Pareto-Efficient Utilization of Coated Vermiculite Aggregate in High-Strength Lightweight Mortar with Mohr-Coulomb Parameter Analysis.

A multilayered coating process, based on cement and silica fume, was applied to the surface of expanded vermiculite aggregate (EVA) using a cold bonding method. This investigation represents the first systematic study of this multilayered coating method, with the objective of evaluating the effectiveness of coating thickness in the production of high-performance lightweight mortar. In the experimental phase of this study, a range of aggregate replacement levels was examined, and a series of tests were conducted to assess parameters such as dry density, porosity, thermal conductivity, water absorption, sorptivity, compressive strength, flexural strength, and shear strength. The obtained Mohr-Coulomb (MC) constitutive model parameters and shear strength properties were verified numerically. The verification process facilitated the simulation of the three-dimensional (3D) combined behavior of the produced mortar with cement paste, cement-silica fume liner, and EVA. The simulation was conducted using a micro-scale finite element (FE) model based on the Computer Tomography (CT) data. The Pareto-efficient utilization boundaries of coated-EVA in the production of high-strength lightweight mortar are then specified using Response Surface optimization analyses. The present study demonstrates that the cold bonding multilayered coating process is a highly effective aggregate-strengthening method. This study revealed that the Pareto-efficient replacement range of coated-EVA is 24-58%, corresponding to a coating thickness of 0.9-2.6 mm. It is evident that the effective utilization of the replaced aggregate in the mortar production is subject to a limit, which can be determined through Pareto-efficiency analysis, and it is contingent upon the performance requirements of the resulting mortar.