Research on asphalt concrete pavement deicing technology

In order to reduce the cohesive force between pavement and ice, the approach of pavement surface coating with hydrophobic admixtures is investigated. The deicing effect of this approach is examined by the contact angle test and the shear test. The durability of the approach is examined by the accelerated abrasion test, and the skid resistance of the pavement with surface coating is examined by the British pendulum test and the surface texture depth test. In the contact angle test, the contact angle between hydrophobic admixture and water is 100.2°. In the shear test, the maximum shear stress is 0.06 MPa for the specimen coated with hydrophobic admixture, which is much lower than that of the specimen without hydrophobic admixture coating, 3.5 MPa. Furth- ermore, the ice and asphalt surface are completely separated for the coated specimen while not for the uncoated specimen. Based on the accelerated abrasion test, the residual hydro- phobic admixture in the veins of the pavement after abrasion still has a deicing effect. From the skid resistance tests, the British pendulum number （BPN） and the texture depth （TD） of the specimen coated with hydrophobic admixtures are larger than those of the standard requirements. The overall experi-mental observation indicates that the approach can effectively reduce close contact between asphalt pavement and ice; therefore, it can be a promising solution to road icing problems in winter.

The Frost-resisting Durability of High Strength Self-Compacting Pervious Concrete in Deicing Salt Environment

A high strength self-compacting pervious concrete(SCPC) with top-bottom interconnected pores was prepared in this paper. The frost-resisting durability of such SCPC in different deicing salt concentrations(0%, 3%, 5%, 10%, and 20%) was investigated. The mass-loss rate, relative dynamic modulus of elasticity, compressive strength, flexural strength and hydraulic conductivity of SCPC after 300 freeze-thaw cycles were measured to evaluate the frost-resisting durability. In addition, the microstructures of SCPC near the top-bottom interconnected pores after 300 freeze-thaw cycles were observed by SEM. The results show that the high strength SCPC possesses much better frost-resisting durability than traditional pervious concrete(TPC) after 300 freeze-thaw cycles, which can be used in heavy loading roads. The most serious freeze-thaw damage emerges in the SCPC immersed in the 3% of Na Cl solution, while there is no obvious damage in 20% of Na Cl solution. Furthermore, it can be deduced that the high strength SCPC can be used for 100 years in a cold environment.

Influential Factors on Deicing Performance of Electrically Conductive Concrete Pavement

The deicing experiment of carbon fiber reinforced electrically conductive concrete （CFRC） slab was conducted in laboratory at first, then the deicing process of CFRC parement was analyzed by means of finite element method （FEM）. At last, based on the energy conservation law and the computing restdts of finite element method, the influential factors including the setting of electric heating layer, environmental temperature, the thickness of ice, material parameters, and deicing power on deicing performance and energy consumption were discussed.

Experimental Study on Deicing Performance of Carbon Fiber Reinforced Conductive Concrete

Carbon fiber reinforced concrete (CFRC) is a kind of good electrothermal material. When connected to an external power supply, stable and uniform heat suitable for deicing application is generated in the CFRC slab. Electric heating and deicing experiments of carbon fiber reinforced concrete slab were carried out in laboratory, and the effect of the temperature and thickness of ice, the thermal conductivity of CFRC, and power output on deicing performance and energy consumption were investigated. The experimental results indicate that it is an effective method to utilize the thermal energy produced by CFRC slab to deice. The time to melt the ice completely decreases with increasing power output and ice temperature, and increases with increasing thickness of the ice. The energy consumption to melt 2 mm thickness of ice varies approximately linearly from 0.556 to 0.846 kW·h/m2 as the initial temperature ranges from -3℃ to - 18℃. CFRC with good thermal conduction can reduce temperature difference in CFRC slab effectively.

