Filling layer self-compact concrete for resisting freezing and dynamic load coupling effect in severe cold regions

Abstract

The invention discloses a filling layer self-compact concrete for resisting the freezing and dynamic load coupling effect in severe cold regions. The filling layer self-compact concrete is formed by ordinary Portland cement, a composite mineral admixture, a deformation regulator, a workability improver, a durability guaranteeing component, water and a sand aggregate component, and the 56 d strength level is C40. After the filling layer self-compact concrete undergoes 300 cycles of freeze-thaw, the compressive strength loss rate is not more than 25%, the dynamic elastic modulus loss rate is less than or equal to 40%, and the mass loss rate is less than or equal to 2.3%; and after the filling layer self-compact concrete undergoes freezing-bending load coupling 100,000 times, the flexural strength loss rate is less than or equal to 10%. The self-compact concrete has the ability to resist freeze-thaw cycles and freeze-bending fatigue load coupling when used under freezing and dynamic load-resistant conditions in the severe cold regions, effectively reduces the damages of freeze injury and load coupling in the severe cold and freezing regions to high speed railway filling layers and other concrete structures, prolongs the service life of a ballastless track structure, and has significant technical and economic effects.

Description

technical field [0001] The invention belongs to the technical field of civil engineering materials, and in particular relates to a self-compacting concrete for high-speed railway ballastless track filling layer under the conditions of freezing resistance and dynamic load in severe cold regions. Background technique [0002] China's high-speed railway has developed rapidly in the past ten years. As of the end of 2016, the total mileage of high-speed railways reached 22,000 kilometers, accounting for 65% of the world's total mileage. The CRTS III slab ballastless track structure with independent intellectual property rights has gradually developed into China's high-speed One of the salient features of the main track structure types of railways is the use of self-compacting concrete as the filling layer material, which plays the role of support adjustment and limit control, which is crucial to the smoothness and safety of high-speed railway trains [1]. my country has a vast ter...

AI Technical Summary

Problems solved by technology

[0003] At present, although many domestic and foreign scholars have conducted a lot of research on the frost resistance of concrete, it has been shown that the freeze-thaw cycle has a serious impact on the durability of concrete; Although the static mechanical properties of concrete can be improved to a certain extent [3-6], under the action of dynamic load and freeze-thaw cycle, the mechanical properties of concrete will be significantly deteriorated [7-12], compared with the single freeze-thaw cycle The rate of deterioration is greater

Some researchers have also tried to improve the performance of concrete against freeze-thaw cycle damage by adding fibers and air-entraining agents [13-14], but the effect is still limited; especially for long-term freezing-dynamic load coupling However, the research on the durability of concrete has not been reported yet. Judging from the existing practice in our country, under the action of freezing-dynamic load, the concrete has undergone obvious surface spalling damage in a short period of time (such as figure 1 ), how to improve the durability of concrete under negative temperature and freezing in severe cold areas under the dynamic load of trains has become a major challenge for the construction of high-speed railways in my country

Images