Study On The Optimal Design And Road Performance Of An Industrial Waste Residue Composite Soil Stabilizer

With the rapid development of coastal construction projects in domestic,the waste muddy clay is increasing day by day.This kind of waste silt soil has the characteristics of high natural water content,high compressibility and low bearing capacity,which is not conducive to practical engineering application and causes accumulation problems.Therefore,the solidification treatment of this kind of waste soil has attracted the attention of various engineering fields in society.In addition,the output of industrial waste residue is increasing day by day,and its utilization rate is relatively low.Thus,industrial waste residue has caused great obstacles and losses to the development of human society and environmental protection.In this paper,aiming at two problems,namely,the solidification of waste muddy soil and the improvement of the resource utilization of industrial waste residue,an alkali-activated curing agent with industrial waste residues: ground granulated blast furnace slag(GGBS),calcium carbide slag(CCS)and desulfurization gypsum(DG)as raw materials is proposed to solidify waste muddy clay in Wenzhou,which will help the low-carbon development of traffic construction in coastal areas of Zhejiang Province.Firstly,the response surface method(RSM)was used to experiment design for the ratio of soil stabilizer,and the influence of different industrial waste ratios on the UCS of solidified soil through the unconfined compressive strength(UCS)test and the best ratio of industrial waste solidify materials were studied.On the basis of determining the best soil stabilizer parameters,the effects of soil stabilizer content,initial moisture content and curing time on the UCS and tensile mechanical properties of solidified soil were explored;Then the durability of its solidified soil is evaluated by water stability test,freeze-thaw test and dry-wet cycle test,and compared with cement solidified soil;Finally,the influence and mechanism of industrial waste residue composite curing agent on the microstructure of muddy clay were studied by scanning electron microscope and X-ray diffraction.The main results of this study are as follows:(1)In this Study,the three factors and three levels design scheme based on Box-Behnkend design(BBD)in RSM was adopted for the mixture ratio test of soil stabilizer.The optimal mixture ratio(OMR)of industrial waste residue composite soil stabilizer(GCD soil stabilizer)was determined to be 61 ∶ 31 ∶ 8 through UCS test and optimization verification.(2)Though UCS test and splitting tensile strength test,it can found that: on the basis of the determined OMR of GCD soil stabilizer,the unconfined compressive strength of GCD solidified soil and cement solidified soil were increased with the increase of GCD soil stabilizer and cement dosages.Under the same dosage condition of GCD curing agent and cement,the early strength of soil stabilized with GCD soil stabilizer was lower than UCS of soil stabilized with cement,but the strength of GCD solidified soil was exceeded that of cement solidified soil in the later stage.The UCS of GCD stabilized soil and cement stabilized soil were increased with the increase of curing age.Compared with cement stabilized soil,the UCS of GCD solidified soil was increased more than that of cement solidified soil in the later stage;Also,the splitting tensile strength(STS)of GCD and cement solidified soils were increased with the increase of soil stabilizer dosages,and under the same conditions,the STS of soil stabilized with GCD soil stabilizer was obviously higher than STS of soil stabilized by cement,that is,GCD stabilized soil had more effective tensile properties.(3)The road durability test results show that: On the basis of the optimum proportion of GCD curing agent,the more the curing agent is added,the better the water stability,frost resistance and dry-wet cycle performance of GCD solidified soil are;The water stability coefficient of GCD solidified soil was significantly higher than that of cement solidified soil;When the freezing resistance of GCD solidified soil is compared with that of cement solidified soil after one freeze-thaw cycle for five times,the strength loss rate of GCD solidified soil is obviously lower than that of cement solidified soil,that is,GCD curing agent has good freezing resistance;The order of mass loss rate of GCD solidified soil and cement solidified soil after dry-wet cycle is cement solidified soil > GCD solidified soil.The UCS of soil solidified with GCD soil stabilizer first was increased and then decreased with the increase of dry-wet cycle times,and the order of UCS loss rate of soils stabilized by GCD soil stabilizer and cement due to dry-wet cycle was cement solidified soil > GCD solidified soil,which shows that the dry-wet cycle performance of GCD stabilized soil was stronger than that of cement stabilized soil.(4)The main mechanism of GCD curing agent comes from the cementitious hydration products(C-S-H,C-A-H)and expansive hydration products(AFt)generated in the process of alkali-activated reaction.These hydration products make the soil microstructure of muddy soil more compact by cementing adjacent soil particles,filling the gaps between particles and forming a compact three-dimensional network structure,which brings about the improvement of macro-mechanical properties and durability of soil.