油页岩渣对混凝土抗压强度和抗氯离子侵蚀的影响

Effect of Oil Shale Residue on Compressive Strength and Chloride Corrosion Resistance of Concrete

油页岩经干馏或燃烧后留下大量油页岩渣(OSR),OSR的堆弃占用土地和污染环境。以OSR干馏渣为粗骨料制备了油页岩渣混凝土(OSRC),测试了其工作性能、微观结构、抗压强度和氯离子渗透性能。试验结果表明,OSRC的工作性能、力学性能和抗氯离子侵蚀性能均随油页岩渣取代率(V_(r))的增加而降低,V_(r)为25%和43%时,OSRC的立方体抗压强度分别为29.9 MPa和25.5 MPa,氯离子渗透性能评价分别为很低和低。V_(r)大于50%时,OSRC的通电量随V_(r)的提高而快速增加。通过微观形貌测试发现,离OSR与界面过渡区(ITZ)界线越远,ITZ中的钙矾石晶体越少,水化硅酸钙凝胶越多,但氢氧化钙晶体较少,OSR具有“返水”特性。OSRC的受压破坏形态为OSR折断且断面平整,天然骨料周边的水泥砂浆剥落。OSR和ITZ是OSRC的薄弱区域,是后续研究之关键。OSR等多孔废弃物可以用作混凝土的填充料和内养护材料。

Ahuge amount of oil shale residue is left after retorting or burning of oil shale.The dumping of oil shale residue occupies land resources and seriously pollutes the environment.Oil shale residue concrete(OSRC)was prepared with oil shale retort residue as coarse aggregate.The workability,microstructure,compressive strength and chloride ion permeability of OSRC were tested.The results showed that the workability,mechanical properties and chloride corrosion resistance of OSRC decrease with the increase of oil shale residue replacement(V_(r)).When V_(r) is 25%and 43%,the cubic compressive strength of OSRC is 29.9 MPa and 25.5 MPa,and the chloride ion permeability is respectively evaluated as very low and low.While V_(r) is greater than 50%,the electric flux of OSRC increases rapidly with the increase of V_(r),so 50%is the critical V_(r) of OSRC chloride ion permeability.It was found that the farther away from the boundary between the OSR and the interface transition zone(ITZ),the fewer ettringite crystals and more calcium silicate hydrate gel in ITZ,and there is very little calcium hydroxide crystals in whole ITZ.OSR has water absorption and desorption characteristics.In addition,the compressive failure mode of OSRC is OSR fracture with smooth fracture surface and cement mortar spalling around natural aggregate.Finally,OSR and ITZ are the weak areas of OSRC,which are the key to the follow-up research.And porous wastes such as OSR could be used as concrete fillers and internal curing materials.