Abstract: will contain repair agent material such as polyurethane and acrylic ester of hollow glass fiber embedded in cement mortar matrix, intelligent bionic self-healing system is formed within the cement mortar, mortar cracking hollow glass fiber fracture, after the repair agent into the matrix, microfracture and repair injury healing matrix interface. Use INSTRON testing machine and acoustic emission instrument, respectively, to test the strength of mortar heals and quality. The results show that the slurry of healing effect is obvious, and has a certain improved fracture toughness.
Key words: self-healing concrete; The intensity of reply; Acoustic emission; Fracture toughness
Concrete materials in use and under the influence of the environment, will inevitably produce local cracking and damage, the macroscopic damage of concrete can be found by hand to repair to the naked eye. In addition, ultrasonic and radiography nondestructive testing technology to detect internal injury is very effective. But because of the limitations of these technologies, it is not available for microscopic damage detection, such as micro cracks and microscopic damage repair is even more difficult. These microscopic damage if not timely repair, not only affect the normal use of structure, shorten the service life, but also may the resulting macroscopic fracture and brittle fracture, resulting in a serious disaster [1, 2]. In the past the repair of concrete material form mainly after the repair and maintenance regularly, as modern multi-functional and intelligent building is more and more high to the requirement of concrete material, already can not adapt to repair this way. The work mechanism of bionic self-healing concrete is imitation of biological tissue is able to automatically produce certain substances have function of healing the wounded parts through special component in the concrete composite (e.g., hollow fiber containing binder), form a kind of intelligent bionic self-healing neural network system, can think, bionic self-healing concrete is a kind of intelligent bionic materials [3].
1 experimental apparatus and methods
This study use the materials such as polyurethane and acrylic ester as the repair agent, buried them into hollow glass fiber and 40 mm x 40 mm x 160 mm of cement mortar specimen, hollow glass fiber diameter 2 mm, wall thickness of 0.5 mm, 160 mm long, its embedded location is shown in figure 1. Water-cement ratio of mortar specimens is 0.44, contrast ratio is 1:2.5, the age of 28 d. Specimen in three point bending test NSTRON8501 universal testing machine (figure 1), through the midspan deflection control for sample loading, loading speed is 0.025 mm/min. Under certain load mortar matrix micro cracks, leading to repair fiber fracture, releasing the repair agent infiltration within the matrix. The specimen and then continue to be returned to the curing room maintenance (20 ° C at room temperature, relative humidity 100%), until the repair for three point bending test again after curing agent. The bending test at the same time, using acoustic emission technology to test the specimen failure process, the test method as shown in reference [4] 

2 the result of the experiment and analysis
2.1 since the healing the strength of the cement mortar
Figure 2 for repairing agent containing two kinds of mortar specimens before and after the repair of the load deflection curve. Calculated according to the strength of the bearing capacity of the specimens before and after the repair status response rates, the results are shown in table 1. Among them, using acrylic ester repair repair agent, high strength of specimens after repair, polyurethane. And, the repaired specimens compared with before the repair, rather than falling on its strength, and slightly increases, this is because the specimen cracking after the loaded area to reduce, the bearing capacity drops, and after repair agent into the specimen of microfracture, just repaired the cracks, so strength increased slightly.
2.2 the self-healing toughness of cement mortar
By load - deflection curve is shown in figure 2, before the repair material is brittle. After repair agent repair, brittleness improved. Among them the acrylate repair specimen brittleness improvement effect is bigger, specimen fracture can be significantly increased; After polyurethane fixing the load deflection curve of the specimen, the decline is not acrylate is slow, but than not repair the specimen, its toughness has been greatly improved. In addition, in a large number of experiments on cement mortar fracture observation, the author found that the fracture healing of the cement mortar interface bonding too bad and too strong on fracture toughness of material adverse, only when moderate interface bonding, its fracture toughness is optimal. The interface bonding is too strong, the crack will be directly extended from the matrix, the load deflection curve shape will become sharp and steep, and formation of brittle fracture; Poor interfacial bonding, because of the fracture energy is not enough to absorb, will lead to the complete debonding interface, cannot have the effect of healing. So only moderate interface bonding, allowing interface has certain debonding, will produce the optimal fracture toughness, therefore, self-healing concrete interface control design, the improvement of the fracture toughness of concrete is very important.