废弃粘土砖用于混凝土内养护的研究

发布时间：2018-06-09 12:47

本文选题：废砖渣 + 内养护　；参考：《广东工业大学》2017年硕士论文

【摘要】：由于水胶比较低且添加了硅灰等超细矿物掺合料,高性能混凝土的内部相对湿度在水泥水化反应早期下降较快,容易发生自干燥,导致混凝土收缩,引起开裂。传统的外部养护方法并不能完全解决混凝土的干燥收缩开裂问题,而掺入预湿处理的内养护材料可以有效从内部缓解混凝土的自干燥,降低自收缩。基于饱水轻集料内养护技术原理,发现废弃粘土砖有作为内养护材料的潜质,同时也能为废弃粘土砖的再利用提供新的方法。本文测定并分析了废砖渣的基本物理性能,以废砖渣取代部分细骨料研究了掺废砖渣对混凝土的工作性能、收缩开裂性能、力学性能和耐久性能的影响,同时研究了复掺废砖渣与超吸水树脂(SAP)对混凝土内养护效果的影响,为废砖渣用作内养护材料提供一定的科学依据。本文主要研究成果如下:(1)综合对废砖渣的基本物理性能、微观结构、吸水率的分析,得出废砖渣具备作为内养护材料潜质的结论。研究了废砖渣取代部分细骨料对混凝土基本性能的影响。结果表明饱水后的废砖渣掺入到混凝土中后增大了混凝土的流动性。随着废砖渣掺量的提高,水泥砂浆的自收缩和干燥收缩率逐渐降低,抗裂性能也提高。(2)研究了废砖渣对混凝土抗压强度的影响。当废砖渣掺入比例不大于30%时,混凝土后期强度基本与基准混凝土相同;废砖渣掺入比例为20%时,其90d强度超过了基准混凝土。另外,废砖渣的内养护作用对低水胶比混凝土的后期强度提高更加明显,能有效促进硅灰火山灰效应的发挥。随着废砖渣粒径的减小,混凝土强度逐渐降低,且单一粒径的废砖渣混凝土强度都低于混合粒径的废砖渣混凝土强度。复掺SAP和废砖渣能改善SAP对强度的不利影响。(3)研究了废砖渣对混凝土抗碳化性能的影响。当废砖渣掺量不超过30%时,基本不影响混凝土的抗碳化能力。废砖渣对低水胶比的混凝土抗碳化性能影响更加显著,但对不同掺量硅灰混凝土影响较为一致,会使碳化深度增大3倍左右。混合粒径废砖渣混凝土的碳化深度均大于单一粒径废砖渣混凝土的碳化深度。复掺SAP和废砖渣能改善SAP对抗碳化性能的不利影响。(4)当废砖渣掺量为10%时,电通量比基准混凝土降低25.3%;超过10%后,随着掺量的增加,混凝土电通量逐渐增大。水胶比越高,废砖渣对混凝土的电通量影响越小。掺入废砖渣后,硅灰比例越大,废砖渣对混凝土电通量的影响越不明显。另外,废砖渣的粒径大小对混凝土电通量影响差别不大,但混合粒径的废砖渣混凝土电通量要大于单一粒径时的情况。同时,复掺SAP和废砖渣后的混凝土电通量相比单掺SAP的混凝土反而有所增大。综上述,废砖渣在不明显影响混凝土的强度和耐久性前提下,可以有效减小混凝土的早期收缩,改善抗裂性能。废弃粘土砖用作混凝土内养护材料是可行的。
[Abstract]:Because of the low water glue and the addition of ultrafine mineral admixtures such as silica fume, the internal relative humidity of high performance concrete decreases rapidly in the early stage of hydration reaction of cement, and self-drying easily occurs, which leads to shrinkage and cracking of high performance concrete. The traditional external curing method can not completely solve the problem of drying shrinkage cracking of concrete, but the internal curing material mixed with pre-wet treatment can effectively alleviate the self-drying and reduce the self-shrinkage of concrete from the inside. Based on the principle of internal curing technology of saturated lightweight aggregate, it is found that abandoned clay brick has the potential as internal curing material, and it can also provide a new method for reuse of waste clay brick. In this paper, the basic physical properties of waste brick slag are measured and analyzed. The effects of waste brick slag on the working performance, shrinkage cracking property, mechanical property and durability of concrete are studied by replacing some fine aggregates with waste brick slag. At the same time, the influence of waste brick slag and superabsorbent resin (SAP) on the curing effect of concrete is studied, which provides a scientific basis for waste brick slag to be used as internal curing material. The main research results of this paper are as follows: (1) the basic physical properties, microstructure and water absorption of waste brick slag are analyzed, and the conclusion that waste brick slag has potential as internal curing material is concluded. The effect of waste brick slag replacing some fine aggregate on the basic properties of concrete was studied. The results show that the fluidity of concrete is increased by adding waste brick slag into concrete. With the increase of waste brick slag content, the self-shrinkage and drying shrinkage of cement mortar decreased gradually, and the crack resistance of cement mortar was improved. (2) the influence of waste brick slag on the compressive strength of concrete was studied. When the ratio of waste brick and slag is less than 30, the later strength of concrete is basically the same as that of standard concrete, and when the proportion of waste brick and slag is 20, its strength of 90 days is higher than that of standard concrete. In addition, the internal curing effect of waste brick slag is more obvious to the later strength of low water cement than concrete, and it can effectively promote the exertion of the ash effect of silica ash. With the decrease of the particle size of the waste brick slag, the strength of the concrete decreases gradually, and the strength of the concrete with a single particle size is lower than that of the waste brick slag concrete with mixed particle size. The influence of adding SAP and waste brick slag on the strength of concrete was studied. When the amount of waste brick slag is less than 30, the carbonation resistance of concrete is not affected. The effect of waste brick slag on the carbonation resistance of concrete with low water-binder ratio is more significant, but the effect on the concrete with different content of silica fume is more consistent, which will increase the carbonation depth by about 3 times. The carbonation depth of mixed size waste brick slag concrete is higher than that of single size waste brick slag concrete. The addition of SAP and waste brick slag can improve the adverse effect of SAP on the carbonization performance of SAP.) when the content of waste brick slag is 10%, the electric flux of concrete decreases by 25. 3% compared with the standard concrete, and after more than 10%, the electric flux of concrete increases gradually with the increase of the content of waste brick slag. The higher the water-binder ratio, the smaller the influence of waste brick slag on the electric flux of concrete. With the addition of waste brick slag, the larger the ratio of silica fume is, the less the influence of waste brick slag on the electric flux of concrete is. In addition, the particle size of the waste brick slag has little effect on the electric flux of concrete, but the electric flux of the waste brick slag concrete with mixed particle size is larger than that of the concrete with a single particle size. At the same time, the electric flux of concrete mixed with SAP and waste brick slag is larger than that of concrete mixed with SAP alone. Under the premise of not obviously affecting the strength and durability of concrete, the waste brick slag can effectively reduce the early shrinkage of concrete and improve its crack resistance. It is feasible to use waste clay brick as curing material in concrete.
【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528

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