MICHEM SHP 90 Silicone Hydrophobic Powder
MICHEM SHP 90 is an organosiloxane-based additive engineered for cementitious dry-mix systems where reducing capillary water uptake is required without turning the mortar into an impermeable plastic film.
Hydrophobicity is Not the Same as Pore Blocking
A conventional densification strategy reduces water ingress by making the pore network physically smaller or less connected. A hydrophobic strategy works entirely differently.
Organosilicon chemistry reduces the surface energy and water affinity of mineral pore walls. Liquid water cannot easily wet or enter capillaries, yet the pore network remains open. This allows hydrophobized mortars to achieve substantial liquid-water resistance while preserving essential water-vapor transmission.
Ideal for façades, exterior renders, and waterproof mortars where driving rain resistance is essential but trapping interior moisture vapor is unacceptable.
Capillary Water Absorption is the Key Mechanism
Porous cementitious materials draw water spontaneously through capillary suction forces. When pore walls are hydrophilic, narrow capillaries generate powerful suction.
Hydrophobic modification reverses this wetting affinity, substantially lowering capillary liquid uptake across the hardened matrix.
Hydrostatic Water Pressure Distinction
Capillary repellency is fundamentally distinct from positive or negative hydrostatic pressure containment. A mortar can resist wind-driven rainwater effectively while requiring membrane or barrier design under continuous hydrostatic heads. Never treat “waterproof” as an unlimited claim.
Organosiloxane Chemistry Works at the Mineral Interface
Peer-reviewed research confirms that silane and siloxane chemical groups interact with hydrated cementitious compounds (such as calcium silicate hydrate phases) to chemically anchor hydrophobic organic groups onto pore surfaces.
MICHEM identifies SHP 90 specifically as an organosiloxane powder. What matters to the dry-mix formulator is the stable surface interaction and verified capillary-absorption reduction across diverse mineral substrates.
Dosage Window: A Starting Point, Not a Universal Optimum
The current MICHEM TDS recommends a typical dosage of approximately 0.2–0.5 wt%, noting an upper operational level around 1.0%. This provides a baseline reference, but hydrophobic response depends strongly on formulation variables:
- Binder content and mineral filler reactivity
- Water-to-binder ratio and aggregate fines distribution
- Polymer modification and cellulose ether levels
- Jobsite curing temperature and application layer thickness
Establish a multi-point dosage curve in the actual mortar system to optimize performance cost-effectively.
Hydrophobicity & Compressive Strength Trade-Offs
Hydrophobic additives alter the mineral-water wetting interface during initial hydration. Excessive or uncalibrated dosages can interfere with cement hydration kinetics or weaken inter-particle matrix bonding.
Formulators should avoid the assumption that “more SHP 90 automatically equals more durability.” The engineering target is the lowest robust dosage that achieves target capillary-water resistance while preserving compressive strength, tensile bond strength, and workability.
Vapor Breathability & Efflorescence Transport Control
SHP 90 delivers exterior moisture protection while enabling internal vapor drying, offering an advanced mechanism to mitigate surface salt staining.
Vapor Permeability Verification
Because SHP 90 modifies capillary surface tension rather than filling pores with a solid polymer barrier, water-vapor diffusion is retained. In ETICS and exterior façades, always test the complete composite layer to certify compliance with regional building standards.
Efflorescence Mitigation Dynamics
Efflorescence requires soluble salts, moisture transport, and evaporation. By suppressing capillary liquid movement, SHP 90 cuts off the salt vehicle. However, it does not remove ions from aggregates or cement; raw material selection remains essential.
Dry-Mix Matrix Additive Compatibility
MICHEM SHP 90 is fully compatible with standard dry-mix functional additive families. Assign formulation tasks to the correct chemistry.
Cellulose Ethers (HPMC / HEMC)
Cellulose ethers manage fresh-state water retention and workability during application and curing. SHP 90 governs hardened-state water repellency. Do not reduce HPMC dosage expecting SHP 90 to retain fresh water.
Explore HPMC Grades →Starch Ethers
Starch ethers provide low-shear yield stress, anti-sag resistance, and creamy troweling feel. SHP 90 does not alter sag resistance, and starch ethers do not reduce capillary absorption. Each chemistry solves its designated challenge.
Explore Starch Ethers →Redispersible Powders (RDP)
RDP delivers adhesion, flexural flexibility, and cohesion. When combined with hydrophobic RDP grades like MICHEM 5034H, optimize the dual-package balance to maximize bonding and minimize liquid-water absorption.
Explore RDP Portfolio →Engineered for High-Exposure Cementitious Systems
From weather-exposed exterior envelopes to moisture-intensive wet rooms, SHP 90 delivers tailored water resistance.
Waterproof Mortars
Reduces capillary uptake while maintaining balanced crack bridging and substrate adhesion through proper polymer synergy.
