Study On Properties Change And Influence Of Admixtures Of Reclaimed Gypsum

Gypsum is widely used in China, but the technology behind the production of gypsum plaster lead to annual waste piles. After a series of abandoned gypsum plaster regeneration process becomes. The performance of recycled gypsum research to find the underlying causes of performance rules and changes, and the impact of the admixture of recycled gypsum-depth study can provide a theoretical basis for a broader reuse of waste gypsum. Regenerate degraded plaster find effective solutions,Eventually abandoned gypsum can be recycled, saving resources and protecting our homeland.Subject to the preparation and regeneration of different grade gypsum plaster variation of performance and causes chemical changes in the regeneration of gypsum performance, comparing performance change mechanism changes the performance of natural gypsum and chemical regeneration, Polycarboxylate, sodium tripolyphosphate and lemon acid retarder native influences and regeneration gypsum conducted a series of studies on.Native regeneration Hemihydrates standard thick water demand and strength are reduced with lower grade, recycled gypsum-related performance degradation and taste, all three grade gypsum reduce the magnitude of the intensity increases with lower grade, compressive strength compared to a decline of greater flexural strength. Decline in phosphorus chemical gypsum plaster regeneration <natural regeneration gypsum <desulfurization gypsum regeneration, regeneration is about half the remaining two phosphorus gypsum strength decline, which phosphogypsum crystal itself is poor, the intensity is not high, structural stability related.Exclude the impact of the specific surface area, exploring the reasons for the regeneration of other gypsum performance degradation. Regeneration hemihydrate crystal grain size smaller than the specific surface area measured under identical conditions measuring the surface area average particle diameter, the average particle size consistent contrast, the apparent reproduction hemihydrate gypsum coarse particles, there are many defects. Raw gypsum and recycled gypsum hemihydrate its transformation do thermal analysis and XRD analysis, the regeneration of the transition temperature is lower than the original plaster gypsum, hemihydrate gypsum regeneration crystallinity difference.Reducing agent in a small dosage, lower than 0.12%, with the increase in dosage of superplasticizer, water-reducing effect of the rapid increase in the intensity of the rate of increase of renewable raw gypsum and gypsum are constantly increased, but the original gypsum is less than the rate of increase strength gypsum regeneration. When reached 0.12 percent after the water-reducing effect, although it continues to increase leveled off. Polycarboxylate content of 0.12%, the original crystalline gypsum most, the most intensive particle lap. In the regeneration.Hemihydrat directly adding polycarboxylate superplasticizer, the formation of hardened superplasticizer compared with the original, the rod-like particles increased significantly, almost arranged together, rod-like grains were reunited trends, clusters, almost no pores.Native Hemihydrate after adding water reducer, the process, the regeneration of a small portion of gypsum superplasticizer desorption occurs, most desorption occurred, the effect is still there.After the original gypsum added sodium tripolyphosphate, standard thick water demand has slightly increased with increasing content of setting time and significantly extend the intensity is reduced after the first rise, and increased marginally, renewable plaster The performance changes even opposite. The impact of sodium tripolyphosphate content on plaster setting time and early strength has a critical value of 0.10%. Raw gypsum crystals mostly columnar and long rod, and then mixed with sodium tripolyphosphate retarder gypsum mostly for short stick. Citric acid retarding effect is better than sodium tripolyphosphate.