Loading Stress Analysis of Cement Concrete Pavement in Mountainous Areas

The suitable cement concrete pavement for mountainous areas is a form of low-cost cement concrete pavement that uses unconventional graded stones in different proportions in ordinary concrete,allowing the concrete to fully contact the stones and form a stable and well-bonded slab with large particle stones.As large particle stones replace a certain volume of cement concrete,they have good economic performance and are a low-cost form of cement concrete pavement.This study researches the use of ANSYS tools to analyze the influence of geometric dimensions and material properties of rigid pavement structural layers on the mechanical properties of pavement structures.

Toughness improvement mechanism and evaluation of cement concrete for road pavement:A review

Traditional cement concrete has the disadvantages of low tensile strength,poor toughness,and rapid development of cracks while cracking,which causes a significantly negative influence on the safety and durability of concrete road pavement.This paper presents a state-of-the-art review of toughness improvement mechanisms and evaluation methods of cement concrete for road pavement.The review indicates that(i)The performance of concrete material depends on its material composition and internal structure.Aggregate size,cement properties and admixtures are the main factors of concrete toughness.(ii)The incorporation of rubber or fiber in pavement concrete improves the toughness of concrete materials.However,these additions must be maintained within a reasonable range.The amount of rubber and fiber are encouraged not more than 30%of the volume of fine aggregate and 2%of the volume of concrete,respectively.(iii)The toughness of pavement concrete material includes the toughness regarding bending,impact and fracture.The toughness of cement concrete for highway and municipal pavement is generally evaluated by bending and fracture toughness,while the toughness of airfield pavement concrete is more focused on impact toughness.(iv)The toughening measures of cement concrete for road pavement are mainly mixed with rubber or fiber,while these two materials have their defects,and the application of hightoughness cement concrete in the actual road still faces many challenges.For example,the synergistic effect of rubber and fiber,the development and application of new flexible admixtures,and the formulation of the toughness index of pavement cement concrete materials need further research.

In-site health monitoring of cement concrete pavements based on optical fiber sensing technology

Premature stress of cement concrete pavements i the coupled action of construction technique,structural ma-terial and environmental action.It is quite diffiault to accurately get the actual stress distribution merely based on the theoretical or simulation analysis.Ther efore,in-situ health monitoring is particularly si gnificant to obtain the stress or strain information for the assessment on structural perfor mance of cement concrete pavements.To contribute this topic,different kinds of FBG based sensors have been specially designed to measure the tem-perature,pressure and deformation in cement concrete pavements.A relatively long-term monitoring has been aonducted to collect the effective data after the solidification of the pavement lasts for about 15 d.Data analysis indicates that the temperature variation inside the pavement was very stable,with maximum ampltude smaller than 2.25°C in Sep.2020.The longitudinal,transverse and ver tical deformations of the pavement behaved in non-umniform distribution,and partial me asuring points suffered from large tensile force.The concrete course had better deformation resi stance than that of the soil base,and local interfacial micro void defects existed in the soil base.The preliminary results can help to understand the actual structural performance of cement concrete pavements based on the optical fiber sensing sys tem.

Characterizing properties of magnesium oxychloride cement concrete pavement

The performance of magnesium oxychloride cement concrete(MOCC)in road engineering in the arid region in northwest China was investigated over a two-year period.Two categories of MOCC pavement,light-burnt magnesia concrete road(Road-L)and dolomite concrete road(Road-D),were prepared with light-burnt magnesia and a mixture of light-burnt magnesia and caustic dolomite(1:3 by mass),respectively.Variations in the properties of the MOCC pavement,such as compressive and flexural strength,mineralogical phase,and microstructure,after being exposed to two rainy seasons in the field were monitored.The compressive strength of the cored samples were conducted after being aged for 28 d,and the compressive and flexural strength were tested at ages of 1,2,3,28,90,180,270,360 and 720 d.The mineralogical phase and microstructure of the pavement were also analyzed by X-ray diffraction(XRD)and scanning electron microscopy(SEM).The results demonstrate that MOCC pavement obtained desirable compressive and flexural strengths after curing for 3 d for Road-L and 28 d for Road-D.Both of the compressive and flexural strength of Road-L and Road-D decreased slightly after experiencing two rainy seasons,with the major hydration products being 5Mg(OH)2 MgCl28H2O(Phase 5)and 3Mg(OH)2 MgCl28H2O(Phase 3).The decomposition of Phase 5 is mainly responsible for reducing the mechanical strength of the MOCC pavement.

