Metakaolin and demolition wastes in eco-based sand consolidated concrete

authors	Lazaar, K; Hajjaji, W; Moussi, B; Rocha, F; Labrincha, J; Jamoussi, F
nationality	International
journal	BOLETIN DE LA SOCIEDAD ESPANOLA DE CERAMICA Y VIDRIO
author keywords	Silica sand; Metakaolin; Demolition materials; Geopolymers; Mechanical properties
keywords	ALUMINA; ALKALI; MORTAR; SILICA; ASH
abstract	This study was undertaken to valorize naturally occurring silica sand in the synthesis of new consolidated concrete materials. The mixtures of silica sand, calcium sulphate, com-mercial metakaolin, demolition materials were designed to propose sulphate and sodium silicate/NaOH activate concretes and geopolymers, respectively. Three raw silica sand sam-ples were collected from various locations in Tunisia. The obtained new materials were characterized by SEM and mechanical properties were investigated. The calcium sulphate-based concretes displayed good technological properties with a compressive strength close to 15 MPa and 40-56% of water adsorption. When, metakaolin and demolition reject were added the mechanical resistance decreased due to the lower pozzolanic properties of these materials. Concerning the geopolymer-based sand concrete, lower compressive strength values were registered. Moreover, by incorporating demolition materials, the mechanical resistance decreased in all consolidated products. The effect of the metakaolin reactivity is more sig-nificant when it is activated with a alkaline solution. However, the sodium silicate/NaOH activation of metakaolin governs the reaction when it is highly reactive. Finally raw silica sand from Tunisia provided good consolidated concrete materials in the presence of calcium sulphate. As well, the silica sand provided good geopolymers in the presence of metakaolin and alkaline solution. Published by Elsevier Espana, S.L.U. on behalf of SECV. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
publisher	ELSEVIER
issn	0366-3175
isbn	2173-0431
year published	2021
volume	60
issue	4
beginning page	229
ending page	242
digital object identifier (doi)	10.1016/j.bsecv.2020.02.004
web of science category	14
subject category	Materials Science, Ceramics
unique article identifier	WOS:000684215000004