| With the convening of 19 th CPC National Congress,the state would pay much more attention to the construction of ecological civilization.The infrastructure construction created lots of exposed slopes,which have caused a certain impact on the surrounding environment and need for ecological control.Vegetation growing concrete is an excellent ecological slope protection substrate.After years of research,it has accumulated rich experience in the application of engineering effects,mechanical properties and stability analysis.Numerous studies have greatly promoted the promotion and application of this material.However,as of today,the mechanism of the shrinkage and fissure of vegetation growing concrete,and the mechanism that may cause the instability of slope,is still blank.Based on the vegetation growing concrete mixed with the commonly used three kinds of organic materials(sawdust,cattle manure,and corn vinasse),this paper comprehensively analyzed the water loss shrinking characteristics,fissure development law and permeability characteristics of the vegetation growing concrete by conducting indoor wetting and drying cycles test.At the same time,it discusses the influence of the organic materials on the three properties of the vegetation growing concrete.The main research contents and results are as follows:Laboratory tests are conducted to study the water loss shrinking characteristics of the vegetation growing concrete using sawdust,cattle manure,and corn vinasse as organic material.The number of pixels is used to quantitatively describe the horizontal shrinkage of the sample.It is found that the rate of shrinkage in all directions of the vegetation growing concrete using corn vinasse is the largest,and sawdust one is the smallest.There is significant anisotropy in the shrinkage of the vegetation growing concrete,and the vertical shrinkage is larger.In vertical direction,the shrinkage can be divided into acceleration phase,deceleration phase,and stabilization phase.The cement and organic materials will both affect the shrinkage of the vegetation growing concrete.The effect of the cement is mainly in the first dewetting process.Organic materials will affect the shrinkage of vegetation growing concrete in a longer period,and the degree of effect is greater.Laboratory test is conducted to study the evolution law of the fissures of the vegetation growing concrete using sawdust,cattle manure,and corn vinasse as organic material.The binarization and vectorization techniques are used to extract fracture parameters.It is found that the vegetative quality of vegetation growing concrete using corn vinasse has the highest degree of fissure development,and the cattle manure one is smaller,while there are almost no fissures in the sawdust one.The fissure development of vegetation growing concrete is mainly the change of length.The gradient of moisture content is the main reason for the development of fissures in vegetation growing concrete.Meanwhile,the shrinkage strength and tensile strength has effects on the shrinkage of the vegetation growing concrete,and the latter is larger.Laboratory test is conducted to study the permeability characteristics of the vegetation growing concrete using sawdust,cattle manure,and corn vinasse as organic material.It is found that in the process of wetting and drying,the permeability coefficient of the vegetation growing concrete using corn vinasse is the largest,and the sawdust one is the smallest.The water holding capacity and spatial distribution of organic materials affects the permeability characteristics of vegetation growing concrete.However,the porosity is a key factor affecting the permeability.By correlation analysis,there is a significant positive correlation between the fissure index and the permeability coefficient of vegetation growing concrete,and there is a significant negative correlation between the shrinkage rate and the permeability coefficient.The development of fissures is the main reason for the change of the permeability coefficient.By contrasting the effects of three organic materials on the shrinkage,fissure resistance and permeability of the vegetation growing concrete,it is considered that the cattle manure is the best choice for the organic material of the vegetation growing concrete. |
