水洗砂中絮凝剂残留量的检测方法研究

Study on Detection Method of Flocculant Residue in Washed Sand

絮凝剂被广泛应用于水洗砂的生产过程中,其残留于机制砂中对混凝土的各项性能均造成不良影响。但迄今为止还没有有效的检测方法对水洗砂中的絮凝剂残留进行检测。这对机制砂与混凝土的质量控制具有重要意义。因此研究通过向砂中外掺不同掺量的聚丙烯酰胺模拟不同絮凝剂残留量制得水洗砂悬浊液。结果显示采用《混凝土用水标准:JGJ 63—2006》中可溶物方法进行检测,参照《建设用砂:GB/T 14684—2022》通过颜色比对的方式均缺乏准确性,且敏感度不足。而参照《水下不分散混凝土絮凝剂技术要求:GB/T 37990—2019》和《水质浊度的测定浊度计法:HJ 1075—2019》,对不同悬浊液浊度的絮凝剂残留、不同沉淀时间进行研究,得到该方法所需的沉淀时间较长,在残留低、沉淀时间短的情况下用浊度计还无法测得悬浊液的浊度。通过对浊度计方法进行改进,在符合实际中絮凝剂残留≤10 mg/L条件下,测定静置沉淀所需时间,能够较好地反映出絮凝剂残留量。并且方法简单可靠。

Flocculants are widely used in the production process of washed sand,its residue in artificial sand has a negative impact on the performance of concrete.However,there is no effective detection method to detect the flocculants residue in washed sand so far.This is great significance for the quality control of artificial sand and concrete.Therefore,this study simulates different residues of flocculants by adding different amounts of polyacrylamide to the sand to obtain the suspension of sand.The results show that the data accuracy and sensitiv‐ity is poor when using the soluble matter method according to JGJ 63—2016 and color comparison method for organic matter content accord‐ing to GB/T 14684—2022.The method of GB/T 37990—2019 and HJ 1075—2019 for different turbidity of flocculant residues and sedimenta‐tion times shows that the required sedimentation time need too long,and the turbidity of the suspension cannot be measured by turbidimeter when the residue is low and the sedimentation time is not enogh.By improving the turbidity meter method,the settling time required under the condition of residual flocculant≤10 mg/L in practice can be determined,which can reflect the residual flocculant content better.The method is simple and reliable.