Preparation And Properties Of Slag-based Geopolymer Fir Fiber Composites

1.The slag-based geopolymer with plant fiber composite is a new type of environmentally friendly building material.The composite has many excellent properties such as high bending strength,fire resistance,high temperature resistance,water resistance,frost resistance,sound insulation,heat preservation.It can be applied to foundation building fields such as ceilings,fireproof materials,insulation materials,sound insulation materials,and.For these reasons,geopolymer composites are highly concerned by researchers at home and abroad.In the study,the slag-based geopolymer with fir fiber composite is made by using slag,plant fibers and alkaline activator solution as raw materials.The compatibility between the slag-based geopolymer and plant fibers was evaluated to select the plant fibers suitable with geopolymer;the orthogonal test and single factor analysis were used to obtain the optimized experimental parameters by analysing the properties of strength;the water resistance and frost resistance were tested by 24 h water-immersion experiment and freeze-thaw cycle experiment respectively;the effects of plant fiber incorporation on geopolymer was explored by the FTIR;the high temperature resistance was investigate by thermogravimetricits of composites;the crystal phase changes of geopolymer was analysis by XRD;the reinforcement mechanism of slag-based geopolymer plant fiber composites was studied with SEM.The findings are as follows:1.When the size of the plant fibers is 20 and 40 mesh,the fibers have the best effects of reinforcing and toughening on the slag-based geopolymer composite materials.2.The compatibility between the slag-based geopolymer and 12 plant fibers(fir sawdust,rice straw,sisal,bamboo,bagasse,cassava stalks,eucalyptus stalks,poplar wood chips,corn stalks,peanut shells,sorghum stalks,rice hulls)was study by the measurement of the maximum temperature of hydration(Tmax),the time required to reach the temperature(tmax),the ratio of the amount of heat released from a plant geopolymer mixture in 3.5-24 h interval(CA),the calculation of the inhibitory index(I)and the properties of strength.The bending strength of slag-based geopolymer with fir fiber is up to 12.53 MPa,Tmax is 38.9℃,tmax is 93 min,CA is95.82%,I is 0.1793%。3.In this paper,orthogonal test of L16(43)and single factor analysis were used to study the influence of many factors.The optimized experimental parameters are that the water glass modulus is 1.9,the water to glue ratio is 0.4,the fiber content is 13%,the curing temperature is60℃,the curing time is 28 days,and the water glass solid content is 36%.The mechanical properties were tested under the optimal parameters,the density is 1.68 g/cm3,the bending strength is 14.90 MPa,the internal bond strength is 4.09 MPa,and the gripping screw force is3480 N.According to the water-resistant immersion experiment of slag-based geopolymer withplant fiber composite,the water absorption rate was 10.55%,the water absorption expansion rate was 0.12%,the strength before and after water absorption was 13.02 MPa and 11.87 MPa respectively,and the strength loss rate was 8.83%.All factors exceeds the Standard requirements specified by the China National Standard(GB/T 24312-2009).The test of freeze-thaw cycle indicated that there is no change in the appearance of the slag-based geopolymer with plant fiber composite between before and after freeze-thaw.There are No obvious cracks and detachments were observed between the substrate and the plant fiber interface before and after freeze-thaw from the SEM.4.Orthogonal test of L16(45)and single factor analysis are applied to study for metakaolin-slag-based geopolymer with plant fiber composite.The optimized experimental parameters are that the metakaolin to slag is 2:8,the water glass modulus is 1.9,the water to glue ratio is 0.4,the fiber content is 13%,the curing temperature is 60℃.The mechanical properties were tested under the optimal parameters,the bending strength is 16.26 MPa,the density is 1.42g/cm3,the internal bond strength is 3.20 MPa,and the gripping screw force is 2618 N.According to the water-resistant immersion experiment of metakaolin-slag-based geopolymer with plant fiber composite,the water absorption rate was 18.30%,the water absorption expansion rate was0.53%,the strength before and after water absorption was 14.75 MPa and 10.17 MPa respectively,and the strength loss rate was 31.05%.All factors exceeds the Standard requirements specified by the China National Standard(GB/T 24312-2009).The test of freeze-thaw cycle indicated that there is no change in the appearance of the slag-based geopolymer with plant fiber composite between before and after freeze-thaw.There are No obvious cracks and detachments were observed between the substrate and the plant fiber interface before and after freeze-thaw from the SEM.5.FTIR and XRD analysis showed that the addition of plant fibers had no effect on the polymerization reaction of geopolymer composites.There also no new bonds and crystalline phases were found.6.TG analysis shows that slag-based geopolymer with plant fiber composites and metakaolin-slag based geopolymer with plant fiber composites have high-temperature resistance.At about 250℃,the composites began to lose carbonization and crystal water,and the C-S-A-H gel of geopolymer dehydrated at about 650℃.