Study On Road Performance Of High Liquid Limit Clay Improved By Lignin

High liquid limit clay has high content of fine particles,uneven grading distribution and poor compaction,which leads to insufficient structural stability of its own;at the same time,its unique high liquid limit,high plasticity index and high natural water content characteristics are easy to cause uneven settlement of the foundation,which has a very serious impact on the overall stability of the road structure.Nowadays,environmental problems are becoming increasingly prominent.It is particularly important to find a new type of improver that is economical,efficient,and environmentally friendly.Among them,soil reinforcement technology based on industrial by-product lignin has become one of them.Based on the lushan Avenue-Zhangxin Road Interflow project in Zibo city,this paper takes the high liquid limit clay widely distributed along the project as the research object,and USES lignin sulfonate and quicklime as the modifiers to improve it,and carries out the experimental research on the improvement of subgrade filler.The main research contents and conclusions are as follows:(1)Physical and mechanical properties of high liquid limit clay.Natural moisture content test,particle analysis test,limit moisture content test,specific gravity test,compaction test,unconfined compressive strength test,CBR test,direct test soil Shear test,rebound modulus test and unconfined compressive strength test have mastered the basic physical and mechanical properties of the test soil.Studies have shown that the high liquid limit clays distributed along the Lushan Avenue-Zhangxin Road Interconnection Project in Zibo City have poor mechanical properties such as bearing ratio and rebound modulus,which do not meet the requirements of roadbed filling.(2)Improvement method of high liquid limit clay.Through calcium lignosulfonate,sodium lignosulfonate,quicklime,6% quick lime + calcium lignosulfonate,6% quick lime +sodium lignosulfonate.Comparing the five improved methods,it was found that the calcium lignosulfonate improved soil improved significantly,while being friendly to the surrounding environment,and was determined as the best improvement method.(3)Physical and mechanical properties and micro characteristics of modified soil with calcium lignosulphonate.Related physical and mechanical tests and micro-characteristic tests are carried out on the calcium lignosulfonate improved soil to evaluate the physical properties,mechanical properties and microstructure changes of the improved high-liquid limit clay.Compared with the original high-liquid limit clay,the improved soil has improved physical properties after a period of curing,and the mechanical properties have been greatly enhanced.The cement formed by the calcium calcium and clay minerals can effectively fill the pores and make the connection between the soil particles closer.According to various indicators,the optimal amount of calcium lignosulfonate is 3%.(4)Durability of calcium lignosulfonate improved soil.Dry-wet cycle test and freeze-thaw cycle test were carried out on the lignin-modified soil,and the limestone modified soil was used as a comparative experiment to explore the influence of the changes in the external environment on the stability of the improved soil.When the dry and wet environment alternates,the durability of wood calcium improved soil is better than quick lime improved soil;during the temperature rise and fall,the calcium lignosulfonate modified soil has a higher frost heave rate and strength loss rate,and the frost resistance is not as good as the quicklime-modified soil.