改性粉煤灰制备固态聚羧酸减水剂的试验研究

Preparation of solid polycarboxylic acid superplasticizer by modified fly ash

为了解决液态减水剂不易运输与储存的问题以及满足一些特殊工程的需要,本研究以粉煤灰为原料采用吸附法将液态聚羧酸减水剂固相化处理,为避免引入大量粉煤灰造成混凝土强度等性能变差,首先对粉煤灰进行改性.试验确定了适宜的改性条件:温度20℃、作用时间60 min、改性剂为2 mol/L的盐酸溶液.改性粉煤灰在试验条件下,较好的吸附温度是20℃,吸附时间60 min,改性粉煤灰与液态减水剂固液比1∶1,且为PC8000的减水剂,吸附动力学结果表明,改性粉煤灰的吸附活化能比未改性粉煤灰的低6.86%.本研究制备的固态聚羧酸减水剂对水泥凝结时间、混凝土性能无不良影响,与其液态聚羧酸减水剂相比差别不大,所以用改性后的粉煤灰制备固态聚羧酸减水剂是可行的.

Solid polycarboxylic acid superplasticizer was prepared by adsorption after modification of fly ash.This method solves the problem that liquid water reducing agent is not easy to transport and store,and can also meet the needs of some special projects.At the same time,it avoids the concrete strength decline and frost resistance deterioration caused by introducing a lot of fly ash.Aimed at the influence factors of adsorption and adsorption type were analyzed,and the best conditions for modification temperature 20℃,60 min modification time,concentration of modifying agent for 2 mol/L hydrochloric acid solution,the best adsorption conditions for adsorption temperature 20℃,the adsorption time 60 min,solid-liquid ratio 1:1 PC8000 adsorption water-reducing,this conforms to the Langmuir adsorption rule,is exothermic process and can oceur spontaneously,without a new chemical bonds in the process of adsorption and chemical adsorption.The properties of solid superplasticizer prepared under optimal adsorption conditions are not different from that of liquid superplasticizer.