Thermal and Strength Properties of Lightweight Concretes with Variable Porosity Structures

Garbalińska, H.; Strzałkowski, Jarosław

doi:10.1061/(asce)mt.1943-5533.0002549

Cited by 18 publications

(10 citation statements)

References 25 publications

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“…To evaluate the air-void characteristics of the concrete specimens, automated image analysis systems based on a linear traverse method (conforming EN 480-11) were performed, with the use of a RapidAir 457 Automated-Air-Void-Analyzer produced by Germann Instruments A/S, Copenhagen Denmark (Figure 5a). This method can be successfully applied to analyze the air-void characteristics of both normal- and lightweight concretes [21,22,23,24]. Air-voids measured from RapidAir have the size larger than 10 µm, which is the maximum available resolution of the device.…”

Section: Methodsmentioning

confidence: 99%

Influence of Nanosilica on Mechanical Properties, Sorptivity, and Microstructure of Lightweight Concrete

et al. 2019

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This study presents the results of an experimental investigation of the effects of nanosilica (NS) on the strength development, transport properties, thermal conductivity, air-void, and pore characteristics of lightweight aggregate concrete (LWAC), with an oven-dry density <1000 kg/m3. Four types of concrete mixtures, containing 0 wt.%, 1 wt.%, 2 wt.%, and 4 wt.% of NS were prepared. The development of flexural and compressive strengths was determined for up to 90 days of curing. In addition, transport properties and microstructural properties were determined, with the use of RapidAir, mercury intrusion porosimetry (MIP), and scanning electron microscopy (SEM) techniques. The experimental results showed that NS has remarkable effects on the mechanical and transport properties of LWACs, even in small dosages. A significant improvement in strength and a reduction of transport properties, in specimens with an increased NS content, was observed. However, the positive effects of NS were more pronounced when a higher amount was incorporated into the mixtures (>1 wt.%). NS contributed to compaction of the LWAC matrix and a modification of the air-void system, by increasing the amount of solid content and refining the fine pore structure, which translated to a noticeable improvement in mechanical and transport properties. On the other hand, NS decreased the consistency, while increasing the viscosity of the fresh mixture. An increment of superplasticizer (SP), along with a decrement of stabilizer (ST) dosages, are thus required.

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Section: Methodsmentioning

confidence: 99%

Influence of Nanosilica on Mechanical Properties, Sorptivity, and Microstructure of Lightweight Concrete

et al. 2019

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“…The magnitude of these forces is related to the rate of capillary action and this depends on the size of the pores and their structure. The increase in capillary action correlated with the increase of number of pores in the structure, and its dynamics depends on the pore size [ 25 , 26 ].…”

Section: Resultsmentioning

confidence: 99%

The Influence of Incinerated Sewage Sludge as an Aggregate on the Selected Properties of Cement Mortars

2021

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In line with the trend of using waste raw materials in the technology of building materials, experimental studies of cement mortars containing various amounts of fine-grained waste aggregate were carried out. The waste aggregate was based on an incinerated municipal sewage sludge which was mechanically crushed to an appropriate grading. Chemical and physical properties of the waste aggregate are presented. Mortars with varying amounts of waste aggregate as a replacement for natural sand were prepared. Study determines compressive strength and flexural strength up to 56 days. Properties such as capillary action, air content and thermal conductivity were determined. The results of the tests has shown that the incinerated waste sludge can be used as a partial or total replacement for natural aggregate. In mortars with waste aggregate, a favorable relation between flexural and compressive strengths was observed, which translates into increased strength of the interfacial transition zone. A significant increase in water absorption was observed for mortars containing high amounts of waste aggregate, which is directly related to its porous structure. Conducted studied prove that the aggregate obtained from incineration of the municipal sewage sludge can a feasible alternative for natural aggregates in production of masonry and rendering mortars for construction purposes.

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“…This is due to the increased porosity of the cement composites, which significantly depends on the amount of silica aerogel introduced into the structure. The effect of the porosity of aerogel cement composites on their physicomechanical parameters, mainly their compressive strength and thermal conductivity coefficient, has been studied by many researchers [ 68 , 89 , 104 , 105 , 106 ]. According to Shah et al, silica aerogel, in introducing a high degree of hydrophobicity into the structure of the cement matrix, contributes to an increase in the number of macropores, which in turn causes a decrease in the density of the material by 35% and compressive strength by 76% while enhancing the absorbability and water absorption rate of the composite [ 89 ].…”

Section: Composition Mechanical and Insulating Properties Of Cementit...mentioning

confidence: 99%

Research Development in Silica Aerogel Incorporated Cementitious Composites—A Review

2022

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This paper presents an analysis of research results for silica aerogel cement composites over the past twenty years. Recently, two trends in the development of these composites have been noted, towards structural applications and towards ultralight composites for coatings and renders. Ongoing research shows that important aspects of cementitious composites with good mechanical performance are the proper selection of aggregates and improved adhesion at the silica aerogel–cement binder interface, which will guarantee high compressive strength with the lowest possible thermal conductivity. The best physicomechanical performance of aerogel cement composites with low thermal conductivity below 0.03 W/(m·K) was obtained when cenospheres and aerogel were used in a weight percentage of 5%. In turn, the prerequisites for using aerogel cement composites as coatings for energy-efficient building façades are the use of large amounts of silica aerogel as a substitute for lightweight aggregates or the selection of an optimal composition of lightweight aggregates and aerogel, ensuring the lowest possible thermal conductivity coefficient. Other important standpoints are water transport and moisture protection of the silica aerogel-based coatings. Therefore, in recent years, more and more elements of the hygrothermal performance, porosity and durability of silica aerogel cement composites have been developed. The article also points out the weaknesses of the application of silica aerogel in the cement matrix, the most important of which are the lack of adhesion at the boundary of the aerogel–cement binder, the increased porosity of the composite, the high water absorption capacity and the significant decrease in compressive strength with large volumes of silica aerogel. Solving these issues will certainly contribute to the wider applicability of these materials in the construction industry.

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Thermal and Strength Properties of Lightweight Concretes with Variable Porosity Structures

Cited by 18 publications

References 25 publications

Influence of Nanosilica on Mechanical Properties, Sorptivity, and Microstructure of Lightweight Concrete

Influence of Nanosilica on Mechanical Properties, Sorptivity, and Microstructure of Lightweight Concrete

The Influence of Incinerated Sewage Sludge as an Aggregate on the Selected Properties of Cement Mortars

Research Development in Silica Aerogel Incorporated Cementitious Composites—A Review

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