Test Research Of Effects Of Cement Content On Frost Resistance Of Concrete

Antifreeze is very important to the durability of concrete, the durability of concrete has been frozen form of a typical representative of deterioration, and frost resistance and durability of concrete is closely related to other aspects. Antifreeze properties of concrete are many factors, but the amount of cement is one of the most important influencing factors, it is the subject of a study on this issue, that is, to explore the amount of cement on the properties of concrete frost resistance.A total of 12 sets of concrete design, namely, non-air-entraining agent, without admixture of the 3 groups of concrete (water-cement ratio 0.35,0.40,0.45, respectively), no air-entraining agent, incorporation of 3 groups mixture of concrete (water-cement ratio 0.35,0.40,0.45, respectively), introduction of air-entraining agent, without admixture of the 3 groups of concrete (water-cement ratio 0.35,0.40,0.45, respectively), as well as air-entraining agent incorporation, incorporation mixture 3 groups of concrete materials (water-cement ratio 0.35,0.40,0.45, respectively). Designed for 12 sets of concrete, according to "ordinary concrete long-term performance and durability testing methods" (GBJ82-85), to carry out concrete freeze-thaw cycle tests under different conditions to identify the different frost resistance of concrete to meet the minimum requirements of cement.Pilot studies have shown that:(1) In the absence of air-entraining agents and without admixture, the concrete of the highest number of freeze-thaw cycle 50, instead of cement corresponding to the minimum value of 240 kg/m3 (water-cement ratio 0.35) and 240 kg/m3 (water-cement ratio 0.40).(2) In the absence of air-entraining agent and admixture incorporation circumstances, the concrete of the highest number of freeze-thaw cycles 75 times, with the corresponding value of the minimum amount of cement 240 kg/m3 (water-cement ratio 0.35) and 260 kg/m3 (water-cement ratio 0.40 and 0.45).(3) The introduction of air-entraining agents and without admixture, the water-cement ratio is 0.35, the highest concrete freeze-thaw cycles for 225 times, instead of cement corresponding to the minimum value of 260 kg/m3; water ash ratio of 0.40, the concrete freeze-thaw cycles the maximum of 200 times, instead of cement corresponding to the minimum value of 280 kg/m3; water-cement ratio of 0.45, the highest concrete freeze-thaw cycles for 175 times, instead of cement should be relatively the amount of the minimum value of 300 kg/m3.(4) air-entraining agent in the incorporation and mixing of the mixture, the water-cement ratio 0.35 and 0.40, the different amount of cement concrete are freeze-thaw cycles the maximum of 300 times. Water-cement ratio of 0.45, the concrete of the highest number of freeze-thaw cycle 275 times, instead of cement corresponding to the minimum value of 260 kg/m3.It can be seen that the same water-cement ratio, with the increase in cement, concrete antifreeze performance; a certain amount of cement, along with the increase in water-cement ratio, concrete antifreeze less; the incorporation of fly ash or primer air-entraining agent can improve the mixing of the antifreeze properties of concrete; fly ash and air-entraining agent will at the same time mixing the antifreeze properties of concrete was significantly improved.In this study, the different circumstances of the minimum amount of cement, on the one hand, from theory, as an ordinary concrete mix design to provide a scientific basis; On the other hand, works in the concrete practice of freezing the project to provide a reliable basis for evaluation.