共查询到20条相似文献，搜索用时 62 毫秒
1.
王汉立 《湖北第二师范学院学报》2009,26(8):50-53
高效减水剂是满足HPC工作性要求必不可少的组分。由于高效减水剂的作用,水泥净浆流动度、水泥砂浆流动度大大提高,进而使混凝土拌和物的流变性能得到改善,混凝土拌和物不离析、泌水少、坍落度大、坍落度经时损失小。研究结果表明,在改善混凝土拌和物工作性方面聚羧酸高效减水剂优于萘系减水剂。聚羧酸高效减水剂的掺量相对于萘系减水剂可减半。 相似文献
2.
高效减水剂是满足HPC工作性要求必不可少的组分。由于高效减水剂的作用,水泥净浆流动度、水泥砂浆流动度大大提高,进而使混凝土拌和物的流变性能得到改善,混凝土拌和物不离析、泌水少、坍落度大、坍落度经时损失小。研究结果表明,在改善混凝土拌和物工作性方面聚羧酸高效减水剂优于萘系减水剂。聚羧酸高效减水剂的掺量相对于萘系减水剂可减半。 相似文献
3.
贺凤伟 《辽宁科技学院学报》2010,12(3):38-40
研究了氨基磺酸系高效减水剂（ASP）对水泥净浆流动度、新拌砼硬化性能及力学性能影响以及ASP减水率、ASP与水泥适应性：ASP与萘系减水剂复合性能。试验表明：ASP与萘系减水剂相比,具有低掺量、高减水率,以及控制坍落度损失的功能,而且与水泥具有很好的适应性,与萘系减水剂具有很好的相容性。 相似文献
4.
研究了以丙烯酰胺、聚乙二醇系列、丙烯酸、顺酐、烯丙基磺酸钠、丙烯酸羟乙酯为原料合成的XYZ聚羧酸系减水剂对净浆水泥性能及混凝土使用性能的影响.结果表明,XYZ系列减水剂具有缓凝特性,能够显著延缓水泥水化的放热,降低水泥水化热;减水剂使水泥早期微小晶体大量生长并填充孔隙,气孔细化且分布更加合理,晶体向外伸长使水泥粒子相互搭接而形成网络结构,提高了水泥石的密实性;减水率达25%,坍落度损失低,各龄期混凝土抗压强度都有较大提高. 相似文献
5.
陈宝璠 《福建工程学院学报》2012,10(6):552-558
采用自制的MPEGAA-AA-AMPS高效减水剂和P(AA-co-MA)/PEG、FDN-A减水剂,以不同掺量掺入P.O 42.5普通硅酸盐水泥,运用混凝土外加剂匀质性试验方法和水泥胶砂强度检验方法,研究不同掺量对水泥净浆流动度、水泥砂浆减水率、水泥净浆泌水率以及水泥砂浆的抗压强度等性能的影响,并利用电镜对添加MPEGAA-AA-AMPS高效减水剂的硬化水泥石的内部结构进行表征。结果显示,MPEGAA-AA-AMPS高效减水剂掺量为1.0%时,水泥净浆流动度达322 mm,砂浆减水率为47%,泌水率仅1.1%,28 d水泥胶砂抗压强度可达67.9 MPa。可见MPEGAA-AA-AMPS高效减水剂无论对水泥净浆或水泥砂浆的分散能力、保水性能和减水作用,还是对力学强度均有明显优势。从水泥石的内部结构SEM图看,添加MPEGAA-AA-AMPS高效减水剂后更能保证水泥石的抗压强度和经时耐受力。 相似文献
6.
7.
钢渣是炼钢工业所排放的工业废渣,它与高效减水剂的适应性是高性能钢渣系列混凝土掺和料研究开发的主要工作内容。本文通过Marsh时间和净浆流动度的测试分析,对比研究了萘系和聚羧酸系两类高效减水剂对慢冷钢渣和水淬钢渣这二种转炉钢渣净浆的适应性。试验结果表明,聚羧酸系高效减水剂的使用效果优于萘系减水剂,水淬钢渣粉体与高效减水剂的适应性优于慢冷钢渣粉体。 相似文献
8.
