灰钙对掺PCE的磷建筑石膏性能影响研究

Study on effect of ash calcium on properties of phosphorus building gypsum doped with PCE

为了进一步促进磷建筑石膏的应用,以灰钙为碱性调节剂,对比研究了灰钙掺量对添加或不添加聚羧酸减水剂(PCE)的磷建筑石膏工作性能、力学性能、物相组成及微观形貌的影响。结果表明,在未添加PCE时,随着灰钙掺量的增加,磷建筑石膏p H逐渐增大,水溶性P_(2)O_(5)含量逐渐降低,流动度下降超59.5%,标准稠度用水量升高,强度先降低后升高,但均低于原状磷建筑石膏的强度,抗折、抗压强度最低时较原状磷建筑石膏分别下降63.3%、54.4%。添加PCE后,掺入灰钙可使磷建筑石膏对PCE的吸附量提高10倍以上,从而改善因灰钙掺入对磷建筑石膏流动度、标准稠度用水量、强度造成的不利影响,强度随灰钙掺量的增加先升高后降低再升高,抗折、抗压强度最高时较未掺灰钙时分别提高11.1%、48.9%。XRD及SEM分析结果表明,灰钙主要与磷建筑石膏中H_(3)PO_(4)和H_(2)PO_(4)~-发生反应,生成难溶性无定型小颗粒,降低二水石膏晶体间的相互搭接程度,导致强度下降。在磷建筑石膏生产加工应用中灰钙掺量宜大于1.3%,并搭配PCE使用。

In order to further promote the application of phosphorus building gypsum,with ash calcium as the alkaline regu‐lator,a comparative study was conducted on the effects of ash calcium content on the working performance,mechanical properties,phase composition,and micro‐morphology of phosphorus building gypsum with or without polycarboxylate super‐plasticizer(PCE).The results showed that,without PCE,as the ash calcium content increased,the pH of the phosphorus building gypsum was gradually increased,the water‐soluble P2O5 content was gradually decreased,the fluidity was de‐creased by more than 59.5%,the standard consistency water consumption was increased,and the strength was firstly de‐creased and then increased,but the strength was still lower than the original phosphorus building gypsum.The flexural and compressive strengths were reduced by 63.3%and 54.4%,respectively,compared to those without ash calcium.When PCE was added,the incorporation of ash calcium could increase the adsorption capacity of phosphorus building gypsum for PCE by more than 10 times,thus improving the adverse effects of ash calcium incorporation on the fluidity,standard consistency water consumption,and strength of phosphorus building gypsum.The strength was firstly increased,then decreased,and then increased again as the ash calcium content increased.The flexural and compressive strengths were increased by 11.1%and 48.9%,respectively,compared to those without ash calcium.The results of XRD and SEM analysis showed that ash cal‐cium was mainly reacted with H_(3)PO_(4) and H_(2)PO_(4)-in phosphorus building gypsum to form insoluble and amorphous small par‐ticles,reducing the mutual overlap degree between dihydrate gypsum crystals,resulting in a decrease in strength.In the pro‐duction and processing of phosphorus building gypsum,the ash calcium content should be greater than 1.3%,and should be used with PCE.