| Calcium silicate board is an important green building board,which has been widely used in light construction field and has gradually become one of the most important building boards.Plant fiber is an ideal reinforcement material for calcium silicate board because of its wide source,environmental friendliness,suitable aspect ratio,good tensile strength and renewability.In this study,plant fiber is used as the reinforcing fiber of calcium silicate board,and the applicability selection method of strengthening calcium silicate board fiber is established.The influence of beating technology on the physical properties of calcium silicate board is explored.The influence of microfibrillation cellulose on mechanical properties of calcium silicate board is discussed,which provides theoretical guidance for the green development of calcium silicate board industry.The specific contents are as follows:(1)To establish fiber selection criteria,the fiber morphology,composition and mechanical properties of 14 different brands of plant fiber pulp were analyzed.The influence of the addition amount of plant fiber on the physical force and mechanical properties of calcium silicate board was explored,and the optimal addition amount of plant fiber was determined to be 8%.Through multiple linear regression analysis of fiber properties and mechanical properties of calcium silicate board,the enhancement and toughening indexes of plant fiber.The strengthening and toughening index of plant fiber can provide some guidance for the selection of suitable plant fiber in calcium silicate board industry.(2)In order to enhance the adhesive between plant fiber and substrate,the effects of beating on the preparation process and the properties of calcium silicate board were studied.The results show that the improvement of the beating degree can improve the retention performance of the slurry in the wet end but prolong the drainage time of the slurry.The more appropriate beating degree is 45 °SR,and the calcium silicate at this time has the best mechanical properties,the flexural strength and fracture toughness are 26.13 MPa and 2.7KJ/m2 respectively.In addition,the plant fiber pretreated by commercial beating enzymes can significantly improve the fracture toughness of the calcium silicate board,but it will have an adverse effect on the flexural strength.(3)Using microfibrillated cellulose(MFC)and Micro silica(MS)as modified materials,MFC/Ms synergistically modified calcium silicate boards were prepared.The results showed that with the increase of Ms dosage to 18%,the cumulative pore volume of calcium silicate board decreased from 0.117 cm3/g to 0.02 cm3/g.The analysis of mechanical properties shows that the MFC and Ms in the calcium silicate board have good synergistic characteristics.When the MFC and Ms content are 0.3% and 12% respectively,the flexural strength of the calcium silicate board can reach 35.96 MPa.After 25 freeze-thaw cycles,its flexural strength can still be maintained at 25.03 MPa,showing good freeze-thaw resistance. |
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