About Master Builders Solutions MasterMatrix UW 440

{“name”:”MasterMatrix UW 440″,”slug”:”mastermatrix-uw-440″,”brand”:”Master Builders Solutions”,”realProduct”:”yes”,”officialSource”:”https://www.master-builders-solutions.com/en-gb/products/mastermatrix/mastermatrix-uw-440″,”category”:”admixtures”,”metaTitle”:”MasterMatrix UW 440 | Anti-Washout Admixture | Space Arc”,”metaDescription”:”MasterMatrix UW 440 is Master Builders Solutions’ powdered anti-washout admixture for underwater concrete and piling, complying with BS 8443:2005 standards.”,”heroSubtitle”:”A ready-to-use powdered anti-washout admixture that keeps cement and fines in the mix, not in the water, when concrete has to go in underwater or through a bored pile.”,”glance”:{“whatIsIt”:”A beige, ready-to-use powdered anti-washout (viscosity-modifying) concrete admixture from Master Builders Solutions, supplied in water-soluble sachets and dosed into the mixer alongside a high-range water reducer.”,”whereUsed”:”Tremie-placed pile caps and marine substructures, diaphragm walls and secant piles cast below the water table, cofferdam plug slabs, bored piling in high-water-table ground, and underwater repair of submerged RCC members.”,”whyUse”:”Fresh concrete placed underwater loses cement paste and fine aggregate to the surrounding water unless it is given enough internal cohesion to resist dispersion. MasterMatrix UW 440 raises that cohesion sharply, without materially changing set time, and without turning the mix unworkable at the pump.”,”howApplied”:”The 1 kg water-soluble sachets are dropped straight into the concrete mixer during batching, where they dissolve fully, and are always used together with an MBS high-range water-reducing admixture. Dosage runs 1.0-3.0 kg/m3 (typically 1.5 kg/m3) for underwater concreting, or 0.4-1.0 kg/m3 for piling — confirmed by trial mixes before site use.”},”about”:”MasterMatrix UW 440 is Master Builders Solutions’ purpose-built anti-washout admixture for concrete that has to be placed where water can get at it before it sets — through a tremie pipe into a river, off the back of a barge at a jetty, or down a bored pile casing sitting below the water table. It is a ready-to-use, chloride-controlled powdered admixture (chloride content ≤0.10%) that ships in 1 kg water-soluble sachets, twelve to a tub, so there is no on-site weighing or liquid dosing pump involved — the sachet goes into the mixer and dissolves. The product is formally assessed against BS 8443:2005 Table 2, the UK specification for underwater concrete admixtures, and its washout performance is verified using the Annex A test method against an EN 480 control mix: manufacturer data shows washout dropping from well above the 15% Table 2 ceiling on the untreated control down to comfortably under it at 1-3 kg/m3 dosage.\n\nWhat MasterMatrix UW 440 is not is a stand-alone product. Master Builders Solutions specifies it for use together with a high-range water reducer from its own MasterGlenium, MasterPolyheed, MasterEase or MasterSure ranges — the anti-washout polymer manages cohesion and thixotropy, the superplasticizer manages flow and pumpability, and the two are meant to be trial-mixed as a pair rather than dosed independently. For Indian marine, bridge-foundation, port and metro-piling contractors this is a genuinely specialised, low-volume line rather than a shelf item — Space Arc, as an authorised Master Builders Solutions distributor and applicator, sources it through the MBS network for specific project requirements and runs the trial-mix and dosage-verification process alongside the client’s RMC plant or piling contractor rather than shipping it blind.”,”technicalInsight”:”The working mechanism is rheological rather than chemical retardation. MasterMatrix UW 440’s water-soluble copolymers associate with the mix water to build a network that raises plastic viscosity and yield stress at rest — enough that cement grains and fines resist being carried away by turbulence or flowing groundwater — while shear from pumping or vibration temporarily breaks that structure down so the concrete still flows and places normally. Once shear stops, the thixotropic effect lets the mix stiffen back up quickly at the placement face, which is exactly what limits the boundary layer where washout happens. The manufacturer’s own BS 8443:2005 Annex A data illustrates the dose-response clearly: an EN 480 control mix records the highest washout, and washout falls in a step pattern as dosage climbs through 1, 2 and 3 kg/m3 of MasterMatrix UW 440, crossing below the Table 2 15% ceiling at the lower end of that range under the tested cement content (450 kg/m3) and w/c ratio (<0.45). The trade-off, and it is a real one, is that the same viscosity increase that stops washout also entrains more air and works against compressive strength as dosage rises — which is why the TDS is explicit that trial mixes, not the dosage table alone, should set the final rate for a given job.”,”applications”:[“Tremie-placed pile caps and pier footings in rivers, lakes and tidal zones”,”Marine jetty, berth and quay wall substructure concreting”,”Diaphragm walls and secant or contiguous pile panels cast below the water table”,”Cofferdam base/plug slabs poured ahead of dewatering”,”Bored cast-in-situ piling in high-water-table ground, particularly where a deep reinforcement cage has to be lowered in after the pour”,”Underwater repair and patching of submerged RCC members such as bridge piers and dock walls”,”Offshore and near-shore foundation works”,”Box culvert or sump-pit concreting in wet excavations where full dewatering isn’t practical”],”advantages”:[“Cuts cement and fines washout from well above 30% down to under the BS 