The Preparation Of Geological Polymer Construction Waste Dust Using Experimental Research

There are nearly200million tons of construction waste annually in China. Along with the utilization ratio of the construction wastes improved,a lot of construction waste powder that were produced in the process of construction wastes’reclamation is hard to deal with.This problem is very outstanding and it go against resource conservation and environmental protection.The main components of the construction wastes powder is CaO,SiO2,Al2O3,etc.Its size is very small and it have the basic properties for the preparation of geopolymer.Geopolymer,a new category of inorganic nonmetal materials developed in recent years,which is synthesized from alumio-silicates containing source materials by simple manufacture process,actived by alkaline solution and cures below150or even at room temperature.It is the new high performance inorganic polymer materials with high strength,good resistance to corrosion and durability.It that use of construction waste powder to polymer preparation can solve the problem that the powder produced in the process of construction waste reclamation is difficult to deal with.It is helpful for the research of construction waste reclamation.This thesis research preparation of geopolymer used by solid waste.This thesis mainly research the technical feasibility of preparation of Geopolymer used by construction waste powder.And its performance,structure,and polymerization mechanism is discussed.The experiment use construction waste powder as main materical,sodium hydroxide as alkali-activator.The performance of main raw material and geopolymer were tested.Discuss geopolymer’s capability through the main influence factors as:category and quantity of admixture,category and quantity of alkali-activator,water cement ratio,curing temperature,curing time and so on.(1)The optimum mix proportions of construction waste powder/fly ash geopolymer are determined by analyzing the influence of different single factors.When the construction waste powder is added by75percent,fly ash occupy25percent,the concentration of NaOH is8mol/L,the ratio of the powder material and liquid is0.34,the curing temperature is60℃,the curing time is1hour,the7-day compressive strength of the geopolymer can reach21.34MPa;the7-day breaking strength can reach2.75MPa.The products possess strong acid resistance,losing rate just2.45percent after dip in acid liquor;the relationship of density and compressive strength is "when reduce the density of material,compressive strength decline dramatically", it limit the thinner material;and the rate of containing and absorbing water is high.(2)The XRD and SEM texts were used to study the composition,structure,microcosmic appearance and polymerization rigidification of construction waste powder/fly ash geopolymer.The result show that there are both crystalline and agraphitic in the material; polymerization products exist C-S-H gel and amorphous inorganic polymer in the interim;the microscopic morphology of sample’s fracture surface exist small amounts of schistose gel,contact little floccus gel;the materials themselves closely combined with no apparent crack and gaps exist.Although micro hole appeared,other phenomena influence the material microstructure density have not been observed.(3)During the polymerization of the geopolymer,both of silicate and aluminate oligomers formed by Si-Al materials in construction waste powder and fly ash,in the alkaline solution products aluminosilicate gel by hydroxy polymerization,then transformed into a three-dimension network structure matrix with [SiO4]4-and [AlO4]5-tetrahedron.(4)Research the macroscopical performance,microstructure and the morphological features of the sample what is prepared from construction waste powder.The result show that hot method have a function for the elevation of construction waste powder’s activity.When the heat treatment temperature is600℃,heat treatment time is4h,the7-day breaking strength of the construction waste powder/fly ash geopolymer can reach3.25MPa,7-day compressive strength can reach24.73MPa.Compared to the construction waste powder without activation,the breaking strength of construction waste powder/fly ash geopolymer raised18.2%,the compressive strength raised15.9%.Further indication that the method of hot activation-alkaline active can used in preparation of construction waste powder/fly ash geopolymer.