X-Z聚羧酸系减水剂的性能研究 总被引：1，自引：0，他引：1
研究了以聚乙二醇系列、丙烯酸、顺酐、烯丙基磺酸钠、丙烯酸羟乙酯为原料合成的X-Z聚羧酸系减水剂对水泥水化过程及微观结构的影响,并测试了掺加减水剂的混凝土性能.结果表明,X-Z系列减水剂具有缓凝特性,能够显著延缓水泥水化的放热;可使水泥气孔细化且分布更加合理,水泥石的后期水化更充分,水化产物结构更紧密更有力量;减水率达25%,坍落度损失低,各龄期混凝土抗压强度都有较大提高.yh 相似文献
9.
张凡 《宁德师专学报(自然科学版)》2007,19(3):239-241,245
通过自由基溶液的共聚合、磺化和酯化接枝等反应，合成一类主链带羧基、磺酸基，支链带聚氧乙烯基醚的聚羧酸高效减水剂．探讨了聚羧酸系减水剂的分散作用机理及对水泥净浆流动度和混凝士减水率的影响． 相似文献
10.
在普通混凝土中掺入PFAC明显改善普通混凝土的和易性,且具有显著的缓凝作用,使混凝土坍落度的经时损失减小,随着PFAC掺量的增加,水泥净浆的初凝和终凝时间随之延长,混凝土早期强度下降的幅度也随之增大,PFAC对混凝土的后期强度有着显著的增强效应．配制的掺PFAC混凝土28d的抗折强度超过5．0MPa,均能满足重交通和特重交通开放交通的要求,该混凝土的拉压比、折压比比普通混凝土有一定提高,试验结果为普通混凝土高性能化提供了技术保障。 相似文献
11.
邱崇丙 《唐山师范学院学报》2014,(1):21-23
汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。 相似文献
12.
13.
14.
《海外英语》2007,(5):10-11
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? 相似文献
15.
Rachel Zupek 《海外英语》2007,(11):40-41
我们绝大部分人都同意一件事情——我们喜欢金钱。但是你对金钱的喜欢之情足够到让你创立一份事业么?.财富通常被人忽视,主要在于人们不能真正了 相似文献
16.
《海外英语》2007,(4):36
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. 相似文献
17.
YANGShiguo 《重庆大学学报(英文版)》2004,3(1):86-88
The problem on the geometrc inequalities involving an n-dimensional simplex and its inscribed simplex is studied. Aninequality is established, which reveals that the difference between the squared circumradius of the n-dimensional simplex andthe squared distance between its circumcenter and barycenter times the squared circumradius of its inscribed simplex is not lessthan the 2(n-1)th power of n times its squared inradius, and is equal to when the simplex is regular and its inscribed siplex is atangent point one. Deduction from this inequality reaches a generalization of n-dimensional Euler inequality indicating that thecircumradius of the simplex is not less than the n-fold inradius. Another inequality is derived to present the relationship betweenthe circumradius of the n-dimensional simplex and the circumradius and inradius of its pedal simplex. 相似文献
18.
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. 相似文献
19.
20.
GUO Bao-feng Xiao Da-wei 《重庆大学学报(英文版)》2005,4(3):129-133
Using virtual reality for interactive design gives a designer an intuitive vision of a design and allows the designer to achieve a viable, optimal solution in a timely manner. The article discusses the process of making the Virtual Reality System of the Humble Administrator＇s Garden. Translating building data to the Virtual Reality Modeling Language （VRML） is by far unsatisfactory. This creates a challenge for computer designers to do optimization to meet requirements. Five different approaches to optimize models have been presented in this paper. The other methods are to optimize VRML and to reduce the file size. This is done by keeping polygon counts to a minimum and by applying such techniques as object culling and level-ofdetail switching. 相似文献