Study On Water Stabiliyt And Mechanical Properties Of Soda Residue Geopolymer For Subgrade Soil

In order to consolidate the soda residue and improve the water stability of the soda residue,chose to solidify the soda residue by the geopolymer gel.The paper makes full use of two kinds of waste material of soda residue and fly ash,and tries to add a variety of alkaline activator.Through the experiment,the comparison and analysis of several parallel test groups are carried out,and also studied the water stability,mechanical properties and microscopic appearance of soda residue mixing soil under the optimal ratio.The main research content as follows:1.For the preparation of geopolymer which is based on fly ash to strengthen soda residue,we mixed soda residue with fly ash.And then added three kinds of alkaline activators,Na₂SO₄,NaOH and Na₂SiO₃.Through unconfined compression strength test and immersion test,the optimum ratio is SR:FA=8:2 added to Na₂SiO₃ 2%,and the sample is configured without covering treatment.The soda residue mixed soil under various alkaline activators was analyzed by scanning electron microscope（SEM）.The test results show that:in the process of sample preparation,because of the effect of geopolymer,the strength of preparing sample directly is higher 2～3 times than covering the material the whole night before preparing sample;The excitation effect of Na₂SiO₃ to fly ash is better than NAOH,And the excitation effect of NAOH to fly ash is better than Na₂SO_4.2.Through laboratory tests,the water stability of the soda residue mixing soil under optimum ratio was studied.The results show that with the increase of soaking time and the increase of dry wet cycle times,the strength of soda residue mixing soil shows a steady trend,and the stability of the water stability of the sample with age of 60 days is very stable.Through the dry and wet freeze-thaw cycle test,the loss of strength between the two groups of samples is 8%,but the loss of mass is not much.It was proved that the number of freeze-thaw stability of soda residue mixing soil was 6 times,and the frost stability coefficient was 56%under freeze-thaw stability times.3.The mechanical properties of soda residue mixing soil under optimum ratio were studied through experiments.The results showed that the strength growth rate of soda residue mixing soil increased fast at the first and then slowed down with the long age of the unconfined compressive strength test.Through direct shear test,the c=279.78kPa and φ=63.76°of soda residue mixed soil was measured,and the CBR of soda residue mixed soil was 28.91% and the expansion amount was 0.28% through CBR test.