Masteremaco A 660
MasterEmaco A 660 (formerly known across the construction industry as Rheomix 141 or Concresive A 660) is a premium water-based acrylic polymer bonding agent and modifying admixture manufactured by Master Builders Solutions. Engineered specifically to enhance the mechanical performance of cementitious repair mortars, plasters, and concrete toppings, this milk-white acrylic emulsion significantly improves tensile bond adhesion, flexural strength, and chemical durability. By reducing water-cement ratios and sealing capillary voids, MasterEmaco A 660 transforms brittle patches into resilient, freeze-thaw-resistant structural repairs.
Chemical Composition, Polymer Modification, and Physical Properties
At the molecular level, MasterEmaco A 660 is formulated from a non-re-emulsifiable acrylic polymer dispersion engineered to integrate seamlessly into portland cement hydration chemistry. Unlike basic PVA (polyvinyl acetate) glues that soften, hydrolyze, and fail when exposed to ongoing exterior moisture, acrylic polymers form an irreversible, cross-linked interpenetrating polymer network throughout the cement matrix. This network bridges micro-fissures and permanently locks Portland cement crystals together.
When blended into repair mortars as an admixture, MasterEmaco A 660 acts as a powerful plasticizer, dramatically improving workability while allowing contractors to slash mixing water volume. The resulting cured composite exhibits vastly improved flexural, tensile, and compressive properties. Furthermore, the coalesced acrylic film lines capillary pores, creating an impermeable barrier that resists the intrusion of deicing salts, acid rain, atmospheric carbonation, and industrial contaminants.
Review the physical, mechanical, and technical properties of MasterEmaco A 660 acrylic bonding admixture:
| Technical Property | ASTM Test Standard | Standard Mortar Baseline | MasterEmaco A 660 Modified |
|---|---|---|---|
| Direct Tensile Bond Strength | ASTM C1583 / C1042 | 120 to 150 psi (substrate failure) | 400 to 550+ psi (monolithic bond) |
| Flexural Strength (Modulus of Rupture) | ASTM C348 | 650 psi at 28 days | 1,200 to 1,500 psi at 28 days |
| Compressive Strength | ASTM C109 | 3,500 psi at 28 days | 5,500 to 6,800 psi at 28 days |
| Freeze-Thaw Resistance | ASTM C666 | Poor (rapid surface spalling) | 95%+ Relative Dynamic Modulus |
| Rapid Chloride Ion Permeability | ASTM C1202 | High (>4,000 Coulombs) | Very Low (<1,000 Coulombs) |
| Re-emulsification in Water | Immersion Test | Re-emulsifies if PVA based | Non-re-emulsifiable permanent acrylic |
Dual Application Methods: Slurry Bonding Primer vs. Mixing Admixture
One of the hallmarks of MasterEmaco A 660 is its versatile dual-functionality on commercial construction jobsites. First, it serves as an exceptional bonding slurry primer when mixed with dry repair mortar or neat Portland cement. Applied with a stiff-bristle scrub brush into pre-dampened concrete pores immediately prior to mortar placement, this wet slurry forms an unbreakable molecular bridge between old aged concrete and newly cast repair patches.
Second, MasterEmaco A 660 functions as a full or partial mixing liquid admixture. Contractors dilute the concentrated polymer with clean potable water—typically at a 1:1, 1:2, or 1:3 ratio depending on project specifications—substituting the mixture for standard gauging water in repair mortars like MasterEmaco S series, standard shotcretes, stucco coats, and sand-cement screeds. This imparts superior trowelability, razor-sharp featheredge transitions, and enhanced impact abrasion resistance.
Compare mixing ratios and coverage rates for MasterEmaco A 660 application methods:
| Application Method | Polymer to Water Ratio | Mortar / Cement Blend | Practical Application Use |
|---|---|---|---|
| Bonding Slurry Primer | 1 Part A 660 : 1 Part Clean Water | Mix with neat cement or mortar to cream | Scrubbed into pores before casting repair patches |
| Heavy-Duty Modifying Admixture | 1 Part A 660 : 1 Part Water (1:1) | Use as gauging liquid for mortar mix | Industrial floor toppings, thin featheredge repairs |
| Standard Mortar Admixture | 1 Part A 660 : 2 Parts Water (1:2) | Standard repair mortar gauging liquid | Structural spall repairs, overhead & vertical patches |
| Stucco & Plaster Enhancer | 1 Part A 660 : 3 Parts Water (1:3) | Plaster sand-cement mix gauging water | Exterior stucco brown coats, masonry repointing |
Proper mechanical surface preparation ensures the slurry achieves maximum penetration.