Numerical Simulation of an Airfoil Electrothermal-Deicing-System in the Framework of a Coupled Moving-Boundary Method

A numerical method for the analysis of the electrothermal deicing system for an airfoil is developed taking into account mass and heat exchange at the moving boundary that separates the water film created due to droplet impingement and the ice accretion region.The method relies on a Eulerian approach(used to capture droplet dynamics)and an unsteady heat transfer model(specifically conceived for a multilayer electrothermal problem on the basis of the enthalpy theory and a phase-change correction approach).Through application of the continuous boundary condition for temperature and heat flux at the coupled movingboundary,several simulations of ice accretion,melting and shedding,runback water flow and refreezing phenomena during the electrothermal deicing process are conducted.Finally,the results are verified via comparison with experimental data.A rich set of data concerning the dynamic evolution of the distribution of surface temperature,water film height and ice shape is presented and critically discussed.

Protection and Treatment of Landscape Plant Secondary Disasters (Deicing Agent Damage) Caused by Extreme Weather

Deicing agent is always applied to alleviate urban traffic pressure after snowing in winter,however,such a snow melting agent is extremely harmful for landscape plants.To eliminate or avoid such damages,we have been actively exploring protection and treatment means.By analyzing the protection of landscape plants before using the deicing agent and the treatment after being damaged by the salt,the paper described how landscaping industry of Beijing handled extreme weather and influence of certain urban environment on landscape plants in a high-efficiency and low-cost way,and then figured out the balance point of normal social life and healthy development of ecological environment.

The Third-Order Viscoelastic Acoustic Model Enables an Ice-Detection System for a Smart Deicing of Wind-Turbine Blade Shells

The present work is based on the third-order partial differential equation (PDE) of acoustics of viscoelastic solids for the quasi-equilibrium (QE) component of the average normal stress. This PDE includes the stress-relaxation time (SRT) for the material and is applicable at any value of the SRT. The notion of a smart deicing system (SDS) for blade shells (BSs) of a wind turbine is specified. The work considers the stress in a BS as the one caused by the operational load on the BS. The work develops key design issues of a prospective ice-detection system (IDS) able to supply an array of the heating elements of an SDS with the element-individual spatiotemporal data and procedures for identification of the material parameters of atmospheric-ice (AI) layer accreted on the outer surfaces of the BSs. Both the SDS and IDS flexibly allow for complex, curvilinear and space-time-varying shapes of BSs. The proposed IDS presumes monitoring of the QE components of the normal stresses in BSs. The IDS is supposed to include an array of pressure-sensing resistors, also known as force-sensing resistors (FSRs), and communication hardware, as well as the parameter-identification software package (PISP), which provides the identification on the basis of the aforementioned PDE and the data measured by the FSRs. The IDS does not have hardware components located outside the outer surfaces of, or implanted in, BSs. The FSR array and communication hardware are reliable, and both cost- and energy-efficient. The present work extends methods of structural-health/operational-load monitoring (SH/OL-M) with measurements of the operational-load-caused stress in closed solid shells and, if the prospective PISP is used, endows the methods with identification of material parameters of the shells. The identification algorithms that can underlie the PISP are computationally efficient and suitable for implementation in the real-time mode. The identification model and algorithms can deal with not only the single-layer systems such as the BS layer without the AI layer or two-layer systems but also multi-layer systems. The outcomes can be applied to not only BSs of wind turbines but also non-QE closed single- or multi-layer deformable solid shells of various engineering systems (e.g., the shells of driver or passenger compartments of ships, cars, busses, airplanes, and other vehicles). The proposed monitoring of the normal-stress QE component in the mentioned shells extends the methods of SH/OL-M. The topic for the nearest research is a better adjustment of the settings for the FSR-based measurement of the mentioned components and a calibration of the parameter-identification model and algorithms, as well as the resulting improvement of the PISP.

