Six testing methods for common indicators of waterproof coatings

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China Paint Network News/ I. Film thickness inspection； The needle-penetration method should be used, with three points pierced per 100 square meters; their heights should be measured with a ruler and the average value taken. The film thickness should be greater than 2 millimeters. Use a colored pen to make marks during puncture for easy repair. II. Fracture elongation test: During waterproofing work, supervisors can go to the construction site and apply the mixed material in several layers onto a flat glass plate (the glass plate should be waxed first); the film thickness should be 1.2–1.5 millimeters. After leaving it there for 7 days, it is immersed in 1% alkaline solution for another 7 days, followed by drying in an oven at 50°C ± 2°C for 24 hours. A dumbbell-shaped tensile test is then conducted, with the requirement that the elongation retention rate reach 80% (compared to 200% for untreated samples). If the standard is not met, it indicates that the proportion of emulsion added during construction was insufficient. III. Water resistance test: Apply the coating to the cement blocks in several layers, achieving a film thickness of 1.2–1.5 millimeters. After allowing it to dry for 7 days, soak it in 1% alkaline solution for another 7 days; it is considered qualified if there is no delamination or bubbling. IV. Water impermeability test: When possible, instrumental testing should be carried out. The method involves preparing the coating in the appropriate proportions and applying it in multiple layers onto a glass plate (which has been waxed first), with a thickness of 1.5 millimeters. The plate is then left to stand for 7 days, after which it is placed in an oven at 50°C ± 2°C for 24 hours. Once taken out, it is allowed to rest for 3 hours before the water impermeability test is conducted; the required standard for water impermeability is 0.3 MPa. A failure to leak for 30 minutes is considered acceptable. If the necessary conditions are not available, the waterproofing effect can be checked visually by applying the coating to the non-woven fabric in 4–6 applications; once it has dried completely (after about 24 hours), the film thickness should be 1.2–1.5 millimeters. The resulting structure should be shaped like a box and hung in the air, with no dead corners remaining. Then, 1% alkaline solution is added to the box, and if there is no leakage after 24 hours, it is considered acceptable. V. Adhesion test: For G-type polymer waterproof mortar, an “8” shape mold can be used for direct molding, with demolding taking place after 24 hours. Soak it in water for 6 days, then cure it indoors at a temperature of 25°C ± 2°C for 21 days, and conduct a bonding test. G-type waterproof mortar: ratio of ash to water to adhesive = 1:0.11:0.14; the compressive strength of G-type waterproof mortar is 2.3 MPa. The R-type coating is mixed until it reaches a sesame paste-like consistency. This mixture is then applied to two semi-\"8\" shaped mortar blocks, and after 7 days have passed, a bonding test is conducted. For the R-type formula (high elasticity), the ratio of powder to adhesive is 1:1.4 ； (Shot), Powder:Glue = 1:0.8-1. The R value is 0.5 MPa; a value greater than or equal to the bonding index is considered acceptable. VI. Low-temperature flexibility test: Wax the glass plate, and apply the paint prepared at the construction site in several layers onto the plate, aiming for a film thickness of 1.2–1.5 millimeters. Once it has dried completely, remove the plate from the glass surface and place it indoors at a temperature of 25°C ± 2°C for 7 days. Then cut strips that are 120–150 millimeters long and 20 millimeters wide from the plate. Set the temperature of the refrigerator to -25°C and place the test strips inside for 30 minutes. Wrap them around a circular rod with a diameter of 10 millimeters once on each side; no cracks present indicate that the sample meets the requirements. The presence of cracks indicates that the emulsion does not have sufficient low-temperature flexibility. Note: Type G waterproof mortar is only subject to routine inspections, impermeability tests, and bond strength tests. Samples should be taken at the construction site to prepare test pieces, and the test pieces should be coated using the cross-hatching method. The film thickness per application should be 0.25–0.35 millimeters.