3D Printed Slag-based Geopolymer Material Design And Its High Temperature Performance

The application of 3D printing construction technology based on 3D printing technology in the construction industry can improve the traditional construction model to a certain extent,improve production efficiency and better guarantee the construction quality.But it is more noteworthy that 3D printing construction technology has special requirements for materials,and traditional construction materials cannot meet the demand for the time being.The geopolymer material is currently one of the materials that are very suitable for application in 3D printing construction technology.Although there have been studies showing the feasibility of using geopolymers in 3D printing construction technology,there are still many problems at present.Therefore,based on the existing research,four geopolymer materials with different slag content were selected to systematically study the basic properties and printability of the new slag base polymer materials with different slag content.The effects of curing conditions on the mechanical properties of the printed matter and the performance of the printed matter under high temperature conditions have reached the following conclusions:(1)The four groups of slag content of 20%,40%,60% and 80% can be used to meet the basic performance requirements of 3D printing technology for the new mixed slurry;After studying the printability,it was found that except for the slurry with 20% slag content that cannot be printed by 3D printing construction technology,the remaining three groups of materials all performed well in printability;the reason for this phenomenon is that Because the slurry with a slag content of 20% is slightly dry,its friction is greater when it is extruded from the pipeline,and it is more likely that the slurry cannot be extruded or the slurry is in a poor state after extrusion.(2)Through the characterization of the mechanical properties of the three groups of samples with slag content of 40%,60% and 80% and the effect of different maintenance conditions on the mechanical properties of the printed matter,it was found that the slag content was 60% and 28 days old.80% of the samples had good interlayer bonding strength.The interlayer bonding strength of the sample group with a slag content of 40% is relatively low;the flexural strength of the printed matter and the interlayer bonding strength are positively correlated.With the increase of the interlayer bonding strength,the flexural strength of the printed matter The strength will also increase;the compressive strength values of the printed matter increase with the increase of the slag content;the mechanical properties of the samples with slag content of 40%,60% and 80% under different curing conditions are tested It was later found that the samples of each group performed best under standard curing conditions.And regardless of the conditions under which the test block is maintained,the compressive strength value of each group of samples in the loading direction of P1 always remains the highest.This may be due to the fact that the compressive strength in this direction during 3D printing becomes denser due to the dead weight of the slurry and the squeezing action between the slurry layers,and the compressive strength is relatively high.(3)Different slag content and a constant temperature of 0.5 hours to 2 hours have no obvious influence on the linear expansion rate of the printed matter under high temperature conditions,but the temperature condition has a great influence on the linear expansion rate of the printed matter.When the temperature is between 300℃ and 600℃,the printed matter shrinks.When the temperature is 900 ℃,the printed matter of each group has swelled;the mass loss rate of the printed matter at high temperature increases with the increase of the slag content,but the degree of increase is low;the constant temperature time is 0.5 hours~ Within the range of 2 hours,with the extension of the constant temperature time,the mass loss rate will not appear to float too much;different temperatures are the main reasons affecting the quality loss rate of the printed matter.As the temperature continues to increase,the corresponding printed matter the rate of quality loss is also increasing.(4)The effect of temperature on the mechanical properties and microstructure of the printed matter is obvious.When the temperature is 300℃,the loss of free water inside the printed matter will make the microstructure of each group of printed matter more uniform,resulting in a significant improvement in the mechanical properties of the printed matter.When the temperature is 600℃~900℃,the free water,bound water and the decomposition of hydration products and aggregates inside the printed matter will cause the mechanical properties of the printed matter to deteriorate;within a constant temperature range of 0.5 hours to 1 hour With the extension of the constant temperature time,the mechanical properties of the printed matter have not been significantly affected;after exploring the effect of the mass loss rate of the printed matter on the compressive strength of the printed matter,it is found that the compressive strength of the printed matter will increase with the quality loss rate.Increase and decrease continuously.