矿物掺合料对PHC管桩混凝土性能的影响
发布时间：2019-04-27 00:15
【摘要】：C80预应力高强混凝土(Prestressed High-Strength Concrete,即PHC)管桩,广泛应用于各种桩基工程。石英粉、矿粉、粉煤灰是常用的三种矿物掺合料,鉴于目前有关这三种掺合料对压蒸工艺制备PHC管桩混凝土性能的差异性影响研究报道较少,本文系统地研究了三种矿物掺合料对PHC管桩混凝土的力学性能、界面性能、抗氯离子渗透性能及抗硫酸盐侵蚀性能的影响。论文的主要成果如下:(1)单、双掺石英粉、矿粉、粉煤灰对PHC管桩混凝土立方体抗压强度(fcu)、劈裂抗拉强度(fts)和轴心抗压强度(fcp)影响的研究结果表明,与纯水泥混凝土试件相比,掺量在10%-30%范围内,单掺石英粉对提高fcu和fcp幅度效果最明显,次之是单掺矿粉,在掺量不超过10%时单掺粉煤灰对fcu和fcp稍有提高,超过10%时则会降低fcu和fcp;石英粉和粉煤灰、矿粉和粉煤灰在满足fcu和fcp要求的前提下,石英粉和粉煤灰、矿粉和粉煤灰两两双掺有利于提高fts。(2)与纯水泥混凝土试件相比,无论单掺或两两复掺矿物掺合料石英粉、矿粉、粉煤灰,均可提高PHC管桩混凝土的韧性,而掺入粉煤灰的效果最为明显。SEM分析表明,掺入粉煤灰的压蒸净浆试件中水化产物大孔少,形成了较为明显的空间网架结构,有利于提高管桩混凝土的韧性。(3)矿物掺合料对PHC管桩混凝土的应力-应变关系的影响研究表明,不同掺合料对PHC管桩混凝土的峰值应力和峰值应变的影响规律与其对立方体抗压强度的类似,均呈单调线性增加趋势。三种掺合料制备的PHC管桩高强混凝土的应力-应变曲线上升段相近,应力达到峰值的范围均在峰值应力的80%~90%,当应力达峰值前曲线的上升段基本变成了直线,临界裂缝应力点和峰值应力接近;但是下降段区别较大,掺入粉煤灰或矿粉时,下降段较为平缓,掺入石英粉时下降段斜率较大,呈直线。在试验的基础上,构建了掺矿物掺合料PHC管桩混凝土的应力-应变本构模型。(4)矿物掺合料对PHC管桩混凝土水泥石和骨料界面性质的影响研究表明,压蒸工艺制备的管桩混凝土的水泥石和骨料的界面仍存在明显的界面过渡区,与纯水泥混凝土试件相比,掺入石英粉、矿粉、粉煤灰界面过渡区的CH厚度均有所减小,掺合料对显微硬度的影响规律与对立方体抗压强度的影响规律相似。(5)矿物掺合料对PHC管桩混凝土的抗氯离子渗透性和抗硫酸盐腐蚀性的影响研究表明,与纯水泥混凝土试件相比,掺入掺合料的混凝土抗氯离子渗透性均有所提高,双掺掺合料的效果优于单掺的;单掺石英粉会降低PHC管桩混凝土的抗硫酸盐侵蚀性,单掺矿粉、粉煤灰或三种矿物掺合料两两双掺均有利于提高PHC管桩混凝土的抗硫酸侵蚀性。压汞试验表明掺入矿物掺合料均能有效改善管桩混凝土的孔结构,但是单掺石英粉会增加有害孔含量,这是单掺石英粉降低管桩混凝土抗硫酸盐侵蚀性的主要原因。
[Abstract]:C80 prestressed high strength concrete (Prestressed High-Strength Concrete,) pipe pile is widely used in various pile foundation projects. Quartz powder, mineral powder and fly ash are three kinds of mineral admixtures in common use. In view of the influence of these three admixtures on the performance difference of PHC pipe pile prepared by autoclave process, there are few reports reported at present. In this paper, the effects of three mineral admixtures on the mechanical properties, interface properties, chloride penetration resistance and sulfate corrosion resistance of PHC pipe pile concrete are systematically studied. The main achievements of this paper are as follows: (1) the effects of single, double-mixed quartz powder, mineral powder and fly ash on the cube compressive strength of PHC tubular pile concrete (fcu), splitting tensile strength (fts) and axial compressive strength (fcp) are studied. Compared with the pure cement concrete specimen, the addition of quartz powder has the most obvious effect on increasing the amplitude of fcu and fcp in the range of 10% and 30%, followed by the single mineral powder. When the content of fly ash is less than 10%, the fcu and fcp can be increased slightly. Lower fcu and fcp; when more than 10% Quartz powder and fly ash, mineral powder and fly ash meet the requirements of fcu and fcp, both of quartz powder and fly ash, mineral powder and fly ash can improve fts. (2) compared with pure cement concrete. The toughness of concrete with PHC pipe pile can be improved by adding quartz powder, mineral powder and fly ash with single or dual admixture of mineral, and the effect of admixture with fly ash is the most obvious. SEM analysis shows that the toughness of concrete can be improved by adding fly ash. There are few hydration products in the autoclaved paste specimen mixed with fly ash, and the space structure is formed. (3) the effect of mineral admixture on the stress-strain relationship of PHC pipe pile concrete is studied. The influence of different admixtures on the peak stress and strain of PHC tubular pile concrete is similar to that of the cubic compressive strength. The stress-strain curve of high-strength concrete of PHC pipe pile prepared by three kinds of admixtures is similar, and the range of stress reaching peak value is 80% ~ 90% of peak stress. When the stress reaches peak value, the rising section of curve becomes straight line basically. The stress point and peak stress of critical crack are close to each other; When the fly ash or ore powder is added, the descending section is relatively smooth, and the slope of the descending section is larger when the quartz powder is added, showing a straight line. On the basis of experiment, the stress-strain constitutive model of PHC pipe pile concrete with mineral admixture is constructed. (4) the effect of mineral admixture on the interface properties of cement paste and aggregate of PHC pipe pile concrete is studied. The interface between cement stone and aggregate of pipe pile concrete prepared by autoclave still has obvious interface transition zone. Compared with pure cement concrete specimen, the CH thickness of interface transition zone of concrete mixed with quartz powder, mineral powder and fly ash decreases to a certain extent. The influence of mineral admixture on microhardness is similar to that of opposite square compressive strength. (5) the influence of mineral admixture on chloride ion permeability and sulfate corrosion resistance of PHC pipe pile concrete shows that the effect of mineral admixture on chloride ion permeability and sulfate corrosion resistance of concrete is similar to that of opposite square. Compared with the pure cement concrete specimen, the chloride ion permeability of the concrete mixed with the admixture is improved, and the effect of the double admixture is better than that of the single admixture. The anti-sulfate corrosion resistance of PHC pipe pile concrete can be reduced by adding single quartz powder, single admixture of mineral powder, fly ash or three kinds of mineral admixture can improve the resistance of PHC pipe pile concrete to sulfuric acid erosion. Mercury pressure test shows that adding mineral admixture can effectively improve the pore structure of pipe pile concrete, but only adding quartz powder will increase harmful pore content, which is the main reason for reducing sulfate corrosion resistance of concrete pipe pile concrete with single addition of quartz powder.
