新型石灰石土抗压强度试验及微观机理研究

发布时间：2018-01-06 20:05

本文关键词：新型石灰石土抗压强度试验及微观机理研究　出处：《安徽理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着时代的发展,土木工程中对材料的要求越来越高,石灰三合土(石灰土)强度发展缓慢且相对较低的特点使得自身应用受到限制。但三合土具有易取材、易施工、造价低的优点,是一种相对经济和环保的工程材料,在路基、坝体、基础等工程中仍有应用。因此,寻求一种有效、可行的新方法来提高土体抗压强度就成为了一项有意义的研究课题。本文以石灰土作为对照,用石灰石替换石灰土中的熟石灰得到新的土体——石灰石土,并用DAP(磷酸氢二铵)作为添加剂,分别以0、1%、2%、4%、8%的比例加入两种土中,得出各组试样的抗压强度变化情况,并结合SEM实验和XRD实验进行微观分析,以此探究该方法对土体的加固效果及其加固的机理。试验结果表明:1)石灰石替代熟石灰后,使得土样在7天的抗压强度降低了 17.46%,且前后强度基本无发展,108天时的抗压强度与石灰土相比降低了 68.64%;2)石灰石土中的DAP添加量达到2%后,试样的抗压强度随着DAP量的增加而逐渐提升,试验中添加8%的DAP对土体的加固效果最好,使得石灰石土的7 天、28 天、56 天、108 天抗压强度分别提高了 298.07%、417.64%、469.81%、494.34%;3)石灰土中,DAP的最优添加量为2%,可以使得石灰土前期(7天)和后期(108天)的抗压强度分别提高73.02%和13.61%,不仅早期强度发展较快,而且后期强度仍缓慢提高;4)当石灰石土的DAP添加量达到4%时,其前期、后期的抗压强度均大于DAP添加量为2%的石灰土;5)石灰石土加入DAP后,依靠CaCO3与DAP反应生成凝胶物质,胶结土体,提高土体的强度。综上所述,以石灰石替代石灰,并加入不少于4%的DAP作为添加剂,是本文探索出的提高土体抗压强度的新方法。该方法在提高土体强度的同时,还可以减少工程中石灰的使用,减少石灰生产过程中产生的能源消耗和大气污染,达到节能减排的目的。
[Abstract]:With the development of the times, the demand for materials in civil engineering is higher and higher. The characteristics of slow development and relatively low strength of lime trinity (lime soil) make its application limited. The advantages of easy construction and low cost are relatively economical and environmentally friendly engineering materials, which are still used in subgrade, dam, foundation and so on. The feasible new method to improve the compressive strength of soil has become a meaningful research topic. In this paper, limestone is used to replace the slaked lime in lime soil to obtain new soil-limestone soil. With DAP (diammonium hydrogen phosphate) as additive, the compressive strength of each group of samples was obtained by adding 8% ratio of 0 ~ 1 / 2 and 4% to two kinds of soil respectively. Combined with SEM experiment and XRD experiment, the microcosmic analysis was carried out to explore the reinforcement effect of this method on soil and its reinforcement mechanism. The experimental results show that: 1) Limestone replaced the hydrated lime. The compressive strength of the soil sample in 7 days was reduced by 17.46%, and the compressive strength of the soil sample decreased by 68.64% compared with lime soil at 108 days after the development of the strength. 2) when the content of DAP in limestone soil reaches 2%, the compressive strength of the sample increases with the increase of DAP content, and the strengthening effect of the soil is best with the addition of 8% DAP in the test. The compressive strength of limestone soil was increased by 298.07 days, 417.64 days and 469.81 days, respectively, and the compressive strength of limestone soil was increased by 298.07 days, 28 days and 56 days and 108 days, respectively. 3) the optimum addition amount of DAP in lime soil is 2, which can increase the compressive strength of lime soil by 73.02% days and 13.61% days, respectively. Not only the early strength developed rapidly, but also the later strength increased slowly. 4) when the DAP content of limestone soil reaches 4%, the compressive strength of lime soil in the early and late stages is higher than that of lime soil with DAP addition amount of 2%; 5) after adding DAP to limestone soil, CaCO3 reacts with DAP to form gel material, cement soil and improve the strength of soil. To sum up, limestone is used to replace lime. Adding not less than 4% DAP as additive is a new method to improve the compressive strength of soil, which can not only increase the strength of soil, but also reduce the use of lime in engineering. Energy consumption and air pollution in lime production are reduced to achieve the purpose of energy saving and emission reduction.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU521

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