Along with the development of science and technical,the development of polycarboxylate superplasticizer have rapid growth recent years,it have widly use in concrete construction.Althought it have good waer reducing effect and use convenience ,But in practical application , have some special problem itself.
Scientific experiments have show that:
Polycarbolic acid superplasticizer temperature sensibility:
The same mix ratio,the same amount of water reducer,with the rise of temperature,cement hydration degree increases,the consumption of water increses,the fluidity of concrete mixture shows a down wardtrade.
The relationship between temperature and the effect of polycarboxylic acid superplasticizer on hydration degree of cement:
At low temperature, cement hydration rate decreases, and polycarboxylic acid superplasticizer has the greatest retarding effect on cement paste. At high temperature, cement hydration speed is accelerated, and polycarboxylic acid water reducer has little retarding effect on cement paste.
And compared under the condition of room temperature (20 ℃), with the reduction of temperature with the cement hydration rate significantly decreased, which results in the decrease of the activity of water reducing agent on the properties of concrete mixture effect is greater than that of cement hydration speed to reduce the effect on the performance of concrete mixture, delayed reaction happened, created a slump when the increase of strange phenomenon; On the contrary, with the increase of temperature, cement hydration speed accelerated, cement hydration speed on the performance of concrete mix is greater than the effect of the activity of water reducer on the performance of concrete mix, resulting in the initial state of concrete not only can not meet the design requirements, but also have obvious slump loss.
In order to meet the requirements of site construction, it is of great significance to grasp the change law between temperature and polycarboxylic acid superplasticizer when concrete mix ratio is used, and to make accurate and timely adjustment according to the change of season and temperature, so as to better guide construction and ensure the quality of the project.