Study On The Technology And Properties Of Light-transmitting Cement-based Fiber Composite Materials

Light-transmitting Cement-based Fiber Composite Materials is a kind new type of functional building materials,which makes cement-based materials transparent by combining with various light transmitting materials,and it has excellent architectural energy saving and visual performance effects.However,there are still problems with the immature preparation process at present,such as low strength,poor safety and durability of light-transmitting cement-based composites(LTCC).Based on the above situation,this article selects L·SAC and PMMA to constitute transparent cement-based composites by fixed optical fiber arrangement.A series of experiments were conducted to enhance the mechanical strength of the cement matrix using carbon fiber(CF),glass fiber(GF).And to enhance the composite interface bonding strength between the PMMA and the cement matrix using latex powder(VAE),cement expansion agent(EA),and silane coupling agent(KH-550).The effects of reinforcement materials with different treatment methods and dosage on the flexural strength,compressive strength,composite interface bonding strength,hydration process,and light transmittance of transparent cement-based composites were mainly investigated.The main conclusions of this paper are as follows:(1)Treating carbon fibers with sodium carboxymethyl cellulose as dispersant can significantly improve the dispersion state of the fibers,resulting in uniform distribution of fibers in the specimen and good adhesion to the matrix.The curve of the hydration process indicates that the treated carbon fiber increases the highest hydration temperature,delays the time node to reach the highest temperature,and plays a certain promoting role in the hydration degree of cement specimens.(2)Fiber has a high elastic modulus,which can bear the stress transmitted from the matrix during the fracture of the cement,absorb energy,effectively suppress the development of cracks,and enhance the mechanical strength of the cement substrate.The results indicate that the reinforcement effect of carbon fiber and glass fiber on the specimen within the experimental range first increases and then decreases.This is because if the fiber content is too low,the number of fibers at the crack is insufficient to bear stress,and if the content is too high,fiber aggregation phenomenon will occur,introducing a large number of interfaces into the matrix.Adding 0.5% chopped CF can increase the flexural strength and compressive strength of composite specimens by 57.5% and 35.7%,respectively;Adding 3% GF can increase the flexural and compressive strength of composite specimens by 72.5% and 6.4%,respectively.(3)The results show that VAE and EA within the experimental range have a certain enhancing effect on the bonding strength between optical fibers and cement matrix,as well as the mechanical strength of LTCC.Among them,adding 2% VAE can increase the interfacial bonding strength by 29.0%,and increase the flexural strength and compressive strength of LTCC specimens by 17.5% and 12.5%,respectively;Adding 0.5% EA can increase the interfacial bonding strength by 22.5%,and increase the flexural strength and compressive strength of LTCC specimens by 12.5%and 5.7%,respectively.Scanning electron microscopy shows that after adding these two polymers separately,there is almost no gap between the interface between the optical fiber and the cement matrix inside the specimen,indicating that in LTCC,an appropriate amount of VAE can play a water retaining and surface active role,while an appropriate amount of EA can play a swelling role,making the cement more tightly wrap the optical fiber and reducing the gap formed by adding the optical fiber.At the same time,when the specimen is damaged,the optical fiber acts as a tie,suppressing further damage of the specimen.(4)When 0.8% carbon fiber and 2% VAE are simultaneously added to LTCC,the reinforcement effect of fibers and the toughening effect of polymers are maximized,resulting in a significant increase in the mechanical strength and interfacial bonding strength of the specimen.The test results show that this scheme can increase the interfacial bonding strength,flexural strength,and compressive strength of LTCC by 37.5%,90.0%,and 76.8%,respectively.And it has no effect on the light transmittance of the specimen,reaching 6.52%.This is because the polymer makes the cement matrix denser and more expansive,and during the setting process,it compresses towards a uniformly dispersed carbon fiber.The carbon fiber exerts its own tensile effect to a greater extent at the point of crack formation.CF and VAE promote each other,further improving the mechanical strength of the specimen.