Optimal Loading Rate Design Method for Cement Stone Mechanical Test

Abstract

The loading rate has a significant influence on the mechanical parameters tests of cement stone, which lacks systematic research. There are no corresponding optimal loading rates for different types of cement stones. In this work, the uniaxial compressive strength tests with different loading rates under force loading and displacement loading were carried out for typical cement stones with low, normal, and high density. Seven rate points were designed in the range of static and quasi-static loading rates. Statistical analysis of the test data showed the following. First, the Poisson’s ratio of some cement stones increases with the increase of the loading rate and some decrease. The value of Poisson’s ratio does not change much under the two loading modes. However, Poisson’s ratio shows a certain regularity with density; the higher the density, the greater the Poisson’s ratio. Second, the compressive strength and Young’s modulus show an upward trend with the increase of loading rate. The compressive strength correlates best with the optimal loading rate. In the force loading mode, the optimal loading rate increases linearly with the increase of the compressive strength, and its value can be determined by the established comparison table or calculation formula. In the displacement loading mode, the optimal loading rate is 0.35 mm/min for cement stones with strength values below 15 MPa and 0.7 mm/min for those above 15 MPa. The findings can provide a basis for designing mechanical testing methods for cement stones.

Analytical Perspectives on Cement Sheath Integrity: A Comprehensive Review of Theoretical Research

“…The stress–strain curves of uniaxial and triaxial tests for cement stone are depicted in the Figure . Cement stone specimens are either cubic with a side length of 50 mm or cylindrical with a height-to-diameter ratio ranging from 1.8 to 2.2. , Cement stone exhibits brittle behavior under unconfined conditions. , When stressed below the yield strength, approximately 0.7 times the compressive strength, cement stone undergoes elastic deformation, fully recovering after unloading, resulting in an approximately linear stress–strain curve. However, when stresses exceed the yield strength, the stress–strain curve deviates from linearity, exhibiting nonlinear characteristics.…”

“…56 , 57 Cement stone exhibits brittle behavior under unconfined conditions. 58 , 59 When stressed below the yield strength, approximately 0.7 times the compressive strength, cement stone undergoes elastic deformation, fully recovering after unloading, resulting in an approximately linear stress–strain curve. However, when stresses exceed the yield strength, the stress–strain curve deviates from linearity, exhibiting nonlinear characteristics.…”