聚乳酸表面包裹对氧化钙膨胀性能提升的影响

摘要

利用聚乳酸(PLA)表面包裹改性CaO膨胀剂,采用约束变形测试方法和改进的双圆环方法,系统研究了0.5%、1.0%和2.0%PLA包裹改性CaO对约束密封条件下水泥净浆、砂浆及混凝土膨胀性能的影响.结果表明:相比未改性CaO膨胀剂,PLA包裹改性后CaO膨胀率明显提升,且随着包裹率增加膨胀率增幅扩大;相比于掺未改性CaO膨胀剂的净浆、砂浆和混凝土,掺PLA包裹率为2.0%的CaO-PLA膨胀剂可使水泥净浆和砂浆28 d膨胀率分别提高27.4%和17.6%,混凝土密封养护和水养膨胀率分别提高51.1%和32.4%;砂浆膨胀应力40 h提高了45%.%CaO expansive agent was modified by surface encapsulating of polylactic acid (PLA). The expansion properties of cement paste,mortar and concrete with 0.5%,1.0% and 2.0% PLA encapsulated ratio in CaO-PLA were investigated by con-strained deformation tests and improved dual rings restraint tests. The results show that the expansion property with PLA modified improved more significantly than unmodified CaO,and the amplification enlarged with the increase of encapsulation rate. Compared with the pastes,mortars or concretes with unmodified CaO expansive agent,the expansion rates of pastes and mortar were increase by 27.4% and 17.6% respectively at the age of 28 days of the 2.0% encapsulating ratio CaO-PLA and the expansion rates of concretes under seal and water curing were increase by 51.1% and 32.4%. The dual rings restraint tests show that the expansion stress of mortar with PLA-CaO of 2.0% encapsulating ratio increased by 45% within 40 hours comparing with the stress with un-modified CaO expansive agent.