Method For Fast Determining The Water Reducing Rate Of Polycarboxylate Superplasticizer

The water reducing rate is an important indicator of water reducing agent, which is generally used to characterize the effects of the water reducing agent. Currently, the water-reducing rate is mainly measured in the laboratory according to the national standard. However, water reducing rate, when tested in the laboratory, has special requirements for raw materials. This will lead to its deviation from the actual water-reducing rate tested in the construction site. Therefore, the construction site urgently needs a test method that can quickly and accurately reflect the actual concrete water reducing rate.This paper mainly researched and discussed the national standard mortar method, respectively studied the influence of gelled material and sand in concrete raw materials for water reducing rate. The results showed that:The compatibility of cement and water reducing agent has a direct impact for water reducing rate.With the increase of mineral powder dosage, the water reducing rate increase continuously. When the dosage of fly ash is 0-30%, the water-reducing rate increases along with the increase of the dosage of fly ash. When more than 30%, the water reducing rate remained unchanged with the increase of the dosage of fly ash.The fineness modulus of sand has an obvious effect on water reducing rate, while the type has little influence on water reducing rate. When mud powder or mountain flour contained in the sand, the water-reducing rate has a tendency to decrease. According to the above results, a rapid method for the determination of water reducing rate can be put forward. That is, When the sand distribution area at all levels to meet specific mass ratio,under the condition of a good compatibility of cement and water reducing agent and according to the types and fineness modulus of sand, select a reasonable sand cement ratio, which can be used, combined with cement mortar, to determine the water-reducing rate. If the fineness modulus of sand is beyond the scope of regulation, a simple screening is needed. In this method, the mud powder content need to be controlled within 2%, the mountain flour content need to be controlled within 12%. If beyond the scope, sand washing is needed, until it reached within the standard.