Study On Water In Fly Ash-based Geopolymer And Its Concrete Interfacial Transition Zone

As a new cementing materials,as well as with characteristics of ceramics,cement and Polymer Materials,fly ash-based geopolymer has many advantages performances over traditional cementitious materials and become hot spots of green cementing material in researches home and abroad.since the current study on fly ash-based geopolymer mainly focus on alkali activator,Si/Al ratio of raw materials,fixed heavy metal ions and durability and so on,there is few report of researches on water effect on fly ash-based geopolymer system and interfacial transition zone of fly ash-based geopolymer concrete and few consensus.The passage mainly focus on researches on water effect,compatibility of superplasticizer and state of interfacial transition zone of concrete in fly ash-based geopolymer,Macro-properties of the fluidity,setting time and strength were tested,represented by SEM.XRD,EDS.The main achievement are as follows:1.The role and form of water in fly ash-based geopolymer is related with reaction ways in polymerization.In the context of the designed water-fly ash ratio,the increasing water content of alkali-Activator can promote polymerization,and after the reaction it presents as combined water and structured water.Except for the water in alkali-activator,the additional mixed water is known as the additional water,which may obviously affect the performance of fly ash-based geopolymer.Increasing content of additional water can restrain the polymerization and generate plenty of pores,after the reaction it presents as free water,and water in curing environment will affect transfer of free water in fly ash-based geopolymer,which will obtain the best curing effect in a relative humidity of 70%～80%.2.There is huge difference between the effect of superplasticizer on fly ash-based geopolymer and traditional portland cement.Observed from the experiment of superplasticizer as polycarboxylate and naphthalene,it appeared that addition of the efficiency water reducer will discourage polymerization and naphthalene superplasticizer has better effect than Polycarboxylate superplasticizer.3.The interfacial transition zone of fly ash-based geopolymer is different from that of traditional portland cement,which contains no CH and AFt crystal and denser interfacial transition zone.The state of transition zone is related with aggregate type and parameters of mixture ratio,and specimens made of limestone as coarse aggregate have higher interfacial bonding strength.Lower the cement water ratio,higher the interfacial bonding strength.Addition of slag will significantly improve the interfacial bonding strength and contribute to early effect.Increase of concentrations of alkali-activator or decrease of modulus both help the promotion of active ingredients dissolution of coarse aggregate,contributing to the development of interfacial bond strength...