RHOPLEX™ CS-3800 VOC-Compliant Concrete Cure Membrane Formulation and Test Data
Rhoplex™ CS-3800 is a styrene-acrylic copolymer designed for use in concrete curing membrane formulations. For many years, formulation CCM-38-1 (based on Rhoplex™ CS-3800) has been recommended for cure membrane applications to meet the ASTM C-309 water retention requirement of <0.55 kg/m2 at a coverage rate of 200 ft2/gal. CCM-38-1 contains only 20% solids, and is therefore a very economical choice for cure membrane applications.
With a minimum film formation temperature of 45°C, Rhoplex™ CS-3800 is not a film former at room temperature. A coalescing agent is required to achieve optimal performance properties. Formulation CCM-38-1 contains propylene glycol phenyl ether (Dowanol PPh), which has been found to be an optimal coalescing solvent for Rhoplex™ CS-3800. The 3.2% Dowanol PPh level in formulation CCM-38-1 translates into a volatile organic compound (VOC) level of 148 g/L. However, at this VOC level, formulation CCM-38-1 does not meet the current South Coast Air Quality Management District (SCAQMD) limit of 100 g/L.
Formulation CCM-38-100 shown below has been developed by Dow Construction Chemicals and features:
- A calculated VOC of 93 g/L, thereby meeting the current SCAQMD limit of <100 g/L
- Good low temperature film formation, with MFFT < 0°C
- 20% solids, while still meeting the ASTM C-309 specification of <0.55 kg/m2
Optifilm 400 plasticizer was used to achieve a formulation at <100 g/L, while maintaining good low temperature film formation and cure membrane performance. It may be possible to achieve these features with other plasticizers, but only Optifilm 400 has been qualified at this time.
| Concrete Cure Membrane Formulation Suggested Starting Sample Formulation With RHOPLEX™ CS-3800 CCM-38-100 |
|
| Material | Parts by Weight |
| Water | 52.18 |
| RHOPLEX™ CS-3800 (45% solids) | 44.44 |
| Dowanol PPh | 2.00 |
| Optifilm 400 (plasticizer) | 1.00 |
| Foamtrol 14L (defoamer) | 0.033 |
| Lodyne S-100 | 0.027 |
| Aqueous ammonia (28%) | 0.32 (pH 9.0) |
| Total weight | 100.00 |
Note: Please see Suggested Co-Suppliers for co-supplier raw material information located on the customer e-center. Or, for more information, email dowconstructionchemicals@rohmhaas.com. If using Zonyl FSJ (instead of Lodyne S-100), use 0.017 parts by weight in the above formulation.
| Formulation Parameters | |
| Solids content | 20 weight % |
| Coalescent/Plasticizer content | 3.0 weight % (15% on polymer solids) |
| pH | 9 |
| Density, lbs./gal. | 8.46 |
| VOC, g/l | 93 |
| MFFT (°C) | <0 |
RHOPLEX™ CS-3800 Performance Data for Concrete Cure Membrane Formulation CCM-38-100
The ASTM C-309 test requires the preparation of samples of fresh concrete coated with the concrete curing membrane being tested. Although the name of the test is water retention, the results are expressed in terms of water loss from the samples after 72 hours of cure at 100°F and 32% relative humidity. A lower number indicates better water retention performance. ASTM C-309 requires a maximum of 0.55 kg/m2.
The table below contains water retention results tested by an independent test lab1. Formulations were applied with a sprayer to fresh concrete 100 minutes after mixing the concrete at a 200 ft2/gallon spread rate. The concrete test specimens were formed in cylindrical cups of 160 mm diameter (surface area = 20100 mm2) x 35 mm height as specified in ASTM C-156. Formulation CCM-38-100 passes the ASTM C-309 specification with a water loss of 0.49 kg/m2 (statistical p-value of p<0.05). For comparison, formulation CCM-38-1 was run side-by-side with CCM-38-100 and found to have a water loss of 0.39 kg/m2. A statistical comparison of the cure membrane data shows that CCM-38-100 has a higher water loss than CCM-38-1, but it is still clearly passes the ASTM C-309 specification of <0.55 kg/m2.
| Formulation | Water Retention in kg/m2 |
| CCM-38-100 based on RHOPLEX™ CS-3800 at 20% solids and 93 g/L | 0.49 ± 0.03 |
| CCM-38-1 based on RHOPLEX™ CS-3800 at 20% solids and 148 g/L | 0.39 ± 0.03 |
1 Bee Laboratory, 570 Payne Branch Rd., Blowing Rock, NC 28605
2 Mix ratios: 0.4 parts water, 1.0 parts cement (cement source: Saylor's), 2.5 parts sand
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