Study On Preparation Of Straw Micro-powder Strengthened Ecological Concrete

There are a large number of interconnected pore structures inside the ecological concrete,which has good water permeability and the ability to protect the ecology,which has played an active role in promoting the construction of sponge cities.However,the porous structure inside it makes it impossible to retain the water necessary for the hydration of the gel tissue using traditional external maintenance methods,which further affects its performance.This thesis takes water-carrying straw micro-powder as the internal curing material prepared by ecological concrete,takes the improvement of ecological concrete curing conditions as the starting point,and conducts experimental research with the aim of improving mechanical properties and working performance.The main conclusions are as follows:(1)The preparation process of straw micro-powder ecological concrete was studied.The results confirmed that the reasonable addition of water-carrying straw micro-powder can significantly increase the uniaxial compressive strength and increase the water permeability coefficient.(2)The significance of the relationship between each control factor in the preparation process and its working performance was studied.The primary and secondary factors affecting compressive strength are the amount of straw micro-powder blended,water-cement ratio,and coarse aggregate particle size;the primary and secondary factors affecting the water permeability ratio are the water-cement ratio,straw micro-powder blended amount,coarse aggregate particle size;The primary and secondary factors are aggregate particle size,straw micro-powder blending amount,and water-cement ratio.(3)The response surface method is used to further analyze the interaction between various factors and establish a prediction model.It was confirmed that the interaction between straw micro-powder incorporation and water-cement ratio and straw micro-powder incorporation and aggregate particle size had significant effects on compressive strength and water permeability coefficient.According to prediction and experimental verification,the best compressive strength and water permeability coefficient in the study interval were 8.37 MPa and 7.40 mm / s,respectively,and the prediction results were reliable.(4)The freeze-thaw cycle experiment was used to study the freeze-thaw cycle durability of the straw micro-powder eco-concrete.The results show that the addition of saturated water-carrying straw micro-powder can significantly improve the overall antifreeze performance.When the amount of straw micro-powder mixed is 2.0%,the freeze-thaw cycle durability of ecological concrete is the best.Compared with the case without adding straw micro-powder,the mass loss rate decreased by 63.64 %,and the strength loss rate decreased by 46.40 %(5)The non-contact strain measurement system was used to track the compression process of the straw micro-powder ecological concrete,and the damage and damage rules were analyzed.The study confirmed that when the concrete was loaded in one direction,its failure path evolved along the loading direction,and the crack first occurred at the maximum tensile.In the path of strain transmission,the stress continues to increase after the crack is generated,resulting in increased strain and eventually structural damage.(6)The microscopic morphology and element distribution of straw micro-powder concrete were analyzed by SEM.The results show that the straw powder in the concrete gel structure will slowly release water during the curing stage to meet the hydration water demand,improve the strength of the gel structure,and then improve its mechanical properties.