Straw/Inorganic Cementitious Composite Molding Equipment Design And Process Optimization

At present,there are still a lot of straw waste or burn,which leads to the waste of resources and environmental pollution.On the other hand,the shortage of construction resources restricts economic development.Adding straw as a building raw material to the inorganic cementing material matrix can improve the bending resistance,cracking resistance and thermal insulation properties of building materials.However,when the amount of straw is high,it is difficult to prepare materials in large quantities by conventional molding or pressing mold locking.Therefore,in this paper,the compression characteristics of high content straw/inorganic cementing mixture are studied.Develop molding equipment suitable for the production of straw/inorganic cementitious composite materials,optimize the molding process of composite materials,actively promote the building materials of straw.In order to solve the problems of environmental pollution and wood supply and demand contradiction,to achieve the goal of carbon peak,carbon neutrality.The main research contents and conclusions of this paper are as follows:(1)Study on compression characteristics of straw/inorganic cementitious mixture.The influence law of straw moisture content and dosage on the compression characteristics of mixture is investigated by single factor compression test of mixture.The results showed that the compressibility of the mixture could be improved by increasing the moisture content or decreasing the content.Through fitting analysis of Kaliyan model and test data,8% moisture content and 30% content are selected as the basic material parameters for the preparation of straw/inorganic cementing composite.(2)Straw/inorganic cementitious composite material molding equipment design.Based on the compression characteristics of straw/inorganic cementing mixture and selected material parameters,the molding equipment of composite material is designed from two aspects of structure and hydraulic system.The structure is mainly composed of the frame,the hopper,the compression piston and the hatch door.The frame plays the role of supporting and fixing,the hopper ensures that the mix falls into the compression chamber smoothly,the compression piston is responsible for the compression and forming of the mix,and the hatch door plays the role of the roof when the mix is compressed.The hydraulic system mainly includes compression push-out and hatch door opening and closing system.The compression and extrusion system is responsible for the compression,shape preservation and product extrusion of the mix.(3)Optimization of Straw/inorganic cementitious composite material molding process.From the point of view of equipment,the influence law of process parameters on the forming index of composite materials is explored.Pressure,compression speed and feeding amount are taken as process parameters,and material forming density,residual force and specific energy consumption of equipment are taken as test indexes.Single factor compression tests,response surface optimization tests and validation tests are carried out for straw/inorganic cementing mixture.The results show that the test indexes increase with the increase of pressure,and decrease with the increase of feeding rate or compression speed.The influence degree of density and specific energy consumption is the same as: pressure > feeding amount > compression speed,and the influence degree of residual force is: pressure > compression rate > feeding amount.The best parameters are: pressure 0.47 MPa,feeding amount 280.98 g,compression speed91.42mm/min.(4)Performance analysis of straw/inorganic cementing test block.The influence of pressure on the performance of the test block is explored through the tests of compressive,flexural and thermal conductivity.The results show that the properties of the test block increase with the increase of pressure.The test block prepared under the optimal process has a compressive strength of 3.71 MPa,which meets the requirements of the Code for Lightweight Wallboard.Meanwhile,its flexural strength can reach2.84 MPa,and its thermal conductivity is 0.218 W /(m·K),which is 3.71 times that of ordinary clay bricks.