Hydraulic binder obtained from recycled cement and sand powder

Hydraulic binder obtained from recycled cement and sand powder

Abstract Environmentally eco-efficient concrete is currently a popular choice of construction material. Reviewing relevant literature indicates that heating of cement paste can remove hydrating water, and that quartz sand of appropriate granulometry can act as a supplementary cementitious material;...

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Published in:Revista IBRACON de estruturas e materiais Vol. 11; no. 6; pp. 1178 - 1185
Main Authors: MENEZES, R. M. R. O., SILVA, R. M. DA, FIGUEIREDO, E. P., BEZERRA, A. C. DA SILVA, AGUILAR, M. T. P., CETLIN, P. R.
Format: Journal Article
Language:English
Published: IBRACON - Instituto Brasileiro do Concreto 01-12-2018
Instituto Brasileiro do Concreto (IBRACON)
Subjects:
cement microstructure
construction residues
ENGINEERING, CIVIL
sand functionalization
thermal analysis
X-ray diffraction
difração de raios-x
resíduos de construção
cement microstructure
funcionalização de areia
sand functionalization
X-ray diffraction
análise térmica
construction residues
microestrutura
thermal analysis
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Summary:Abstract Environmentally eco-efficient concrete is currently a popular choice of construction material. Reviewing relevant literature indicates that heating of cement paste can remove hydrating water, and that quartz sand of appropriate granulometry can act as a supplementary cementitious material; however, there have been virtually no reports on the reuse of these materials as alternative binders. This work evaluates the phases present in cementitious compounds produced with binders obtained by thermomechanically treating cement pastes with and without a 15% substitution of quartz sand powder (specific surface area 37.4 m²/g), referred to as RCQ and recycled cement RC, respectively. Testing included thermogravimetric analysis (performed with stripped gases), X-ray diffraction, and scanning electron microscopy with phase identification. The obtained data indicated RC cement paste possesses a predominantly ettringite microstructure, whereas the presence of calcium hydroxide and hydrated calcium silicate predominates in RCQ paste. Resumo Atualmente tem-se buscado a obtenção de concretos ecoeficientes por meio da reciclagem dos resíduos de concreto. Estudos da literatura mostram que o aquecimento da pasta pode remover a água de hidratação e que areia quartzosa pode atuar como material cimentício suplementar quando na granulometria adequada. Entretanto, praticamente inexistem relatos sobre reuso desses materiais como aglomerantes alternativos. Este trabalho avalia as fases presentes em compostos cimentícios confeccionados com aglomerante obtido do tratamento termomecânico de pastas com 15% de pó de areia quartzosa (RCQ) e sem substituição (RC) com superfície específica de 37.4 m²/g. Foram realizadas termogravimetrias com análise de gases desprendidos, difração de raios X e microscopia eletrônica de varredura com identificação de fases. Os dados obtidos mostram que a pasta RC possui microestrutura predominante de etringita enquanto na pasta RCQ predomina a presença de hidróxido de cálcio e silicato de cálcio hidratado.
ISSN:1983-4195
1983-4195
DOI:10.1590/s1983-41952018000600003