混凝土冻融耐久性的试验研究

以混凝土冻融耐久性为研究内容，用不同种类混凝土的抗压强度、动弹性模量、超声波声速等指标的损失率来表征冻融过程中混凝土的性能劣化状况，并系统比较了不同种类混凝土的抗冻性优劣．通过研究得出：无论是普通混凝土，还是高强混凝土或高性能混凝土，其动弹模损失率、抗压强度损失率、超声波声速损失率均随冻融次数的增加而增大；提高混凝土强度在一定程度上可以提高混凝土抗冻融性能；掺入高效减水剂、优质引气剂和优质掺合料等，高性能混凝土抗冻融性能比对应的基准混凝土性能显著改善，而且通过这样的技术措施，较低强度等级的混凝土也可以获得高抗冻性．鉴于超声波测试方法方便、快捷、准确。而且可以直接用于实际工程的混凝土性能检测，所以，与动弹模测试方法相比，采用超声波测试技术来评价实际工程中混凝土的耐久性劣化程度具有明显的优势．     

对高性能混凝土几个问题的探讨

高性能混凝土是一种新型高技术混凝土，是在大幅度提高普通混凝土性能的基础上采用现代混凝土技术制作的混凝土．但因高性能混凝土的水胶比很低，给配制与施工带来如下问题：水泥标号的”标志”作用淡化，矿物掺合料的作用显著改善，拌合物的高粘聚性，混凝土的收缩等，这些都是值得设计、施工人员注意的问题．     

高性能混凝土的强度与渗透性的关系

通过对纯水泥高性能混凝土以及掺有矿渣或粉煤灰的高性能混凝土的一系列试验,研究了高性能混凝土的强度与渗透性的关系。结果表明,纯水泥混凝土的强度与渗透性之间有很好的相关性,其相关系数为0.9768;矿渣混凝土及粉煤灰混凝土的强度与渗透性之间相关性较差,相关系数分别为0.8075和0.8419;而所有混凝土的强度与渗透性之间的相关性更差,相关系数仅为0.6568。可见,除非用于纯水泥混凝土之间的相对比较,高性能混凝土的强度通常不能反映其渗透性。     

高性能混凝土配合比设计正交试验研究

运用正交试验设计法对高性能混凝土的配合比进行试验，研究了水泥、粉煤灰、矿渣和水胶比四个因素对高性能混凝土抗压强度的影响，找出了其中显著的影响因素：根据试验结果，进行线性回归，给出了预测模型。     

粉煤灰对高性能混凝土综合性能影响的研究

优质粉煤灰合理地应用于高性能混凝土中,不但能部分代替水泥,降低工程造价,而且其特有的性能还有效地改善和提高混凝土的性能。该论文就粉煤灰与水泥的作用及对高性能混凝土性能的影响进行了系统的研究分析,对粉煤灰在高性能混凝土中的工程应用具有一定的参考价值。     

碳纤维片材加固技术在某工程框架梁抗剪加固中的应用

粘贴碳纤维片材加固技术是一项新的应用外粘高性能复合材料加固结构的技术．碳纤维片材重量轻、高强度、高弹性、高耐久性，易于施工，现已开始应用于各类混凝土结构的加固处理．本文根据工程实际情况，简要介绍了碳纤维片材加固技术在混凝土框架梁抗剪加固工程中的应用．     

高性能外加剂和水泥相容性的试验研究

为配制高强高性能混凝土的要求，本对国内有代表性的10多种高性能的外加剂进行了水泥和外加剂的相容性试验，得到了外加剂和水泥的试验结果，为配制高强高性能混凝土的选择提供了依据。     

复合胶凝材料配伍技术研究

武广客专设计时速为350km/h,设计使用寿命为100年,对混凝土的耐久性等提出很高的要求,按普通配合比设计规范设计采用单一的胶凝材料配制混凝土已不能满足高性能混凝土的质量要求,复合混凝土胶凝材料,将胶凝材料中的两种、三种、或四种进行复配,通过试验确定其最佳复配比例,然后将其掺入混凝土中改善混凝土的性能,对各种胶凝材料的配制技术的研究,减少了高性能混凝土配合比的设计时对选材的困惑。     

低强度等级自密实混凝土配合比优化试验研究

通过在河北地区低强度等级自密实高性能混凝土的试验研究,得出自密实高性能混凝土的工作性能规律,研制出低强度等级的免振捣自密实高性能混凝土,促进自密实高性能混凝土在我国的推广应用.     

复合胶凝材料配伍技术研究

武广客专设计时速为350km／h,设计使用寿命为100年,对混凝土的耐久性等提出很高的要求,按普通配合比设计规范设计采用单一的胶凝材料配制混凝土已不能满足高性能混凝土的质量要求,复合混凝土胶凝材料,将胶凝材料中的两种、三种、或四种进行复配,通过试验确定其最佳复配比例,然后将其掺入混凝土中改善混凝土的性能,对各种胶凝材料的配制技术的研究,减少了高性能混凝土配合比的设计时对选材的困惑。     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

Western and Eastern culture differences in commercial field

The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity.     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

风的曲线

Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose.