Efficiency of Portland-pozzolana cements: Water demand, chemical reactivity and environmental impact

Abrão, P. C. R. A.; Cardoso, F. A.; John, Vanderley M.

doi:10.1016/j.conbuildmat.2020.118546

Cited by 39 publications

(17 citation statements)

References 38 publications

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“…A previous study on Algerian kaolin-based refractories reported a density of 2.75 g/cm 3 [40], while another study reported a density value of 2.95 g/cm 3 for silica-alumina refractories, such as calcined kaolin-based concrete [41]. The density of the refractory waste in this research was consistent with those of previous studies on cement containing SCMs such as acidic slag (2.98 g/cm 3 ), fly ash (3.01 g/cm 3 ), and diatomaceous earth (3.03 g/cm 3 ) [42]. The results of the chemical analysis by X-ray fluorescence spectroscopy are shown in Table I.…”

Section: Resultssupporting

confidence: 89%

Evaluation of the use of silica-alumina refractory waste as a supplementary cementitious material

et al. 2021

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The use of supplementary cementitious materials (SMCs) is one of the three essential factors for the sustainability of the cement industry. To reduce CO 2 emissions, several studies have introduced new methods for the utilization of industrial wastes such as the addition into cementitious materials. The objectives of this study were to chemically and physically characterize refractory ceramic industry waste and determine its viability as an SMC. The pozzolanic characteristics or SMC characteristics of the refractory waste were investigated using standard tests. The results revealed that the refractory waste was mainly composed of Al 2 O 3 and SiO 2 . The mineralogical analysis revealed that the mullite was the major phase of the waste, followed by small amounts of cristobalite and quartz phases. The results of the modified Chapelle test and pozzolanic activity index with lime after 7 days indicated that the waste did not meet the minimum pozzolanicity required by the standard. However, the waste improved the mechanical resistance of the cement specimens containing the waste after 28 days compared with the reference sample, indicating the promising potential of the material for this application. This result indicated that the refractory waste shows a filler type effect, and thus, can be employed as an SCM.

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Section: Resultssupporting

confidence: 89%

Evaluation of the use of silica-alumina refractory waste as a supplementary cementitious material

et al. 2021

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“…The CPV Portland cement (density of 3.1 g mL –1 and specific area of 1.5 m 2 g –1 ) used in this study had the chemical composition shown in Table S1 (Supporting Information) . The MgAl-CO 3 -LDH sample was prepared according to the coprecipitation method as follows: a solution containing Mg(NO 3 ) 2 ·6H 2 O (48 mmol) and Al(NO 3 ) 3 ·9H 2 O (24 mmol) in water (250 mL) was added dropwise, under vigorous stirring, to a solution containing Na 2 CO 3 (73 mmol) in water (1000 mL).…”

Section: Methodsmentioning

confidence: 99%

MgAl-Layered Double Hydroxide Nanoparticles as Smart Nanofillers To Control the Rheological Properties and the Residual Porosity of Cement-Based Materials

Almeida

Santos

Rosa

et al. 2022

ACS Appl. Nano Mater.

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Nanotechnology in building materials has still not been widely explored, despite its great potential in developing a new generation of smart and eco-efficient cementitious materials based on the addition of nanoparticles. In this context, layered double hydroxides (LDH) are a family of anionic clays that can regenerate their nanostructure after thermal decomposition to the corresponding mixed oxides (MO). This memory effect involves the reversible recrystallization of the LDH nanoparticles from nanocrystalline MO in contact with water or anionic solutions. It has shown promise in the immobilization of different anions, such as chloride and carbonate, that could compromise the durability of reinforced concrete. This study proposes the incorporation of nanocrystalline MO in the cementitious matrix to control the rheological properties of the paste and reduce the porosity of the cement because the regeneration of the lamellar nanostructure occurs by the dissolution and reprecipitation of LDH nanoparticles inside the pores formed during the consolidation of the paste. Time-resolved wide-angle X-ray scattering (WAXS) was used to study the mechanism of regeneration of the LDH structure following contact of the MO with the cement pore solution. The results showed that the regeneration of the LDH, which occurs by an aggregative growth of anisotropic nanoparticles, changed the rheological behavior by increasing the elastic modulus (G′) and consequently contributing to the consolidation of the paste, demonstrating the potential of these materials for application in threedimensional (3D) printing. Regarding the pore structure of the hydrated cement, a porosity reduction of up to 20% was observed with the addition of 2.0 wt % of MO. Furthermore, after 28 days of hydration, the specific surface area of the cement was reduced from 60 to 36 m 2 g −1 with the incorporation of 1.0 wt % of MO. The use of LDH nanoparticles as a cement smart nanofiller proved to be advantageous in the kinetic control of cement curing and improvement of the porous structure of the hydrated cement.

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“…Due to the serious environmental problems posed by the production of cement, a series of green supplementary cementitious materials (SCMs) are being studied and developed to partially replace cement and thus decrease environmental pollution [ 5 ]. SCMs can be mainly classified into two categories: natural pozzolanic minerals (such as pozzolana, kaolin or metakaolin, and calcined clay) [ 6 , 7 , 8 ] and industrial by-products [ 9 , 10 , 11 ]. Considering their relatively low cost and the benefits to environmental protection, industrial by-products with high pozzolanic activity and/or hydration capacity, such as steel slag [ 12 ], slag [ 13 , 14 ], fly ash [ 15 , 16 ], and silica fume [ 17 ], are very suitable to be used in the development of cementitious composites as a substitute for cement.…”

Section: Introductionmentioning

confidence: 99%

Effect of Particle Size and Morphology of Siliceous Supplementary Cementitious Material on the Hydration and Autogenous Shrinkage of Blended Cement

Zhao

et al. 2023

Materials

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Supplementary cementitious material (SCM) plays an important role in blended cement, and the effect of the particle size and morphology of siliceous supplementary cementitious material on hydration should not be ignored. In this study, 0.5 h and 1 h of wet grinding was applied to pretreat iron ore tailing powder (TP), and the divergence in pozzolanic behavior and morphology were investigated. Then, the treated TPs were used to replace the 30% cement contents in preparing blended cementitious paste, and the impact mechanism of morphology on performance was studied emphatically. M, the autogenous shrinkages of pastes were tested. Finally, hydration reaction kinetics was carried out to explore the hydration behavior, while X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were used to characterize the hydration product properties, respectively. Meanwhile, microscopy intrusion porosimetry (MIP) was also carried out to characterize the pore structures of hardened specimens. Results indicated that wet grinding has a dramatic effect on particle size and morphology, but hardly affects the phase assemblages and pozzolanic reactivity of TP, while the particle shape of TP changes from sub-circular to clavate and, finally, back to sub-circular. The results of hydration reaction kinetics, representing the morphology of particles, had a significant effect on hydration rate and total heat, and compared with the sub-circle one, the clavated particle could inhibit the hydration procedure. With the increasing grinding time, the compressive strength of cementitious paste was increased from 17.37% to 55.73%, and the micro-pore structure became denser; however, the autogenous shrinkage increased.

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Efficiency of Portland-pozzolana cements: Water demand, chemical reactivity and environmental impact

Cited by 39 publications

References 38 publications

Evaluation of the use of silica-alumina refractory waste as a supplementary cementitious material

Evaluation of the use of silica-alumina refractory waste as a supplementary cementitious material

MgAl-Layered Double Hydroxide Nanoparticles as Smart Nanofillers To Control the Rheological Properties and the Residual Porosity of Cement-Based Materials

Effect of Particle Size and Morphology of Siliceous Supplementary Cementitious Material on the Hydration and Autogenous Shrinkage of Blended Cement

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