影响乳胶漆耐冻融性的因素

讨论了分散剂、成膜助剂、防冻剂、乳液、增稠剂对乳胶漆耐冻融性的影响。

造纸厂剩余物用于混凝土 提高混凝土的耐冻融性

使用引气剂是提高混凝土在冻融环境下的耐久性的重要方法。但是，一些混凝土难以甚至不能掺加引气剂，这包括碾压混凝土和含有高钙粉煤灰的混凝土。另外有一些混凝土即使加入引气剂性能也不够好，例如，含有大量粉煤灰的混凝土，一般能显示较好的耐冻融性，但是暴露于有盐的环境下会发生剥离。

高掺量粉煤灰/塑料复合材料耐久性研究

对55％-65％粉煤灰增强聚乙烯（灰塑）复合材料的耐热老化性能和耐冻融性能进行了测试分析。结果表明，经过耐人工气候老化试验后，掺55％，65％细粉煤灰复合板材的最大弯曲荷载保留率为85．0％～82．5％，弯曲强度下降了14．8％～17．3％，弯曲模量下降了约10％。经过冻融循环试验后，掺55％～65％细粉煤灰复合板材的最大荷载保留率为86．7％～84．0％，弯曲强度下降了13．5％-16．5％，弯曲模量下降了13．4％-16．5％。掺量在55％-65％时，粉煤灰的粗细程度对灰塑复合材料的耐人工气候老化和耐冻融性能几乎没有影响。

部分钢结构性能检测方法

本方法用于测定薄涂型钢结构防火涂料涂层的抗弯性能。试件与抗振性试验用的试件相同。试件干燥后，将其两端简支平放在压力机工作台上，在其中部加压至挠度达L／100时(L为支点间距离，长1000mm)，观察试件上的涂层有无起层、脱落发生。

硅烷基防护剂对砖质材料防护性能的研究

砖质材料建筑物结构使用年限一长,会出现粉化、开裂、剥落等问题。借鉴混凝土结构防护的经验,考察了硅烷基防护剂对不同砖质材料的防护性能,探讨了防护机理,研究了硅烷基防护剂对砖质材料内部结构、吸水量比、耐酸性、耐冻融性以及表面憎水效果的影响。结果表明,硅烷基防护剂能降低砖质材料的吸水量比,提高其耐酸、耐冻融性能。

Air-void parameters measurement of fresh concrete and hardened concrete

Air content, spacing factor and specific surface of fresh concrete and hardened concrete with different air contents, slumps and mineral admixtures (fly ash, slag, fly ash + slag, fly ash + slag + silica fume composite) were studied by the air-void analyzer (AVA) method and the microscopical method. The correlations between the test results obtained from different methods were analyzed. The results show that, there is a close correlation of air content and spacing factor between the fresh concrete and the hardened concrete, but the specific surface correlation is weak. The air content of concrete measured by the AVA method is smaller than that of the pressure method and the microscopical method, because AVA device captures only the air voids with the size smaller than 3 mm. Spacing factor of the fresh concrete measured by the AVA method is greater than that of the hardened concrete measured by the microscopical method, while the specific surface is smaller. When the criterion of 4%-7% air content measured by the pressure method and microscopical method is acceptable for concrete freezing-thawing (F-T) durability in cold weather, the air content measured by the AVA method should be 2.4%-4.6%. For the concrete F-T durability, when the criterion of the spacing factor measured by the microscopical method is 300 μm, the spacing factor measured by the AVA method should be 360 μm.

Freezing and Thawing Durability of Ultra High Strength Concrete

Resistance to freezing and thawing of two UHSC （ultra high strength concrete） mixtures was evaluated in accordance with ASTM C 666 Procedure A. The two mixtures （plain and fiber reinforced） were developed using materials local to southern New Mexico, USA. Three different curing regimens were investigated for the mixture with fibers and one curing regimen was studied for the mixture without fibers. All curing regimens included 24 h of ambient curing followed by four days of wet curing at 50 ℃, and then two days dry curing at 200 ℃. At an age of seven days, one batch of fiber reinforced specimens was air cured at ambient conditions for the following six days and then placed in a water bath at 4.4 ℃ for 24 h prior to initiating freezing and thawing cycles. The second batch was air cured from day seven to day 12, and then wet cured for one day at 23 ℃ prior to being placed in the 4.4 ℃ water bath. The final batch was wet cured at 23 ℃ from the seventh day to an age of 13 days and then placed in the 4.4 ℃ water bath. The mixture with no fibers was air cured from the seventh day to an age of 12 days and then wet cured for one day at 23 ℃ prior to being placed in the 4.4 ℃ water bath. Higher moisture levels during curing produced greater initial dynamic elastic modulus values and durability factors at the end of the freezing and thawing tests, with the greatest durability factor being 87.5. Steel fibers were observed to improve both compressive strength and durability factor for UHSC.

有机硅改性醋丙乳液的研究

为了改善醋丙乳液的耐水性、耐冻融性及胶膜附着力等综合性能,采用种子乳液聚合方法合成了一种有机硅烷改性醋丙乳液,乳液性能测试结果表明采用有机硅改性能够明显提高乳液性能,有机硅氧烷的加入量以1%左右为宜。