刍议混凝土裂缝控制技术在路桥施工中的应用

随着我国经济水平的持续提升和路桥工程整体水平的不断进步，在我国路桥工程的施工过程中，混凝土裂缝控制技术得到了越来越广泛的应用。本文对混凝土裂缝进行了简析，对路桥施工中混凝土裂缝控制技术的应用进行了分析。     

Evaluation of the corrosion inhibition of salts of organic acids in alkaline solutions and chloride contaminated concrete

This paper summarizes the results of testing on salts of organic acids for evaluating their use as inhibitors of rebar corrosion in chloride‐contaminated concrete. Initially a screening based on electrochemical tests in alkalinized calcium hydroxide solutions was performed on a number of carboxylic acid salts with different number of carbon atoms in the chain and carboxylic groups, also covering substances with hydroxyl and amine group substituents. The screening was completed by testing on carbon steel rebars in concretes with chlorides and substances added at 1:1 molar ratio, focused on sodium lactate, sodium oxalate and sodium borate for comparison. The monitoring of free corrosion potential and linear polarization resistance of steel bars have confirmed significant inhibition only for lactate. Corrosion was only restricted to occluded zones where the access of substance was limited by disadvantageous geometry, producing shallow attacks. Results of further tests in saturated calcium hydroxide solution are reported in order to assess the inhibition ability of lactate as a function of its content, chloride content and pH.     

浅论大体积混凝土施工质量控制

近年来，新建铁路设计必须以双线铁路为主。本文主从裂缝的分类、产生的原因、控制方法等方面入手，对混凝土原材料的控制直至施工完成后的养护和成品保护等问题进行了探讨，力争保证大体积混凝土的施工质量。     

Numerical simulation of self-consolidating concrete flow as a heterogeneous material in L-Box set-up: Effect of rheological parameters on flow performance

A computational fluid dynamics (CFD) software was used to simulate the effect of rheological parameters on the heterogeneous performance properties of self-consolidating concrete (SCC) in the horizontal and vertical directions of the L-Box set-up. These properties consist of flowability, blocking resistance, and dynamic segregation. Different suspending fluids having five plastic viscosity values (10–50 Pa.s), three yield stress values (14–75 Pa), two fluid densities (2000 and 2500 kg/m³), and two shear elasticity modulus values (100 and 1000 Pa) were considered. The suspensions consisted of a number of 135 in total spherical particles with 20-mm in diameter and 2500 kg/m³ density.The results of 25 simulations in total are found to correlate well with the rheological parameters of the suspending fluid. Plastic viscosity of the suspending fluid was shown to be the most dominant parameter affecting flow performance of SCC in the L-Box test. A new approach was also proposed to classify SCC mixtures based on the filling ability properties.     

高速公路路基基层施工技术

随着国民经济的发展,高速公路得到了大力发展,水泥稳定碎石基层和贫砼基层成为了高速公路路基基层中常见的形式。本文主要结合工程实际,对某高速公路合同段内的路基基层采用的水泥稳定碎石基层和贫砼基层的施工工艺与施工方法做了简要分析。     

The performance of steel-making slag concretes in the hardened state

The use of oxidizing slag from electric-arc furnaces as an aggregate is a sustainable option in the manufacture of concrete, the performance of which is similar to an ordinary aggregate concrete. This study examines the reuse of two different types of oxidizing slag in concretes designed for use in structural components and compares their performance against relevant specifications contained in current working standards. Fundamental aspects are discussed, among which density and workability that are related to the proportioning of the concrete and its mechanical and physical properties. The results show that overall concrete quality is maintained and that its performance is acceptable for the proposed application.     

浅谈PKPM框架结构设计注意事项

本文主要讲述在PKPM框架结构设计中注意的几个事项。从结构设计总说明各层布置图到基础平面图及详图几方面讲述。     

Performance of a Tied-Arch Reinforced Concrete Railway Bridge: Rating, Safety Assessment, and Bond Length Evaluation

This study presents investigations regarding visual inspection, dynamic testing, and finite-element modeling of an approximately 80-year old reinforced concrete tied-arch railway bridge that is still in service in Turkey. Investigations were conducted as part of a systematic periodic inspection along Ankara-Zonguldak railway line. The bridge is subject to heavy freight trains with increasing axle loads. Field tests such as material tests and dynamic tests were used to calibrate the finite-element model of the bridge. Detailed information regarding testing and model updating procedure is given. Based on test results, computer model was refined. The calibrated model of the bridge structure was then used for structural assessment and evaluation. Despite sufficient overall safety, local details were found to be problematic. Due to insufficient bond length in hanger-to-arch connection, a strengthening scheme using steel channel sections was proposed.     

聚丙烯纤维再生混凝土柱受压性能的模拟分析

对聚丙烯纤维再生混凝土柱进行了研究,从柱的受压性能方面进行了论述,并采用ABAQUS有限元模拟的方法,对极限承载力和荷载—挠度曲线进行了分析,得到了柱的承载力变化和荷载—挠度关系。     

Autogenous deformation and RH-change in perspective

Autogenous deformation and change of the relative humidity (RH-change) have been described and registered for a century. However, it is only within the last decade that these phenomena have received appreciable attention. The reason for this is that autogenous deformation and autogenous RH-change are phenomena of special importance within high-strength (high-performance) concrete technology, and a significant utilisation of these concretes did not take place until the early 1980s. In the present paper an historical overview of autogenous deformation and RH-change is given. In addition, due to the present status of this research field both terminology and measuring techniques are described in detail. Finally, some expectations for future research in this field are given.