Innovative MOS-based fiber cement boards: Effect of kraft pulp mills waste and curing by accelerated carbonation

Author(s)

Azevedo, A. G. S. ; Filomeno, R. ; Goncalves, M. M. ; Faria, P. ; Savastano, H.

• Document type: Journal article
• Source: CONSTRUCTION AND BUILDING MATERIALS; v. 431, p. 18-pg., 2024-05-14.

Abstract

The increasing global waste generated by industrial activities poses significant environmental challenges. Ecowaste management emerges as an economically viable solution for converting, valorizing, and repurposing these byproducts, aligning with circular economy principles, and aiming to reduce greenhouse gas emissions. Construction, known for its unsustainability due to high energy consumption, non-renewable resource utilization, waste generation, and greenhouse gas emissions, particularly from cement production, has led to the exploration of alternative materials. Magnesium oxide (MgO)-based cement, an alternative to Ordinary Portland Cement (OPC), has gained attention, leveraging Brazil 's prominence as a major magnesite producer. This study explores the valorization of waste from kraft pulp mills of the paper industry, specifically lime sludge (LS) and lime slaker grits (grits), to produce magnesium oxysulfate (MOS)-based fiber cement boards. The effect of accelerated carbonation on cementitious composites produced with formulations containing grits and LS was investigated. Replacing 25% of the limestone with grits showed no noticeable differences in the properties of the boards, and MOR values close to 11.17 MPa were obtained. However, the physical -mechanical performance showed a decrease with the use of LS and higher concentrations of grits, associated with Na 2 SO 4 .XH 2 O formation in the system and ITZ structure formed around the aggregated particle, respectively. Carbonation in a saturated atmosphere led to the carbonation of the 5 -1 -7 phase, which was related to the decrease in mechanical strength of the boards after the curing process. The thermal decomposition of the Hydrated Magnesium Carbonates (HMCs) formed during accelerated carbonation corroborated with the changes in the physical properties of the composites, demonstrating that the carbonation products are formed within the voids and pores of the material and contribute to the reduction in water absorption of the boards. (AU)

• FAPESP's process: 21/04780-7 - Study of durability on cementitious composites reinforced with lignocellulosic fibers with MgO and MgSO4 matrices
• Grantee: Adriano Galvão de Souza Azevedo
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 22/07179-5 - Durability evaluation of MOS matrix fiber cement reinforced with lignocellulosic fibers and submitted to accelerated carbonation process
• Grantee: Adriano Galvão de Souza Azevedo
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• FAPESP's process: 14/50948-3 - INCT 2014: advanced eco-efficient technologies in cementitious products
• Grantee: Vanderley Moacyr John
• Support Opportunities: Research Projects - Thematic Grants