建筑垃圾再生骨料表面改性及其对砂浆性能影响的研究

发布时间：2018-03-28 22:31

本文选题：建筑垃圾　切入点：再生细骨料　出处：《济南大学》2015年硕士论文

【摘要】：据统计仅汶川地震产生的建筑垃圾近六亿吨,不但占用大量土地资源,而且对当地水源、空气、土壤造成严重污染,当前随着我国国民经济建设步伐的不断加快,如何科学合理的利用建筑垃圾成为亟需解决的问题。将建筑垃圾中的废弃混凝土、废弃砂浆经破碎、清洗、分级等工艺制得再生骨料,用于替代天然骨料制备再生混凝土、再生胶砂,可有效利用建筑垃圾。然而再生骨料的压碎指标和吸水率较高对再生混凝土性能影响较大,再生骨料—水泥石界面层是再生混凝土最薄弱区域,而再生骨料与水泥石的界面结合性能不如天然骨料,降低了再生混凝土的性能。本文研究内容包括采用无机改性、有机改性改性以及有机-无机复合改性的方式对再生细骨料进行改性:首先分析了不同改性方式对再生细骨料物理性能的影响,包括表观密度、吸水率、孔隙率以及压碎指标;其次分析了再生细骨料的改性对建筑垃圾再生细骨料水泥砂浆(简称再生胶砂)性能的影响,主要包括力学性能、耐久性、界面层厚度以及微观形貌分析;最后本文针对不同改性方式对再生细骨料的表面改性机理进行分析,并构建了再生细骨料表面微观结构模型。经试验研究得出:1.与天然骨料相比,再生细骨料具有密度小,吸水率、孔隙率大以及压碎指标值高的特点。再生细骨料10min吸水率为其24h吸水率的82.7%,制备再生胶砂其力学性能、耐久性较差。2.无机改性再生细骨料,通过15wt%的矿渣浆液与5wt%的水玻璃溶液复合改性时改性效果较好。结合SEM图,未改性再生细骨料试样其表面存在较大的微裂纹,孔隙较多,结构疏松;而经水玻璃溶液改性后,水玻璃固化生成的凝胶能够在其表面形成一层粘结膜,表面结构致密,同时促进了矿渣微粉,降低了吸水率。3.有机改性再生细骨料,采用10wt%的PVA溶液改性时,降低了其吸水率,改性效果较好,然而VAE乳液对骨料物理性能的作用不明显。4.采用10wt%矿渣微粉浆液、5wt%水玻璃溶液以及10wt%的PVA溶液复合改性骨料试样其吸水率为2.3%,压碎指标值为8.7%。矿渣微粉浆液对再生细骨料的改性效果较明显,与其较小的粒度且较高的活性指数息息相关。5.对传统的再生胶砂制备工艺进行改进,采用预浸泡10min处理再生细骨料的“水泥裹砂”二次搅拌工艺,改善了再生胶砂的力学性能与耐久性。6.针对再生胶砂的ITZ界面层厚度,无机改性起到了一定效果,而粉煤灰改性效果较差,有机-无机复合改性再生胶砂试样其界面过渡区厚度集中在20μm~30μm。7.针对再生胶砂的气孔率,矿渣微粉与水玻璃复合改性试样MA9其气孔率为14.9%,与未改性再生胶砂试样相比,降低了57.2%。有机-无机复合改性显著改善了再生胶砂试样的气孔率。8.针对再生胶砂的力学性能,矿渣和水玻璃复合改性后显著提高了再生胶砂的力学性能,而有机改性对再生胶砂的力学影响作用不明显。有机-无机复合改性效果较好,其中改性再生胶砂试样MC6其抗折强度提高了27.6%,抗压强度提高了41.6%,抗压强度与基准水泥砂浆试样相差仅4.9%。9.针对再生胶砂的干燥收缩性能,粉煤灰改性效果较差,有机改性再生胶砂的干燥收缩值影响较小。这主要是由于粉煤灰颗粒较大且活性较低,难以在水化初期起到对再生胶砂的干燥收缩的抑制作用。针对再生胶砂的抗冻融性能,无机改性、有机改性、有机-无机复合改性对再生胶砂的抗冻性能作用效果较好。综上所述,本文经试验研究得出再生细骨料的最佳改性方案为:10wt%矿渣微粉浆液、5wt%水玻璃溶液以及10wt%的PVA溶液。10.针对再生胶砂的微观结构,未改性再生细骨料—水泥石界面过渡区ITZ存在较大尺寸的六方板状CH晶体,且晶体间存在较大气孔,而改性再生细骨料—水泥石界面过渡区仅可见小尺寸板状CH晶体,水化产物C-S-H凝胶、钙矾石等互相穿插,结构致密,无明显气孔、孔隙。基于传统的“水泥石”理论,提出了再生细骨料微观结构模型。
[Abstract]:According to statistics, only the Wenchuan earthquake construction waste generated nearly six hundred million tons, not only occupy a lot of land resources, and the air of local water, soil, causing serious pollution, with the current pace of national economic construction in China is accelerating, how to scientific and reasonable utilization of construction waste is needed to solve the problem. The waste concrete in the construction waste waste mortar, crushing, washing, grading process of recycled aggregate replacing natural aggregate, for the preparation of recycled concrete, recycled mortar, effective use of construction waste. However, crushed recycled aggregate index and high water absorption has great influence on the performance of recycled concrete, recycled aggregate cement stone interface layer is the most recycled concrete the weak area, with better performance of natural aggregate and aggregate and cement stone regeneration interface, reduces the performance of recycled concrete. The research contents of this paper include the use of inorganic Modification, organic modification and organic inorganic composite modification of recycled fine aggregate was modified: the first analysis of the influence of different modification methods of recycled fine aggregate physical properties, including apparent density, water absorption, porosity and crushing index; followed by analysis of the modified cement mortar of fine aggregate construction waste recycling of recycled fine aggregate (the recycled mortar) properties, including mechanical properties, durability, analysis of the interface layer thickness and microstructure; finally, according to the different modification methods on the mechanism of surface modification of recycled fine aggregate was analyzed, and the construction of the recycled fine aggregate surface microstructure model. It is concluded that: 1. compared with natural aggregate, recycled fine aggregate has small density, water absorption rate, high porosity and high crushing value. The characteristics of recycled fine aggregate water absorption rate of 10min for the 24h water absorption rate of 82.7%, Preparation of recycled