Influence Of The Biomass Ash During The Hydration And Hardening Process Of Complex Binders

Biomass energy is a kind of clean and renewable energy,which are rich in China.Using biomass to generate power can have a significant effect on carbon dioxide and a variety of atmospheric pollutant emission reduction.At present,the development of power plants using biomass as fuel in our country is rapid,and the whereabouts of biomass ash also need to be solved urgently.Many scholars at home and abroad have studied the biomass ashes in cement concrete research for application,and they were found to contain some physical and chemical composition,which are similar to that of fly ash and have a wide range of potential value.The existing research still cannot be used in industrial production,and there are a lot of theoretical research work to be done.In this paper,the difference between biomass ash and fly ash on the particle size distribution,particle morphology,chemical compositions,activity index and the water demand ratio were studied.Through the strength of cement complex mortar in different ages and the study of the hydration performance,the mineral composition,microstructure,pore structure of cement-based paste were studied,so the influence of the biomass ash and ordinary fly ash during the hydration were compared.The results are as followings:In the aspect of basic performance test,the particle shape of biomass ash is irregular,the average particle size and particle size distribution range is larger.It has the slender fibrous particles,and the active components of Al2O3 are less than a third of the ordinary fly ash.The pozzolanic activity of biomass ash is lower than fly ash.In the early hydration,biomass ash's contribution to the strength of composite gelled material is mainly physical filling effect.As the extension of curing age,its pozzolanic effect appears gradually,which is beneficial to the improvement of the strength.Under the same content,the compressive and flexural strength of biomass ash-cement complex mortar is less than fly ash-cement complex mortar at all ages,but it has a less impact on the weakening of the flexural strength.The more dosage,the greater the strength decreased degree compared with the pure cement group.The incorporation of fly ash and biomass ash decreases the total hydration degree of complex binders,but at the same time,promotes hydration degree of cement in complex binders.The higher the content of fly ash and biomass ash is,the higher the hydration degree of cement is.Adding biomass ash and fly ash leads to the decrease of Ca(OH)2 content in hydration products,but it does not affect the type of cement hydration products.Due to the pozzolanic activity of fly ash is greater than the biomass ashes,and its ash reaction consumes more Ca(OH)2,then the second hydration reaction is greater than the biomass ash group.The incorporation of biomass ash and fly ash reduces the total number of harmful holes and much harm holes,which makes the pore size refinement.Both harmless holes and less harm holes increase.Thus,the development of structure of hardened cement paste is beneficial to the durability.The microstructure of adding biomass ash of hardened cement paste is more loose and porous than the sample of containing fly ash,especially the existence of its peculiar slender fibrous particles.