氧化-磺化纤维素高效减水剂的应用性能研究

Application performance of oxidized and sulfonated cellulose based concrete high range water-reducing agent

以亚硫酸氢钠对经高碘酸钠氧化处理的棉浆纤维进行磺化改性,制备氧化-磺化纤维素(OSC),并对其用作混凝土减水剂的性能进行研究。结果表明:氧化-磺化纤维素的减水率随磺酸基取代度增大而提高;氧化-磺化纤维素对水泥具有一定的缓凝作用;当其取代度为0.453,折固掺量为0.8%时,测得的水泥砂浆减水率、净浆凝结时间和3、7、28 d水泥砂浆抗压强度比等指标均符合GB/T 8076—2008《混凝土外加剂》中缓凝型高效减水剂的要求。通过SEM微观结构分析表明:水泥砂浆中掺入氧化-磺化纤维素后,由于缓凝作用导致水泥初期水化反应发展缓慢,而经较长时间(如28 d)后硬化水泥结构比基准样密实、强度更高。因此,OSC有望成为具有实际应用价值的混凝土高效减水剂。

Oxidized and sulfonated cellulose （OSC） was synthesized by oxidizing microcrystal cellulose with sodium periodate followed by the sulfonation reaction with sodium bisulfite. Its performances as water-reducing agent for concrete are studied sys- tematically. The results showed that the water reducing ratio of oxidized and sulfonated cellulose is increased with the degree of substitution（DS）. When the DS reached 0.453 and the mass fraction of OSC is 0.8%,the quality indexes tested including the wa- ter reducing ratio,the setting time of cement mortar and the compressive strength of mortar（3 d,7 d and 28 d） all meet the re- quirements of retarded high-range water-reducing agent in standard GB/T 8076--2008 ＂Concrete Additives＂. In addition,the oxi- dized and sulfonated cellulose presents some set-retarding effects. Results of SEM tests show that the hydration is slow at early days when oxidized and sulfonated cellulose is mixed into the cement mortar. But after a long period of hydration such as 28 days,the structure of the hardened cement mortar becomes more uniform and compact than that of the control,and the compressive strength is also stronger. Thus,OSC has the potential to be developed as high-range water-reducing agent.