利用Ⅱ级粉煤灰的灌注桩室内试件和现场取芯试件的耐久性研究

Comparative research on the durability of concrete samples containing Ⅱ-fly ash drilled from field piles and prepared in laboratory

进行了现场混凝土桩体的钻芯取样的室内抗硫酸盐试验和抗氯离子渗透试验,包括不同物质组分、不同配比、不同外加剂条件下配置的混凝土。研究表明,现场钻芯取样混凝土试件比实验室成型混凝土试件的质量更好,相同配比条件下混凝土试件的强度略高,而混凝土材料的抗硫酸盐性能也稍好。随着混凝土中粉煤灰掺入量的增加,混凝土的抗硫酸盐能力有一定的提升。对比不同试验组混凝土抗硫酸盐性能,发现同一根桩的较深处,混凝土抗硫酸盐性能会好于较浅处的混凝土,而经过硫酸盐干-湿循环侵蚀作用150次后的强度降低幅度也稍小,其原因可归结为桩深处的混凝土受到的重力较大,形成的浆体较为密实,因此其强度和耐久性就好。

The resistance tests to sulfate and chloride ion of concrete samples containing fly ash are accomplished by drilled samples from field piles and prepared in laboratory. These samples include different composition of materials, different mixes of materials, and different admixtures. Studies show that, the quality of concrete samples acquired in field are generally better than those prepared in laboratory, the strength of concrete samples with same mix in field is slightly higher than those prepared in laboratory, and the sulfate resistance is also slightly better. Furthermore, the sulfate resistance of concrete samples is improved obviously with the content of fly ash. It can be found that, for a same pile, the resistance to sulfate in the deep location of a pile is better than that acquired from less deep locations. In addition, the reduction in the strength of field concrete samples subject to 150 dry-wet cycles of sulfate erosion is slightly smaller than the samples prepared in laboratory, which can be attributed to the higher density and strength in the greater depth of the concrete pile due to gravity effect.