MC-Bauchemie MC-Thix 111
A chloride-free, gel-forming anti-washout admixture that keeps cement and fines in the mix when concrete is placed underwater, in tremie pours, and in submerged foundations.
What is it?
A water-soluble, gel-forming anti-washout admixture (AWA) from MC-Bauchemie that thickens the mix water so cement and fine particles resist being stripped out during submerged placement.
Where is it used?
Underwater and tremie concreting: bored cast-in-situ piles, diaphragm walls, cofferdams, bridge and marine footings, and dam works across Delhi NCR and pan-India projects.
Why use it?
It holds the mix together as it falls through water, preserving in-place strength and cutting the cement loss and turbidity that plague ordinary submerged pours.
How is it applied?
Dosed by mass of cement at 0.3 to 0.8 percent during batching at plant or in the truck, usually paired with a PCE superplasticiser to restore flow.
About MC-Bauchemie MC-Thix 111
MC-Thix 111 is MC-Bauchemie’s answer to one of the oldest headaches in submerged concreting: the moment fresh concrete meets water, the paste starts to disperse. Cement and fines wash away, the surrounding water clouds over, and the concrete that finally sets in place is weaker and more porous than the mix that left the batching plant. MC-Thix 111 is a water-soluble, gel-forming polymer of the cellulose-ether and welan-gum family. Blended into the mix water, it builds a thixotropic gel around the cement grains so the paste stays cohesive as it drops through water or feeds down a tremie, rather than bleeding into the surrounding column.
For engineers and contractors in India working on piles, marine footings, and hydraulic structures, that cohesion is the difference between a sound pour and a costly re-do. The admixture is chloride-free, so it will not introduce corrosion risk into reinforced sections, and it has minimal effect on setting time, which keeps site scheduling predictable. It is designed to work alongside modern PCE superplasticisers, including MC-Bauchemie’s own Centrament Nano 500 range, so the mix can be made both cohesive and fluid at the same time. Space Arc Engineering supplies MC-Thix 111 with the trial-mix and tremie-discipline guidance that make the numbers on the datasheet actually hold up on site.
The technical insight
The mechanism is rheological, not chemical set-modification. Dissolved in the mix water, the polymer chains hydrate and entangle to form a weak, reversible gel network, giving the paste high viscosity at rest and under low shear. When concrete is placed underwater or through a tremie, the surrounding water can no longer easily penetrate and dilute the paste, so cement and fines stay bound to the aggregate skeleton instead of clouding off into the water column. Because the gel is thixotropic, it thins again under the higher shear of pumping and placement, then rebuilds once the concrete comes to rest, which is why the same admixture that resists washout does not simply jam up in the line. The trade-off is cohesion versus flow: the very gel that stops segregation also stiffens the mix, so a PCE superplasticiser is added to recover workability without adding water. Get that balance right and the washout resistance shows up as a submerged-to-unsubmerged strength ratio above 0.85, meaning the concrete that cures underwater retains most of the strength it would have reached in the dry.
