Experimental and mechanism study on the impermeability and thermal insulation of foam concrete regulated by nano-silica and fluorine-free foam

Jia, Hailin; Cui, Bo; Niu, Guoqing; Chen, Jie; Yang, Y.B.; Wang, Qingyin; Tang, Chenhui

doi:10.1016/j.jobe.2022.105675

Cited by 4 publications

(6 citation statements)

References 42 publications

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“…The thermal conductivity performance with respect to the water–cement ratio is illustrated in Figure 2 d. It can be observed that the thermal conductivity of the samples shows a significant increase in the range of the water–cement ratio from 0.4 to 0.6, followed by a fluctuating trend within a certain range. Considering that the thermal conductivity of foam concrete is influenced not only by the air content within the material [ 19 , 39 ] but also to a large extent by the pore structure [ 40 , 41 ], the following inference can be drawn: within the range where the water–cement ratio is below 0.6, the variation in air content inside the samples is apparent. In this process, the dominant effect of air content on thermal conductivity results in an increasing trend with the rising water–cement ratio.…”

Section: Resultsmentioning

confidence: 99%

Effects of Mixing Techniques and Material Compositions on the Compressive Strength and Thermal Conductivity of Ultra-Lightweight Foam Concrete

Xu,

Garrecht

2024

Materials

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The research focuses on ultra-lightweight foam concrete with a dry density below 200 kg/m3, primarily used as insulation material. Factors that may affect material properties are categorized into mixing techniques and material composition, and experimental investigations were conducted on the impact of these factors on the rheological properties of cement slurry, density at different time intervals, compressive strength, and thermal conductivity of foam concrete samples. The experimental results indicate the influence of mixing speed and mixing duration on the instrument during the cement slurry production and mixing process with foam. Additionally, variations in foam concrete sample properties are observed due to the water-to-cement ratio, foam content, and foam density in the selected material compositions. By analyzing the material density at different time intervals, the relationship between the ambient air trapped during the mixing process and the viscosity of the material can be indirectly observed. This analysis can also reveal the correlation between the unplanned air content and the properties of the material.

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Section: Resultsmentioning

confidence: 99%

Effects of Mixing Techniques and Material Compositions on the Compressive Strength and Thermal Conductivity of Ultra-Lightweight Foam Concrete

Xu,

Garrecht

2024

Materials

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“…Notwithstanding, all the thermal conductivity values after the 200 • C thermal treatment were above 0.3 W/mK, the required value indicated in the literature for high-temperature concrete [46,47]. According to the following equation, dQ/dt = −kA dT/dt, thermal conductivity (k) is the most important physical property, which guarantees a rapid and complete charge/discharge cycle of a thermal storage unit [43][44][45][46][47][48][49]. A cement paste for plaster could preferably be used for improving the comfort of a building, reducing energy consumption through a heat-storing element for passive solar heating.…”

Section: Thermal Measurementsmentioning

confidence: 99%

Cement Pastes with Hygroscopic Polymeric Additions for Potential Building Applications

Di Maggio,

Maracchini,

Cotini

et al. 2024

Applied Sciences

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The development of highly predictive analysis for designing cementitious composite with improved thermal and hygroscopic performance for building and construction poses a significant challenge. To investigate new potential applications, cement pastes have been prepared using a cement, sand, and crystallization admixture, with highly hygroscopic polymer additions (SA-PA) of sodium polyacrylate and/or recycled polyamide fibers. The porosity evolution was investigated at different curing stages and after heat treatment at 200 °C, the temperature at which the paste dehydrates quickly without structural changes. Mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), cyclic shear tests, thermal conductivity, and diffusivity measurements were carried out on the cement pastes to assess their microstructure. The behavior of the cement pastes varied with polymer additions and thermal treatments; ka−0.5 must be maximized in heat storage applications, where a and k are thermal diffusivity and conductivity, respectively. In contrast, the product a0.5k−1 must be maximized in energy-efficient insulation. Cement pastes with SA-PA exhibited the highest values of both 9.191 102 m−2 K−1 s0.5 W and 1.088 10−3 m2 K s−0.5 W−1, respectively. After the thermal treatment at 200 °C, SA-PA samples maintained the highest heat-storing performance of 6.258 102 m−2 K−1 s0.5 W, while the samples with SA-PA and polyamide fibers performed better in energy-efficient insulation, demonstrating performance of 2.552 10−3 m2 K s−0.5 W−1. These results, discussed in terms of pore size distribution, suggest potential applications in the building field and are valuable for designing plaster and concrete for applications such as thermal and hygroscopic control.