路用蓄盐除冰纤维配比设计及除冰性能确定

为解决道路凝冰问题,基于环保、经济、实用等原则,针对适用于沥青路面主动抗凝冰的蓄盐纤维填料的配合比进行设计,并对其相关性能展开研究。通过基于单纯形重心设计的融冰试验和电导率试验对蓄盐除冰材料配比进行探究,并基于融冰试验和冻粘剪切试验分析其除冰性能。试验结果表明:选用乙酸钠∶乙酸钾∶甲酸钠=7∶2∶1、复合有机盐∶纤维=3∶1为蓄盐纤维各种成分的最佳配合比;在融冰试验中,蓄盐纤维替换率为66%的除冰材料在较高负温下融冰速率能达到1022 g·(h·m 2)-1,表明其融冰性能良好;凝冰后,蓄盐纤维沥青混合料表面冻粘强度比普通沥青混合料下降33%,能够有效降低冻粘强度。基于最佳配合比,新型路用环保蓄盐除冰材料具有良好的融冰能力和除冰降粘功效。

寒区道路桥梁融雪除冰技术研究综述

道路桥面的融雪除冰对车辆行驶安全至关重要,但是目前对于融雪除冰技术的研究主要集中在工程效果及技术评价上,尚未从除冰工作机理进行对比分析和系统阐述。该文基于融雪除冰机理将融雪除冰技术分为被动式除冰技术、主动融雪除冰技术以及能量利用型融雪除冰技术3类,并对其进行归纳总结。系统评价了融雪剂除冰法、机械除冰法两项传统除冰手段的优缺点;探讨了抑制类冻结铺装路面、相变材料路面两项主动融雪除冰技术,并提出相变材料用于路面融雪除冰具有绿色环保价值;介绍了不同能量利用型融雪除冰技术的应用机理。深入分析现有的道路除雪技术及其实际应用效果和存在的问题,以期对寒区道路桥梁冬季融雪除冰研究提供基础性支撑。

基于透明导电膜的光学窗口加热除冰效率研究

为了提高圆形光学窗口表面透明导电膜加热除冰的效率,基于欧姆定律以及热传导效应的理论分析,建立了圆形光学窗口表面透明导电膜的加热除冰效率理论模型。通过数值模拟,计算了直径100 mm圆形光学窗口在-55℃环境中对10 mm厚冰层的加热除冰效率,并采用24 V直流电源加热的方式进行了试验验证。结果表明,理论计算的除冰时间与试验结果之间存在偏差,这主要是由于在除冰过程中,光学窗口表面产生的热能除了大部分用于除冰消耗以外,还有少部分通过热传导散热而被消耗,同时窗口表面一部分水被加热而吸收热量,从而导致能耗增加。基于试验结果和理论分析,进一步提出了提高加热除冰效率的措施。

祁连山无人机增雨(雪)作业积冰条件分析及防除冰技术路线

无人机作为新型人工增雨(雪)作业技术手段,研究其防冰和除冰对业务化具有重要意义。基于飞行积冰报告及外场探测资料、探空及再分析资料,对祁连山地区大型无人机积冰分布气象条件进行统计分析,结合电加热法防除冰试验,形成适用于祁连山地区的无人机防除冰技术路线。研究表明,大型无人机开展人工增雨(雪)作业的强烈积冰区为-8~-2℃,且当云粒子浓度大于0.93 cm^(-3)、云水含量大于0.0043 g·m^(-3)时更容易出现积冰。祁连山地区春、秋、冬三季容易出现积冰的高度在4000—5500 m,夏季在5000—5500 m,积冰中心高度在5000 m上下。搭载电加热防除冰系统可有效解决大型无人机的积冰问题。

