本文選題：風積沙混凝土 + 預應力損傷��； 參考：《內(nèi)蒙古農(nóng)業(yè)大學》2017年碩士論文

【摘要】：混凝土在服役期間,受到意外撞擊、震動和地震等偶然外加荷載作用而出現(xiàn)損傷,導致處于凍融環(huán)境下和氯鹽侵蝕下的風積沙混凝土耐久性變差。所以,風積沙混凝土在預應力損傷后具有的耐久性研究非常重要。在進行耐久性試驗之前,先進行力學損傷試驗,具體可分為三個階段:階段一:施加預應力。采用萬能試驗機外加載的方式施加預應力,施加預應力之前以及之后用非金屬超聲波檢測儀測定試件氣干狀態(tài)下的超聲波波速,通過計算損傷變量和反復加載,最終得到未受預應力的C25風積沙混凝土和損傷度分別為0.0～0.1與0.1～0.2以及0.2～0.3預應力損傷風積混凝土。階段二:對被預應力損傷的風積沙混凝土展開相應實驗。根據(jù)相關文件GB/T50082-2009,即混凝土的耐久性與長期性試驗規(guī)定,在凍融循環(huán)實驗中使用的是文件內(nèi)的"快凍法",并且在評價指標上選擇的是該混凝土的質(zhì)量變換與相對動彈性模量。試驗結果表明:相較之下,被預應力損傷的混凝土在抗凍融性方面的變化是具有梯度規(guī)律的。如果該混凝土的損傷度達到0.0～0.1,那么它在凍融劣化方面的規(guī)律就和基準風積沙相差不大,其抗凍性在損傷度大于0.1之后,就會出現(xiàn)明顯降低。階段三:風積混凝土在被預應力損傷之后的干濕循環(huán)研究。該研究主要是針對該混凝土的抗氯鹽侵蝕性。以質(zhì)量變化率和相對動彈性模量作為評價指標來綜合表征預應力損傷下風積沙混凝土抗氯鹽侵蝕性能。結果表明:與基準風積沙混凝土相比,預應力下風積沙混凝土抗氯鹽侵蝕性能呈現(xiàn)線性變化規(guī)律,損傷度為0.0～0.1的風積沙混凝土試件抗氯鹽侵蝕性能略有下降,可忽略損傷度對其的影響;如果損傷度大于0.1,那么其抗氯鹽侵蝕性就會出現(xiàn)明顯降低。本文在研究了風積沙混凝土的抗凍融性以及氯鹽侵蝕性之后,以此為依據(jù)構建了相應的演化方程,對針對被預應力損傷的風積沙混凝土處于氯鹽中所具有的抗侵蝕性,之后將此當做該混凝土耐久性評價的理論依據(jù),具有很大的意義。
[Abstract]:During the period of service, the concrete is damaged by accidental impact, vibration and earthquake, which results in the deterioration of the durability of the wind-sand concrete under freezing and thawing environment and chlorine salt erosion. Therefore, it is very important to study the durability of eolian sand concrete after prestress damage. Before durability test, mechanical damage test is carried out, which can be divided into three stages: stage one: applying prestress. The prestressing force is applied by the universal testing machine, and the ultrasonic wave velocity in the air-dry state of the specimen is measured by the non-metallic ultrasonic detector before and after the prestress is applied. The damage variable is calculated and the repeated loading is carried out. Finally, the unprestressed C 25 aeolian sand concrete and the damage degree are 0. 0. 1, 0. 1, 0. 2 and 0. 2 ~ 0. 3 respectively. Stage two: the corresponding experiments are carried out on the eolian sand concrete damaged by prestress. According to the relevant document GB / T 50082-2009, that is, the durability and long-term test of concrete, the "quick freezing method" is used in the freeze-thaw cycle experiment, and the quality shift and relative dynamic elastic modulus of the concrete are selected in the evaluation index. The experimental results show that, by comparison, the change of freeze-thaw resistance of prestressed concrete has gradient law. If the damage degree of the concrete reaches 0.00. 1, the law of freeze-thaw deterioration is not different from that of the standard aeolian sand, and the frost resistance of the concrete will decrease obviously when the damage degree is greater than 0.1. Stage three: dry and wet cycle of wind-induced concrete after prestress damage. This study is mainly aimed at the chloride corrosion resistance of the concrete. The rate of mass change and the relative dynamic modulus of elasticity are taken as the evaluation indexes to comprehensively characterize the chloride corrosion resistance of wind-sand concrete under prestress damage. The results show that compared with the standard aeolian sand concrete, the chloride corrosion resistance of the prestressed concrete under the wind sand has a linear variation rule, and the chloride corrosion resistance of the wind sand concrete with damage degree of 0.00. 1 is a little lower than that of the standard eolian sand concrete. If the damage degree is greater than 0.1, the resistance to chloride corrosion will be significantly reduced. After studying the freeze-thaw resistance and chloride erosion of eolian sand concrete, a corresponding evolution equation is constructed based on which the corrosion resistance of eolian sand concrete with prestressing damage in chloride salt is studied. It is of great significance to take this as the theoretical basis for durability evaluation of 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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