Preparation Of Microencapsulated Self-healing Concrete And Study On Self-healing And Mechanical Properties

As people pay more attention to the durability of concrete,the related durability improvement technology has become more and more rich and targeted.Studies have shown that the self-healing behavior of concrete can often enhance the durability of concrete.Therefore,the idea of reducing the maintenance cost and increasing the life of concrete structures through research on self-healing concrete has been increasingly proposed.In this paper,with the support of the National Natural Science Foundation project "Research on the Durability Improvement Technology and Design Theory of Marine Prestressed Concrete Structures(51778272)",a selfhealing concrete with micro-capsules that has expansion and adhesion effect on concrete cracks was developed.The basic physical properties and strength recovery,acoustic performance recovery and chloride ion permeability recovery were studied,and combined with microscopic analysis methods,the repair mechanism of the microcapsule self-healing system was revealed.The main contents are as follows:(1)Sodium silicate and expanded portland cement were selected as the self-healing components of the self-healing microcapsules in this paper,and the self-healing microcapsules with different proportions were prepared by squeeze spray method.It is characterized by microanalysis method to explore whether the self-repairing microcapsules have the preconditions to satisfy the basic mechanism of microcapsule self-repairing concrete.(2)The self-healing microcapsules and the three curing agents selected in the experiment are mixed into the cement mortar material in proportion to explore the effect of the microcapsules on the basic physical properties of the cement mortar material.Subsequently,the completely damaged specimen is repaired,and the strength repair rate of the self-healing cement mortar material is obtained by secondary compression,in order to verify the effectiveness of the self-healing microcapsules under the strength recovery index,and at the same time select.The best curing agent,and obtain a reasonable dosage range of microcapsule materials.(3)Using the orthogonal test method,a set of three-factor and three-level orthogonal tests are designed for different degrees of damage.The basic compressive strength,strength recovery after 30 days of repair and ultrasonic sound velocity recovery are used as indicators,combined with analysis of variance.The significance of these three factors is the best combination of factors under this factor.The SEM and EDS analysis of the concrete samples before and after the damage repair were carried out to discuss the repair mechanism.(4)Select the mix ratio of microcapsule self-healing concrete under the best combination of factors,use the recovery of chloride ion permeability coefficient and load-displacement curve as the self-healing evaluation index,and carry out the repair performance for different crack widths and different repair time Experimental research.Based on the test data and the image,the width of the crack that caused the failure of the microcapsule self-healing concrete system and effect of repair time on recovery effect.