混凝土搅拌站洗浊液碳化处理效应分析  

Analysis on carbonation effect of washing liquid of concrete mixing plant

作　　者：康佳敏 刘赞群[1] 朱嘉慧 周鑫 刘竞 KANG Jiamin;LIU Zanqun;ZHU Jiahui;ZHOU Xin;LIU Jing(School of Civil Engineering,Central South University,Changsha 410075,China;China Academy of Railway Sciences Railway Engineering Research Institute,Beijing 100081,China)

机构地区：[1]中南大学土木工程学院,湖南长沙410075 [2]中国铁道科学研究院集团有限公司铁道建筑研究所,北京100081

出　　处：《铁道科学与工程学报》2023年第11期4185-4194,共10页Journal of Railway Science and Engineering

基　　金：国家重点研发计划资助项目(2022YFB2602602)。

摘　　要：混凝土是世界上用量最大的工程材料,其主要原材料水泥生产排放大量CO_(2),但混凝土又能固化大量CO_(2)。本文提出CO_(2)碳化混凝土搅拌站洗浊液,其目的是一方面可进一步提高混凝土的碳汇能力,另一方面可以科学解决搅拌站洗浊液的回收利用,避免对环境的污染和水资源浪费。为此,研究分别从市政和铁路建设2个搅拌站选取的40组洗浊液样品,自制碳化装置,评价了洗浊液的固碳效应;并通过XRD,TG,SEM和溶液ICP等微观分析手段,研究了洗浊液碳化后固液相组成的变化规律,碳化洗浊液对水泥净浆工作性能和力学性能的影响。研究发现:洗浊液固碳量与其固含量成正比,不受其存放时间的影响,40组洗浊液样品平均固碳量为其固含量的0.58%。洗浊液碳化后,高碱度的洗浊液pH值降至6.3±0.2,洗浊液液相中的Ca浓度显著降低,Si,S,Mg含量显著提高;固相中的硅酸三钙、羟钙石和钙矾石基本消失,沉淀生成大量颗粒粒径小于30μm的碳酸钙颗粒。将碳化洗浊液以固含量等量取代水泥后发现:对比未碳化洗浊液和自来水拌制浆体,碳化洗浊液拌制的水泥净浆流动度损失消失,水泥净浆干燥收缩降低,水泥净浆抗压强度增大。因此,本文提出的碳化处理洗浊液技术,既可以成为一种有效的固碳手段,碳化后的洗浊液可以直接应用于混凝土生产,解决其回收利用的难题。Concrete is the largest engineering material in the world.Its main raw material cement production emits a large amount of CO_(2),but concrete can solidify a large amount of CO_(2).This paper puts forward the carbonation of concrete mixing station washing liquid by CO_(2),which aims to further improve the carbon sequestration capacity of concrete on the one hand,and scientifically solve the recovery and utilization of the washing liquid in the mixing station on the other hand,so as to avoid environmental pollution and waste of water resources.For this reason,40 groups of turbid washing liquid samples were selected from municipal and railway construction mixing stations were studied.The carbon sequestration effect of turbid washing liquid was evaluated by self-made carbonization device,and the change law of solid-liquid phase composition after carbonation was studied by means of XRD,TG,SEM and solution ICP.The effect of carbonation washing liquid on the working and mechanical properties of cement paste was studied.It is found that the solid carbon content of the washing liquid is proportional to its solid content,and is not affected by its storage time.The average carbon fixation amount of 40 groups of washing liquid samples is 0.58%of its solid content.After carbonation,the pH value of the washing liquid with high alkalinity decreases to 6.3±0.2,when the concentration of Ca in the liquid phase decreases significantly.The contents of Si,S and Mg increase significantly,and the tricalcium silicate,hydroxyettringite and ettringite in the solid phase basically disappear.A large number of calcium carbonate particles with particle size less than 30μm are precipitated.After replacing cement with the same amount of solid content,it is found that the fluidity loss of cement paste mixed with uncarbonized solution and tap water disappears,the drying shrinkage of cement paste decreases,and the compressive strength of cement paste increases.Therefore,the carbonization treatment technology proposed in this paper can become an

关 键 词：混凝土洗浊液 固碳能力 工作性能 抗压强度 固废处理 

分 类 号：X703.1[环境科学与工程—环境工程]