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“…Figure 1 shows a diagram that summarises the mechanism by which nanoparticles improve the durability of concrete. Several scanning electron microscopic (SEM) images from different studies presented a denser, homogeneous, and more uniform microstructure of nano-modified concrete [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 ]. The interfacial transition zone (ITZ) was also improved with the addition of nanoparticles owing to their microaggregate filling effect [ 49 , 50 ].…”

Section: Microstructure Of Concrete and C-s-h Gel Hydration With Nano...mentioning

confidence: 99%

“…Furthermore, using the SEM images, it was observed that the microstructure of nanomodified concrete exhibited a lower amount of CH, gypsum, and ettringite needle crystals, in addition to a denser and more homogenous structure. X-ray diffraction (XRD) tests on nanoconcrete were performed and published in several research articles [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 ]. All the test results indicated a higher intensity of the C-S-H gel peak and a lower intensity of CH for concrete in the presence of nanomaterials.…”

Section: Microstructure Of Concrete and C-s-h Gel Hydration With Nano...mentioning

confidence: 99%

“…Some nanoparticles can provide nucleation sites owing to their super fineness, thus accelerating the precipitation and formation of C-S-H gel. Owing to the high efficiency of nanomaterials in improving the mechanical properties of cementitious materials, the applications of nanoparticles were broadened to include ultra-high performance concrete [ 13 ], self-compacted concrete [ 19 ], reactive powder concrete [ 20 ], heavyweight concrete [ 21 ], marine concrete [ 22 ], shotcrete [ 23 ], green concrete [ 24 ], recycled aggregate concrete [ 25 ], lightweight concrete [ 26 ], high-volume fly ash concrete [ 27 ], carbon fibre-reinforced concrete [ 28 ], and foam concrete [ 29 ].…”

Section: Introductionmentioning

confidence: 99%

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An Elucidative Review of the Nanomaterial Effect on the Durability and Calcium-Silicate-Hydrate (C-S-H) Gel Development of Concrete

Al-saffar,

Wong,

Paul

2023

Gels

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Concrete as a building material is susceptible to degradation by environmental threats such as thermal diffusion, acid and sulphate infiltration, and chloride penetration. Hence, the inclusion of nanomaterials in concrete has a positive effect in terms of promoting its mechanical strength and durability performance, as well as resulting in energy savings due to reduced cement consumption in concrete production. This review article discussed the novel advances in research regarding C-S-H gel promotion and concrete durability improvement using nanomaterials. Basically, this review deals with topics relevant to the influence of nanomaterials on concrete’s resistance to heat, acid, sulphate, chlorides, and wear deterioration, as well as the impact on concrete microstructure and chemical bonding. The significance of this review is a critical discussion on the cementation mechanism of nanoparticles in enhancing durability properties owing to their nanofiller effect, pozzolanic reactivity, and nucleation effect. The utilization of nanoparticles enhanced the hydrolysis of cement, leading to a rise in the production of C-S-H gel. Consequently, this improvement in concrete microstructure led to a reduction in the number of capillary pores and pore connectivity, thereby improving the concrete’s water resistance. Microstructural and chemical evidence obtained using SEM and XRD indicated that nanomaterials facilitated the formation of cement gel either by reacting pozzolanically with portlandite to generate more C-S-H gel or by functioning as nucleation sites. Due to an increased rate of C-S-H gel formation, concrete enhanced with nanoparticles exhibited greater durability against heat damage, external attack by acids and sulphates, chloride diffusion, and surface abrasion. The durability improvement following nanomaterial incorporation into concrete can be summarised as enhanced residual mechanical strength, reduced concrete mass loss, reduced diffusion coefficients for thermal and chloride, improved performance against sulphates and acid attack, and increased surface resistance to abrasion.

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Experimental and mechanism study on the impermeability and thermal insulation of foam concrete regulated by nano-silica and fluorine-free foam

Cited by 4 publications

References 42 publications

Effects of Mixing Techniques and Material Compositions on the Compressive Strength and Thermal Conductivity of Ultra-Lightweight Foam Concrete

Effects of Mixing Techniques and Material Compositions on the Compressive Strength and Thermal Conductivity of Ultra-Lightweight Foam Concrete

Cement Pastes with Hygroscopic Polymeric Additions for Potential Building Applications

An Elucidative Review of the Nanomaterial Effect on the Durability and Calcium-Silicate-Hydrate (C-S-H) Gel Development of Concrete

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