Surface Preparation, Application Protocols, and Curing Guidelines
Achieving structural repair longevity with MasterEmaco A 660 requires meticulous concrete surface preparation following International Concrete Repair Institute (ICRI) standards. The existing substrate must be sound, structurally intact, and mechanically abraded to an ICRI Concrete Surface Profile (CSP) of 3 to 5 using grit-blasting, scarifying, or needle-scaling to expose clean aggregate. All oil, dust, efflorescence, and loose micro-fractured paste must be thoroughly removed.
Crucially, the concrete substrate must be saturated with potable water for several hours and brought to a Saturated Surface-Dry (SSD) condition prior to application. An SSD surface contains full internal moisture but zero standing puddles. When using A 660 as a bonding scrub coat, the repair mortar must be placed 'wet-on-wet' over the slurry; never allow the bonding primer to dry or become tack-free, as dried polymer acts as a bond breaker requiring re-abrasion.
How to Apply MasterEmaco A 660 Bonding Primer in 5 Steps
Follow these five ICRI-compliant concrete repair steps to prepare, prime, and patch concrete with MasterEmaco A 660.
Mechanically Prepare Substrate
Chip away deteriorated concrete to solid aggregate, establishing an ICRI CSP 3-5 profile with saw-cut square perimeter edges.
Achieve Saturated Surface-Dry (SSD) State
Soak the concrete cavity with water for 4 hours, blowing away standing surface puddles with oil-free compressed air.
Mix Bonding Slurry Thoroughly
Blend 1 part MasterEmaco A 660 with 1 part clean water, adding dry repair mortar until achieving a lump-free paintable cream.
Scrub Slurry into Concrete Pores
Work the slurry aggressively into the dampened concrete pores using a stiff masonry scrub brush, covering all contact surfaces.
Place Repair Mortar Wet-on-Wet
Cast the modified repair mortar immediately into the wet slurry before it skins over, troweling and wet curing with burlap.
Frequently Asked Questions (8 Questions Answered)
Q1: What is MasterEmaco A 660 used for?
It is an acrylic polymer bonding agent and admixture used to enhance adhesion, tensile strength, and freeze-thaw durability of concrete repair mortars.
Q2: What was MasterEmaco A 660 formerly called?
It was formerly marketed under the brand names Rheomix 141 and Concresive A 660 by BASF / Master Builders Solutions.
Q3: Can MasterEmaco A 660 be used as a standalone surface primer?
Yes, when mixed with Portland cement or dry mortar into a slurry; it should not be applied neat as a paint-on liquid without cement.
Q4: Is MasterEmaco A 660 re-emulsifiable in water after curing?
No, it is a non-re-emulsifiable acrylic polymer that forms an irreversible, water-resistant bond suitable for exterior wet environments.
Q5: What is the recommended dilution ratio for MasterEmaco A 660?
Typical dilution ranges from 1:1 (polymer to water) for severe industrial patches to 1:2 or 1:3 for general stucco and repair mortar admixtures.
Q6: What happens if the bonding slurry dries before applying the mortar?
If the slurry dries, it becomes a bond breaker; you must mechanically abrade and remove the dried film before re-priming.
Q7: Does MasterEmaco A 660 improve freeze-thaw resistance?
Yes, it seals microscopic capillary voids, preventing water intrusion and dramatically increasing cyclic freeze-thaw durability.
Q8: How should concrete repaired with MasterEmaco A 660 be cured?
Perform wet curing using moist burlap or polyethylene sheeting for 24 to 48 hours; avoid excessive rapid evaporation in direct summer sun.
Final Thoughts & Key Takeaways
In conclusion, understanding masteremaco a 660 provides essential clarity, practical strategies, and actionable advice. By incorporating these foundational insights, adhering to verified safety guidelines, and following structured best practices, you ensure reliable, long-term outcomes while preventing common mistakes. Stay informed, consult certified professionals when needed, and maintain consistent quality care.