The early strength of cement mixed with retarding materials is not as good as that without retarding materials. This is because the incorporation of retarding materials effectively delays the early hydration of cement, hinders the formation and development of the initial structure of slurry, making the 3-day compressive strength of concrete relatively low. With the full hydration of cement, The hydration products are fully interpenetrated, overlapped and filled, and the structure is dense, so that the compressive strength of the concrete at the later age is higher than that of the reference concrete.
Because there are many kinds of retarding materials, different retarding agents have different effects on the performance of concrete. Retarding material variety and collocation or mixed with improper use, not only will affect the workability of concrete will also appear abnormal concrete setting time and finally lead to strength problems, in the selection of retarding material type should be fully considered with the adaptability of concrete raw materials but also consider the construction season, economic cost and other factors, After determining the required retarding retarding materials, we should choose to use alone or mixed according to the characteristics of various retarding materials to find out the best range of mixing amount. From the test in this paper, we can see that the use effect and economic effect of double mixing sodium gluconate and white sugar are the best.
