地聚物的耐高温性能研究进展

Research Progress on High Temperature Performance of Geopolymers

地聚物是一种使用工业固废作为原料的新型绿色环保建筑材料。固废中含有的铝硅酸盐玻璃体在高碱性条件下经缩聚反应可形成无定型态的硅铝网状类沸石立体结构,从而使地聚物具有类陶瓷的特性,改善其耐高温性能。近年来,地聚物的耐高温性能成为绿色建材领域研究热点。地聚物混凝土是一种多相复合材料,其原料来源多样且配制过程中需要控制的参数较为复杂,这些因素都导致地聚物混凝土在高温下(后)抗压强度变化的多样性。近年来,研究者们开展了大量试验和理论分析工作,发现影响地聚物混凝土高温下(后)抗压强度的三个主要影响因素是:(1)晶相转变;(2)微观结构变化;(3)地聚物和骨料的位移不相容性。地聚物混凝土在高温下(后)的抗压强度最终取决于三个主要因素中占主导的因素和混凝土延性。本文着重探讨了硅铝原子比、碱溶液类型和骨料对地聚物混凝土高温下(后)抗压强度的影响规律,结合三种影响因素分析了地聚物混凝土的抗压强度劣化机理,同时对地聚物的热工性能和地聚物混凝土结构的耐火性能进行了综述。最后,对地聚物材料耐高温性能的未来研究前景进行了讨论。

Geopolymers are a kind of emerging cementitious materials that provide an environmentally alternative to ordinary Portland cement(OPC)based concrete.Compared with OPC concrete,the benefits of geopolymers are mainly based on their ability to bring high volume ratio of industrial wastes into construction products.Generated via the dissolution and polycondensation reaction of aluminosilicate vitreous in industrial waste under high alkaline conditions,geopolymers possess the zeolite-like network structures in which aluminum and silica tetrahedrally interlink alternately by sharing all the oxygen atoms.The formation of this three-dimensional structure leads to ceramic-like properties.Therefore,geopolymers are generally considered to provide excellent fire resistance,and research in this field has been attracting increasing interest in recent years.Geopolymeric concrete is a multiphase composite material,and its composition has wide variations.The orthotropic nature of the constituent materials results in the variation of high-temperature performance.Owing to the considerable research efforts,it has been recognized that there are mainly three factors which can affect compressive strength of geopolymeric concrete(exposed to high temperature):(Ⅰ)phase transition;(Ⅱ)microstructure changes;(Ⅲ)thermal incompatibility of geopolymer matrix and aggregates.The compressive strength of geopolymeric concrete under(or experienced)high temperatures depends on the dominant factor and the material s ductility.In this paper,the influence of Si/Al ratio,type of alkali solution and aggregates on the compressive strength of geopolymeric concrete under(and after experiencing)high temperatures are discussed.Combined with three factors,the compressive strength degradation mechanisms of geopolymeric concrete is analyzed.The paper also summarizes the thermal performance of geopolymers and the fire resistance of geopolymeric concrete structures.Finally,the future research prospect of high temperature performance of geopolymers is discussed.