Study of interfacial transition zones between magnesium phosphate cement and Portland cement concrete pavement

The Portland cement concrete pavement(PCCP)often suffers from different environmental distresses and vehicle load failure,resulting in slab corner fractures,potholes,and other diseases.Rapid repair has become one of the effective ways to open traffic rapidly.In this study,a novel type of rapid repair material,basalt fiber reinforced polymer modified magnesium phosphate cement(BFPMPC),is used to rapidly repair PCCP.Notably,the mechanical properties and characteristics of the repair interfaces which are named interfacial transition zones(ITZs)formed by BFPMPC and cement concrete are focused on as a decisive factor for the performance of the rapid repair.The changing trend of the elastic moduli was studied by nanoindentation experiments in the ITZs with the deconvolution analysis that the elastic moduli of certain kinds of substances can be determined.The experimental results show that the elastic modulus of ITZ-1 with a width of about20μm can be regarded as 0.098 times of the aggregate,and 0.51 times of the ordinary Portland cement(OPC)mortar.The BFPMPC-OPC mortar ITZ has roughly the same mechanical properties as the ITZ between aggregate and BFPMPC.A multi-scale representative two-dimensional model was established by random aggregate and a two-dimensional extended finite element method(XFEM)to study the mechanical properties of the repair interface.The simulation results show that the ITZ formed by the interface of BFPMPC and OPC mortar and basalt aggregate is the most vulnerable to failure,which is consistent with the nano-indentation experimental results.

快通水泥混凝土路面与水泥稳定基层建造新技术

文中针对水泥混凝土路面与基层快速建造、提早通车运营的难题,将其他建筑混凝土工程中的早强混凝土应用于公路水泥混凝土路面工程,并参照美国ACPA水泥混凝土路面协会相关技术,提出了我国快通水泥混凝土路面的定义、建造技术和基本技术要求,以期实现我国公路水泥混凝土路面工程在建造和养生中少堵车、不堵车、快速畅通的目的,为我国公路交通建设及路面建造、养生、运营做出贡献。

装配式水泥路面夹环连接式传力杆接缝设计及验证

面向可拆卸装配式水泥路面,提出了一种夹环连接式传力杆接缝,在阐述其特征和基本参数的基础上,选取挠度传荷系数和弯沉差作为指标,使用有限元方法分析了下开口槽、传力杆、夹环构件等参数对夹环连接式传力杆接缝传荷能力的影响,同时分析了夹环连接式传力杆接缝的构件及界面应力的变化规律,得到了合理的接缝参数;此外,通过室内足尺试验评价了夹环连接式传力杆接缝的传荷性能。结果表明,提出的夹环连接式传力杆接缝的传荷能力满足要求,具有一定的工程应用价值。

水泥混凝土道面可靠性设计指标计算方法

基于水泥混凝土道面可靠性设计指标的计算方法,分析目前计算方法存在的问题与不足,并提出算法的改进。我国工程结构设计标准提供的可靠指标基本采用安全系数换算、分项系数基本采用安全系数或可靠指标换算,该算法可能存在不同设计状况的设计结果不符合可靠性宏观规律、不同设计指标的设计结果不具有一致性的问题,原因在于可靠性设计指标的计算忽视了设计变量之间的相关性;将变量间相关性纳入工程整体可靠度考虑,改进得到的可靠指标与分项系数计算式具有更好的适用性;应用到水泥混凝土道面工程,通过抗力性质判断变量之间是否具有相关性,再分别定量统计相关系数值,最后通过改进算法计算可靠性指标的适宜值。

