Implementation of Alternative Mineral Additives in Low-Emission Sustainable Cement Composites.

Ewa Kapeluszna,Wojciech Szudek,Adam Zieliński,Paweł Wolka

doi:10.3390/ma14216423

Ewa Kapeluszna, Wojciech Szudek + Show 2 more

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https://doi.org/10.3390/ma14216423

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Abstract

The influence of four naturally occurring mineral additives (zeolite, diatomite, trass and bentonite) on the hydration and properties of cement pastes and mortars was investigated. The materials change the phase composition, heat of hydration (determined by calorimetry) and mechanical properties of composites. After 28 days, the amount of Ca(OH)2 was reduced by up to 23% and up to 35% more C-S-H was formed, as proved by TG measurements. Differences were observed in the kinetics of heat release, especially for 25% of the addition. In the calorimetric curves, an additional exothermic effect is observed, related to the alteration in the hydration of C3A in cement. From the point of view of beneficial influence on mechanical properties of mortars, the additives could be ranked as follows: bentonite < diatomite, zeolite < trass after 2 days and bentonite < diatomite < trass < zeolite after 28 days of curing. The highest compressive strength (58.5 MPa) was observed for the sample with a 10% addition of zeolite. Zeolite, trass, bentonite and diatomite are all pozzolanic materials; however, their activity varies to an extent due to the differences in their specific surface area and the content of the amorphous phase, responsible for the pozzolanic reaction.

Highlights

Published research [1,2,3,4] clearly indicates a demand for new supplementary cementitious materials (SCMs) that could be potentially introduced as components of common cements, alongside well-described additives of anthropogenic origin that are currently used in the cement industry–mainly siliceous and calcareous fly ashes (FA), granulated blast furnace slags (GBFS) and finely ground limestone
In order to evaluate the impact of selected mineral additives on the performance of cements, water demand and setting time measurements were carried out on samples in which 10% and 25% of CEM I 42.5R OPC was substituted with zeolite, diatomite, bentonite and trass
The article presents a comparison of alternative mineral additives, relatively rarely used in the cement and concrete industry

Summary

Introduction

Published research [1,2,3,4] clearly indicates a demand for new supplementary cementitious materials (SCMs) that could be potentially introduced as components of common cements, alongside well-described additives of anthropogenic origin that are currently used in the cement industry–mainly siliceous and calcareous fly ashes (FA), granulated blast furnace slags (GBFS) and finely ground limestone. European standards, including EN 206, allow the use of fine-grained mineral additives in concrete in order to improve or obtain certain features of the material. The exact standard requirements are given only for fly ashes (EN 450-1), ground granulated blast furnace slags (EN 15167-1) and silica fume (EN 13263-1). The use of alternative SCMs in concrete technology requires comprehensive research, as there are no official guidelines that would allow a straightforward assessment of their applicability. Recent research is focused on the incorporation of mineral additives in non-standard, innovative concrete applications, such as 3D printing [7,8,9]

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