Research On The Mix Design And Properties Of 3D Building Printed Concrete

The 3D architecture printing technology is an upgrades product which has developed from the construction technology and the production technology in recent years.The core advantages of the building printing are mainly from the continuous upgrading of the building materials science and the transformation advantage of the traditional machinery manufacturing industry to the intelligent automation.The 3D printing concrete is a new building material based on the manufacturing process of material adding.This article starts with the selection and optimization of 3D printing concrete raw materials,starting with the material properties to meet the 3D printing architectural process requirements.First,it finds the the ratio of glue to sand that is suitable for the output of the printer,and then determines the water cement ratio of the experimental groups according to the pipeline output properties of the different mortar and the shaping performance.At last,the orthogonal experimental method is used to design the mix ratio of 3D printed concrete.and the optimum amount of mineral admixtures,chemical additives,fibers,and other modified materials were selected to find the most suitable pipeline transport performance,the test body shaping performance and the shear resistance and compression performance of the test wall.In the experimental study of 3D printed concrete,the performance evaluation of the 3D printed concrete is combined with the printing process for the first time.The evaluation of the conveying performance of the 3D printed concrete pipes is determined by the pump speed,the material pushing height and the conveying length.The superiority of the 3D printed concrete morphology is controlled by intuitively analyzing a number of apparent features of the printed test body wall.The evaluation of the moldability of 3D printed concrete was obtained by printing the standing height and the extension width of the test body wall.Through testing the interlaminar shear strength test and compressive strength test of the printed test block,the evaluation of the bonding performance and bearing capacity of the 3D printed concrete was completed.The main conclusions of this paper:The analysis of the pipe transport performance of 3D printed concrete shows that:the best cement-to-water ratio is 0.32for medium sand=1:1,and the optimum water-cement ratio for cement:medium sand=1:1.5.Should be 0.36.When the cement:medium sand=1:2,the best water-cement ratio is 0.40 after adding polypropylene fiber and cellulose ether;the moldability performance test of 3D printed concrete is designed according to the orthogonal table,and the most obvious results are obtained through the test.The optimal ratio result is A2B3C1.The ratio of glue to sand is 1:1.5,the content of cellulose ether is 0.15%,the content of polypropylene fiber is 0.6kg/m~3;the compressive strength of 3D printed concrete is lower than the compressive strength of ordinary cast-in-place concrete by 25%,and The modified structures of cellulose ethers and polypropylene fibers increase their compressive strength to 13.8%of the general 3D printed concrete compressive strength.In addition,the addition of cellulose ether and polypropylene fiber can make up for the lack of intrinsic shear strength of 3D printed concrete;When the content of cellulose ether is 0.15%,the shear strength of printed concrete is best.For the glue-sand ratio,the experimental conclusion is that the shearing effect is best when the ratio of glue to sand is equal to1:1,and the effect of the polypropylene fiber content on the shear strength is a maximum of 1.2 kg/m~3.The compressive effect of printed concrete is best when the ratio of glue to sand is 1:1,and for polypropylene fiber,the experimental conclusion is that the shearing effect is best when the amount is 0.6 kg/m~3.The effect of the cellulose ether content on the compressive strength was minimal,and the optimum content was 0.1%.