高流态泵送粉煤灰高性能混凝土的试验研究

近几年利用粉煤灰来配制混凝土,其社会效益、经济效益和技术效益已经得到公认。但是,对于高标号、流动的粉煤灰混凝土目前国内研究并不多,进一步开展利用粉煤灰来配置高效混凝土的研究就显得很有必要。本文通过掺加高效减水剂,调整水灰比等途径配制了泵送高强高性能粉煤灰混凝土,并力求加大粉煤灰掺量来降低混凝土成本。利用525#普通硅酸盐水泥,采用常规施工工艺,进行了9组混凝土配合比试验,给出了高流态高性能混凝土推荐配合比,分析讨论了泵送高强粉煤灰混凝土的性能,配制了强度大于50Mpa坍落度大于80mm的高流态、高性能混凝土,旨在为开发粉煤灰高性能混凝土提供试验依据使之实用化、商品化。     

混凝土缓凝剂的分类及其作用机理

缓凝剂在混凝土夏季施工、泵送施工中得到广泛应用。根据化学成分的不同,将混凝土用缓凝剂划分为无机缓凝剂和有机缓凝剂两种,并分别论述了无机缓凝剂和有机缓凝剂的作用机理。     

医院建筑防辐射大体积混凝土施工

记述防辐射大体积混凝土施工中模板工程、钢筋工程及混凝土工程采取的技术措施,同时还记述了混凝土产生裂缝及混凝土温度控制所采取的技术措施。     

混凝土构件质量问题调查与分析

重点阐述了混凝土质量问题的主要表现方面,影响混凝土强度的主要因素及混凝土质量的检测方法。     

某大桥群桩承台大体积混凝土施工温控计算

以某黄河大桥第40号和41号主塔墩承台为例,采用有限元法模拟三维瞬态温度场,考虑施工过程和温控措施的影响,选取了计算模型,并介绍了计算原理,通过分析得到了大体积承台混凝土内部温度场分布规律,得出了理论计算分析与实测结果符合较好的结果。     

梵净山区香瓜双膜小棚早熟丰产栽培技术

梵净山区香瓜双膜小棚早熟丰产栽培技术要点:1.选用良种,严格轮作;2.酿热育苗,钵内点播;3.培育壮苗,栽前炼苗;4.合理密植,覆膜移栽;5.中午换气,晴天对流;6.摘心整枝,防落保果;7.病虫早治,加强管理;8.适期采收,增值增效。     

Effect of chloride content on bond behavior between FRP and concrete

For reinforced concrete structures located along the seaside, the penetration of chloride ions into concrete may be a threat to the durability of the structures. Experimental investigations were carried out to study the effect of chloride content on the bond behavior between concrete and fiber reinforced polymer (FRP) plates. Direct shear tests were conducted on the FRP strengthened concrete members. Before testing, the specimens were immersed in NaCl solutions with concentrations ranging from 3%—15% for different time (0—120 d). Then, the specimens were dried and tested to obtain the initial and ultimate debonding loads, together with strain distributions along the FRP plates of different load values. The correlations between chloride content and debonding parameters are established. Test results show that the debonding parameters are closely related to the immersing time rather than the chloride content of the solution.     

Replacing stirrups of self-compacting concrete beams with steel fibers

Based on the investigation of fiber influence on workability of self-compacting concrete (SCC), tests were carried out on two series of SCC rectangular simply supported beams, which were made of hooked steel fibers reinforced concrete with or without stirrups, subjected to four-point symmetrically placed vertical loads. The major test variables are steel fiber contents and stirrup ratios. The results indicate that the ultimate load significantly increases with the increase of fiber content; the addition of ...     

混凝土结构加固技术性能比较

综合介绍了混凝土结构加固技术现状,对各种方法的特点和适用范围进行了比较,并对混凝土结构加固技术目前需要完善的地方以及发展方向提出了几点个人的看法,对于施工人员进行混凝土结构加固时进行适宜的方法选择具有一定的指导作用.     

评新《企业会计准则-基本准则》——论构建财务会计概念框架

《企业会计准则-基本准则》比修订前更符合财务会计概念框架的特征,但仍存在无法克服的自相矛盾。无论是从形式上还是从功能上分析新《企业会计准则-基本准则》,都不如直接采用概念框架的形式更为合适。结合我国现实的环境,对财务会计概念框架的构成内容及其相互之间的关系进行探讨,以期为构建我国财务会计概念框架提供若干参考。