All our waterstops are manufactured in accordance with national standards and have undergone strict tests before leaving the factory to ensure high quality. However, the quality of waterstops on the market varies widely. You may use the following method to check whether bentonite swellable waterstops are qualified.
Volume expansion rate
Bentonite swellable waterstops are further divided into C type (expansion type) and S type (slow expansion type).
The average value of three samples is taken as the volume expansion rate, and is calculated as follows:
According to the equation aforesaid, calculate the volume expansion rate at corresponding period. The results that meet the following technical data are considered as qualified.
Prepare three samples with a length of 100 mm. These samples were passed through a wire and suspended in an oven at 80 °C for 2 h. Observe whether the heated samples have flow trace. If three samples have no flow trace, it is considered as qualified.
Low temperature resistance
Prepare three samples with a length of 150 mm. Lay these samples flat and a metal rod with a diameter of 20 mm in a refrigerator at -20 °C for 2 hours. Open the refrigerator door, place the frozen samples on the metal rod surface within 3 seconds. Wind these samples around the metal rod at 180° and take them out. Observe these samples with a 5x magnifying glass. The three samples are considered as qualified if there is no crack on the surface.
|Material||Test Item||Technical Index|
|C Type||S Type|
|Bentonite Swellable Waterstop||Volume expansion rate within specified period||4 h||200% – 250%||—|
|24 h||—||200% – 250%|
|Maximum volume expansion rate (%)||≥ 4 00||≥ 300|
|Heat resistance||80 °C, 2 h, no flow|
|Low temperature resistance||-20 °C, 2 h around φ 20 mm round rod, no crack|
Only when all technical indicators are met, it can be deemed as qualified. If an indicator fails to meet the technical requirements, double samples shall be prepared for retest. If the test result is unqualified, this batch of products is considered as unqualified.
All our products are produced in strict accordance with national standards, and each batch of products will be tested before leaving the factory. Corresponding test report will be provided, you can buy these waterstops without worry.