Study On The Engineering Properties And Microstructure Of Calcium Lignosulfonate Stabilized Loess

Loess is a sediment with large porosity,weak cementation,poor water stability,etc.,often can not be directly used as a subgrade or foundation filler,need to be improved.Lignin,which has a large stock in nature,is an industrial by-product of the bioenergy and paper industries and is not used effectively.It is of great practical significance to carry out research on the improvement of loess by calcium lignosulfonate.In this paper,taking calcium lignosulfonate as the improver and aiming at improving the engineering properties and microstructure of loess,based on indoor experiments,the physical properties,mechanical properties and hydrological properties of the improved soil were studied,and the reinforcement mechanism was discussed in combination with the microstructure and mineral composition,and a comprehensive comparative evaluation was carried out with the conventional curing agent cement and lime.The findings are as follows:(1)Calcium lignosulfonate has a significant effect on the improvement of loess.The improved soil has greatly improved in terms of strength and impermeability,especially the improvement effect of high blending(5%,7%)lignosulfonate stabilized soil is particularly significant.(2)The unconfined compressive strength and shear strength of lignosulfonate stabilized soil show a tendency to increase first and then decrease with the increase of doping,5%to 7%of the doping amount reaches the peak,and the maximum strength can reach 5000k Pa;with the extension of the maintenance age period,the 28d change is stable;when the engineering application,5%is the optimal dosage,and 28d is the optimal maintenance age.(3)The permeability coefficient of the improved soil decreases with the increase of calcium lignosulfonates doping,decreases with the increase of age,and tends to stabilize in 28d.The disintegration time increases first with the increase of doping and then decreases,which is optimal at 7%,gradually increases with age,and reaches stability at 28d.(4)The microscopic characteristics of lignosulfonate stabilized soil show that calcium lignosulfonates forms a stable overall structure by filling pores and wrapping soil particles,and this cementing action is caused by the hydrolysis reaction,ion exchange reaction,protonation reaction and electrostatic attraction of calcium lignosulfonates and soil to form colloidal polymers.(5)The microstructure and reinforcement mechanism of lignosulfonate stabilized soil and cement stabilized soil and limstabilized soil are different,which is also the reason for the difference in the properties of improved soil engineering;the lignosulfonate stabilized soil curing agent is less mixed,and the shear strength of wood-calcium soil mixed with 5%to 7%is comparable to that of 3:7 ash soil,and it is higher than 10%cement soil,lignosulfonate stabilized soil has the advantage of strength and has good solidification performance;in terms of permeability,lignosulfonate stabilized soil performance is lower than that of gray soil,but it also reaches the order of 10^-6cm/s,with low-grade anti-seepage requirements,so the strength function is the mainstay.When the osmotic function is supplemented,lignosulfonate stabilized soil is a better backfill material.