P505 is compatible
- Reinforced and prestressed concrete where a chloride-free admixture is required to protect embedded steel
Key advantages
- Chloride-free to BS 5075 and BS EN 934, suitable for reinforced and prestressed concrete
- Reduces mixing water at constant workability, helping improve strength and durability
- Improves workability for easier placement and compaction without adding water
- Provides controlled retardation to extend working time in hot conditions
- At higher dosages reduces concrete permeability and resistance to water penetration
- Compatible with OPC, PFA, GGBFS, SRC and microsilica cementitious systems
- Brown liquid that disperses instantly in water for straightforward dispenser addition
- Conforms to recognised standards: BS 5075, BS EN 934-2 and ASTM C494 Type B & D
Limitations & considerations
- It is a water-reducing retarder, not an accelerator, and is not suitable for rapid-set or early-strength applications
- Overdosing can cause increased retardation of set and increased air entrainment
- Must be added with the mixing water through a recommended dispenser, not dosed at a nozzle
- Optimum dosage within the 0.4 to 1.2 litres/100 kg range should be confirmed by trial mix for each specific mix design
- Freezing point is approximately -3°C; the product should be protected from freezing in storage
- Not intended for sprayed concrete, shotcrete, tunnel lining or emergency rapid repair applications
Selection & best practice
Establish the optimum dosage for your specific mix by trial within the normal range of 0.4 to 1.2 litres per 100 kg of cementitious material, and add Conplast P505 with the mixing water using a recommended dispenser rather than dosing it manually or at a nozzle. Account for the retarding effect when planning placement and finishing times, particularly in hot weather, and avoid overdosing as it increases both retardation and air entrainment. Store the product between 2°C and 50°C, protect it from freezing (freezing point approximately -3°C), and use within its 12-month minimum shelf life. For projects using PFA, GGBFS, SRC or microsilica blends, confirm compatibility and dosage with Space Arc Engineering’s technical team.
Specifications
| Chemical base | Sugar-reduced lignosulphonate (chloride-free water-reducing admixture) |
| Appearance | Brown liquid that instantly disperses in water |
| Specific gravity | 1.18 @ 25°C |
| Chloride content | Nil to BS 5075 / BS EN 934 |
| Normal dosage range | 0.4 to 1.2 litres/100 kg of cementitious material |
| Standards compliance | BS 5075, BS EN 934-2, ASTM C494 Type B & D (depending on dosage) |
| Air entrainment | Low at normal dosage; overdosing may cause increased air entrainment |
| Primary use | Water reduction / improved workability; at higher dosages reduces permeability. Compatible with OPC, PFA, GGBFS, SRC, microsilica |
| Shelf life | Minimum 12 months at 2°C to 50°C; freezing point approx -3°C |
| Supply / packaging | 210 litre drum, 1000 litre totes or bulk |
Industry use cases
Ready-mix concrete
Used by RMC plants to reduce the water-cement ratio at target workability and to extend working time during transit and placement in hot Indian conditions.
Reinforced concrete structures
Chloride-free chemistry makes it suitable for reinforced and prestressed elements where corrosion protection of embedded steel is essential.
Water-retaining and below-grade structures
At higher dosages within range, the reduced permeability and resistance to water penetration benefit tanks, basements and other structures exposed to water.
Blended-cement and sustainable concrete
Compatible with PFA, GGBFS, SRC and microsilica systems used to lower clinker content and improve durability on infrastructure projects.
Hot-weather concreting
Controlled retardation helps maintain workability and reduce the risk of premature stiffening during summer concreting across Delhi NCR and Pan-India.
Frequently asked questions
Is Fosroc Conplast P505 an accelerator?
What is the recommended dosage of Conplast P505?
Which standards does Conplast P505 comply with?
Is Conplast P505 chloride-free and suitable for reinforced concrete?
What does Conplast P505 do to concrete?
How is Conplast P505 supplied and stored?
How we position Fosroc Conplast P505
Positioned as Fosroc’s general-purpose, chloride-free water-reducing and retarding admixture (ASTM C494 Type B & D) for structural and ready-mix concrete. Within the Fosroc Conplast plasticiser range it serves water-reduction, workability and permeability-reduction needs, distinct from accelerating or high-range superplasticising grades. Comparable market alternatives include BASF MasterPozzolith, Sika Plastiment and Chryso Plast water-reducing ranges. Supplied and supported by Space Arc Engineering as an authorised Fosroc distributor and applicator across Delhi NCR and Pan-India.
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