8443 Table 2 15% ceiling at typical dosage”,”Reduces or eliminates concrete bleeding in the treated mix”,”Maintains workability broadly comparable to untreated concrete rather than stiffening the mix unworkably”,”Virtually eliminates segregation even in highly fluid, high water-cementitious-ratio mixes”,”Thixotropic stiffening after placement resists continued material loss once the pour has stopped moving”,”Cuts down or eliminates costly dewatering methods on the pour”,”Minimal to no effect on concrete set time”,”Low, controlled chloride content (≤0.10%) suitable for reinforced work”],”limitations”:[“Not a stand-alone product — must be paired with an MBS high-range water reducer (MasterGlenium/MasterPolyheed/MasterEase/MasterSure); it isn’t designed to be dosed into just any ready-mix on its own”,”Compressive strength drops as dosage increases, so trial mixes to the actual job cement content and w/c ratio are mandatory, not optional, before site use”,”Tends to raise entrained air content versus a conventional mix, which needs to be allowed for in the mix design and QC plan”,”The published TDS is written to BS 8443:2005 and EN 480, not an IS code, so Indian specifiers and PMCs need to agree washout acceptance criteria with the consultant rather than cite a direct Indian standard”,”A specialised, low-volume import line rather than an India shelf product — lead time and minimum order quantities need to be planned with Space Arc well ahead of the pour date”,”Powder-in-sachet dosing needs disciplined batching sequencing on site; it can’t be metered the way a liquid admixture is through an automatic dispensing pump”],”bestPractice”:”Treat MasterMatrix UW 440 as one half of a two-admixture system: select the paired MBS superplasticizer first, then trial-mix both together at the project’s actual cement content and w/c ratio rather than relying on the generic 1.0-3.0 kg/m3 (underwater) or 0.4-1.0 kg/m3 (piling) dosage bands from the data sheet. Add sachets directly to the mixer and confirm full dissolution before the truck leaves the plant — partial dissolution is the single most common cause of inconsistent washout resistance on site. Where the project specification calls for a measured washout limit, run the Annex A test method against an EN 480 control mix before the pour, not after. Budget for the higher air content the product typically brings and adjust the mix design accordingly, and keep sachets stored between 5°C and 30°C, sealed and out of direct sun, since the 18-month shelf life assumes those conditions are met.”,”specs”:[{“property”:”Appearance”,”value”:”Beige powder”},{“property”:”Uncompacted bulk density @ 20°C”,”value”:”560 kg/m³”},{“property”:”Chloride content”,”value”:”≤ 0.10%”},{“property”:”Dosage — underwater concrete”,”value”:”1.0-3.0 kg/m³ (typically 1.5 kg/m³)”},{“property”:”Dosage — piling applications”,”value”:”0.4-1.0 kg/m³ (typically 0.4-0.5 kg/m³)”},{“property”:”Standard compliance”,”value”:”BS 8443:2005 Table 2 (Underwater Concrete Admixtures); washout <15% per EN 480 Annex A”},{“property”:”Pack size”,”value”:”1.0 kg water-soluble sachets, 12 sachets per tub”},{“property”:”Shelf life”,”value”:”18 months in unopened container, per stated storage conditions”},{“property”:”Storage”,”value”:”5°C to 30°C, under cover, protected from direct sunlight”}],”useCases”:[{“sector”:”Bridge & river infrastructure”,”detail”:”Tremie concreting of pier footings and pile caps cast directly in flowing or tidal water, where conventional concrete would lose fines to the current.”},{“sector”:”Ports & marine works”,”detail”:”Jetty, berth and quay-wall substructure pours placed from a barge or through a tremie in coastal and estuarine conditions.”},{“sector”:”Deep foundations & piling”,”detail”:”Bored cast-in-situ piles and diaphragm wall panels below the water table, especially where a long reinforcement cage must be lowered in after concreting.”},{“sector”:”Dewatering-sensitive sites”,”detail”:”Cofferdam plug slabs and sump/box structures in wet excavations where continuous pumping to keep the pour dry isn’t feasible or affordable.”},{“sector”:”Marine repair & rehabilitation”,”detail”:”Patch repairs to submerged bridge piers, dock walls and other RCC elements that can’t be taken out of water for the repair.”}],”faq”:[{“q”:”Can I just add MasterMatrix UW 440 to my regular ready-mix without changing anything else?”,”a”:”No. The data sheet is explicit that it has to be used together with a high-range water reducer from the MasterGlenium, MasterPolyheed, MasterEase or MasterSure ranges — the two are trial-mixed and dosed as a pair, not added independently.”},{“q”:”Will it reduce my concrete’s strength?”,”a”:”Yes, and the effect scales with dosage — the manufacturer states compressive strength is impacted proportionally as the dosage rate goes up, which is exactly why trial mixes at the actual job mix design are called for rather than picking a number off the dosage table.”},{“q”:”Does it meet Indian standards?”,”a”:”The published data sheet is written against BS 8443:2005 and EN 480, not an IS code — there isn’t a direct Indian equivalent for anti-washout admixtures, so on Indian projects the washout and strength-impact criteria need to be agreed with the structural consultant and written into the project spec rather than referenced against IS.”},{“q”:”How is it actually dosed on site?”,”a”:”It comes in 1 kg water-soluble sachets, 12 to a tub. The sachet is added straight into the concrete mixer during batching and dissolves completely — there’s no liquid dosing pump or on-site weighing involved, but full dissolution before the pour needs to be confirmed.”},{“q”:”What’s the difference between the underwater dose and the piling dose?”,

