INTRODUCTION
Reducing the construction schedule is becoming more and more critical to complete concrete repair projects on-time or ahead of schedule. When a waterproofing system is required to be applied over a newly-placed concrete repair material, membrane applicators are generally unaware of the optimal time-frame for applying a membrane on to King Construction Products which ensure early return-to-service. In this context, a study was undertaken to determine the earliest possible time after placement that a given waterproofing system can be applied to the surface of certain King Construction Products. In order to ensure a successful adhesion between the applied membrane and the King Construction Products, the products must first be tested for compatibility and a sufficient bond strength must be developed.
MATERIALS
The King Construction Products tested for rapid membrane application and adhesion are listed and briefly described in Table 1. For each King Construction Product, four (4) different SOPREMA Waterproofing Systems (including the primer and membrane) were applied at different times/ages after concrete placement, and then tested for adhesion. The four (4) SOPREMA Waterproofing Systems (primer and membrane) tested are listed in Table 2.
METHOD
For each King Construction Product, several batches were prepared and placed at 20 °C in 600 mm x 600 mm (24” x 24”) by 50 mm (2”) thick, wooden molds. The concrete surface was then roughly finished using a wood-float and covered with a plastic sheet until the considered primer and membrane were applied at different times/ages, as noted in Table 3. Neither wet nor dry curing was performed on the concrete specimens before membrane application, the surface was only covered with a plastic sheet, and the specimens were kept at 20 °C until membrane application. Any excess water present on the concrete specimens caused by condensation was removed prior to the application of the primer.
After each curing period, the primers and membranes utilized in this testing program were applied, at 20 °C, to the surface, in accordance with the recommendations provided by SOPREMA. For each specimen, the bond strength between the King Construction Product and SOPREMA membranes were tested at 7 days after membrane application, using a portable pull-off tester (Elcometer 106-6) in accordance with ASTM D 4541.
TABLE 4: *Bond strength requirement for the adhesive bond of an elastomeric membrane used for Parking Structures in accordance with CAN/CSA-S413-14. **Bond strength requirement for bitumen-based self-adhesive membranes used as air barrier material as per the Air Barrier Association of America (ABAA). ***Average bond strength values obtained for heat welded membranes applied over concrete slabs.
TABLE 5: *Bond strength requirement [>1.4 MPa (203 psi)] for the adhesive bond of an elastomeric membrane used for Parking Structures as per CAN/CSA-S413-14. **Bond strength requirement (>16 psi) for bitumen-based self-adhesive membranes used as air barrier material as per the Air Barrier Association of America (ABAA). ***Average bond strength values [>0.43 MPa (62 psi)] obtained for heat welded membranes applied over concrete slabs.
RESULTS AND RECOMMENDATIONS
The bond strength test results measured for the four (4) SOPREMA membranes, applied at different times/ages over each King Construction Product, are reported in Table 4. According to the bond strength results reported in Table 4, a satisfactory adhesive bond can be achieved using the combined SOPREMA Waterproofing System and selected King Construction Product, even when membrane application is performed at a very early age after concrete placement.
In conclusion of this study, Table 5 summarizes the minimum curing time required before applying the indicated SOPREMA primer/membrane system over the indicated King Construction Product, while satisfying the bond strength requirements considered for each membrane type.