| Red mud-based light soil is a kind of foam light soil with red mud as the main cementitious material.It is used for the first time in the subgrade project of the test section of Shandong Zhanlin Expressway,which provides a new way to realize the resource utilization of red mud.However,in the actual application of roadbed engineering,red mud-based light soil is inevitably affected by various unfavorable natural factors in the environment.Under long-term action,mechanical properties may be deteriorated or even damaged due to poor durability,The durability of lightweight soil is highly valued by all parties in the project,and it is urgent to conduct systematic research on its durability and give a reasonable evaluation.In this paper,the Bayer process red mud is used as the raw material,and the red mud-based light soil is prepared by prefabricating foam through physical foaming.The influence of ash content on the relevant durability performance,and its internal mechanism is analyzed through microscopic test,which provides theoretical support for the relevant durability research and engineering application of red mud-based light soil in the future.The research results of this paper are as follows:The freeze-thaw cycle test studies show that: with the increase of freeze-thaw cycles,the weight of red mud-based light soil increases first and then decreases,and the compressive strength decreases continuously and then accelerates in the later period.The anti-freeze-thaw cycle performance of red mud-based light soil increases with the increase of density grade and decreases with the increase of red mud content,and when the content of red mud exceeds 50%,the anti-freeze-thaw cycle performance has a tendency to decline obviously;The addition of 3% and 6% silica fume can improve its anti-freeze-thaw cycle performance,while the addition of 9% silica fume is detrimental to its anti-freeze-thaw cycle performance;Microscopic tests have found that there are a large number of microcracks in the stomata wall of the red mud-based lightweight soil after the freeze-thaw cycle,and the stomatals are interconnected,and no other substances are generated,so the freeze-thaw damage of red mud-based light soil is a physical damage.The dry-wet cycle test research shows that: with the increase of the number of dry-wet cycles,the weight of the red mud-based light soil decreases continuously,and the compressive strength first increases and then decreases.The anti-dry-wet cycle performance increases with the increase of the density grad,but decreases with the increase of the red mud content.When the red mud content reaches 55%,the anti-dry-wet cycle performance decreases significantly;adding 3% silica fume can improve the its anti-dry-wet cycle performance is unfavorable when 6% and 9% of silica fume is added;through microscopic testing,it is found that there is a large amount of calcium alum in the pores and cracks of the red mud-based light soil after the dry and wet cycle,and the pulverized layer and the white salt layer can be found at the macroscopic level,so the dry and wet destruction of the red mud-based light soil is a complex physical-chemical destruction.The corrosion test of sodium sulfate solution shows that with the increase of immersion age within 120 d,the weight and compressive strength of red mud-based light soil show a continuous increase;the sodium sulfate corrosion resistance of red mud-based light soil increases with the increase of density;it decreases with the increase of red mud content;the addition of silica fume will reduce the corrosion effect;red mud-based light soil has good corrosion resistance,soaked in sodium sulfate solution for 120 d There are no cracks inside,and corrosion damage can not occur for a long time.The corrosion of sodium sulfate solution(within 120 days)is mainly a chemical reaction to generate ettringite. |
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