Supercritical carbonation treatment on extruded fibre–cement reinforced with vegetable fibres

Santos, S.F.; Schmidt, René; Almeida, A. E. F. S.; Tonoli, Gustavo Henrique Denzin; Savastano, Holmer

doi:10.1016/j.cemconcomp.2014.11.007

Cited by 93 publications

(117 citation statements)

References 38 publications

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“…The morphology and distribution of the hydration products formed during the carbonation curing, hardening, and secondary hydration of cement (dominated by AFm, AFt, and other minority phase)-based composites cannot yet be controlled with the same precision as for metals and other engineered materials, but the better understanding may permit new strategies for predicting the evolution of microstructure and properties, and ultimately engineering microstructure and overall performance. Additionally, there is still a lack of information about the changes promoted by the carbonation at early ages and after the exposition to accelerated aging cycles on the mineralogical phase composition at the transition zone of cellulose fibers and microstructure of the fiber-cement composites [24]. The objective of this work was to analyze the evolution of the fiber to matrix interface and chemical and dimension stability promoted by the use of carbonation at early ages and after accelerated aging of fiber-cement composites.…”

Section: Introductionmentioning

confidence: 99%

Rationalizing the impact of aging on fiber–matrix interface and stability of cement-based composites submitted to carbonation at early ages

et al. 2016

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The objective of this work is to show the effect of carbonation at early stages on fiber-cement composites and impact on hydration, chemical and dimension stability. Carbonation increased the content of CaCO 3 polymorphs and consumed Ca(OH) 2 and other hydrated calcium phases. Micrographs and energydispersive spectrometry showed the CaCO 3 formed is precipitated in the pore structure of the matrix, decreasing diffusion of Si, S, and Al during hydration. Therefore, a refining process of pore sizes is produced, and fiber-matrix interface in carbonated composites was improved, leading to volume stabilization of the composite, as indicated by lower drying shrinkage and lower porosity.

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Section: Introductionmentioning

confidence: 99%

Rationalizing the impact of aging on fiber–matrix interface and stability of cement-based composites submitted to carbonation at early ages

et al. 2016

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“…The authors also evaluated the effects of accelerated carbonation in fiber-cement reinforced with cellulosic pulps at the initial ages of hydration, after 200 and 400 soak and dry cycles, and after one year of natural aging. According to the authors, the fiber-cement showed a significant decrease in Ca(OH) 2 and a significant increase in CaCO 3 and, consequently, low porosity, high density, good fiber-matrix interface and good mechanical performance, according to Santos et al [28] investigated the effects of supercritical carbonation on extruded fiber-cement reinforced with lignocellulosic fibers (eucalyptus bleached pulp and sisal fibers) after three days of curing. The cure with supercritical carbonation at early ages involves a different chemical kinetics of conventional accelerated carbonation using CO 2 gas, because it uses 100% of liquid CO 2 .…”

Section: Accelerated Carbonation Curingmentioning

confidence: 99%

“…The main objective of fiber-cement curing thru accelerated carbonation is to minimize the degradation of lignocellulosic fibers in cement matrix and to maintain CMSS-2017 mechanical performance of composites when they are under aggressive weather conditions [26]- [28].…”

Section: Accelerated Carbonation Curingmentioning

confidence: 99%

Vegetable fiber as reinforcing elements for cement based composite in housing applications – a Brazilian experience

Santos

Savastano

2018

MATEC Web Conf.

