Analysis Of Structural Characteristics And Mechanical Properties Of Macroporous Concrete

With the rapid development of urbanization,drainage during rainfall problem in urban areas and how to effectively utilize construction waste have attracted much attention.Research on sand-free macroporous concrete has been carried out in many countries.The application of macroporous concrete can effectively solve a series of problems caused by a large amount of construction waste and poor drainage of roads in urban construction,and protect natural resources and ecological environment.Ceramsite permeable concrete is a kind of porous lightweight concrete,which is characterized by large porosity and light weight.Recycled aggregate permeable concrete is a kind of eco-environmental protection concrete,which is made by special technology and has continuous pore.It is characterized by good permeability and certain strength.In this study,the encapsulation quality and thickness of cement slurry with single particle and multiple composite particles and the plastic damage of aggregate simulated by software were discussed and studied from the aspects of water cement ratio,particle size and accumulation form.The main research contents and results are as follows:From the aspect of water cement ratio,in the range of 0.26～1,the slurry holding ratio first increases and then decreases,and the optimal slurry wrapping ratio is 0.28;from the aspect of particle size,the particle size mass ratio increases with the decrease of particle size,but the proportion fluctuates due to the irregularity of the surface of recycled aggregate.As for the thickness of cement slurry coating,when the cement ratio is 0.28,the thickness of mud shoulder and waist of ceramsite surface with particle size of 11.3 mm is the same and the distribution of cement slurry at bottom is relatively uniform.Under the same particle size condition,the fold line of mud coating quality in the shoulder of ceramsite distributes more evenly at the cement-water ratio of 0.28.Under this water cement ratio and particle size,aggregates have better workability.From the perspective of composite aggregate space,the liquid bridge with large double spherical aggregate interface existing in the contact or gap between powder and solid or powder particles has the highest slurry holding capacity in the vertical state,followed by the horizontal state under the same water cement ratio.The slurry holdup fluctuated little at 45,60 and 30 degrees.From the analysis of aggregate accumulation form,there are two kinds of aggregate accumulation form in spherical aggregate accumulation form,face-centered cubic accumulation and body-centered cubic accumulation.The compressive strength of face-centered cubic 28 days is better than that of body-centered cubic 28 days under the water-cement ratio of 0.28,0.30 and 0.32 experimental conditions.From the point of view of the compressive strength of recycled aggregate concrete,the water cement ratio has an effect on the compressive strength of recycled aggregate concrete.When the water cement ratio is 0.28,0.32 and 0.36 in the range of 9.5-16 mm,the recycled aggregate concrete has a higher compressive strength when the water cement ratio is 0.32.With the increase of water cement ratio,the strength of recycled concrete increases first and then decreases with the same particle size and cement ratio.ABAQUS software was used to simulate the plastic damage and failure mode of double spherical aggregates under uniaxial compression.It was concluded that the cracking of aggregates was in the weakest position of cement bond at the joint of two aggregates.