Experimental Study On Frost Resistance Of Road Structure Cement Concrete

Cement concrete pavement, bridge and other road concrete structures are facing serious freezing-and-thawing damages, because they have small sections and large contact areas with the natural environment, and suffer from both repeatedly traffic loads and poor natural environment at the same time. Besides, the using of deicers in winter accelerates their freezing-and-thawing damages. To enhance the overall level of air-entrained concrete design and frost resistance evaluation on concrete structures in road engineering, "MIC-840-01 automatic air-void characteristics analyzer" was initially introduced into China to measure the air-void parameters of hardened concrete, and rapid freezing-and-thawing experiment was performed to test the durability factors of the concrete specimens. On the foundation of extensive experimental study, the relationship between spacing factors and durability factors of concrete was advanced, the spacing factors as frost resistance evaluation index are made more precise specifications, and the guiding procedures and methods for evaluating on frost resistance of concrete structures with automatic air-void analyzer are also brought forth in the paper. Moreover, the effect of air contents, air-entraining agent types and water-to-cement ratio on air-void characteristics of hardened concrete was studied through a large number of laboratory tests to provide references and guides for designing air-entrained concrete, evaluating on air-entraining agent quality, making relevant standards and so on. At last, the high-frequency vibration rod was used to simulate concrete vibration on site to study the effect of high-frequency vibration on frost resistance of hardened concrete. The experimental results show that although high-frequency vibration leads to a great loss of air contents of concrete, as long as the time of high-frequency vibration is appropriately controlled, which can improve the air void system of air entrained concrete and has no negative effect on frost resistance of hardened concrete.