MC-Bauchemie MC-Grout Rapid
A single-component, water-only non-shrink grout that hits 25 MPa in 4 to 6 hours, turning a two-day machine shutdown into a same-shift maintenance window.
What is it?
A factory-blended, rapid-setting non-shrink cementitious grout that develops early load-bearing strength within a working shift, supplied ready to use with only clean water added on site.
Where is it used?
Emergency machine base-plate re-grouting, fast-track precast pocket grouting, and infrastructure repairs on bridges, highways and operational plants where downtime is expensive.
Why use it?
It compresses the usual 24-48 hour strength wait to roughly 4-6 hours, so equipment can be re-commissioned or traffic reopened the same day without sacrificing non-shrink performance.
How is it applied?
Remove failed grout, prepare and pre-wet the substrate to SSD, set formwork, then mix small batches with 0.14-0.18 L water per kg and pour continuously within the short pot life.
About MC-Bauchemie MC-Grout Rapid
MC-Grout Rapid is MC-Bauchemie’s answer to a problem every plant engineer and site agent knows well: a conventional non-shrink grout is dependable, but its 24 to 48 hour strength gain can hold an entire programme hostage. When a compressor foundation fails on a Friday night, or a precast column has to carry load before the next lift, that waiting period is measured in lost production and idle cranes. This grout is engineered to close that gap. It is a single-component, factory-blended powder that needs nothing but clean water at the mixer, and it reaches around 25 MPa within four to six hours at normal temperatures, enough to bear working loads the same shift it was poured.
What makes it useful in Indian conditions is that it does this without giving up the two things that matter most in a grout: dimensional stability and long-term strength. It remains genuinely non-shrink, filling the base plate cavity with full contact and no settlement voids, and it continues to gain strength to a healthy 40-50 MPa by 28 days, on par with standard precision grouts. In practice, that means a contractor is not trading durability for speed. It is a specialist tool for time-critical work rather than a general-purpose grout, and understanding where that trade sits is the key to using it well.
The technical insight
The early strength is not an additive gimmick, it is chemistry. Ordinary Portland grouts rely on the slow hydration of C3S and C2S, which is why usable strength takes a day or more. MC-Grout Rapid pairs a finely ground, modified Portland clinker rich in the fast-reacting C3A and C3S phases with a calcium sulphoaluminate reactive component. When water is added, that sulphoaluminate phase forms ettringite within the first two to six hours, and it is this rapid ettringite growth that delivers both the early load-bearing strength and the controlled positive expansion that keeps the grout non-shrink. The same reaction that sets the grout fast is what stops it from shrinking away from the base plate. The catch is that ettringite formation is strongly temperature-driven, so initial set can arrive in 10-20 minutes at 35 C but stretch to 45-60 minutes near 15 C. That is why the material is unforgiving of delay and why batch discipline, not just correct mixing, decides whether a pour succeeds.
Where it is used
- Emergency re-grouting of machine base plates after foundation or grout failure
- Same-day equipment re-commissioning where production downtime carries a high cost
- Precast column and beam pocket grouting on fast-programme high-rise construction
- Bridge and highway infrastructure repairs requiring rapid return to service
- Bearing pad replacement and re-seating on operational road and rail structures
- Anchor bolt and holding-down bolt re-grouting in guard rails and safety barriers
- Overhead sign gantry and signal support base repairs on live carriageways
- Cold-joint and cavity filling on time-critical maintenance shutdowns
Key advantages
- Reaches approximately 25 MPa in 4-6 hours, enabling same-shift loading and re-commissioning
- Fully non-shrink despite the rapid-setting chemistry, giving complete base-plate contact
- Single-component and water-only, so no on-site batching of resins or gauging errors
- Continues to a robust 40-50 MPa at 28 days, comparable to standard precision grouts
- Converts a typical 48-hour production shutdown into a 4-6 hour maintenance window
- Controlled positive expansion from ettringite eliminates settlement voids under load
- Consistent factory blend removes the site variability of hand-mixed grout
Limitations & considerations
- Very short pot life, roughly 12-18 minutes at 30-35 C, leaves no room for delay between mixing and pouring
- Set time and early strength are strongly temperature-dependent, requiring batch sizes to be adjusted on the day
- Small batches only (around 4 bags / 100 kg per 200 L mixer) mean it is labour-intensive for large-volume pours
- Rapid initial set (20-35 minutes) demands that formwork, mixer and crew are fully ready before the first bag is opened
- It is a premium specialist grout, so on non-urgent work a standard non-shrink grout is more economical
Selection & best practice
Success with MC-Grout Rapid is decided before the first bag is opened. Fully remove the failed or laitance-affected grout, clean the cavity with compressed air, and pre-wet the concrete to a saturated surface-dry (SSD) condition so the substrate does not rob the mix of water. Complete precision re-levelling of the base plate with a machinist level and install tight, leak-free formwork in advance, because there is no time to adjust once mixing starts. Gauge 0.14-0.18 L of clean water per kg of powder for a flowable, groutable consistency, and keep batches small, no more than about 4 bags (100 kg) per 200 L mixer. Pour continuously from one side to avoid trapping air, and do not disturb the grout during the 30-75 minute set window. Above all, size each batch to the ambient temperature: on a hot Delhi afternoon, pot life can drop below 15 minutes, so mix less and pour faster.
