【作者】 李中华；

【导师】 巴恒静；

【作者基本信息】 哈尔滨工业大学 ， 结构工程， 2009， 博士

【摘要】 在寒冷地区,使用除冰盐对路面进行除雪,往往会导致路面的剥蚀和开裂,使水泥混凝土路面达不到设计的使用年限。目前,道路混凝土所采取的措施提高了混凝土的抗水冻性能,但没有解决道路混凝土的盐冻剥蚀问题。为此,本文选择适合评价寒冷地区道路混凝土抗盐冻性能的试验方法,研究降低混凝土盐冻剥蚀量和相对动弹性模量损失率的措施,提高道路混凝土的抗盐冻剥蚀性能,使混凝土能够满足寒冷地区的使用要求。本文比较了国内外的混凝土抗冻性能试验方法。从传热介质的种类、试件与传热介质的接触方式、评价参数及试验方法的可操作性方面考虑,选择CDF方法研究道路混凝土抗盐冻剥蚀性能。并根据CDF方法的规定,研发了混凝土盐冻试验机组。该设备具有自动控制温度、自动断电保护及自动记录存储数据等功能。研究了抗折强度、水灰比、掺合料及引气剂对道路混凝土抗盐冻剥蚀性能的影响,结果表明:混凝土的盐冻剥蚀量和相对动弹性模量损失率随抗折强度的增加而减小;混凝土的抗盐冻剥蚀性能随水灰比的减小而提高;在混凝土中添加掺合料及引气剂能够减小混凝土的盐冻剥蚀量和相对动弹性模量的损失率,其中复掺掺合料混凝土的抗盐冻剥蚀性能优于单掺掺合料的混凝土。因此,在实际工程中应提倡掺合料的复掺技术。采用WHY-100型全自动应力试验机进行重复加载试验,研究重复荷载对道路混凝土抗盐冻剥蚀性能的影响。结果表明:重复荷载作用后,混凝土的盐冻剥蚀量和相对动弹性模量损失率随荷载水平的增加而增大,道路混凝土抗盐冻性能明显下降。研究内掺有机硅对混凝土抗压强度、盐冻剥蚀量及相对动弹性模量损失率的影响,同时观察混凝土试验面的剥蚀状况。结果表明:内掺有机硅后,普通混凝土28d抗压强度提高了4.9%,高性能混凝土28d抗压强度基本保持不变;普通混凝土及高性能道路混凝土的盐冻剥蚀量和相对动弹性模量损失率明显降低。有机硅外加剂改善了混凝土表面的剥蚀状况和内部微观结构,提高了道路混凝土的抗盐冻性能。此外,本文配制的有机硅涂料能够显著地降低混凝土的盐冻剥蚀量和相对动弹性模量损失率,较明显地改善了道路混凝土盐冻后的表面剥蚀状况。经SEM观察表明:盐冻后微观结构较致密,没有出现裂缝,干燥后没有NaCl晶体析出。与减小水灰比、添加掺合料和引气剂相比,表面涂刷有机硅是提高寒冷地区道路混凝土抗盐冻剥蚀性能的更有效措施。本文评价了各种措施对道路混凝土抗盐冻性能的改善作用,阐述了提高寒冷地区道路混凝土的抗盐冻剥蚀机理及技术途径,为抗盐冻剥蚀道路混凝土的应用及推广提供了依据。更多还原

【Abstract】 Deicing salt was used to thaw snow on the concrete pavement in cold regions. It can lead to scaling and cracking of pavement so that cement concrete pavement did not reach service life to design. At present some measures adopted improved pavement concrete in freeze-water resistance but freeze-deicer salt resistance of pavement was not improved obviously. So the test method for freeze-deicing salt resistance of pavement concrete in cold regions was selected in this paper. Then the measures decreasing the scaled mass and relative dynamic modulus of elasticity loss factor were researched. Freeze-deicing salt resistance of pavement concrete was improved and the pavement concrete can be applied for cold regions.In this paper the domestic and foreign test methods for freeze-deicer resistance of concrete were compared. According to the kinds of heat transfer medium, contact style between concrete specimens and heat transfer medium, evaluation parameters and operation of test method, CDF method was selected to research freeze-deicing salt resistance of pavement concrete. And in accordance with the CDF method the test equips for freeze-deicer resistance were researched and developed. It had automatic control of temperature, automatic power-off protection and automatic data storage functions.Effect of the flexural strength, water cement ratio, admixture and air-entrained agent on freeze-deicer scaling resistance of pavement concrete was researched. The results showed the scaled mass and the loss rate of dynamic elasticity modulus decreased with increase of flexural strength. The freeze-deicer scaling resistance tended to improve with the reduction of water cement ratio. The scaled mass and the loss rate of dynamic elasticity modulus were decreased in the extent as result of admixture and air-entrained agent added into concrete. And freeze-deicer resistance of concrete with multiple kinds of admixture was superior to concrete with a kind of admixture so multiple admixtures should be advocated to use in practical engineering.WHY-100 automatic stress-testing machine was used for repeated loads and effect of repeated loads on freeze-deicer scaling resistance of pavement concrete was researched. The results showed that the scaled mass and relative dynamic modulus of elasticity loss factor increased with increase of load level after repeated loads, the freeze-deicing salt resistance of pavement decreased obviously.The effect of organosilicone on the compress strength, the scaled mass and loss rate of dynamic elasticity modulus of concrete were studied, the test surface of concrete specimens was observed. The results showed that the compress strength of ordinary concrete increased by 4.9% and the compress strength of high performance concrete was not changed at 28 day as result of organosilicone added into concrete. The scaled mass and loss rate of dynamic elasticity modulus of ordinary concrete and high performance concrete were greatly decreased. Organosilicone can decrease scaling on the surface, improve microstructure and freeze-deicer salt resistance of pavement concrete.In addition, the organosilicone coat prepared by our lab can obviously decrease the scaled mass and loss rate of dynamic elasticity modulus. Scaling on the surface of pavement concrete after deicer-frost was decreased. SEM observation showed that the microstructure of concrete was dense and there are few micro-cracks inside the concrete painted with the organosilicone. After drying no cubic NaCl crystals formed inside concrete. Compared with reducing the water and cement ratio and adding admixture and air-entrained agent the organosilicone painted on the surface of concrete was the more effective way to improve the freeze-deicing salt resistance of pavement concrete in cold regions.In this paper improvement of several measures in the freeze-deicing salt resistance of pavement concrete was appraised. The mechanics and technology way to improve the freeze-deicer scaling resistance of pavement concrete was summarized so it provided evidence for application and popularization of pavement concrete with freeze-deicer resistance.更多还原