Preparation and Mechanical Properties Study on Wood Fiber Alkali-activated Geopolymer Cementitious Materials
Geopolymers have attracted increasing attention due to their low carbon emissions,excellent durability and me-chanical properties.However,they generally have large shrinkage and are prone to brittle failure,which limits their promotion and application.In order to improve the shrinkage and strength of geopolymer,the effect of wood fiber content on the physical and mechanical properties of fly ash-slag geopolymer was studied,and its microstructure was analyzed.The results show that when the wood fiber content reaches 12.5 kg/m3,the dry shrinkage of the geopolymer test block is 0.58 mm after 28 days of curing,which is 52.5%lower than that of the geopolymer cementitious material test block without wood fiber.The flexural strength and compressive strength of wood fiber geopolymer cementitious materials increase first and then decrease with the in-crease of wood fiber content.When the wood fiber content is 10 kg/m3 and cures for 28 d,the flexural strength and compressive strength are the largest,which are 6.3 MPa and 79.8 MPa,respectively.The flexural strength and compressive strength reach the C60 and C80 standards of ordinary concrete test blocks,respectively.The incorporation of wood fibers can significantly im-prove the shrinkage resistance and mechanical properties of geopolymer cementitious materials test block,mainly due to its in-herent water regulation ability.When the hydration reaction of geopolymer matrix requires water,the stored water is released to maintain the continuity of the reaction and promote the formation of products.At the same time,the wood fiber with high specif-ic surface area is easy to be closely combined with the geopolymer matrix and makes it a reinforcing phase,which plays a key role in improving the shrinkage resistance and mechanical properties of the material.
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