Specifications
| Compressive strength (4-6 hours) | Minimum 25 MPa at 25 C |
| Compressive strength (24 hours) | 35-40 MPa |
| Compressive strength (28 days) | 40-50 MPa |
| Initial set time | 20-35 minutes (temperature dependent) |
| Final set time | 45-75 minutes |
| Water-to-powder ratio | 0.14-0.18 litres per kg |
| Fresh grout density | Approximately 2,050-2,100 kg/m3 |
| Volume change | Zero to slight positive expansion (non-shrink) |
| Pack size | 25 kg bags |
Industry use cases
Manufacturing & Process Plants
Re-grouting compressor, pump and turbine base plates during an unplanned shutdown, letting maintenance teams reload the machine within the same shift instead of losing two days of production.
Precast & Fast-Track Construction
Grouting precast column pockets and connections on tight high-rise programmes so the next lift or floor cycle is not held up waiting for conventional grout to gain strength.
Highways & Bridges
Emergency bearing pad replacement, sign gantry base repair and anchor re-grouting on live carriageways, where lanes must be reopened to traffic in hours, not days.
Power & Heavy Engineering
Rapid re-seating of generators and heavy rotating equipment where every hour of outage has a direct commercial cost and early load-bearing strength is critical.
Infrastructure Maintenance
Time-boxed night-work repairs on rail, ports and industrial structures, completing pour and cure inside a single maintenance window before operations resume.
Frequently asked questions
How quickly can I load a machine after grouting with MC-Grout Rapid?
Is it still non-shrink even though it sets so fast?
What is the pot life and how does temperature affect it?
How much water do I add, and can I add more for better flow?
What pack size does it come in and how big should batches be?
When should I choose this over a standard non-shrink grout?
How we position MC-Bauchemie MC-Grout Rapid
MC-Grout Rapid sits at the specialist, time-critical end of MC-Bauchemie’s grouting range. Where the programme is not racing the clock, a standard MC-Bauchemie universal or high-performance non-shrink grout is the more economical choice for routine base-plate and anchor work, and MC-Bauchemie’s epoxy-based grouts (the MC-DUR grout family) are the answer where chemical resistance or dynamic and vibrating loads, rather than raw speed, are the priority. For deeper, single-pour reinstatement, a mineral-based micro-concrete from the same range suits large-section repairs better than a flowable grout. Across our other brands, engineers who need this same same-day capability from Fosroc will find the closest equivalent in the Conbextra high-early-strength grouts, and for very high early strength the Conbextra BB90 line is worth comparing on 1-day figures. Talk to our technical team so the grade is matched to the actual downtime window, gap thickness and load case rather than defaulting to the fastest product on the shelf.
Fosroc Conbextra HES — A specifier already standardised on Fosroc may prefer Conbextra HES, which similarly reaches about 25 MPa within two hours for same-shift loading and handles gap thicknesses up to 150 mm in a single pour.
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