“a”:”Underwater concreting typically runs 1.0-3.0 kg/m3 (around 1.5 kg/m3 is the usual starting point), while piling applications — where the goal is mainly to stop the surrounding ground absorbing moisture from the mix rather than resisting open-water washout — use a lower 0.4-1.0 kg/m3 range.”},{“q”:”Can Space Arc supply and support this for a project in Delhi NCR or elsewhere in India?”,”a”:”Yes — as an authorised Master Builders Solutions distributor and applicator, Space Arc sources MasterMatrix UW 440 through the MBS network against confirmed project requirements and coordinates the trial-mix and dosage-verification process with the RMC plant or piling contractor; because it’s a specialised low-volume line, lead time should be planned in well ahead of the pour date.”}],”positioning”:”MasterMatrix UW 440 sits in the anti-washout corner of the broader MasterMatrix rheology-control family, alongside viscosity-modifying grades such as MasterMatrix VMA 450 and VMA 358 that are built for segregation control in self-compacting and pumped concrete on dry, above-water sites — those are the products to reach for when the problem is segregation risk rather than open-water or wet-ground washout. On every underwater or piling job it’s also inseparable in practice from an MBS high-range water reducer — MasterGlenium, MasterPolyheed, MasterEase or MasterSure — which the data sheet requires as its dosing partner, and from MasterSet retarders where hot-weather transport times threaten open time before the pour reaches the tremie. Where a project team wants a second-source or a locally stocked alternative, Fosroc’s Conplast UW is a genuine like-for-like anti-washout admixture — also a powdered, chloride-controlled product for tremie and underwater placement — and is a reasonable specifier’s choice when Fosroc is already the approved brand on the project or when its 4.5 kg bag format and Indian stock availability suit the programme better than an imported MBS sachet pack.”}