用于微波除冰的吸波骨料选择及路面吸波功能层设计

相比传统除冰方式,微波可穿透冰层并选择性加热路面,进而破坏冰对路面的粘附性。针对现有吸波混凝土应用于整个面层,进而导致吸波骨料利用率不足的问题,本工作设计了一种具有吸波功能层的路面结构。首先综合对比分析了三种吸波骨料与石灰岩的微波升温特性、微波耐久性、骨料与水泥石粘附性以及经济性能,选择综合性能较好的吸波骨料;然后探究了不同粒径的吸波骨料的升温速率和替代石灰岩后其对混凝土力学性能的影响程度,以及不同厚度的吸波混凝土上、下表面温度及上下表面温度差变化规律,推荐了最佳的吸波骨料替换粒径及功能层厚度;最后研究了石墨掺量对微波均匀性及力学强度的影响,推荐了最佳石墨掺量。结果表明:在四种骨料中,磁铁矿的综合性能较好;磁铁矿的粒径为16~19 mm时升温速率最快,且其替换相应粒径的石灰岩所制备的吸波混凝土结构强度比普通混凝土高50%,吸波混凝土功能层设计厚度为5 cm可保证材料的最优利用率。同时,3%的石墨掺量可改善微波加热的均匀性并满足力学要求。研究结果可为微波除冰应用于道路及机场路面提供参考。

混凝土道面微波加热除冰效率及表面温度分布研究

冬季冰雪侵害对道路交通产生了严重的威胁,各种传统的除冰方法都存在或多或少的缺陷,微波除冰是一种新型除冰方法,使用微波进行除冰具有绿色环保、除净率高的特点,利用自主设计的开放式微波除冰仪器对微波除冰过程中混凝土的表面温度分布规律进行了研究,结果表明,微波除冰过程中,混凝土表面温度分布呈现出中心区域高、周围温度低的现象。温度分布具有方向性,混凝土表面温度沿微波源波导口的长边方向的温度衰减速度快于短边方向的温度衰减速度。微波源高度越高,混凝土表面中心点的温度越低,加热范围越大,混凝土表面的加热均匀性更好。当微波源高度位于40 mm时,混凝土道面的除冰面积为83.4 cm^(2)。

高黏疏水抑冰雾封层材料设计和性能评价

为解决南方秋冬季道路被动抑冰滞后和效率低等问题,研发了主动型高黏疏水抑冰雾封层材料。通过正交理论设计、层次模型分析法进行综合性能评价,确定了增黏剂、疏水剂的最佳用量,采用多性能试验评价了路用性能和抑冰性能,确定了抑冰剂的最佳用量。研究结果表明:相比于乳化沥青基材,综合设计得到的最佳掺量高黏疏水雾封层材料的黏聚性和疏水性分别提升了55.7%、144.3%。抑冰剂掺量为9%~12%时,雾封层材料储存稳定性较好,最佳洒布量为0.06 g/cm^(2)时,固化性能和抗滑性能明显提升,达到最佳平衡状态。抑冰剂掺量与电导率呈显著线性相关,多次浸水循环后,高黏疏水抑冰雾封层材料具有缓释持久性。最佳抑冰剂掺量为9%时,雾封层材料抗凝冰效果达到最佳。

蓄盐沥青混合料与冰层粘结程度评价方法探究

为了能更精确地评价蓄盐沥青混合料与冰层的粘结程度,通过对拉拔头、冰层冻结方式、拉拔方式等方面进行改进,采用粘结强度和残冰率作为蓄盐沥青混合料与冰层粘结程度的评价指标,开发出一种基于马歇尔试件全断面的试验方法。试验结果表明,试件与冰层之间的粘结强度及残冰率随温度降低而增加,蓄盐沥青混合料在-10℃以内能降低试件与冰层的粘结强度30%以上,-7℃的粘结强度相比于普通沥青混合料减小约50%,-9℃以内残冰率减小比例均大于50%。冰层与试件粘结强度的测量准确度随残冰率的增大而降低,建议在-10℃内采用本试验方法。开发的评价试件与冰层粘结程度的试验方法区分度较高,试验的变异系数在10%以内,稳定性较好。

