Mechanical Properties and Frost Resistance Durability of Early Frozen Cement Concrete in Alpine Regions
The newly poured concrete in alpine areas is susceptible to frost damage,which leads to potential safety hazards in pavement structure and limited service life.Three groups of C30,C40 and C45 cement concrete specimens were prepared with the actual construction materials in Tibet.The specimens were cured in a standard curing room for 0,3,7,and 28 days,and then cured outside for 150 days.The changes of their compressive strength,flexural strength and dynamic modulus of elasticity were studied,and 300 freeze-thaw cycles were performed on the specimens naturally cured for 150 days.It is found that when the concrete with the standard curing age of 28 days is considered to be free from freezing,the increase of the standard curing age can effectively improve the frost resistance of the concrete at the initial stage of service and that the probability of the concrete being frozen decreases with the increase of the curing age.The addition of fly ash and antifreeze enables the concrete naturally cured for 150 days to withstand 275～300 freeze-thaw cycles.After 250 freeze-thaw cycles,there are obvious macropores and cracks emerging in the concrete,and its frost resistance index decreases rapidly.The established freeze-thaw damage degree transformation formula can quickly predict the mechanical properties of concrete buildings with different service life in alpine regions.The prediction can provide theoretical support for the safety evaluation of buildings in operation.
万方数据
维普