mortar mechanical properties, durability of.2. inorganic modified recycled fine aggregate, the slag slurry and 5wt% 15wt% composite modified water glass solution modified better. Combined with the SEM diagram, the unmodified recycled fine aggregate on the surface of specimen are more micro cracks, pores more structure osteoporosis; through the water glass solution modified water glass curing the gel to form a layer of adhesive film on its surface, compact surface structure, and promote the slag, reduce the water absorption rate of.3. organic modification of recycled fine aggregate, using the 10wt% PVA solution is modified, the water absorption rate decreased however, the modification effect is better, the role of VAE on the properties of emulsion aggregate physical is not obvious by using 10wt%.4. 5wt% micro slag slurry, water glass solution and 10wt% solution of PVA composite modified aggregate samples and the water absorption rate was 2.3%, crushing index value of 8.7%. slag powder The slurry of recycled fine aggregate modification effect is obvious, granularity and high activity index and smaller is closely related to the traditional.5. recycled mortar preparation process was improved by pre soaking 10min processing of recycled fine aggregate cement wrapped sand two mixing process, the thickness of ITZ interface layer improved reclaimed sand the mechanical properties and durability of recycled mortar for.6., inorganic modification played a certain effect, but the modified fly ash effect is poor, the organic-inorganic composite modified recycled mortar specimens of the ITZ thickness in 20 m~30 m.7. for the rate of recycled mortar porosity, slag powder composite with water the modification of glass specimen MA9 the porosity was 14.9%, compared with the unmodified recycled mortar, reduces the 57.2%. organic-inorganic composite mechanical properties of modified significantly improve the porosity of recycled mortar specimens for.8. rate of recycled mortar, slag Glass and water after composite modification significantly improves the mechanical properties of recycled mortar, and organically modified mechanics of reclaimed rubber sand effect is not obvious. Organic inorganic compound modification effect, the modification of recycled mortar specimens MC6 the flexural strength increased 27.6%, compressive strength increased by 41.6%. The compressive strength of the cement mortar specimen was only 4.9%.9. benchmark for recycled mortar dry shrinkage performance of modified fly ash effect is poor, the dry shrinkage of organic modification of recycled mortar value has little effect. This is mainly because the fly ash particles were large and low activity, difficult in the inhibition of the early hydration to the dry shrinkage of recycled mortar. The mortar for regeneration of freeze-thaw resistance, inorganic modification, organic modification, organic inorganic compound modification effect on the frost resistance of recycled mortar is better. In summary, through the experimental investigation to regeneration The best modification scheme of fine aggregate is 10wt% micro slag slurry, the microstructure of recycled mortar for 5wt% and 10wt% PVA solution of water glass solution.10., unmodified six plate CH crystal of recycled fine aggregate and cement paste interfacial transition zone ITZ has larger size, and the crystal between the larger pores the modification of recycled fine aggregate and cement paste interfacial transition zone is visible only small size plate CH crystal, the hydration products of C-S-H gel, ettringite and interspersed with each other, compact structure, no obvious pores, pores. The traditional "cement" based on the theory, put forward the fine aggregate micro structure model of regeneration.

【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU578.1

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