本文選題：石灰石粉 + 機(jī)制砂　； 參考：《廣西大學(xué)》2017年碩士論文

【摘要】：機(jī)制砂再生混凝土作為一種新型環(huán)保綠色建筑材料,在實(shí)際投入生產(chǎn)前仍需對其材料性能進(jìn)行大量的理論和試驗(yàn)研究。本文以試驗(yàn)為主,結(jié)合理論方法,針對含石粉機(jī)制砂再生混凝土的拉壓強(qiáng)度、單軸受壓應(yīng)力-應(yīng)變本構(gòu)關(guān)系和水泥水化微觀機(jī)理進(jìn)行研究。在普通混凝土配合比公式的基礎(chǔ)上,采取附加用水量的方法進(jìn)行調(diào)整再生混凝土的配合比,試驗(yàn)配制相同水灰比(0.4)設(shè)計(jì)強(qiáng)度為35MPa,不同石粉含量(0%、5%、10%、15%)、不同再生粗骨料取代率(0%、33.3%、66.6%、100%)的機(jī)制砂再生混凝土。主要完成了以下工作:首先,本文對120個立方體試塊進(jìn)行混凝土立方體抗壓和劈裂抗拉強(qiáng)度試驗(yàn),分析石粉含量、再生粗骨料取代率對機(jī)制砂再生混凝土拉、壓性能的影響,并建立立方體抗壓強(qiáng)度和劈裂抗拉強(qiáng)度的換算關(guān)系。試驗(yàn)結(jié)果表明,機(jī)制砂再生混凝土中含有一定量的石粉對混凝土強(qiáng)度的提高起促進(jìn)作用,建議的合理石粉含量為10%。機(jī)制砂再生混凝土的抗壓和抗拉強(qiáng)度隨著再生粗骨料取代率的增加先降低后提高,在再生粗骨料取代率為66.6%時達(dá)到最小值;隨著再生粗骨料取代率繼續(xù)增大至100%,其強(qiáng)度有所提高。根據(jù)試驗(yàn)建立的立方體抗壓強(qiáng)度和劈裂抗拉強(qiáng)度的換算關(guān)系為:ft=0.175fcu0.75;較普通混凝土,在相同立方體抗壓強(qiáng)度下,換算得到劈裂抗拉強(qiáng)度值較小。其次,完成了 60個棱柱體軸心受壓試驗(yàn),得到不同石粉含量、不同再生粗骨料取代率下的機(jī)制砂再生混凝土單軸受壓應(yīng)力-應(yīng)變?nèi)�。結(jié)果表明,機(jī)制砂再生混凝土立方體抗壓強(qiáng)度與軸心抗壓強(qiáng)度的換算公式為:fc=0.818fcu;較普通混凝土,在相同立方體抗壓強(qiáng)度下,換算得到軸心抗壓強(qiáng)度值較大。機(jī)制砂再生混凝土單軸受壓應(yīng)力-應(yīng)變?nèi)�與普通混凝土大致相同,根據(jù)曲線特點(diǎn)采用損傷力學(xué)理論分析機(jī)制砂再生混凝土的單軸受壓破壞過程,建立機(jī)制砂再生混凝土單軸受壓應(yīng)力-應(yīng)變損傷本構(gòu)方程。最后,通過對混凝土各水化齡期試驗(yàn)樣品進(jìn)行X射線衍射物相分析(XRD)和掃描電鏡觀測(SEM),分析機(jī)制砂再生混凝土水化產(chǎn)物的種類及其微觀形貌特征,揭示石粉對機(jī)制砂再生混凝土力學(xué)性能的影響機(jī)理,從微觀的角度分析石粉對混凝土強(qiáng)度的影響。試驗(yàn)結(jié)果表明,石灰石粉微細(xì)骨料起填充、反應(yīng)和晶核效應(yīng)等作用,其中反應(yīng)效應(yīng)主要發(fā)生在水化過程的中后期;摻入石灰石粉微細(xì)骨料還對水化產(chǎn)物的形貌產(chǎn)生了影響。
[Abstract]:As a new environmental protection green building material, recycled concrete with machine-made sand still needs a lot of theoretical and experimental research before it is put into production. In this paper, the tensile strength, uniaxial compressive stress-strain constitutive relation and hydration micromechanism of recycled concrete with stone powder are studied in terms of tensile strength, uniaxial compressive stress-strain constitutive relation and cement hydration mechanism. On the basis of the formula of ordinary concrete mix ratio, the method of additional water consumption is adopted to adjust the mix ratio of recycled concrete. The design strength of the same water-cement ratio is 0.4) the design strength is 35 MPA, the content of different stone powder is 0 0 and 5%, and the replacement rate of different recycled coarse aggregate is 33.3% and 66.6% respectively). The main works are as follows: firstly, the concrete cube compressive and splitting tensile strength tests are carried out on 120 cube specimens, and the effects of stone powder content and recycled coarse aggregate replacement rate on the tensile and compressive properties of recycled concrete made of machine-made sand are analyzed. The conversion relationship between cube compressive strength and split tensile strength is established. The test results show that a certain amount of stone powder in recycled concrete with machine-made sand can promote the improvement of concrete strength, and the suggested reasonable stone powder content is 10. The compressive and tensile strength of recycled concrete with recycled sand decreases first and then increases with the increase of the replacement ratio of recycled coarse aggregate, and reaches the minimum value when the replacement rate of recycled coarse aggregate is 66.6. The strength of regenerated coarse aggregate increases with the ratio of replacement of recycled coarse aggregate to 100. The conversion relationship between the cube compressive strength and the splitting tensile strength established by the test is: (1) ftr 0.175 fcu0.75; compared with ordinary concrete, the value of splitting tensile strength is smaller than that of ordinary concrete under the same cube compressive strength. Secondly, the axial compression tests of 60 prisms have been completed, and the stress-strain curves of recycled concrete under uniaxial compression with different content of stone powder and different replacement rate of recycled coarse aggregate have been obtained. The results show that the conversion formula of cube compressive strength and axial compressive strength of recycled concrete with mechanism sand is: 1 / fc0. 818 fcu. compared with ordinary concrete, under the same cube compressive strength, the value of axial compressive strength can be obtained by conversion. The stress-strain curve of recycled concrete under uniaxial compression is approximately the same as that of ordinary concrete. According to the characteristics of the curve, the damage mechanics theory is used to analyze the uniaxial compressive failure process of recycled concrete with machine-made sand. The stress-strain damage constitutive equation of recycled concrete under uniaxial compression was established. Finally, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to observe the hydration products of recycled concrete from different hydration ages of concrete. The types and microscopic morphology of hydration products of recycled concrete with machine-made sand were analyzed. The influence mechanism of stone powder on the mechanical properties of recycled concrete made of machine-made sand is revealed, and the influence of stone powder on the strength of concrete is analyzed from the microscopic point of view. The results show that the effect of filling reaction and nucleation of limestone fine aggregate mainly occurs in the middle and late stage of hydration and the morphology of hydration product is also affected by the addition of limestone fine aggregate.
【學(xué)位授予單位】：廣西大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU528

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