Polycarboxylate superplasticizer is known as the fourth generation of superplasticizer. It has the characteristics of small dosage, high water reducing rate, good slump retention performance, strong adaptability with cement and small shrinkage of concrete. In this way, the first-time users feel that the superplasticizer is more convenient, safe and efficient than previous generations. But any product, in the process of using, will more or less encounter some problems, the following are some problem cases and solutions
It is not suitable for a cement seriously. The concrete sent to the site cannot use a famous brand cement in the area where a mixing station is used, and the QL P · o42.5r cement is used to supply C50 concrete to a site. Polycarboxylic acid system superplasticizer is used. When making concrete mix ratio, it is found that the amount of water reducing agent used for the cement is slightly more than that of other cement, but when it is actually mixed, The slump of the concrete mixture is 200 mm visually measured. When unloading the concrete into the concrete pump truck at the site, it is found that the concrete of the truck can not be discharged. After notifying the factory to send a bucket of water reducing agent to the plant for mixing, the slump is 170 mm visually, which can basically meet the pumping requirements. However, when the concrete is discharged for about 1 cubic meter, it can not be discharged. The concrete of the truck is returned to the factory immediately, Add a large amount of water and a small amount of water reducing agent to release, and almost solidify in the mixer.
Reason: did not insist on each batch of cement before opening to do with admixture adaptability test.
1. Each batch of cement shall be tested with construction mix proportion before opening.
2. Avoid using coal gangue as admixture of cement and polycarboxylate superplasticizer to prepare concrete as far as possible.