The effects of pre-compress on the mortar/concrete bond and their in-situ compressive strength using “pull-off” and “twist-off” methods

International Journal of Advanced Structural Engineering

مقاله 4، دوره 12، شماره 1، خرداد 2022، صفحه 571-589   

نوع مقاله: Original Article

شناسه دیجیتال (DOI): 10.1007/ijase.2022.692297

نویسندگان

Ali Saberi Varzaneh^{* 1}؛ Mahmood Naderi²

¹Ph.D, Department of Civil Engineering, Imam Khomeini International University, Qazvin, Iran

²Professor, Department of Civil Engineering, Imam Khomeini International University, Qazvin, Iran.

چکیده

The paper aimed to quantify the compressive strength of cementitious materials using in-situ “pull-off” and “twist-off” tests. Apart from determining the correlation coefficient, calibration plots and equations are presented to convert the results of in-situ tests to mortar compressive strength. The crack distribution was calculated in the tests using the nonlinear ABAQUS software. Additionally, the methods mentioned above were used to investigate the effect of pre-compression on mortar/concrete shear and tensile adhesion strength. Thus, the effect of pre-compression on the tensile and shear adhesion strength of mortar/substrate concrete was investigated using the scanning electron microscopy (SEM) method and physical adsorption theory. The results indicated that pre-compression positively affected adhesion and could be measured using the simple twist-off machine instead of the other machine. By applying 0.1 kg/cm2 of pre-compress, the tensile and shear adhesion between the mortar and concrete layers increased by 5.8% and 8.8%, respectively, after 90 days. Additionally, a linear relationship between the results of “twist-off” and “pull-off” tests and those obtained from experimental tests was observed.

کلیدواژه‌ها

Mortar؛ Pre-compress؛ adhesion؛ Twist off؛ Pull off