"Microcement" is a marketing umbrella over four chemically distinct systems. They look similar at 2 mm thickness. They behave nothing alike. Pick the wrong family for your wet room, your sun-exposed terrace, or your kitchen worktop and the floor cracks, blooms, peels, or discolours within eighteen months. The decision begins with the TDS — not the trade name on the bucket.
Why the trade name is a trap
Walk into any IL paint trade counter and ask for microcement. You will be offered Topciment Sttandard, Sika DecoDur, Pavistamp PAVICEM, Mortex, Marmorino, Tadelakt, Béton Ciré, and at least three private-label bags. All of them get called microcement in conversation. Their binder chemistry spans four families with entirely different cure mechanisms, water response, and failure modes.
The single most useful question to ask before specifying is not "what colour" or "what brand," but: what is in the binder. The technical data sheet (TDS) tells you in two lines under "composition" or "chemistry". If the seller cannot produce a TDS, you do not specify the product. ICRI 320.5R, EN 13813, and every major flooring warranty all reference binder chemistry, not marketing labels.
The four families
| Family | Composition | Cure mechanism | Strength | Weak point |
|---|---|---|---|---|
| Cement + polymer (2-component) | White or grey cement (CEM I 52.5) + fine quartz/limestone aggregate + acrylic or styrene-acrylic resin + pigments | Hydraulic + film-forming. Functional 24–48 h, full 7 d | Hard, abrasion-resistant, fast turnaround | Needs PU sealer for wet areas; can hairline-crack on flex |
| Cement + lime + polymer (hybrid) | Cement + slaked lime + acrylic resin + mineral pigment | Hydraulic + carbonation + film-forming | Mass-water-repellent, organic look, mildly breathable | Softer than pure-cement, acid-sensitive, slower cure |
| Pure lime (no cement) | Slaked lime putty (Ca(OH)₂) + crushed marble dust + lime-fast mineral pigments. Tadelakt adds olive-oil soap. | Carbonation with atmospheric CO₂ — weeks to months | Breathable, bacteriostatic, period-authentic | Slow cure, demanding application, light-traffic only |
| Epoxy / PU pseudo-microcement | Epoxy or PU resin + ground stone aggregate + pigment (no hydraulic cement) | Reaction cure of resin system | Chemically robust, dimensionally stable | Not breathable, not technically microcement, UV-yellowing in epoxy |
1. Cement + polymer (2-component) — the modern microcement
This is what most IL specifiers mean when they say microcement. The system ships in two bags: component A (powder) and component B (liquid). The liquid is not water — it is an acrylic or styrene-acrylic polymer dispersion. Trade examples: Topciment Sttandard, Pavistamp PAVICEM, Sika MicroTop, Sika DecoDur (region-dependent), Smartcret.
Hydraulic binder — white or grey cement, often CEM I 52.5R for whiteness and early strength
Aggregate — fine quartz or limestone, granulometry 0.1–0.9 mm depending on coat (base coarser, finish finer)
Resin — acrylic, styrene-acrylic, or hybrid polymer dispersion (the "B" component)
Additives — mineral pigments, rheology modifiers, fibres for crack resistance, water-retainers
Cure is dual: cement hydrates with the resin's water content, the resin film forms as water evaporates. Functional traffic at 24–48 hours; full mechanical and chemical resistance at seven days. The resin gives flex (typical elongation 3–8% before crack), abrasion resistance (Taber CS-17 1 kg ~ 60–90 mg loss per 1000 cycles), and reduced shrinkage cracks vs straight cement.
The most-cited TDS in this family is Topciment Sttandard, which publishes binder ratios, Taber wear, and pull-off adhesion in a single document. Pavistamp PAVICEM follows the same template. Read both — they are the industry reference points.
Where this family fails
- Inadequate PU sealer in wet rooms. The base is water-permeable. Two coats of polyurethane sealer are mandatory in showers. Skip the second coat and the floor mottles in three months.
- Hairline cracks at substrate joints. 2 mm of cement-polymer has no chance of bridging a moving joint. Decoupling membrane plus fibreglass mesh at every joint is non-negotiable.
- Acid attack in kitchens. Vinegar, lemon, wine, citrus juice etch the surface within minutes if the sealer has worn. Renew sealer every 2 years in wet zones, every 4–5 in dry.
2. Cement + lime + polymer (hybrid) — Mortex and Mineral Skin
The Belgian brand Mortex (Beal International) defines this family commercially. Composition: cement + slaked lime + acrylic resin + mineral pigment. The lime adds carbonation cure on top of the hydraulic cement cure, slowing the overall hardening and giving the matrix a slightly higher pore tortuosity. Combined with the polymer dispersion, the system is genuinely water-repellent in the mass.
The practical consequence: in IL bathroom and shower work, Mortex is the only product that is regularly specified without a separate waterproof membrane below it — on stable substrates, in projects where the substrate is verified not to move. Good IL practice still uses tanking even with Mortex; the failure mode is at the joint between substrate and microcement, not in the microcement itself.
Mineral Skin is Beal's lighter-pigment line on the same chemistry. Both cure to a matt-to-silk finish with a softer hand than pure-cement microcement.
Where this family fails
- Soft compared to pure-cement. Surface scratch resistance is lower. Heavy commercial use is not the target.
