Predicting mechanical development of mine functional mortar: experiment and thermodynamic analysis

Abstract

Shotcrete mortar is an imperative material for tunnel surface supporting. The mine environment with different temperature affects the mechanical development of mortar, resulting in a difficult to predict its compressive strength development at high temperature. In this investigation, the compressive strength, hydration heat, mineral evolution, pore content of mortar samples at 20 and 60 °C, containing partial steel slag powder, were comprehensively compared by experiment and simulation in order to provide a reliable approach for underground materials compressive strength prediction. Results show that the compressive strength development of the samples cured at 20 and 60 °C, is consisted with the corresponding cumulative hydration heat, and the correlation coefficient is higher than 0.96. The hydrates and heat of the samples are significantly affected by the cement type, mineral admixture, and temperature. Indeed, increasing temperature significantly accelerates the minerals’ hydration and heat release. Combining the composition, pore and single mineral hydration heat simulation, the mortar compressive strength development of the mortar in deep mine can be predicted by a thermodynamic model.