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Vegetable fibers are a hierarchical structure material in the macro, micro and nanometric scales that have been used as reinforcement in cementitious materials. In nanoscale, the nanofibrillated cellulose has the advantage of having good mechanical performance and high specific surface, which contributes to improve the adhesion between fiber and matrix. In hybrid reinforcement, with micro and nanofibers, nanofibrillated cellulose forms bonding with the matrix and acts as stress transfer bridges in the nano-cracking with corresponding strengthening of the cementitious composite. Processing has a strong influence on performance of the fiber cement composite. Two fabrication methods were evaluated: (i) slurry dewatering followed by pressing and (ii) extrusion. The extrusion process strongly depends on the rheological characteristics of the fresh cement material but it can better organize the microstructure of the fiber cement due to the partial orientation of the fibers in the extruder direction. Curing process also plays a key role in the performance of the final product. Accelerated carbonation at early age is a promising technology and a strategy to mitigate the durability problems with the composite materials; it decreases porosity, promotes a higher density in the interface guarantying a good fiber-matrix adhesion and a better mechanical behavior. Alternative MgO-SiO2 clinker free binder is also presented as a suitable alternative to cementitious products reinforced with cellulosic pulps. Finally, mechanical behavior of fiber cement under flexural loading is evaluated by modulus of rupture, fracture toughness, the initial crack growth resistance in cement matrix, and fracture energy that is obtained to evaluate the influence of toughening mechanisms promoted by fibers, such as pullout and bridging, on the mechanical performance of the composites. Degradation during the service life is also crucial for the evaluation of the durability of the resulting materials and components in real applications exposed to different environmental conditions as roofing, partitioning or ceiling elements. It can be concluded that more sustainable and high performance components based on engineered natural raw materials for civil construction can bring valuable contributions for the affordable housing in particular to developing region.

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“…Even with such a short curing time, the carbonated products exhibited a good fiber-matrix bonding, improved mechanical properties with a reduction of composite degradation. Santos et al [16] studied the supercritical carbonation of extruded fiber-cement reinforced with bleached eucalyptus pulp and residual sisal chopped fibers, with specimens placed in a chamber with total saturation (close to 100% concentration) of supercritical CO 2 at 20 MPa with the chamber immersed in water at 45 • C. The results showed that the supercritical carbonation treatment for only 2 h could significantly improve the physical characteristics and mechanical performance.…”

Section: Introductionmentioning

confidence: 99%

Early Age Carbonation of Fiber-Cement Composites under Real Processing Conditions: A Parametric Investigation

et al. 2018

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This paper presents the outcome of a comprehensive experimental program undertaken to study the performance of cellulose pulp and synthetic PVA (polyvinyl alcohol) based fiber-cement composite under both carbonated and non-carbonated curing conditions at early age. The composites were produced at different rolling pressures (2.5 to 9.0 bar) and subjected to various curing conditions in which the effects of CO 2 pressure (1 to 3 bar) and curing time (3 to 9 h) were studied. The mechanical properties (modulus of elasticity (MOE), modulus of rupture (MOR), and toughness), as well as the physical properties (porosity, bulk density, and water absorption), were measured for all samples. Scanning electron microscopy (SEM) was used to investigate the effect of carbonation on porosity change and adhesion of fiber-matrix. A parametric investigation of the effects of the carbonation curing period, CO 2 pressure, and rolling pressure on the improvement of the physical and mechanical properties during carbonation curing was performed. Results showed that fiber-cement composites cured with an elevated CO 2 pressure of 3 bar, rolling pressure of 3 bar, and 5 h of curing time provided optimal curing conditions resulting in the most desirable mechanical and physical properties. However, toughness was greatly reduced with the increase of the CO 2 pressure, curing time, and rolling pressure. Additionally, the carbonation curing improved the bonding between the fiber and the cement matrix because of the precipitation of calcite particularly in the pores of the interfacial transition zone (ITZ) between the cement matrix and the fibers.

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Supercritical carbonation treatment on extruded fibre–cement reinforced with vegetable fibres

Cited by 93 publications

References 38 publications

Rationalizing the impact of aging on fiber–matrix interface and stability of cement-based composites submitted to carbonation at early ages

Rationalizing the impact of aging on fiber–matrix interface and stability of cement-based composites submitted to carbonation at early ages

Vegetable fiber as reinforcing elements for cement based composite in housing applications – a Brazilian experience

Early Age Carbonation of Fiber-Cement Composites under Real Processing Conditions: A Parametric Investigation

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