脱硫石膏对水泥性能的影响及其品质差异分析

对不同产地脱硫石膏作缓凝剂对水泥物理性能影响进行了研究比较,并分析探讨了脱硫石膏的品质差异及其对水泥性能影响机制。试验结果表明,与天然石膏相比,脱硫石膏对水泥早期和后期强度均有不同程度提高,但水泥凝结时间有不同程度延长。不同产地脱硫石膏对水泥与外加剂相容性、保水性、流变性和干缩率等性能的影响均存在较大差异。研究还发现,亚硫酸钙含量及钙硫比低的脱硫石膏,其水泥凝结时间、干缩性、保水性和砂浆流变性等物理性能均优于或与掺天然石膏的接近;同时,脱硫石膏的结晶程度、晶体形态和石膏溶解速率对水泥凝结时间、与外加剂相容性等也均有较大影响。

Effect of desulphurization gypsum on performance of cement and discussion on influence of desulphurization gypsum with different quality

The desulphurization gypsum,as cement retarder,may produce by different factories.Therefore there should be some difference effects on the physical properties of cement and should be studied with its principle as well.The results showed that the compressive strength of both early and later age,and setting time of cement would be increased and elongated if the natural gypsum were replaced by desulphurization gypsum as cement retarder.The effect of desulphurization gypsum on compatibility between cement and admixture,water retention,rheological property and dry shrinkage rate of cement could be varied in large scale if the desulphurization gypsum were from different sources.The cement blended with desulphurization gypsum of low calcium sulfite content and calcium sulfur ratio,could have better properties including setting time,dry shrinkage and water retention of cement and rheological property of mortar or at least close to that used natural gypsum.The degree of crystallization,crystal morphology and gypsum dissolution rate of desulphurization gypsum had tremendous influence on the setting time of cement and compatibility between cement and admixture.