Study On Preparation Process And Performance Of Road Use Geopolymer Cementitious Materials Prepared By Multisource Solid Waste

Inner Mongolia,as a major resource and energy province in China,emits a large amount of industrial solid waste every year,bringing enormous pressure to the already fragile local ecological environment.The traditional cement stabilized crushed stone pavement base has problems such as poor durability,weak resistance to acid and alkali corrosion,and high road shrinkage.Therefore,it is urgent to develop a new type of cementitious material for road construction.As a three-dimensional network structure inorganic polymer composed of tetrahedral units of[Al O₄]and[Si O₄],geopolymer has advantages such as high mechanical properties,strong freeze-thaw resistance,acid and alkali corrosion resistance,and low production energy consumption.It is considered a new type of green cementitious material.This article will use solid waste such as fly ash,calcium carbide slag,and blast furnace slag,which have a large amount of emissions and serious environmental pollution in Inner Mongolia,as the main raw materials.Based on the principle of geopolymer preparation,the aim is to develop a suitable geopolymer cementitious material for road base,and achieve the coordinated development of solid waste treatment and road infrastructure construction in Inner Mongolia Autonomous Region.（1）XRD,FTIR,TG-DSC,NMR,SEM-EDS and other means were used to detect and analyze the existing forms of Si and Al in each raw material in this paper.The test results show that the content of mullite in fly ash is about 79.8%,the content of amorphous solid phase is about 20%,the Si element is dominated by Q¹ structure and Q⁴structure,the Al element is dominated by Al-OH bond and Al-O-Si bond,the amorphous solid phase of slag is about 99%,the Si element is dominated by Q¹ structure and Q⁴ structure,and the Al element in slag is dominated by Al O₄ and Al O₆,Each solid waste meets the potential for preparing geopolymers.（2）Activate multi-source solid waste through physical and chemical means.As the grinding time increases,the cementitious activity of fly ash and slag gradually increases.When grinding for 10 minutes,the cementitious activity after 28 days increases by 4.31%and 2.85%,respectively.When Na OH,Na₂CO₃ and calcium carbide slag were used as alkali activators to study the cementitious activity of fly ash and slag,it was found that when Na OH was 6.45%,the cementitious activity increased by 11.79%,and the activation effect on solid waste was the best.The generated hydration products were mainly rod-shaped C（N）-A-S-H and flocculent C-S-H gel.The[Si O₄]expansion vibration peak was strong,and the microscopic morphology was dense.（3）In the early research process,it was found that Ca²⁺and Na⁺had synergistic and inhibitory effects on each other during the preparation of geopolymer cementitious materials.Therefore,research was conducted on the hydration mechanism of multi source geopolymer prepared by Ca²⁺and Na⁺synergistic methods.The results show that when（Na+Ca）/（Si+Al）≤0.6 in the hydration product,C-S-H and N-A-S-H gel coexist,and Ca²⁺and Na⁺have synergistic effects.When 0.6<（Na+Ca）/（Si+Al）≤0.95,Ca²⁺and Na⁺have an inhibitory effect.With the increase of Ca²⁺content,N-A-S-H gel undergoes single displacement reaction to form C-A-S-H gel.Some of the displaced Na⁺permeates into the liquid phase through the pore structure.When Al/Si≈0.6,（Na+Ca）/（Si+Al）≈0.95,the concentration of Na⁺in the liquid phase is about 49.465ug/ml to reach equilibrium.（4）Based on the hydration mechanism of Ca²⁺and Na⁺synergistic preparation of geosynthetics,an optimization experiment was conducted on the ratio of multi-source solid waste to prepare road geosynthetics.When the blast furnace slag,fly ash,calcium carbide slag and Na OH are 66.5:28.5:5:2.58,the 28 day compressive strength and flexural strength of the geopolymer mortar specimen can reach 35.85MPa and 9.01MPa respectively,and the 90 day compressive strength can reach 46.54MPa.The hydration products are mainly C-S-H and C-A-S-H gel.At the same time,its engineering performance and linear dry shrinkage performance meet the requirements of the standards and specifications of Cement for Highway Engineering Pavement Base Stabilization（JT/T994-2015）,The durability meets the standard specification requirements of the"Test Specification for Cement and Cement Concrete in Highway Engineering"（JTG 3420-2020）.Compared to Portland cement,in terms of freeze-thaw resistance,the strength loss rate is only 1.03%,the mass loss rate is 0.19%,and the relative dynamic modulus is97.24%.In terms of resistance to acid and alkali corrosion,the corrosion resistance coefficients in Na OH,Na₂SO₄,and HCl environments are 143.54%,119.96%,and 97.24%,respectively.In terms of energy conservation and emission reduction,the maximum cost per ton is reduced by 75.43%,and industrial CO₂emissions are reduced by 72.54%.