The Cathode Ray Tube Glass Sand Alkali-Aggregate Reaction Discrete Element Simulation And Study Of How To Inhibit It By Fly Ash

The cathode ray tube(Cathode ray tube, CRT) glass is no longer used in the manufacture of electronic displays. A large number of the waste CRT glass need to be processed. In the prior studies,the CRT waste glass pulverized as fine aggregate to prepare radiation protection concrete is theoretically proved to be feasible. But the key is how to solve concrete alkali aggregate reaction expansion problem. For the study of the CRT glass alkali activity and the expansion caused by alkali-aggregate reaction, and looking potent inhibitors which can effectively inhibit the alkali aggregate reaction, the glass is ground in the test,and the radio of the CRT glass in the sand is respectively 0%,10%,20%,30%,40%,50%,60%,then use fly ash as an alkali aggregate reaction inhibitors-to replace the original cement content of 10%, 20%, 30%,remake experimental group specimens. Use Accelerated Mortar Bar(ASTM 1260) to test all of specimens 3d, 7d, 14 d, 28 d alkali aggregate reaction expansion and the rate of the 28 d expansion inhibition of fly ash test group,then compare the data and analyze the alkali activity of CRT glass aggregate and study the inhibitory effect of the fly ash to the alkali aggregate reaction.We can get the deterioration mechanism of the alkali aggregate from the microscopic point by particle flow discrete element model. The degree of the alkali aggregate can be defined as a function which decided by the temperature and time. In the numerical simulation,Because the continuous temperature process of aggregate in the model is consistent with the degree of alkali aggregate reaction,the strain of thermal expansion can be approximately equivalent alkali aggregate reaction expansion. The test use particle flow code simulate glass mortar bar,then establish different CRT glass mortar bar model and set the appropriate temperature parameters. We can get the temperature contours of the late mortar bar and the curve of thermal expansion cracks at any time step.Further analyze the expansion mechanism of alkali aggregate reaction of the CRT glass mortar bar.The results show:CRT glass is an alkali-active substance,the expansion coefficient becomes larger with CRT glass content increases in the mortar specimens,the fly ash can effectively inhibit the ASR expansion of the CRT glass mortar. The 14 d expansion ratio of all the specimens which contain fly ash is less than 0.1%. The inhibition rate increased with the increase of fly ash content.when the fly ash content is between 20%-30%,the rate of expansion inhibition is all above 80%,the inhibition to the ASR expansion of CRT glass mortar is efficient and obvious. The result of the PFC discrete element simulation shows that the major factor which lead mortar bar expansion is the CRT glass aggregate.CRT glass will produce a tensile stress cracks at the interface of the mortar. The cracks gradually become dense with increasing content of glass. It will take shorter time to reach the damage threshold with the increase of glass aggregate. When the temperature exceeds the threshold,the number of cracks in mortar bar will increase with the CRT glass aggregate content increases.