Physical and mechanical properties of fly ash and slag geopolymer concrete containing different types of micro-encapsulated phase change materials

Pilehvar, Shima; Cao, Vinh Duy; Szczotok, Anna M.; Carmona, Manuel; Valentini, Luca; Lanzón, Marcos; Pamies, Ramón; Kjøniksen, Anna–Lena

doi:10.1016/j.conbuildmat.2018.04.016

Cited by 96 publications

(50 citation statements)

References 29 publications

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“…The addition of PE‐EVA‐PCM to mortars significantly increases the viscosities (Figure 6A,C). This is probably due to the high quantities of water adsorbed onto PE‐EVA‐PCM compared to the sand it replaces 18 . The viscosities of suspensions increase when the solid content becomes higher 51,52,53,54 .…”

Section: Resultsmentioning

confidence: 99%

“…The hydrophobic shell of St‐DVB‐PCM contains styrene (St) and divinylbenzene (DVB) 6 . PE‐EVA‐PCM and St‐DVB‐PCM have been found to adsorb 1.75 and 0.7 grams of water per mL MCPCM, respectively 18 …”

Section: Methodsmentioning

confidence: 99%

“…This is reported to be a combination of several factors: (a) the MPCM particles are softer than to the other solids in the mixture, 16,17 (b) the addition of MPCM causes more air voids to be formed within the matrix, 12,14 and (c) air gaps is formed between MPCM and the surrounding matrix 14,15 . In addition, the workability of concrete becomes poorer with the addition of MPCM due to water adsorbing onto the microcapsules, which decreases the available water in the samples and causes lower slump values 15,18 …”

Section: Introductionmentioning

confidence: 99%

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The effect of microencapsulated phase change materials on the rheology of geopolymer and Portland cement mortars

et al. 2020

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The effect of microencapsulated phase‐change materials (MPCM) on the rheological properties of pre‐set geopolymer and Portland cement mortars was examined. Microcapsules with hydrophilic and hydrophobic shells were compared. The shear rate dependency of the viscosities fitted well to a double Carreau model. The zero shear viscosities are higher for geopolymer mortar, illustrating poorer workability. The time evolution of the viscosities was explored at shear rates of 1 and 10 s−1. New empirical equations were developed to quantify the time‐dependent viscosity changes. The highest shear rate disrupted the buildup of the mortar structures much more than the lower shear rate. Microcapsules with a hydrophobic shell affect the rheological properties much less than the microcapsules with a hydrophilic shell, due to the higher water adsorption onto the hydrophilic microcapsules. Shear forces was found to break down the initial structures within geopolymer mortars more easily than for Portland cement mortars, while the geopolymer reaction products are able to withstand shear forces better than Portland cement hydration products. Initially, the viscosity of geopolymer mortars increases relatively slowly during due to formation of geopolymer precursors; at longer times, there is a steeper viscosity rise caused by the development of a 3D‐geopolymer network. Disruption of agglomerates causes the viscosities of portland cement mortars to decrease during the first few minutes, after which the hydration process (increasing viscosities) competes with shear‐induced disruption of the structures (decreasing viscosities), resulting in a complex viscosity behavior.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The effect of microencapsulated phase change materials on the rheology of geopolymer and Portland cement mortars

et al. 2020

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“…Some authors concluded that the presence of the paraffin waxes reduces the heat of hydration, aggravated when the capsules break during mortars' processing. Adding silica fume or fly ashto improve the hydration process at an early stage or long-termcan help to overcome this problem [12]. It is also important to note that, despite sometimes a significant reduction in mechanical strength, the overall numbers are high enough to allow its use in many structural and non-structural applications [13].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of latent heat storage in mortars containing microencapsulated paraffin waxes – a selection of optimal composition and binders

Lucas

Aguiar

2019

Heat Mass Transfer

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The application of phase change materials (PCMs) in mortars have been extensively researched, however, most studies are focused in one single binder. Conducting comparative assessments using different binders can facilitate the development of compositions with adequate heat storage and suitable mechanical properties. In this work, several PCM-mortars using cement, lime and gypsum as binders, have been studied using a laboratory simulation that mimicked the day/night temperature changes that the material will be subject during service applications. It has been demonstrated that the addition of PCMs in mortars allows the material to retain heat, indicating that these mortars can have a positive impact on the overall energy demand of buildings. There is a combined effect of delay and lowering of temperature peaks, triggered by the heat released from the capsules. The cells with PCMs showed not only a smaller temperature gradient between night and day, but it also exhibited lower peaks. The tests conducted with this laboratory setup prove that PCMs can be successfully mixed into mortars without compromising its durability, hence their applicability as wall renderings.

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“…Active compounds, inorganic material or organic material can be microencapsulated using chemical, physicochemical, or mechanical methods [2]. These core-shell structure particles exhibit significant physical changes in response to environmental stimuli such as temperature [3], pH [4,5,6,7], light irradiation [8], electric [9], magnetic fields [10], redox [11] and mechanical stress [12]. Microcapsules are tiny core-shell particles with large surface area and inner volume, which can develop environment-responsive sensitive and rapid stimuli in response.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Properties of Self-Assembly Graphene Microcapsules: Effect of the pH Value

Guo

et al. 2019

Nanomaterials

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Graphene has attracted attention in the material field of functional microcapsules because of its excellent characteristics. The content and state of graphene in shells are critical for the properties of microcapsules, which are greatly affected by the charge adsorption equilibrium. The aim of this work was to investigate the effect of pH value on the microstructure and properties of self-assembly graphene microcapsules in regard to chemical engineering. Microcapsule samples were prepared containing liquid paraffin by a self-assembly polymerization method with graphene/organic hybrid shells. The morphology, average size and shell thickness parameters were investigated for five microcapsule samples fabricated under pH values of 3, 4, 5, 6 and 7. The existence and state of graphene in dry microcapsule samples were analyzed by using methods of scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). Fourier Transform Infrared Spectoscopy (FT-IR) and Energy Dispersive Spectrometer (EDS) were applied to analyze the graphene content in shells. These results proved that graphene had existed in shells and the pH values greatly influenced the graphene deposition on shells. It was found that the microcapsule sample fabricated under pH = 5 experienced the largest graphene deposited on shells with the help of macromolecules entanglement and electrostatic adherence. This microcapsules sample had enhanced thermal stability and larger thermal conductivity because of additional graphene in shells. Nanoindentation tests showed this sample had the capability of deforming resistance under pressure coming from the composite structure of graphene/polymer structure. Moreover, more graphene decreased the penetrability of core material out of microcapsule shells.

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Physical and mechanical properties of fly ash and slag geopolymer concrete containing different types of micro-encapsulated phase change materials

Cited by 96 publications

References 29 publications

The effect of microencapsulated phase change materials on the rheology of geopolymer and Portland cement mortars

The effect of microencapsulated phase change materials on the rheology of geopolymer and Portland cement mortars

Evaluation of latent heat storage in mortars containing microencapsulated paraffin waxes – a selection of optimal composition and binders

Microstructure and Properties of Self-Assembly Graphene Microcapsules: Effect of the pH Value

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