除冰盐冻融作用下混凝土界面粘结强度与界面过渡区细观力学性能的关系

界面过渡区(Interfacial transition zone, ITZ)是混凝土内部结构的薄弱环节,也是外界侵蚀性离子向内扩散渗透的通道。通过除冰盐快速冻融实验研究了在除冰盐冻融环境下混凝土界面宏观和细观力学性能的变化规律。结果表明,混凝土粗骨料与砂浆的界面粘结强度和ITZ显微硬度在盐冻过程中均呈现出典型的两段式线性变化,即随着盐冻循环次数增加而增强的初始强化阶段和随着盐冻循环次数增加而降低的后期劣化阶段;初始界面粘结强度或ITZ显微硬度随着水胶比的增大而减小,初始强化速率减慢,后期劣化速率加快,且低水胶比的混凝土有着较好的抗盐冻性能;盐冻过程中混凝土粗骨料和砂浆的界面粘结强度与ITZ显微硬度之间具有较明显的相关性。此研究结果为盐冻环境下混凝土细观力学分析提供了基础数据。

电加热防/除冰过程中溢流水再冻结数值模拟

当飞机飞行过程中遇到结冰工况时,为保证飞机的飞行安全以及气动性能,常使用热防护方法作为飞机防除冰的重要手段。本文通过使用共轭耦合方法建立了机翼内部多层导热与水膜流动的耦合计算模型,并针对电加热防除冰过程进行了一系列数值模拟计算。研究选取了可进行非稳态计算的Myers水膜模型,电加热组件导热模型则采用有限体积法隐式离散进行计算,水膜模型与导热模型通过交换边界值的共轭传热方法实现松耦合。研究发现在电加热防除冰过程中,由于积冰融化和水膜流动会产生溢流水再冻结现象。对电加热系统开启后期的积冰外形进行了流场计算与气动分析,发现机翼上下翼面溢流水冻结部位会对流场产生扰动。通过Q准则判断积冰后侧产生了涡结构,对比未发生结冰的干净翼型,机翼前缘位置溢流水冻结导致压力系数曲线发生较大震荡,因此溢流水再冻结问题影响了机翼的气动性能,未能使电加热防除冰系统达到理想的防护效果。

黄腐酸钾对不同氯盐胁迫下桧柏生长的缓解效应

【目的】探究高浓度氯盐胁迫下桧柏容器苗施加不同质量分数黄腐酸钾(FA-K)后的生长和生理特性,揭示FA-K缓解高浓度氯盐胁迫下桧柏的生理响应机制及差异性,为冬季北方高速公路中央分隔绿化带桧柏的管理维护提供技术支撑。【方法】选取2年生桧柏容器苗开展盆栽试验,以正常生长为对照,设置0.7%NaCl和0.7%CaCl_(2)2种盐分,每种盐分设置0、0.05%、0.10%、0.30%和0.50%5种质量分数FA-K处理,测定各处理下桧柏苗生长指标(苗高生长量、地径生长量、生物量、根冠比)、光合色素含量(叶绿素a、叶绿素b、总叶绿素、类胡萝卜素)、相对电导率、丙二醛含量、渗透调节物质(脯氨酸、可溶性糖)含量、超氧化物歧化酶和过氧化物酶活性。【结果】1)0.7%CaCl_(2)胁迫对桧柏苗生长的抑制作用大于0.7%NaCl胁迫;0.7%CaCl_(2)胁迫下桧柏苗除可溶性糖和类胡萝卜素含量低于NaCl胁迫外,其他生理指标(叶绿素a含量、叶绿素b含量、总叶绿素含量、丙二醛含量、脯氨酸含量、相对电导率、过氧化物酶和超氧化物歧化酶活性)均高于NaCl胁迫;2)2种盐胁迫下,施加FA-K均使桧柏苗苗高生长量、地径生长量、生物量增加,叶绿素a、叶绿素b、总叶绿素、类胡萝卜素含量上升,相对电导率和丙二醛含量下降,超氧化物歧化酶和过氧化物酶活性、脯氨酸和可溶性糖含量呈低-高-低的变化趋势,0.50%FA-K下2种盐胁迫的幼苗生长接近对照;3)相较0.7%NaCl胁迫,FA-K对0.7%CaCl_(2)胁迫表现出更好的缓解作用。【结论】高浓度氯盐胁迫显著抑制桧柏苗生长和存活,0.7%CaCl_(2)抑制作用比0.7%NaCl强;FA-K能够有效缓解NaCl和CaCl_(2)胁迫,0.50%FA-K缓解效果较佳。

