Mechanical and durability performance of ultra-high-performance concrete incorporating SCMs

Abstract

Production of ultra-high performance concrete (UHPC) requires a high volume of micro silica (MS), called silica fume, that accounts for around 20% to 40% by weight of cement. Using large quantity of MS can impede the use of UHPC in the market due to its high cost and limited resources. This paper evaluates the possibility of producing sustainable UHPC utilizing Supplementary cementitious materials (SCMs) such as Metakaolin (MK), Fly Ash (FA) and Natural Pozzolan (NP) as a partial replacement of MS. The mechanical characteristics such as compressive strength, flexural strength, and fracture toughness and durability performance such as chloride penetrability, water permeability, drying shrinkage, water absorption, electrical resistivity and sulfate resistance were investigated. The results exhibited that a partial replacement of MS with 60% NP, 60% FA and 40% of MK contributed the paramount UHPC mixtures, with satisfactory strength and flowability requirements. The outcomes indicate that the increase in ultra-fine dosages decreases the flowability and increases the strength, as the finer particles perform as a filler between the cement and coarser grains. The UHPC specimens containing FA provided the worthiest results in comparison to other specimens. This study outcome also indicated that the SCMs can be used to develop UHPC with significant improvements in the mechanical and durability performance in comparison with conventional UHPC.