The effect of curing temperature on hardening, thermal, and mechanical characteristics of adhesive for retard‐bonded prestressed tendon

Abstract

The effect of curing temperature on hardening, thermal, and mechanical characteristics of adhesive for retard‐bonded prestressed systems is investigated in detail. To evaluate the degree of hardening of the adhesive, the cone penetration and Shore hardness of two samples are tested throughout the curing process under conditions of 25, 35, 45, 55, and 65°C. The thermal performance and curing reaction are characterized using differential scanning calorimetry and Fourier transform infrared spectroscopy, respectively. The mechanical properties with respect to the cure temperatures are characterized by compression strength tests. Experimental results present that after curing under conditions ranging from 25 to 65°C, the hardness of the samples reached its maximum values (85–90 D). As the temperature increased from 25 to 65°C, there was a greater degree of curing cross‐linking, resulting in an increase in compressive strength from 55 to 72 MPa. Based on Shore hardness–time experimental data, a logarithmic model is proposed for predicting the hardness of adhesives at any given time for engineering applications. Additionally, the time–temperature superposition principle is utilized to extrapolate the curing time of the adhesive under low‐temperature conditions. The research findings are of significant importance for the assessment of adhesive hardening.