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Renders & Façades
Resists driving rain penetration while allowing wall systems to dry naturally outward via sustained vapor breathability.
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Tile Grouts
Minimizes water absorption, dirt pickup, and staining during washdown cycles without interfering with installation wetting.
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Repair Mortars
Shields concrete repair zones against aggressive dissolved chlorides and moisture while securing high interfacial bond strength.
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Dry-Blend Distribution & Plant Handling Controls
Because SHP 90 is dosed at low percentages (0.2–0.5 wt%), uniform distribution during dry blending is critical. Segregation or poor mixing leads to inconsistent water repellency across packaging runs.
Key plant processing checkpoints:
- Micro-feeder calibration and high-shear mixer fill levels
- Mixing cycle duration verification prior to discharge
- Moisture barrier packaging integrity to avoid caking in storage
- Prevention of segregation during pneumatic silo transfer
Align Testing Methods with Real Failure Modes
No single test completely characterizes moisture resistance. Match laboratory evaluation methods to jobsite exposure conditions:
Evaluate Against the Whole Moisture Pathway
Hydrophobic modification alters how fresh mortar wets during curing and exterior exposure. In colored mortars, decorative grouts, and colored renders, verify that visual appearance, shade uniformity, and wet/dry contrast meet project requirements.
Diagnose the Ingress Route: If moisture enters through joint failures, structural cracks, or interior condensation, increasing hydrophobic dosage will not resolve the issue. Always align SHP 90 with capillary absorption mechanics.
MICHEM SHP 90 Specification Overview
Standard properties based on current supplier data. Verify commercial requirements against the active Certificate of Analysis (COA).
| Property / Field | MICHEM Technical Source Designation |
|---|---|
| Product Commercial Name | MICHEM SHP 90 Silicone Hydrophobic Powder |
| Chemical Base & Physical State | Organosiloxane (Free-flowing dry powder) |
| Typical Recommended Dosage | Approximately 0.2 – 0.5 wt% of total dry mix |
| Upper Dosage Threshold | Around 1.0% (depending on formulation matrix design) |
| Primary Technical Positioning | Substantial reduction of capillary liquid water absorption |
| Secondary Performance Benefits | Efflorescence reduction, enhanced weatherability, freeze-thaw durability |
| Water Vapor Behavior | Maintains water-vapor permeability without pore sealing |
| Additive Matrix Compatibility | HPMC, HEMC, starch ethers, redispersible polymer powders (RDP) |
* Consult official product TDS for regional storage recommendations and packaging specifications.
Request Official SHP 90 TDSTroubleshooting Hydrophobic Mortar Systems
Resolve formulation inconsistencies with systematic testing procedures.
Water Absorption Remains High
Review dosage levels, dry-blend homogeneity, curing conditions, and verify whether the exposure is capillary or hydrostatic pressure.
Compressive Strength Drops
Re-evaluate dosage. Over-modification can affect hydration kinetics; optimize the dosage curve to find the lowest effective concentration.
Mortar Difficult to Wet or Bond
Dosage may be excessively high or dry distribution uneven. Recheck addition sequence and substrate pre-wetting protocols.
Efflorescence Still Occurs
Identify raw material salt sources (cement, sand, mixing water). Hydrophobicity slows moisture transport but does not eliminate soluble ions.
Bags Exhibit Variable Repellency
Investigate micro-dosing feeder accuracy, plant mixer blending cycle times, and check for powder caking during storage.
Frequently Asked Questions
Key considerations when specifying MICHEM SHP 90 in dry-mix formulations.
What is MICHEM SHP 90?
SHP 90 is an organosiloxane-based silicone hydrophobic powder engineered to reduce capillary liquid-water uptake in cementitious dry-mix systems.
What is the recommended dosage range?
The current TDS recommends approximately 0.2–0.5 wt% of total dry blend, with an upper limit around 1.0% depending on formulation variables.
Does SHP 90 make mortars completely waterproof?
It significantly reduces capillary suction. Pressurized hydrostatic water resistance and structural crack control must be engineered independently.
Can SHP 90 be combined with HPMC or HEMC?
Yes. SHP 90 is compatible with cellulose ethers. HPMC controls fresh water retention, while SHP 90 imparts hardened-state water repellency.
Is SHP 90 compatible with redispersible polymer powder (RDP)?
Yes. It pairs effectively with RDP. For high-flexibility waterproof mortars, optimize the ratio of RDP and SHP 90 in the specific formulation.
Does it reduce the water-vapor permeability of façades?
SHP 90 modifies capillary wall surface tension without closing the pore network, allowing the system to maintain essential water-vapor breathability.
Reduce Liquid-Water Uptake Without Sacrificing Vapor Permeability
Follow the engineering sequence: Capillary Target → SHP 90 Dosage → Formulation Synergy → Hydrophobic Performance → Strength & Durability Verification.