改性聚酯纤维对机场水泥混凝土的增韧阻裂效果分析

为增强机场水泥混凝土的韧性,提升道面结构的抗开裂能力,制备了聚酯纤维(FC)、聚乙烯醇纤维(PVA)和聚丙烯粗纤维(PP)混凝土。以砂率、FC纤维掺量和减水剂掺量为影响因素,28 d抗折强度为响应值,采用响应面法确定了FC纤维混凝土的最佳配比。采用三点弯曲韧性试验和三点弯曲断裂试验,分析了纤维的增韧阻裂机理。结果表明:砂率、FC纤维掺量和减水剂掺量之间存在交互作用,三者对混凝土28 d抗折强度的影响程度排序为FC纤维掺量>减水剂掺量>砂率,最佳配比为砂率34%、FC纤维掺量1.4 kg/m^(3)、减水剂掺量2%。三种纤维P-δ曲线拐点处的荷载峰值和挠度显著提高,拐点尖锐程度下降。相较于素混凝土,FC、PVA和PP纤维混凝土的断裂韧性分别提高了125.8%、118.4%和87.1%,起裂韧度分别提升了38.7%、33.9%和25.2%,断裂韧度分别提升了87.1%、73.2%和55.6%。此外,FC、PVA和PP纤维混凝土开裂过程中所需的断裂能分别提升了216.2%、193.2%和162.9%。结合能量平衡理论,纤维通过能量传递的方式在混凝土中起到增韧阻裂作用,FC纤维的增韧阻裂效果相对显著。

基于振动传递率函数的水泥混凝土铺面脱空识别方法

为提高水泥混凝土铺面脱空识别的准确性和便捷性,提出一种基于振动传递率函数的板底脱空识别方法。首先,建立了九块板全尺寸铺面结构三维有限元模型,获取冲击荷载作用下铺面板的多点加速度响应;其次,在2个振动传递方向上,分别计算相邻2个测点间的振动传递率函数,分析特定频段内传递率函数的差异,并提出传递率损伤指标(transmissibility-damage indicator,TDI)及其矩阵表达式;最后,计算分析11种不同脱空形式、程度下TDI矩阵的差异,并分析测点布设方式、信号噪声水平对TDI矩阵的影响。结果表明:该脱空判定指标能较好识别定位板角和板边局部脱空。所得TDI矩阵在板角脱空的2个传递方向均十分显著,在板边脱空的垂直脱空边方向较为显著;对于板中脱空,2个传递方向上的TDI矩阵均无法有效识别。板中脱空的分布与TDI矩阵的分布一致性较差;对于多区域脱空,其计算得到的TDI矩阵与单区域脱空类似,对于板角和板边局部脱空均能有效识别;测点布设越密,TDI矩阵的分布与脱空分布的一致性越高。然而,该识别方法对噪声水平较为敏感,噪声水平越高,识别精度越低,需要较高精度的传感器或设备予以支撑。

花岗岩机制砂路面混凝土干缩及耐久性研究

为了明确花岗岩机制砂路面混凝土的干缩性与耐久性,通过干缩试验、抗氯离子渗透试验和抗硫酸盐侵蚀性能试验,结合花岗岩机制砂路面混凝土的各项性能,研究了不同水胶比、粉煤灰掺量及砂率对其干缩及耐久性的影响,并建立了花岗岩机制砂路面混凝土干缩收缩预测模型,全面分析了各因素对路面混凝土各性能的影响作用及劣化机制。结果表明:花岗岩机制砂路面混凝土干缩性能受水胶比与粉煤灰掺量的影响较为显著,水胶比在0.34~0.42时,混凝土龄期在3、28、60 d,收缩率最大增加41.6%、115.2%、122.9%,粉煤灰质量分数为20%较15%对抑制干缩性能更明显,在一定范围内掺量越多,抑制效果越显著,受砂率影响不明显;花岗岩机制砂路面混凝土抗渗性能对水胶比变化较敏感,受粉煤灰掺量影响明显,砂率对其抗渗性能的影响较小;花岗岩机制砂路面混凝土抗侵蚀性能受水胶比影响较大,砂率影响较小,粉煤灰的掺入可以改善花岗岩机制砂混凝土抗硫酸盐侵蚀性能。

水泥混凝土路面沥青加铺层病害分析及预防性养护技术研究

随着运营年限增长,水泥混凝土路面会出现不同程度的破损,工程中常采用加铺沥青面层的方式对破损水泥混凝土路面进行修补。依托某水泥混凝土路面沥青加铺层养护工程,对沥青加铺层常见病害及其成因进行分析,并对预防性养护技术在沥青加铺层中的应用进行研究。结果表明:反射裂缝与车辙是沥青加铺层中最常见的病害,采用裂缝填补及微表处技术能够很好地控制沥青加铺层病害发展。

