Study On Performance Of Solid Waste Modified Geopolymer In Pavement Engineering

In this paper,a comparative study of steel slag(SS),brake pad waste(BPW)and fly ash(FA)in metakaolin based geopolymer had been carried out.Firstly,geopolymer strengths with different solid waste contents were investigated under different curing conditions,and the growth law of compressive/flexural strength was discussed for the waste modified geopolymers at the optimum contents.Then,the acid/alkali resistance of the geopolymers with the optimum waste contents were compared and analyzed,as well as their heavy metal immobilization characteristions.At last,the microscopic properties of the geopolymers were tested by Fourier transform infrared spectroscopy(FTIR),scanning electron microscope(SEM)and X-ray diffraction(X-ray diffraction).The results showed that wet curing was the best curing method for geopolymers,and 10% was the best amount of three solid wastes in the geopolymer.Under the optimum dosage,steel slag could accelerate the formation of the strength of the geopolymer,and its ultimate strength was higher than that of the pure geopolymer.The ultimate compressive strength of the modified geopolymer of the brake pad was lower than that of pure geopolymer,but its flexural strength in the later period was slightly higher than that of pure geopolymer,showing the highest ratio of bending-compressive strength.The mechanical properties of fly ash modified geopolymer and brake pad modified geopolymer were completely opposite.Compared with the pure metakaolin geopolymer,in addition to brake pad waste modified geopolymer alkali resistance increased,three kinds of solid waste modified geopolymer acid and alkali resistance were decreased.Heavy metal tests showed that the geopolymer had a good curing effect on heavy metals from solid waste.The microscopic properties show that steel slag,brake pad wastes and fly ash had corresponding chemical physical connection with the geopolymers.Waste morphology and its bonding degree with the geopolymers influenced greatly on the mechanical propertiesof the waste modified geopolymer.