Application Research Of Utilization Of Waste ZSM-5 In Cement Building Material

ZSM-5 zeolite after been used for many cycles recycling has become a new kind of solid waste.The disposal of these used zeolites is an environmental concern since they may contain small amounts of volatile organic substance.Once the treatment method is not correct,it will cause secondary pollution.In this paper,the used ZSM-5has carried on the qualitative analysis and quantitative analysis,and adopted three mainly methods to use this type of solid waste.Firstly,the ZSM-5 waste was processd as a supplementary cementitious material into cement and its physical properties and hydration products were tested and characterized;Secondly,it is used to replace part of fly ash to prepare autoclaved aerated concrete.The influence of the content of waste ZSM-5 on the mechanical properties and reaction products of fly ash-based autoclaved aerated concrete is mainly studied.Thirdly,ZSM-5 waste was used as a siliceous raw material in the preparation of AAC and its mechanical properties,foaming properties and hydration products were studied.The characterization techniques used in this paper include X-ray diffraction（XRD）,Thermal gravimetric（TG）,Fourier transform infrared spectroscopy（FTIR）and Scanning electron microscope（SEM）.The main contents of this paper are as follows:（1）The ZSM-5 waste in this research is composed of 38.9%ZSM-5,5.38%quartz,16.18%cristobalite and 39.54%amorphous Si O₂.According to BET analysis,the waste ZSM-5 has a specific surface area of 319 m²/g and still has a certain adsorption capacity.At the same time,there are a large number of mesoporous in the ZSM-5 waste.（2）The influence of different waste ZSM-5 content on cement performance was studied.Higher compressive strengths were achieved when the addition of ZSM-5waste is increased（5%,7%and 10%）and the fluidity of cement mortar decreased from184.2 mm to 170.1 mm.The pozzolanic activity index varied between 102 and 129%for all silica samples and the calculated activity index confirmed the excellent pozzolanic activity for ZSM-5 waste.Cement paste with the addition of ZSM-5 waste shows a lower amount of portlandite due to the pozzolanic reaction.The pozzolanic reaction of amorphous Si O₂in ZSM-5 waste mainly occurred in the early stage of hydration reaction,while the reaction of ZSM-5 mainly occurred between 7 and 28days.Besides,the microstructure of reaction products exhibited a condensed structure than the reference sample Z0.（3）The influence of the content of waste ZSM-5 on the mechanical properties and reaction products of fly ash-based autoclaved aerated concrete was studied.The addition of ZSM-5 waste can improve the foaming effect,mechanical strength and decrease the bulk density of the AAC.It not only reflected in the improvement of foaming performance of ZSM-5 waste,but also the extremely low bulk density of ZSM-5（far lower than fly ash）.With the addition of ZSM-5 waste increased to 15%,the bulk density and compressive strength of the AAC were 516 g/m³and 3.1 MPa,respectively.The replacement of fly ash by ZSM-5 waste has promoted the formation of tobermorite which further improves the performance of AAC products.Besides,the reaction products with the addition of ZSM-5 waste are thicker and more tightly bound and part of the needle-like and grass-like tobermorite was replaced by plate-like tobermorite.（4）A new type of ACC using ZSM-5 waste as siliceous raw materials was successfully prepared.The mixture proportion of the optimal waste ZSM-5 ACC blocks are:waste ZSM-5 51%,cement 12%,quicklime 34%and gypsum 3%,al powder 0.14%and W/R 0.8.The bulk density and compressive strength of test sample are 500 g/m³and 4.2 MPa.Na OH is used as a foaming accelerant to improve foaming effect.The bulk density and compressive strength of AAC samples based on the best formula with 0.6%Na OH content are 414 g/m³and 2.9 MPa.In the absence of aluminum powder,the sample still produced a volume expansion of 22.1%.Therefore,ZSM-5 waste itself also has foaming ability.