- Acid-sensitive. The lime fraction reacts with citrus, vinegar, and wine more readily than pure-cement matrices. Sealer renewal interval shortens to ~18 months in kitchens.
- Slow cure means longer site time. Carbonation takes weeks to complete. Functional traffic similar to cement-polymer, but full chemical resistance is later.
3. Pure lime — Marmorino, Veneziano, Tadelakt
No hydraulic cement. The binder is slaked lime putty (Ca(OH)₂) mixed with crushed marble, marble dust, or very fine sand. Pigments must be lime-fast — mineral oxides only, no synthetic dyes. Cure is by carbonation: atmospheric CO₂ reacts with calcium hydroxide to form calcium carbonate (CaCO₃, the same chemistry as natural limestone). Functional hardness arrives in weeks, full mineral hardness in months.
This is the family of Marmorino (Stucco Italiano, Vasari, Meoded, FirmoLux) and Tadelakt (Moroccan saponified lime). Marmorino can be burnished to a mirror polish; Tadelakt is stone-rubbed and then sealed by saponification — olive-oil soap reacts with the surface lime to form calcium stearate, plugging the pores. Period-correct for hammams and traditional bath construction.
Step 1 — Slaked lime applied in 2 coats × 0.5–1 mm.
Step 2 — Stone-rubbed (galet) to compact and align particles.
Step 3 — Black-soap (savon noir, olive-oil-based) rubbed in. Saponification: 2 RCOOH + Ca(OH)₂ → Ca(RCOO)₂ + 2 H₂O.
Step 4 — Calcium stearate plugs surface pores. Waterproof for hammam use.
Where this family fails
- Floor use is risky. Lime is intrinsically softer than cement. Heavy-traffic floors are not the target — feature floors, residential bathrooms, and walls are.
- Skilled labour is rare. In IL there are perhaps a dozen plasterers who handle Tadelakt to period standard. Marmorino is more available but still niche.
- Cure timing. Carbonation in low-CO₂ indoor air can take months for full surface hardness. Premature wear in this window leaves visible imprints.
4. Epoxy / PU pseudo-microcement
This family is decorative concrete overlay rebranded as microcement. The binder is not hydraulic cement at all — it is an epoxy or PU resin loaded with stone aggregate and pigment. US examples: Increte Thin-Crete, Decra-Mix, certain ARDEX decorative overlay systems. The look at the surface can mimic cementitious microcement closely.
Why the rebrand is misleading: the failure modes are entirely different. An epoxy overlay does not breathe, does not carbonate, and yellows under UV exposure. A cementitious microcement breathes vapour, hardens by hydration, and is alkali-stable.
Specify these systems where you want a resinous floor that looks like microcement. Do not specify them where breathability matters (heritage buildings, exterior walls), where the substrate has trapped moisture, or where UV exposure is constant. Always confirm with the TDS — if the binder is "epoxy" or "polyurethane," you are not specifying microcement in the strict sense.
How to read a TDS in five lines
- Composition / chemistry. Look for the word "cement" (hydraulic), "lime" (carbonation), "epoxy" or "polyurethane" (resin cure). One of these tells you the family.
- Mixing ratio. Pure water = pure cement system. Two-component liquid = polymer-modified. Three components = check the third (often a hardener for epoxy).
- Cure time table. Functional traffic 24–48 h points to cement-polymer. 7–14 days plus points to lime. Weeks point to pure lime.
- Sealer recommendation. Mandatory PU/epoxy sealer indicates a permeable cement base. Optional wax / mineral seal indicates lime or hybrid.
- EN 13813 class (where listed). CT = cementitious. CA = calcium sulfate. SR = synthetic resin. AS = mastic asphalt. The two-letter prefix is the family.
What to specify in IL practice
For an IL specifier choosing today:
- Modern bathroom or shower, code-compliant build-up: cement-polymer (Topciment Sttandard, Pavistamp PAVICEM) over a tanked substrate with two coats of PU sealer.
- Bathroom without separate membrane, stable substrate: cement-lime hybrid (Mortex). Still add tanking for showers — owner's call on dry-zone bathrooms.
- Hammam, traditional bath, heritage restoration: Tadelakt by a specialist.
- Feature wall in a luxury interior: Marmorino Veneziano, polished, lime-fast pigment.
- Pool deck, sauna, salt-water exposure: Topciment Atlanttic Aquaciment (anti-slip granulometry, chloride-stable).
- Resin-floor look you want to call microcement: understand it is a pseudo-microcement; specify on the basis of resin properties, not microcement folklore.
The decision sequence is always the same: substrate → membrane → binder family → finish coats → sealer system. Inverting that order — picking a brand first and then asking what to do with it — produces the failures the next article catalogues.
Continue reading: Microcement known issues: nine failure modes and how to avoid them · ICRI CSP 1–10: surface profile for each coating · Microtopping system page.
Sources
- Topciment composition reference — cement-polymer family TDS template.
- Beal International Mortex — cement-lime hybrid product line.
- Tadelakt — Wikipedia — historical and chemical reference for pure lime saponification.
- Stucco Italiano Marmorino Fine — pure-lime product line.
- Smartcret microcement problems guide — failure-mode catalogue.
- EN 13813 — Screed material and floor screeds: properties and requirements (binder family classification).
- ICRI 320.5R — Selection of strategies for sealing concrete (binder/sealer interaction).