利用再生骨料制备再生混凝土及其性能的研究

发布时间：2018-01-13 20:44

  本文关键词：利用再生骨料制备再生混凝土及其性能的研究　出处：《广西大学》2013年硕士论文　论文类型：学位论文

  更多相关文章： 废弃混凝土 再生混凝土 再生骨料 抗压强度 抗氯离子渗透性 微观孔结构

【摘要】：本文以南宁市某研究院的废弃混凝土为原料,利用破碎、机械强化技术,将废弃混凝土分离后制备粒径为5mm～20mm的再生粗骨料、粒径为0.16-5mm的再生细骨料以及粒径小于0.16mm的再生微粉。制备的再生骨料性能稳定、颗粒圆润、具有良好的级配,机械强度高,但由于表面附着砂浆,空隙率较低、表观密度略小于传统骨料。 在相同坍落度(180±10mm)要求下,设计制备高低两种水胶比(W/B=0.55、0.35)的再生混凝土,分别用再生粗、细骨料以相同掺量复掺制备再生混凝土,掺量为0%、30%、50%、70%和100%,分析掺量对新拌混凝土的表观密度和硬化混凝土在不同龄期(7d、28d、90d)抗压强度的影响。另外,仅将再生细骨料以掺量为0%、30%、50%、70%单掺替代传统细骨料制备再生混凝土,研究其抗压强度、抗氯离子渗透性和微观结构与再生细骨料掺量的关系。为了探讨再生混凝土性能的相关影响因素,进一步采用正交试验(L934)设计方法探讨了水胶比、粉煤灰掺量、再生粗骨料掺量和再生细骨料掺量对再生混凝土的抗压强度、抗氯离子渗透性和微观结构的影响。 研究结果表明：在两种水胶比条件下,复掺粗、细骨料再生混凝土的表观密度均随着再生骨料总掺量的增加而下降；不同龄期的试块抗压强度基本高于普通混凝土,而且随着掺量的提高,再生混凝土的强度也增加。只有0.35水胶比下,100%再生粗、细骨料替代率90d强度较同龄期普通混凝土有所下降。 对于单掺细骨料混凝土,在两种水胶比下,单掺细骨料也会使再生混凝土的7d、90d抗压强度相对普通混凝土略有上升,最高达到普通混凝土的116.2%,但28d抗压强度相对普通混凝土略有下降。在混凝土快速氯离子渗透性试验中,水胶比为0.35,再生细骨料掺量为30%时,再生混凝土7d、28d、90d的电通量相对其它掺量的混凝土有所下降；水胶比为0.55时,掺再生细骨料的再生混凝土电通量在不同细骨料掺量下变化不大。在不同龄期,随着骨料掺量上升,再生混凝土的电通量略有上升。微观孔结构结果表明,影响再生混凝土的强度和抗氯离子渗透能力的主要是有益孔(d≤100nm)和有害孔(d100nm)各占的比例；掺再生细骨料混凝土的孔隙率与28d强度呈负相关关系,相关系数可达0.976；不同掺量的再生细骨料汞总压入体积与电通量呈正相关关系,相关系数为0.989。 正交试验结果表明：各对再生混凝土7d、28d和90d的抗压强度影响主次顺序均为水胶比粉煤灰掺量再生细骨料掺量再生粗骨料掺量,各因素对7d、28d、90d的电通量和28d的孔隙率、有益孔影响的主次顺序均为水胶比粉煤灰掺量再生粗骨料掺量再生细骨料掺量,并确定了各龄期的最佳理论组合方案；粉煤灰能显著改善再生混凝土28d龄期的孔径分布。
[Abstract]:In this paper, the recycled coarse aggregate with the diameter of 5mm ~ 20mm was prepared by using the technology of crushing and mechanical strengthening with the waste concrete of a certain research institute in Nanning city as the raw material. The regenerated fine aggregate with the diameter of 0.16-5mm and the regenerated powder with the diameter less than 0.16mm have stable properties, round particles, good gradation and high mechanical strength. However, due to the surface adhesion of mortar, the porosity is lower and the apparent density is slightly lower than that of traditional aggregate. Under the same slump (180 卤10 mm) requirement, the recycled concrete with high or low water / binder ratio (W / B _ (0.55) ~ (0.35)) was designed and manufactured respectively. The fine aggregate is mixed with the same amount of recycled concrete, and the amount of fine aggregate is 30% and 50% respectively, and the ratio is 70% and 100%. This paper analyzes the effect of adding amount on the apparent density of fresh concrete and compressive strength of hardened concrete at different ages. In addition, only 0% of recycled fine aggregate is added. The compressive strength of recycled concrete was studied by using 50% 70% concrete as a substitute for traditional fine aggregate. The relationship between chloride ion permeability and microstructure and the content of recycled fine aggregate. In order to study the factors affecting the properties of recycled concrete, the water-binder ratio was further studied by orthogonal test (L934) design method. The effects of fly ash, recycled coarse aggregate and recycled fine aggregate on the compressive strength, chloride ion permeability and microstructure of recycled concrete. The results show that the apparent density of recycled concrete decreases with the increase of the total amount of recycled aggregate under the condition of two kinds of water-binder ratio. The compressive strength of the test blocks of different ages is basically higher than that of ordinary concrete, and the strength of recycled concrete increases with the increase of the content of concrete. Only 0.35% of water / binder ratio is 100% coarse. The replacement ratio of fine aggregate in 90 days is lower than that of ordinary concrete in the same age period. For concrete with single fine aggregate, the compressive strength of recycled concrete at 7d / 90d is slightly higher than that of ordinary concrete under two kinds of water-binder ratio. The maximum is 116.2 of ordinary concrete, but the compressive strength of 28 days is slightly lower than that of ordinary concrete. In the rapid chloride ion permeability test of concrete, the water-binder ratio is 0.35. When the amount of recycled fine aggregate is 30%, the electric flux of recycled concrete decreases compared with that of other concrete at 7 d ~ 28 d ~ 90 d. When the water-binder ratio is 0.55, the electrical flux of recycled concrete with recycled fine aggregate does not change much under different fine aggregate content, but with the increase of aggregate content at different ages. The electrical flux of recycled concrete increased slightly. The main factors affecting the strength and chloride penetration resistance of recycled concrete are the proportion of beneficial pore d 鈮，

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