水泥混凝土路面错台病害处治研究

错台是水泥混凝土路面的常见病害,它的产生不仅会降低行车的舒适性,也给车辆的安全行驶带来隐患,本文从水泥混凝土路面错台产生的原因出发,展开分析研究,并给出系统的错台病害处治办法,对延长道路使用寿命,提高水泥路面养护水平具有十分重要的意义。

水泥混凝土路面计算机辅助设计系统 CCP-CAD

在水泥混凝土路面结构计算方法及典型结构研究的基础上，运用混合语言编程技术和结构化程序设计方法，研制开发了集典型结构、工程设计、工程图生成、数据维护等功能为一体的水泥混凝土路面计算机辅助设计系统ＣＣＰ—ＣＡＤ。

旧水泥混凝土路面沥青铺装层反射裂缝疲劳断裂分析

针对旧水泥混凝土路面沥青铺装层容易产生反射裂缝的特点,采用断裂力学理论,建立了5层体系平面应变模型,对各种荷载作用下不同层间结合状态和路面结构参数的应力强度因子进行了计算分析,并对常用防止反射裂缝措施进行了效果比较。结果表明:层间粘结状态对裂缝扩展的影响较大,土工格栅的防止反射裂缝效果相对较好。

农村公路水泥混凝土路面常见病害的产生机理与养护措施

水泥混凝土路面在现阶段农村公路的应用中逐渐广泛深入,但在交通移动荷载和自然环境等多方面外部因素的作用下,会产生不同类型的常见病害,其不可避免地会缩短路面的全周期服役寿命。依托华容县梅田湖大桥工程项目中沿线路面建设,分析了农村水泥混凝土路面的常见病害类型、影响因素和产生机理,并提出了多方位多角度的养护措施,以期为类似农村路面建设的设计和施工提供借鉴和指导。

高早强路面混凝土研究进展

普通水泥道路在长时间高负荷压力与环境破坏的双重作用下,易出现裂缝、沉陷等破损,同时修复破损的道路需要花费大量人力物力。因此,具有优异耐久性、韧性的高早强路面混凝土对当代道路建设有着重要意义。文中从早强路面混凝土发展进程、设计原理、应用现状及未来展望等方面,对其进行了综合阐述。

温湿效应下寒区水泥路面的破坏模式

为探究我国北方水泥路早期破坏原因,以黑龙江省在役期水泥路为对象,结合数值模拟手段分析环境荷载、轴型、轴重耦合作用下水泥路面的力学性能。结果表明:轴载-温湿度耦合下,水泥路表面最大拉应力急剧增长,约为轴载-路面自重下的14倍;随着轴重增加,板顶拉应力由非线性发展转为线性;多轮轴间的应力叠加作用导致水泥路表面最大拉应力不断增大,其中三轴双轮为单轴双轮的1.079倍,不同轮轴作用下的应力增长趋势均符合二段式模型;轴载-温湿耦合作用是水泥路出现面层-底层拉裂破坏的重要因素,超载及多轮轴间的应力叠加效应是板角出现破碎性破坏的主要原因;建立的二段式回归模型能较好地描述不同轴数、轴重下水泥路表面拉应力发展趋势。

聚合物改性水泥混凝土路面设计

聚合物改性水泥混凝土路面具备诸多优势,可解决传统水泥路面裂缝等质量问题。文中提出了一种聚合物改性水泥混凝土路面设计方案,分析了各项材料选用、指标控制、配合比设计,并对0、5%、10%、15%等不同掺量聚合物条件下的改性水泥混凝土路面性能进行了试验检测。结果表明,掺入聚合物的改性水泥混凝土路面在抗压强度、抗滑性能、耐磨性能等方面均强于素混凝土水泥路面。

装配式透水型复合水泥混凝土路面性能研究

装配式透水型复合水泥混凝土路面在路面施工应用广泛,为探究普通硅酸盐水泥不同的强度等级对装配式透水型复合水泥混凝土路面性能的影响,本文依托实际工程,对使用三种不同强度等级普通硅酸盐水泥制备的装配式透水型复合水泥混凝土路面的28d抗压强度、27d抗弯拉强度以及透水系数等指标进行试验检测,试验结果表明,采用水泥强度等级为42.5时,装配式透水型复合水泥混凝土路面能够获得不错的抗压强度以及较高的抗弯拉强度,且均能满足规范要求与施工要求。