Method for testing shrinkage cracking performance of cement paste or mortar

Abstract

The invention relates to a method for testing the shrinkage cracking performance of a cement paste or a mortar. A molded test piece of a novel mold is adopted to carry out the cracking test to test the shrinkage cracking performance of the cement paste or the mortar. The mold comprises a pedestal, an outer mold and a steel cylinder; the steel cylinder is fixed on the pedestal; the outer mold is movably connected with the pedestal; and the outer mold is square, the steel cylinder is in the outer mold, and the steel cylinder which is not in the center of the square is in a unidirectional eccentric position. The ratio of the diameter of the steel cylinder to the inner side length of the outer mold, i, satisfies a case that i is greater than 0.5 and less than 1; and heights of the steel cylinder and the outer mold satisfy a case that the thickness of the molded test piece is equal to or greater than 5 times the largest particle size used in the test. The selection of the eccentric position of the steel cylinder is determined through carrying out finite element analysis on the molded test piece by ANSYS software. According to the invention, the cracking position can be foreseen, the test piece cracking can be accelerated, and the cracking can start from the outer interface.

Description

technical field [0001] The invention belongs to the technical fields of building materials and civil engineering, and in particular relates to a method for testing the shrinkage and cracking performance of cement paste or mortar. Background technique [0002] Cement paste or mortar is an indispensable building material in the field of construction engineering. Its superior engineering performance has been unanimously recognized by the industry. In 2010, my country's cement output reached 1.868 billion tons, more than 1 / 2 of the world's total cement output. According to the forecast of industry experts, the next 20 years will be the fastest 20 years of urbanization in China. China will become one of the countries with the largest application of commercial mortar in the world. When cement paste or mortar is used in engineering practice on a large scale, a difficult problem occurs—cracking of cement paste or mortar. Once the cement paste or mortar material cracks, it will n...

AI Technical Summary

Problems solved by technology

However, the ring method has the following three shortcomings: (1) The stress distribution on any radial plane is exactly the same, so that in the ring test, the cracking position of the ring specimen cannot be predicted in advance; (2) The cracking time is too long , the sensitivity is poor, and the test period is long; (3) The theoretical analysis of the ring test piece shows that the cracking of the ring test piece starts from the inner interface, which will be affected by the manufacturing error of the ring and uneven oiling

Images