Study On The Improvement Of Mechanical Properties Of Carbonate Soil In Cold Regions By Calcium Lignin Sulfonate-fly As

With the continuous improvement and development of transportation infrastructure in China,many infrastructure facilities need to be built every year in the carbonate saline soil area of Northeast China.However,due to the special physical properties of carbonate saline soil such as salt swelling,erosion,dissolution,and dispersion,it has caused many adverse effects in engineering construction,resulting in an increase in engineering costs.Lignin,as a misplaced resource,is discharged into rivers or incinerated as waste in some industries without being utilized.This not only causes environmental pollution,but also leads to significant waste of available resources.In China,the fly ash produced by coal-fired fossil-fuel power station is mainly used as raw materials for the production of cement,concrete,fly ash bricks and other building materials.How to make good use of these reusable resources has become a new research topic nowadays.Using silty clay from a certain area of Harbin City as a soil sample,carbonate saline soil was prepared by adding sodium bicarbonate(1.00% by mass of saline soil);Adding different mass ratios of calcium lignosulfonate and fly ash to carbonated saline soil respectively,using the sample striking method to prepare standard soil test samples;After a certain number of freeze-thaw cycles of soil samples,the unconfined compressive strength test was conducted using a microcomputer controlled electronic universal testing machine;The effects of calcium lignosulfonate and fly ash on the frost resistance and unconfined compressive strength of carbonated saline soil were analyzed.Then,microscopic analysis is performed by SEM.The results show that calcium lignosulfonate can improve the frost resistance of carbonate saline soil,and its optimal addition amount is 0.75% of the mass ratio of saline soil;Fly ash can improve the unconfined compressive strength of carbonate saline soil,and its optimal addition amount is 3.00% of the mass ratio of saline soil;The combined improvement of both calcium lignosulfonate 0.75% and fly ash 1.00% can take into account the advantages of improving carbonate saline soil when both are added separately.