Test method for bonding strength of chopped ultrafine organic fiber and cement-based composite interface

Abstract

The invention discloses a test method for bonding strength of chopped ultrafine organic fiber and a cement-based composite interface. The method comprises steps as follows: fiber is bonded on a sample loading cuboid, and a part of the lower end of the fiber is exposed; a mold is prepared, uniformly stirred cement-based materials are poured into the mold and compacted, the surface is flattened, and a cement matrix is obtained; the exposed end of the fiber is perpendicularly inserted into the cement matrix; after the cement matrix is cured to a test age, the sample loading cuboid is removed, and a free end of the fiber is exposed; an instant adhesive is bonded to the free end of the fiber and is congealed to form small balls; the fiber is tested on a monofilament stretching machine, the stretching speed is controlled, the fiber is pulled out of the cement matrix, and a load displacement curve is obtained; the bonding strength of the fiber and the cement-based composite interface is calculated. The exposed length of the fiber is controlled in advance, and the embedded length of the fiber in the cement matrix can be controlled precisely; requirements for the length and the diameter of the fiber are low, and the test method can be used for testing longer and thinner fiber; a tested sample is not required to be cut, and the testing result is more accurate.

Description

technical field [0001] The invention relates to the technical field of cement-based composite materials, in particular to a method for testing the interface bond strength between chopped ultrafine organic fibers and cement-based composite materials. Background technique [0002] Organic fibers mainly include synthetic high-performance fibers such as polyethylene fibers, polyvinyl alcohol fibers, polypropylene fibers, and polyester fibers, as well as natural organic fibers such as cellulose fibers. They can be used to prepare high-performance cement-based composite materials and improve cement-based composite materials. Mechanical properties and durability of materials. The interfacial bonding strength between fiber and cement matrix plays a particularly important role in fiber reinforced cement-based composites, and it is a bridge for the stress transmission of the entire composite. Appropriate interfacial bonding strength can make the performance of cement-based composites...

AI Technical Summary

Problems solved by technology

However, the fiber embedding technology and the preparation method of the specimen have a great influence on the test results of the interface bond strength between the fiber and the cement-based matrix.

[0003] At present, the authorized invention patent (Patent No. 201110404137.X) proposes to use a pneumatic clamping device to fix the free ends of organic fibers, but this method is only suitable for the effective clamping of organic fibers with a diameter greater than 39 μm, and cannot reliably clamp the organic fibers with a diameter of Ultrafine chopped organic fibers from 1 μm to 39 μm; since the free end of the fiber is fixed by the pneumatic clamping device, the verticality of the fiber spindle relative to the surface of the hardened cement paste cannot be adjusted freely, and the test results are highly discrete

The invention patent application (Application No. 201410365725.0) proposes a method of fixing both ends of the fiber, embedding the middle part in the matrix and then cutting, but this method is difficult to operate when the length of the fiber is less than 20mm or the length of the embedded fiber is less than 1mm

Images