Where it is used
- Bored cast-in-situ piles and secant piles placed under bentonite or water
- Diaphragm walls and barrettes concreted by tremie
- Cofferdam and caisson foundations for bridges and jetties
- Bridge pier and abutment bases below the waterline
- Marine and coastal footings, seawalls and breakwater elements
- Dam, barrage and spillway works involving submerged concrete
- Underwater concrete repairs and infill to existing submerged structures
- Tremie backfill and plug pours where mix cohesion is critical
Key advantages
- Sharply reduces cement and fines washout during submerged placement
- Keeps the mix homogeneous and resists segregation as it falls through water
- Preserves in-place compressive strength, with a washout strength ratio above 0.85
- Chloride-free, so it adds no corrosion risk to reinforced sections
- Minimal effect on setting time, keeping site schedules predictable
- Compatible with modern PCE superplasticisers, including Centrament Nano 500
- Reduces water turbidity and cement loss, easing environmental compliance near water bodies
- Dosed through conventional batching at plant or in the truck, with no special equipment
Limitations & considerations
- Increases cohesion, so a superplasticiser is needed to restore workable flow
- Overdosing makes the mix sticky and genuinely hard to place
- Response varies with cement and aggregate, so trial mixes are essential before a pour
- Does not, on its own, waterproof or provide corrosion protection to the structure
- Good results still depend on proper tremie discipline and adequate cement content
- It manages washout, not mix design; a poorly proportioned mix will still underperform
Selection & best practice
Start with a laboratory trial using the exact cement and aggregates for the job, dosing MC-Thix 111 at the low end of the 0.3 to 0.8 percent by mass of cement range and adding a PCE superplasticiser to bring flow back to target. Move to the higher end of the dosage where water is moving faster or the tremie drop is longer, since those conditions strip more paste. Add the admixture with the mix water and mix long enough for the gel to develop fully and uniformly. On site, keep the tremie tip embedded in fresh concrete so the mix never free-falls through water, maintain a steady placement rate, and hold adequate cement content, MC-Thix 111 reduces washout but does not replace sound tremie practice. Confirm the final dosage against washout and strength trials rather than assuming a plant recipe transfers unchanged to a new mix.
Specifications
| Product type | Anti-washout / viscosity-modifying admixture (AWA) |
| Chemistry | Water-soluble gel-forming polymer (cellulose ether / welan gum type) |
| Action | Forms a thixotropic gel in the mix water |
| Dosage | 0.3 to 0.8 percent by mass of cement |
| Washout strength ratio | Greater than 0.85 (submerged vs unsubmerged) |
| Chloride content | Chloride-free |
| Effect on set | Minimal effect on setting time |
| Superplasticiser compatibility | Compatible with PCE types, including Centrament Nano 500 |
| Reference standards | IS 9103, ASTM C1240, CRD-C 661 (AWA) |
Industry use cases
Deep Foundations
Bored piles, secant piles and barrettes concreted under water or bentonite, where washout would otherwise weaken the pile shaft and contaminate the slurry.
Bridges & Highways
Cofferdam bases, pier footings and abutment foundations poured below the waterline, keeping submerged concrete sound and low in permeability.
Marine & Ports
Coastal footings, seawalls, jetty bases and breakwater elements where moving water and salt exposure demand cohesive, low-washout placement.
Dams & Hydraulic Works
Barrage, spillway and underwater repair pours in water-retaining structures, cutting cement loss and downstream turbidity.
Underwater Repair
Infill and remedial concreting to existing submerged structures, where the mix must resist dispersion without draining the site of visibility or strength.
Frequently asked questions
What exactly does MC-Thix 111 do in an underwater pour?
How much MC-Thix 111 should I dose?
Do I still need a superplasticiser with it?
Is it safe for reinforced concrete?
Does it waterproof the structure or protect the rebar?
Can I place concrete underwater without proper tremie technique if I use it?
How we position MC-Bauchemie MC-Thix 111
MC-Thix 111 sits in MC-Bauchemie’s admixture line and works hand-in-hand with the Centrament Nano 500 PCE superplasticiser range, the standard pairing to keep an anti-washout mix both cohesive and fluid. Space Arc also supplies the closest cross-brand equivalent from Fosroc, Conplast UW, a chloride-free anti-washout powder for the same underwater and tremie applications, which is worth considering where a project’s approved-vendor list or an existing Fosroc admixture regime favours that family. For the broader concrete package, we can combine MC-Thix 111 with the appropriate integral waterproofing admixture and protective coatings, since washout control and long-term durability are separate jobs that a submerged structure usually needs together.
Fosroc Conplast UW — A specifier standardised on Fosroc admixtures, or bound by an approved-vendor list, may prefer Conplast UW as the equivalent chloride-free anti-washout powder for the same underwater and tremie pours.
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