A method for characterizing the self-healing effect of surface cracks of cement-based materials based on the volume of healing products
A technology for cement-based materials and surface cracks, which is applied to the analysis of materials, material inspection products, instruments, etc., can solve the problems of insufficient accuracy, non-representation, heavy workload, etc., and achieves a method with strong directness and good application prospects , significant effect
Active Publication Date: 2020-07-28
TONGJI UNIV
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Problems solved by technology
There are many methods currently used to characterize the self-healing of cement-based materials, such as strength recovery rate, permeability coefficient, and acoustic emission method. Distinguishing the healing effect of superficial and internal fissures
The most effective and direct way to characterize the healing effect of cracked cement-based materials is to measure the surface crack width. However, due to the long surface cracks, it is not representative if only the surface crack width of some areas is tested; otherwise, if Testing the crack width in all areas of the entire crack would be too much work and impractical
Method used
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Embodiment 1
[0052] The mineral admixture for self-healing cracks of cement-based materials in the following examples is composed of expanded mineral components and crystalline mineral components, and the cement composition ratio is shown in Table 1.
[0053] The components listed in each row in Table 1 are mixed together to prepare the cement composition (cement and mineral admixture, cement is P.O.52.5 cement) that the preparation ratio is I-II, and then the water that quality accounts for 30% of the cement composition Add the cement composition of the above-mentioned ratio Ⅰ-Ⅱ and stir, and mold it in a mold of 70mm×70mm×70mm. Part of the samples need to be prefabricated by the insert method during the molding process. The length of the insert is 8cm, and the thickness is 0.5mm, demould after 24 hours, and use a marking pen to mark from one end of the crack every 1cm, a total of 5 marks, and then put it in an environment with a room temperature of 20°C and a humidity of 45-55% for 7 days...
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Abstract
The invention relates to a method used for representing cement based material surface crack self-healing effect based on healed product volume. The method comprises following steps: 1, slice insertingmethod and slice cutting method are adopted for prefabricating of cracks of same cement based material samples, and the cracks of the cement based material samples with prefabricated cracks are labeled; 2, the labeled cement based material samples with prefabricated cracks are immersed into water for curing; 3, after curing, the cement based material samples are taken out from the water, and pictures of the labeled prefabricated cracks which are prepared through slice inserting method and slice cutting method are taken, the surface average healing area of the cement based material sample treated via slice inserting method is extracted, and the average healing depth of the cement based material sample treated via slice cutting method is extracted; and 4, surface crack healing volume is obtained via calculation based on the arithmetic product of the surface average healing area and the average healing depth, and representing of the surface crack self-heating effect of the cement based material is realized. Compared with the prior art, the method possesses following advantages: the substantivity, the accuracy, and the advancement level are high.
Description
technical field [0001] The invention relates to the technical field of building materials, in particular to a method for characterizing the self-healing effect of cracks on the surface of cement-based materials based on the volume of healing products. Background technique [0002] For concrete materials, whether it is a reinforced concrete structure or a concrete member with a large thickness, cracks caused by shrinkage and external loads are inevitable. The existence and continuous expansion of cracks are the reasons for the reduction of the strength of concrete structures. Although some microcracks have little effect on the strength, they will greatly increase the transmission performance of the structure, and can cause harmful substances to aggravate the damage to the structure, such as steel corrosion caused by chloride ions and carbon dioxide. The self-healing system of cement-based materials provides a new method for the repair of micro-cracks in the concrete matrix a...
Claims
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IPC IPC(8): G01N33/38
CPCG01N33/383
Inventor 蒋正武袁政成李俊
Owner TONGJI UNIV