【摘要】：本文以再生骨料和天然浮石為粗骨料,用再生骨料等體積取代浮石,從宏觀和微觀兩個方面,研究再生骨料取代率分別為0%、30%、50%、70%、100%混合骨料混凝土的基本力學性能及耐久性能,從中篩選出最優(yōu)的取代率。試驗結(jié)果表明:隨著再生骨料取代率的增大,混合骨料混凝土的立方體抗壓強度逐漸在增大,其劈裂抗拉強度以取代率30%為界,呈現(xiàn)先升高后降低的趨勢;從混凝土的質(zhì)量損失、相對動彈性模量損失和外觀剝落情況,發(fā)現(xiàn)再生骨料取代率為50%和70%的混合骨料混凝土表現(xiàn)出了良好的抗凍性;再生骨料取代率增大,混合骨料混凝土中的氣孔含量減小;混凝土中孔結(jié)構(gòu)的含量是影響混凝土抗壓強度的主要因素之一。試驗結(jié)果得出再生骨料取代率為50%為最優(yōu)的取代率,用廢舊輪胎橡膠粉混凝土做進一步的改性研究。廢舊橡膠粉粒徑分別為20目、60目、80目、100目、120目,按照膠凝材料3%、6%、9%摻量進行摻入,分析混合骨料混凝土早期的力學性能及微觀結(jié)構(gòu)。試驗結(jié)果表明:在粒徑相同的條件下,廢舊橡膠粉使混合骨料混凝土的抗壓強度降低率增大;從環(huán)境掃描電鏡中得出,橡膠粉、再生骨料、浮石與水泥界面是薄弱區(qū)域,是造成混合骨料混凝土強度降低的主要原因。
[Abstract]:In this paper, regenerated aggregate and natural pumice are used as coarse aggregate, and regenerated aggregate is used to replace pumice in equal volume. From macroscopic and microscopic aspects, the replacement rate of recycled aggregate is studied to be 0.30% and 50% respectively. The basic mechanical properties and durability of 100% mixed aggregate concrete are selected out of which the optimum substitution rate is obtained. The experimental results show that the cube compressive strength of mixed aggregate concrete increases gradually with the increase of the replacement ratio of recycled aggregate, and the split tensile strength of mixed aggregate concrete is limited by 30% replacement ratio, which increases first and then decreases. According to the mass loss of concrete, the loss of dynamic modulus of elasticity and the appearance of spalling, it is found that the recycled aggregate concrete with 50% and 70% replacement ratio shows good frost resistance. The content of pore structure is one of the main factors that influence the compressive strength of concrete with the increase of replacement ratio of recycled aggregate and the decrease of pore content in mixed aggregate concrete. The results show that the optimum replacement rate of recycled aggregate is 50%. The particle sizes of waste rubber powder were 20 mesh, 60 mesh, 80 mesh, 100 mesh and 120 mesh, respectively. The mechanical properties and microstructure of mixed aggregate concrete in the early stage were analyzed according to the amount of 3% cement material and 6% ~ 9% addition. The experimental results show that under the condition of the same particle size, the reduction rate of compressive strength of mixed aggregate concrete is increased by waste rubber powder. It is concluded from environmental scanning electron microscope that the interface between rubber powder, recycled aggregate, pumice and cement is a weak area, which is the main reason for the decrease of strength of mixed aggregate concrete.
【學位授予單位】：內(nèi)蒙古農(nóng)業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TU528

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