Study On The Mechanical Properties Of Special Concrete Applied To The Low-grade Highway In The Agricultural And Pastoral Areas

With the development of road construction in China,rural roads,as the support of trunk roads,have been paid more and more attention.Due to the restriction of construction economic and social conditions,there are some problems in Xing'an League rural road,such as the construction materials are inconsistent with the engineering requirements,the coarse aggregate size is too large and the aggregate grading is single.Based on the principle of"local materials,economic and applicable",combined with local construction conditions,the effective improvement of the original materials is of great theoretical significance and practical value for reducing the project cost and protecting the environment.In view of the current situation of Xing'an League rural road,this paper makes full use of the local pebble,sand,cement,fly ash and slag,finds out the material mix proportion that meets the strength requirements and has good performance through mix proportion design,and carries out concrete indoor test and numerical simulation,This paper analyzes the influence of fly ash content,slag content and aggregate grade on the performance of concrete from macro and micro aspects.The main research contents are as follows:1.Based on C30 concrete,the basic mechanical properties of concrete are studied by changing the gradation of large size pebble by adding fly ash and slag,The results show that the compressive strength,tensile strength and flexural strength of concrete are improved by adding fly ash and slag,At the same time,the compressive strength,tensile strength and flexural strength of the concrete increase first and then decrease with the increase of the content of small and medium stones in the large size aggregate gradation.2.The microstructure of 28d concrete was tested by mercury porosimetry,and the correlation between microstructure and macro performance was analyzed,The lower the porosity of concrete is,the denser the concrete is,the higher the flexural strength of concrete is,Finally,through regression fitting of experimental data,it is found that the model constructed by hasselman formula has the highest fitting degree and the best effect.3.ANSYS is used to simulate the four point bending beam,to build the concrete internal aggregate,and to realize the rapid generation of aggregate,to reveal the internal stress state and internal damage evolution process of concrete from the micro perspective,The results show that the stress distribution in the concrete is different.The area of the non stress chain with the gradation of 60%:40%is the largest,the aggregate is the largest,and the bearing capacity of the concrete is better.With the damage under the action of external force,the cracks gradually extend,and the expansion of concrete with different grades is different...