The technical insight

The working mechanism is rheological rather than chemical retardation. MasterMatrix UW 440’s water-soluble copolymers associate with the mix water to build a network that raises plastic viscosity and yield stress at rest — enough that cement grains and fines resist being carried away by turbulence or flowing groundwater — while shear from pumping or vibration temporarily breaks that structure down so the concrete still flows and places normally. Once shear stops, the thixotropic effect lets the mix stiffen back up quickly at the placement face, which is exactly what limits the boundary layer where washout happens. The manufacturer’s own BS 8443:2005 Annex A data illustrates the dose-response clearly: an EN 480 control mix records the highest washout, and washout falls in a step pattern as dosage climbs through 1, 2 and 3 kg/m3 of MasterMatrix UW 440, crossing below the Table 2 15% ceiling at the lower end of that range under the tested cement content (450 kg/m3) and w/c ratio (<0.45). The trade-off, and it is a real one, is that the same viscosity increase that stops washout also entrains more air and works against compressive strength as dosage rises — which is why the TDS is explicit that trial mixes, not the dosage table alone, should set the final rate for a given job.

Where it is used

• Tremie-placed pile caps and pier footings in rivers, lakes and tidal zones
• Marine jetty, berth and quay wall substructure concreting
• Diaphragm walls and secant or contiguous pile panels cast below the water table
• Cofferdam base/plug slabs poured ahead of dewatering
• Bored cast-in-situ piling in high-water-table ground, particularly where a deep reinforcement cage has to be lowered in after the pour
• Underwater repair and patching of submerged RCC members such as bridge piers and dock walls
• Offshore and near-shore foundation works
• Box culvert or sump-pit concreting in wet excavations where full dewatering isn’t practical

Key advantages

• Cuts cement and fines washout from well above 30% down to under the BS 8443 Table 2 15% ceiling at typical dosage
• Reduces or eliminates concrete bleeding in the treated mix
• Maintains workability broadly comparable to untreated concrete rather than stiffening the mix unworkably
• Virtually eliminates segregation even in highly fluid, high water-cementitious-ratio mixes
• Thixotropic stiffening after placement resists continued material loss once the pour has stopped moving
• Cuts down or eliminates costly dewatering methods on the pour
• Minimal to no effect on concrete set time
• Low, controlled chloride content (≤0.10%) suitable for reinforced work

Limitations & considerations

• Not a stand-alone product — must be paired with an MBS high-range water reducer (MasterGlenium/MasterPolyheed/MasterEase/MasterSure); it isn’t designed to be dosed into just any ready-mix on its own
• Compressive strength drops as dosage increases, so trial mixes to the actual job cement content and w/c ratio are mandatory, not optional, before site use
• Tends to raise entrained air content versus a conventional mix, which needs to be allowed for in the mix design and QC plan
• The published TDS is written to BS 8443:2005 and EN 480, not an IS code, so Indian specifiers and PMCs need to agree washout acceptance criteria with the consultant rather than cite a direct Indian standard
• A specialised, low-volume import line rather than an India shelf product — lead time and minimum order quantities need to be planned with Space Arc well ahead of the pour date
• Powder-in-sachet dosing needs disciplined batching sequencing on site; it can’t be metered the way a liquid admixture is through an automatic dispensing pump

Selection & best practice

Specifications

Industry use cases

How we position Master Builders Solutions MasterMatrix UW 440

MasterMatrix UW 440 sits in the anti-washout corner of the broader MasterMatrix rheology-control family, alongside viscosity-modifying grades such as MasterMatrix VMA 450 and VMA 358 that are built for segregation control in self-compacting and pumped concrete on dry, above-water sites — those are the products to reach for when the problem is segregation risk rather than open-water or wet-ground washout. On every underwater or piling job it’s also inseparable in practice from an MBS high-range water reducer — MasterGlenium, MasterPolyheed, MasterEase or MasterSure — which the data sheet requires as its dosing partner, and from MasterSet retarders where hot-weather transport times threaten open time before the pour reaches the tremie. Where a project team wants a second-source or a locally stocked alternative, Fosroc’s Conplast UW is a genuine like-for-like anti-washout admixture — also a powdered, chloride-controlled product for tremie and underwater placement — and is a reasonable specifier’s choice when Fosroc is already the approved brand on the project or when its 4.5 kg bag format and Indian stock availability suit the programme better than an imported MBS sachet pack.

Related Concrete Admixtures products

View all Concrete Admixtures products →