Concrete admixtures are essential components of high performance concrete. The selection of admixtures directly affects the functional properties of concrete.However, in order to achieve the expected performance of concrete, it is necessary to understand the selection principles and methods, as well as the precautions in the use process, and take relevant adjustment measures when problems occur.
In accordance with the performance of concrete and construction requirements to choose the types of concrete admixtures.
In order to achieve the concrete pumping, spraying and other new construction technology, it is necessary to apply admixtures, in order to achieve the construction of special projects, according to different engineering requirements and construction technology to choose admixtures.
Ordinary superplasticizer is used in general concrete, high efficiency superplasticizer is used in early strength and high strength concrete;In the condition of higher air temperature, retarder or water reducer with larger air entrainment is generally used, while in the condition of lower air temperature, composite early strong water reducer is often used.Low temperature, especially negative temperature construction should use antifreeze;Waterproof requirements, the use of impermeable agent and waterproof agent;Pump concrete construction should be mixed with pumping agent.
According to the characteristics of various admixtures and engineering characteristics to choose admixtures, generally should not be used in place of each other, otherwise the effect is not obvious or no effect, even negative effects.
The selection of admixtures according to the supplier's production technology level, economy, convenience and other factors.
Admixture factory if directly to the commercial concrete mixing plant to provide water products, admixture quality is relatively guaranteed.However, if the admixture factory provides powder products, then concrete mixing station to mix.
Admixture type can be determined according to the adaptability between cement and admixture.
Engineers in the selection of admixture, must first cement and admixture adaptability test, determine that concrete can achieve its due performance, can use this admixture.