Offsetting strength loss in concrete via ITZ enhancement: From the perspective of utilizing new alternative aggregate
Document Type
Article
Publication Date
3-1-2022
Abstract
In this work, the strength and microstructural changes in the interfacial transition zone (ITZ) of four individual concrete mixes containing four different materials (natural aggregate (NA), recycled concrete aggregate (RA), ceramsite (CA), and carbonated steel slag aggregate (SSA)) as 100% coarse aggregate replacement were inves-tigated. The major takeaway from this work is the formation of better quality ITZ due to the use of carbonated SSA, as reflected by the higher microhardness and denser microstructure. The presence of calcite on the outer surface of SSA helps to form monocarbonate and serves as nucleation site for growth of calcium silicate hydrates, enabling a reduction in porosity and calcium hydroxide content by 56% and 80%, respectively compared to the NA concrete. As a result, SSA concrete achieved similar 28-day compressive strength as the NA concrete. This excitingly brings a new insight into how enhancement of the ITZ region could fully compensate the lower intrinsic strength of alternative aggregate used in the concrete.
Keywords
Interfacial transition zone, Artificial aggregates, Microstructure, Microhardness, C -S -H nucleation
Divisions
sch_civ
Funders
National Natural Science Foundation of China (NSFC),52078202,China Hunan Provincial Science & Technology Department "Program for Innovative Talents of Excellent Postdoctoral Fellow",2020RC2031
Publication Title
Cement & Concrete Composites
Volume
127
Publisher
Elsevier Sci Ltd
Publisher Location
THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND