矿物质混合材对水泥砂浆抗硫酸盐腐蚀的影响

EFFECT OF MINERAL ADMIXTURES ON SULFATE ATTACK OF CEMENT MORTARS

采用GB2420方法检测了掺加不同矿物质混合材后水泥砂浆的抗蚀系数(抗折强度比),并根据ASTMC1012标准检测了砂浆棒在5%硫酸钠溶液中养护15周后的膨胀率。结果表明:由于混合材稀释作用和二次水化作用,水泥中3CaO·Al2O3含量和水化产物中Ca(OH)2含量降低,砂浆样品在3%Na2SO4溶液中养护2个月后的抗蚀系数增加,样品15周的膨胀率显著降低。偏高岭土中大量的活性Al2O3有助于降低石膏饱和系数(即SO3和αAl2O3的摩尔比),从而抑制由于形成钙矾石和石膏引起的膨胀。

The corrosion resistance coefficient （flexural strength ratio） of cement mortars incorporating different mineral admixtures was tested according to GB2420, and the ASTM Cl012 method was employed to measure the expansion ratio of mortar bars after 15 weeks of immersion in 5% Na2SO4 solution. It is shown that all the mineral admixtures are effective in increasing the corrosion resistance coefficient of the samples cured in 3% Na2SO4 solution for 2 months, while the expansion of the samples is considerably decreased, as 3CaO·Al2O3 content in cement and Ca（OH）2 content in hydrated products are reduced through dilution and secondary reaction. The large amount of reactive Al2O3 in metakaolinis is also beneficial to decrease the gypsum saturation factor （molar ratio of SO3 and α-Al2O3）; therefore the expansion due to ettringite and gypsum formation are inhibited.