Microscopic Stabilization Mechanism And Macroscopic Mechanical Strength Analysis Of Ionic Soil Stabilized Clay

Traditionally,the natural stone and gravel were widely used as the primary materials for road construction,however,concerns had been raised that it cost highly and polluted the environmental seriously during the processes of using these materials.Thus,for the sakes of cost saving and environment protection,natural soil resource is generally becoming popular used as the alternative material.The natural soil that widely distributed in Jinhua district of Zhejiang province is red low liquid clays which has poor physical properties(e.g.,low strength and large soil deformation)and could hardly meet the engineering requirements.Thus,it is vital to improve the properties of the natural soil before being used as road construction material.After comparing the applicability and effectiveness of the several kinds of stabilizers,the author attempted to adopt Ionic Soil Stabilizer(ISS)to improve the properties of the red clays.Firstly,the author conducted a series of physical,chemical and microstructure tests to explore the characteristic parameters of the microstructur of red clay and their variation regularities during the process of stabilization,and then understand the compressional character of ionic stabilized soil by unconfined compressive strength test.The results indicated that(1)the ISS which has high conductivity and strong acidity,could strengthen the cementation of the material containing iron ion and increase the strength of red clay;(2)the penetrant conductivity could be increased as the result of ion exchanging reaction between the stabilizer and the +1 cationics on the surface of clay particles;(3)the mineral particles of stabilized soil were contacted in the form of piece-piece,so that makes soil structure closer;(4)the X-ray diffraction atlas of the soil samples before stabilization were corresponded with that after stabilization,without new diffraction peak and eigen value,which indicated that there was no new mineral produced during the process;and(5)after stabilization,the soil aggregated,coagulated,and then gradually formed larger particles.It was worth noting that when the stabilizer content was 0.014%,the surface area and pore volume of soil sample particles reduced to the minimum values,while the compressive strength reached to the maximum value.Secondly,based on the microstructural structure character value and unconfined compressive strength,the author integrated the grey system and artificial neural network model to build the BP neural network model of the microstructural structure character value and unconfined compressive strength of the ionic stabilized soil.Therefore,the unconfined compressive strength of the ionic stabilized soil could be predicted by the microstructural structure character,and the attributing factors could be identified by grey correlation degree method.The results shows that there is a nonlinearity mapping among the strength influence factors,including the amount of ISS admixture,surface area,pore volume,plastic index,average pore size,and standard deviation of SEM angle.Consequently,the nonlinearity mapping BP neural network model could be used to predict the unconfined compressive strength of ionic stabilized soil.Thirdly,in order to further improve the strength of ionic stabilized soil,the author conducted a series of laboratory tests with using the stabilizer mixed with lkalic soil stabilizer(Portland cement and slaked lime)and ISS,and then explored the acting mechanism and effectiveness of the acidic-alkalic stabilizer.The findings included that(1)Portland cement and slaked lime could improve the strength of acidic ionic stabilized soil effectively;(2)the main improvement of strength came from the lime in the later curing time,while the Portland cement had power to provide the strength in the early curing time;(3)the lime could reduce the degree of compaction requirement in the ionic stabilized soil;and(4)there was an advantage period of stabilization superposition effect on the strength of the stabilized clay under the scenario of using acidic-alkalic stabilizer.Finally,the author assessed the performace of ionic stabilized soil and other materials by multi-level fuzzy comprehensive evaluation method considering several relevant factors,i.e.,material availability,construction requirements,load capacity,durability,energy consumption,environment protection,material cost,and service life.The result suggested that the ionic stabilized soil was the better than other road material if energy consumption and environment protection were focused more than other factors.