面向未来低碳道路养护的超薄罩面功能性研究综述

Highway maintenance mileage reached 5.25 million kilometers in China by 2021.Ultra-thin overlay is one of the most commonly used maintenance technologies,which can significantly enhance the economic and environmental benefits of pavements.To promote the low-carbon development of ultrathin overlays,this paper mainly studied the mechanism and influencing factors of several ultra-thin overlay functions.Firstly,the skid resistance,noise reduction,rutting resistance,and crack resistance of ultrathin overlays were evaluated.The results indicated that the high-quality aggregates improved the skid and rutting resistance of ultra-thin overlay by 5%-20%.The optimized gradations and modified binders reduced noise of ultra-thin overlay by 0.4-6.0 dB.The high viscosity modified binders improved the rutting resistance of ultra-thin overlay by about 10%-130%.Basalt fiber improved the cracking resistance of ultra-thin overlay by more than 20%.Due to the thinner thickness and better road performance,the performance-based engineering cost of ultra-thin overlay was reduced by about 30%-40%compared with conventional overlays.Secondly,several environmentally friendly functions of ultra-thin overlay were investigated,including snow melting and deicing,exhaust gas purification and pavement cooling.The lower thickness of ultra-thin overlay was conducive to the diffusion of chloride-based materials to the pavement surface.Therefore,the snow melting effect of self-ice-melting was better.In addition,the ultra-thin overlay mixture containing photocatalytic materials could decompose 20%-50%of the exhaust gas.The colored ultra-thin overlay was able to reduce the temperature of the pavement by up to 8.1℃.The temperature difference between the upper and lower surfaces of the ultra-thin overlay containing thermal resistance materials could reach up to 12.8℃.In addition,numerous typical global engineering applications of functional ultra-thin overlay were summarized.This review can help better understand the functionality of ultra-thin overlays and promote the realization of future multi-functional and low-carbon road maintenance.

一步法制备超疏水表面及其防覆冰性能研究

目的提高铜网表面的防除冰性能。方法以铜网为基底材料,用纳米胶带将铜网和聚四氟乙烯(PTFE)固定在一起,采用飞秒激光直写技术将PTFE纳米颗粒部分嵌入铜网,采用一步法制备了PTFE附着铜网的超疏水表面,并通过扫描电子显微镜和光学显微镜对其微结构进行形貌分析。结果在PTFE低表面能和粗糙度共同作用下,所制备的表面表现出优异的超疏水性能,水的接触角为152°,滚动角为4°。在此基础上探究了其微观结构对表面润湿性和防覆冰性能的影响。结果表明,PTFE附着铜网的超疏水表面能有效延长冷凝液滴结冰时间,与未垫PTFE的铜网相比,结冰时间延长1.2倍。在冷却过程中,液滴从Cassie状态向Wenzel状态转变,PTFE附着铜网的超疏水表面能维持将长时间的Cassie状态。并且结冰后依然能保持较低的黏附力,最小冰黏附力为2.55 kPa,相比普通的超疏水表面缩小了近2.5%。同时能够实现冷凝液滴的高效快速自去除,还显示出优异的自清洁性能。结论PTFE附着铜网的超疏水表面可有效延长结冰时间,降低冰黏附力,具有优异的冷凝自去除和自清洁性能,且在5.01V的电压下,铜网表面能够有效防止冰的形成。