Experimental Study On Preparation Of Gypsum Based Self Leveling Admixture And Mortar

Gypsum is a kind of green and environment-friendly cementitious material,which has excellent performance of ecology,low carbon,environmental protection and health.Gypsum-based self-leveling mortar made of gypsum is used as the ground leveling layer.After pouring on the ground,the ground will not produce cracks,drum and other phenomena.Gypsum-based self-leveling mortar has the social and economic benefits of energy saving and emission reduction,and can promote the comprehensive utilization of industrial solid waste.It is an environment-friendly green leveling mortar for the ground.In order to prepare a special water-reducing agent for gypsum system,a polycarboxylic acid water-reducing agent with high water reduction and plastic retention is prepared by using large molecular weight isopentenol polyoxyethylene ether monomer,chain transfer agent mercaptopropionic acid and acrylic acid.The results showed that the water reducing effect is the best when the molecular weight of polyoxyethylene ether was 4000,the ratio of acid to ether is 6.5:1,and the amount of chain transfer agent is 2.5.On this basis,it is modified by methyl methacrylate and unsaturated phosphoric acid monoester,and finally a special polycarboxylic acid superplasticizer with high water reduction and plasticity retention was obtained.The modification test showed that the superplasticizer had good plasticity retention.With other existing suitable for gypsum system compared to the water reducing agent,water reducing effect of this water reducing agent on gypsum system is more significant,the plastic is better,and has certain inhibiting effect to the plaster,can reduce the dosage of retarder,increase mechanical properties of the gypsum based self-leveling mortar,is a kind of good performance of high conservation reduction model is applied to gypsum system poly carboxylic acid water reducing agent.The effects of different proportion of gypsum,cement and 70-120 mesh quartz sand on various performance indexes of gypsum self-leveling mortar are systematically investigated,and the basic mix ratio of gypsum self-leveling mortar meeting the standard specification is successfully prepared.Prepared with replacing parts of the building gypsum desulfurization gypsum building gypsum based self-leveling mortar,series of experiments with the 6% of desulfurization gypsum instead of buildings of gypsum plaster base self-leveling mortar has the appropriate fluidity,fluidity of 30 min will not damage and strength of self-leveling mortar can meet the specification requirements and other requirements.Adding desulfurization gypsum can reduce environmental pollution and save the cost of self-leveling gypsum base,and can reduce the exploitation of natural gypsum and protect natural gypsum resources.Four retarders,citric acid,protein powder,sodium tripolyphosphate and sodium gluconate,are added into gypsum respectively.Under the same dosage condition,protein powder is the retarder with the best adaptability to initial fluidity,30 min fluidity loss,setting time and strength of gypsum.But for gypsum based self-leveling mortar,protein powder is used as retarder,gypsum base self-leveling mortar fluidity loss for 30 min is bigger,use a retarder are not up to the standard of the gypsum based self-leveling mortar,so the gypsum based self-leveling mortar retarder to distribution,distribution and using different retarder for plaster base self-leveling mortar experiment explored.The best influence of fluidity,setting time and strength on adaptability of gypsum self-leveling mortar is the mixed protein powder and sodium gluconate retarder,the content of which is 0.4‰ protein powder and 0.6‰ sodium gluconate.It can be seen that in order to meet the standard requirements of gypsum based self-leveling mortar,the retarder of protein powder and sodium gluconate can achieve the best retarder effect on gypsum based self-leveling mortar.