Acoustic Emission And High-temperature Behavior Of Geopolymer Under Uniaxial Compression

Geopolymer is a new type of inorganic polymer cementing material At present,researchers in China and abroad focused on the study of the development of mechanicalproperties of geopolymer materials. And if a new material has been used in engineeringthe macroscopic damage evolution and failure mechanism of the material play a crucialrole. In this paper, the writer use the industrial waste-fly ash as the main material to makea geopolymer with different steel fiber content, Experimental synchronous platform makeup by servo press and acoustic emission acquisition device was build to build asynchronous servo presses and acoustic emission acquisition device to make the uniaxialcompression tests. At the same time in order to study the relationship between the strengthloss and quality loss of geopolymer under high temperature. This paper use theOrthogonal experimental design to make different kinds of geopolymer mortar to studythe Studied the association between the mass loss and the strength loss after300℃,600℃,900℃high temperature.The results show that the fiber can raise the strength and ductility of the geopolymer,The hit rate and energy release rate(energy rate)of all samples will rise at the peak of thestress-strain curve, indicate internal damage of the sample starts. as the fiber contentincreases after the peak load, the hit rate and energy rate begin to decrease, indicating thatthe sample destroyed stabilized, the failure mode will change from brittle pattern to ductileone. Through the analysis of the AE signal waveform features shows that as the fibercontent increases, RA(ratio of Riseing time and Amplitude)is decrease,AF(averagefrequency)is increase And the change closely related to the macroscopic damagemodel.High RA value and low AF value tend to brittle one, and low RA value and high AFvalue tend to ductility one. The energy change of acoustic emission signals do not occur inall frequency zones, but in particular frequency zones, mainly around40,100and300kHz.The high-temperature test of geopolymer shows that the optimum mixing ratio issame aim at all strength in room temperature. Mass ratio of sand and total cementingmaterial content of1:2; Slag mass ratio of total cementitious material content of30%; Mass ratio of sodium silicate and NaOH solution content of of2:1;and the curingtemperature of80℃. The strength of most groups of sample increased first then decreasedafter high temperature. When the mass loss is greater than9.5%, the strength of allsamples decreased relative to room temperature, but when the mass loss is less than9.5%,The relationship between the mass loss and the strength loss is unconspicuous.