【学位授予单位】：西安建筑科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TU528
本文编号：2466518
[Abstract]:C80 prestressed high strength concrete (Prestressed High-Strength Concrete,) pipe pile is widely used in various pile foundation projects. Quartz powder, mineral powder and fly ash are three kinds of mineral admixtures in common use. In view of the influence of these three admixtures on the performance difference of PHC pipe pile prepared by autoclave process, there are few reports reported at present. In this paper, the effects of three mineral admixtures on the mechanical properties, interface properties, chloride penetration resistance and sulfate corrosion resistance of PHC pipe pile concrete are systematically studied. The main achievements of this paper are as follows: (1) the effects of single, double-mixed quartz powder, mineral powder and fly ash on the cube compressive strength of PHC tubular pile concrete (fcu), splitting tensile strength (fts) and axial compressive strength (fcp) are studied. Compared with the pure cement concrete specimen, the addition of quartz powder has the most obvious effect on increasing the amplitude of fcu and fcp in the range of 10% and 30%, followed by the single mineral powder. When the content of fly ash is less than 10%, the fcu and fcp can be increased slightly. Lower fcu and fcp; when more than 10% Quartz powder and fly ash, mineral powder and fly ash meet the requirements of fcu and fcp, both of quartz powder and fly ash, mineral powder and fly ash can improve fts. (2) compared with pure cement concrete. The toughness of concrete with PHC pipe pile can be improved by adding quartz powder, mineral powder and fly ash with single or dual admixture of mineral, and the effect of admixture with fly ash is the most obvious. SEM analysis shows that the toughness of concrete can be improved by adding fly ash. There are few hydration products in the autoclaved paste specimen mixed with fly ash, and the space structure is formed. (3) the effect of mineral admixture on the stress-strain relationship of PHC pipe pile concrete is studied. The influence of different admixtures on the peak stress and strain of PHC tubular pile concrete is similar to that of the cubic compressive strength. The stress-strain curve of high-strength concrete of PHC pipe pile prepared by three kinds of admixtures is similar, and the range of stress reaching peak value is 80% ~ 90% of peak stress. When the stress reaches peak value, the rising section of curve becomes straight line basically. The stress point and peak stress of critical crack are close to each other; When the fly ash or ore powder is added, the descending section is relatively smooth, and the slope of the descending section is larger when the quartz powder is added, showing a straight line. On the basis of experiment, the stress-strain constitutive model of PHC pipe pile concrete with mineral admixture is constructed. (4) the effect of mineral admixture on the interface properties of cement paste and aggregate of PHC pipe pile concrete is studied. The interface between cement stone and aggregate of pipe pile concrete prepared by autoclave still has obvious interface transition zone. Compared with pure cement concrete specimen, the CH thickness of interface transition zone of concrete mixed with quartz powder, mineral powder and fly ash decreases to a certain extent. The influence of mineral admixture on microhardness is similar to that of opposite square compressive strength. (5) the influence of mineral admixture on chloride ion permeability and sulfate corrosion resistance of PHC pipe pile concrete shows that the effect of mineral admixture on chloride ion permeability and sulfate corrosion resistance of concrete is similar to that of opposite square. Compared with the pure cement concrete specimen, the chloride ion permeability of the concrete mixed with the admixture is improved, and the effect of the double admixture is better than that of the single admixture. The anti-sulfate corrosion resistance of PHC pipe pile concrete can be reduced by adding single quartz powder, single admixture of mineral powder, fly ash or three kinds of mineral admixture can improve the resistance of PHC pipe pile concrete to sulfuric acid erosion. Mercury pressure test shows that adding mineral admixture can effectively improve the pore structure of pipe pile concrete, but only adding quartz powder will increase harmful pore content, which is the main reason for reducing sulfate corrosion resistance of concrete pipe pile concrete with single addition of quartz powder.
【学位授予单位】：西安建筑科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TU528
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