Analytical modeling and experimental study of tensile strength of asphalt concrete composite at low temperatures

In this study, analytical modeling of the tensile strength of hot-mix asphalt (HMA) mixtures at low temperatures was developed. To do this, HMA mixtures were treated as a two-phase composite material with aggregates (coarse and fine) dispersed in an asphalt mastic matrix. A two-phase composite model, which was similar to Papanicolaou and Bakos's [J. Reinforced Plast. Compos. 11 (1992) 104] model with a particle embedded in an infinite matrix, was proposed. Unlike Papanicolaou and Bakos's model, an axial stress was introduced to the fiber end to consider the load transferred from the asphalt mastic the aggregate. Efforts were also made to consider the effect of aggregate gradation, asphalt mastic degradation, and interfacial damage between the aggregates and asphalt mastic matrix on the tensile strength of the HMA mixtures. Experimental investigations were conducted to validate the developed theoretical relations. A reasonable agreement was found between the predicted tensile strength and the experimental results at low temperatures. Parameters affecting the tensile strength of asphalt mixtures were discussed based on the calculated results.     

砼受压损伤力学本构模型的研究

本文利用ＭＴＳ公司８１５．０２型电液伺服试验系统对砼进行了等应变速率加载控制的应力一应变全曲线试验，应用不可逆热力学和内变量理论的成果建立了砼损伤力学模型，并用概率统计的观点分析了损伤的演化规律。由于考虑了不可逆变形的影响，本文所建本构模型与实验吻合较好。     

龙潭拱坝砼上坝运输方案选择

龙潭拱坝坝高９０ｍ，砼上坝运输是砼施工过程中的中间环节，控制进度的关键，必须因时因地制宜地选择适当的运输机械和运输方案，使砼运输能做到保质、保量、及时和经济，通过论证比较，结合本工程现实情况，砼上坝运输不采用缆机而采用门机方案．     

多层住宅砖混房屋设计中两点问题的探讨

浅议多层住宅砖混房屋中构造柱的作用及设置方法；探讨了砖混结构墙下条形基础底面积重复利用问题及其解决方法。     

三峡工程三期RCC围堰工程

三期RCC围堰工程项目是确保三峡工程2003年蓄水、通航和发电目标按期实现的关键项目，也是右岸厂房坝段和右岸电站厂房等后续施工项目安全施工的保障。受施工通航、施工场地及工期条件等限制，三期RCC围堰的混凝土施工强度和上升高度均超过目前现有施工水平，针对这些难点开发出有效的处理工艺，保证了围堰工程的实施。     

商品混凝土降低成本的技术途径

商品混凝土目前价格偏高 ,用户不情愿接受 ,影响了它的推广应用。针对这一问题 ,本文提出了用“活化填料”、“活化水泥”配制高性能商品混凝土的技术路线并分析了其技术经济效益     

Air entrainment in fresh concrete with PFA

The results of a study into the influence of PFA on air entrainment in fresh concrete are discussed It is shown that the required dosage of AEA to produce an air content of 5.5 ± 0.5% in a PFA modified concrete mix is two-six times that required in the corresponding neat OPC concrete mix. The dosage of a vinsol based air entraining agent (AEA) required appears to be directly related to the PFA content of the mix. Similar direct relationships were obtained with a range of different PFAs. The dosage of an AEA based on the salt of a fatty acid appears to be sensitive to both PFA and OPC contents. For the type of PFA used, the variability of measured air content or the amount of air retained after continued agitation both indicated that vinsol based AEAs show the highest variability whilst fatty acid based AEAs show low variability. The between batch variability of air content was significantly improved by the addition of PFA regardless of the AEA used.     

现浇混凝土构件与砌体接触面收缩和温度应力裂纹的探讨

分析讨论了建筑物由于收缩及温度应力而引起的过纹，提出了在设计施工中应考虑的问题和采取的防止措施。     

镀锡板生产线深基坑施工实践

采用钻孔灌注桩作为深地坑的围护结构，在坑内设排水沟、集水井排水。成功地在珠江三角洲地区狭窄场地进行地坑开挖，既保证了工程质量又有其特色。