Research

17 pages, 9460 KiB

Open AccessArticle

Reutilization of Reclaimed Asphalt Binder via Co-Pyrolysis with Rice Husk: Thermal Degradation Behaviors and Kinetic Analysis

by Hui Zhao, Bao Mi, Na Li, Teng Wang and Yongjie Xue

Materials 2023, 16(22), 7160; https://doi.org/10.3390/ma16227160 - 14 Nov 2023

Viewed by 608

Abstract

Realizing the utilization of reclaimed asphalt binder (RAB) and rice husk (RH) to reduce environmental pollution and expand the reutilization technique of reclaimed asphalt pavement (RAP), co-pyrolysis of RAB with RH has great potential. In this study, the co-pyrolysis behaviors, gaseous products, and [...] Read more.

Realizing the utilization of reclaimed asphalt binder (RAB) and rice husk (RH) to reduce environmental pollution and expand the reutilization technique of reclaimed asphalt pavement (RAP), co-pyrolysis of RAB with RH has great potential. In this study, the co-pyrolysis behaviors, gaseous products, and kinetics were evaluated using thermogravimetric analysis and Fourier transform infrared spectroscopy (TG-FTIR). The results showed that incorporating RH into RAB improved its pyrolysis characteristics. The interactions between RAB and RH showed initial inhibition followed by subsequent promotion. The primary gaseous products formed during co-pyrolysis were aliphatic hydrocarbons, water, and carbon dioxide, along with smaller amounts of aldehydes and alcohols originating from RH pyrolysis. All average activation energy values for the blends, determined through iso-conversional methods, decreased with RH addition. The combined kinetic analysis revealed two distinct mechanisms: (1) at the lower conversion range, the pyrolysis of the blend followed a random nucleation and three-dimensional growth mechanism, while (2) at the higher conversion range, the control mechanism transitioned into three-dimensional diffusion. Full article

(This article belongs to the Special Issue Convergence & Sustainable Technology in Building Materials)

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11 pages, 2980 KiB

Open AccessArticle

Adsorption of Phosphate and Ammonium on Waste Building Sludge

by Eva Bedrnová, Barbora Doušová, David Koloušek, Kateřina Maxová and Milan Angelis

Materials 2023, 16(4), 1448; https://doi.org/10.3390/ma16041448 - 09 Feb 2023

Viewed by 1172

Abstract

Two selected waste building sludges (WBS) were used in this study: (i) sludge from the production and processing of prestressed concrete pillars (B) and (ii) sludge from the production of technical stone (TS). The materials were used in their original and Fe-modified forms [...] Read more.

Two selected waste building sludges (WBS) were used in this study: (i) sludge from the production and processing of prestressed concrete pillars (B) and (ii) sludge from the production of technical stone (TS). The materials were used in their original and Fe-modified forms (B_Fe/TS_Fe) for the adsorption of NH₄⁺ and PO₄³⁻ from contaminated waters. The experiments were performed on a model solution simulating real wastewater with a concentration of 1.7 mmol·L⁻¹ (NH₄⁺) and 0.2 mmol·L⁻¹ (PO₄³⁻). The adsorption of PO₄³⁻ had a high efficiency (>99%) on B, B_Fe and TS_Fe, while for TS, the adsorption of PO₄³⁻ was futile due to the high content of available P in the raw TS. The adsorption of NH₄⁺ on all sorbents (B/B_Fe, TS/TS_Fe) had a lower efficiency (<60%), while TS proved to be the most effective. Leaching tests were performed according to the CSN EN 12457 standard for B/B_Fe and TS/TS_Fe before and after NH₄⁺ and PO₄³⁻ sorption when the contents of these ions in the leachates were affected by adsorption experiments in the cases of B and TS. For B_Fe and TS_Fe, the ion content in the leachates before and after the adsorption experiments was similar. Full article

(This article belongs to the Special Issue Convergence & Sustainable Technology in Building Materials)

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11 pages, 3141 KiB

Open AccessArticle

Mechanical Properties of Cement Mortar Containing Ground Waste Newspaper as Cementitious Material

by Jae-In Lee, Chae-Young Kim, Joo-Ho Yoon and Se-Jin Choi

Materials 2023, 16(4), 1374; https://doi.org/10.3390/ma16041374 - 06 Feb 2023

Cited by 4 | Viewed by 1517

Abstract

In recent years, several studies have reported the recycling of by-products generated by the paper industry and their application to the construction industry. A majority of the existing studies used waste paper sludge ash, and considerable energy is consumed in such incineration processes. [...] Read more.

In recent years, several studies have reported the recycling of by-products generated by the paper industry and their application to the construction industry. A majority of the existing studies used waste paper sludge ash, and considerable energy is consumed in such incineration processes. This may further contribute to air pollution. In this study, we used waste newspaper (WNP), which underwent a simple crushing process without a separate high-temperature treatment process, and we integrated it in cement mortar. We prepared mortars containing 0%, 0.2%, 0.4%, 0.6%, 0.8%, and 1.0% ground WNP as a cement substitute. Subsequently, the fluidity, compressive strength, tensile strength, carbonation depth, drying shrinkage, and microstructure of the mortars were compared and analyzed. The 28-day compressive strength of the mortar samples with WNP was approximately 3.2–16.1% higher than that of the control sample. The 28-day accelerated carbonation depth of the samples with WNP was approximately 1.03–1.61 mm. Furthermore, their carbonation resistance was approximately 5.2–39.4% higher than that of the control sample. Compressive strength, tensile strength, and carbonation resistance were improved by appropriately using ground WNP as a cement substitute in cement mortar. In this study, the appropriate amount of WNP according to the mechanical properties of cement mortar was found to be 0.4–0.8%, and considering the durability characteristics, the value 0.6 was the most ideal. Full article

(This article belongs to the Special Issue Convergence & Sustainable Technology in Building Materials)

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12 pages, 2380 KiB

Open AccessArticle

Physical, Mechanical and Radiological Characteristics of a Fly Ash Geopolymer Incorporating Titanium Dioxide Waste as Passive Fire Insulating Material in Steel Structures

by Pedro Antonio Salazar, Carlos Leiva Fernández, Yolanda Luna-Galiano, Rosario Villegas Sánchez and Constantino Fernández-Pereira

Materials 2022, 15(23), 8493; https://doi.org/10.3390/ma15238493 - 29 Nov 2022

Cited by 3 | Viewed by 1021

Abstract

This research analyzes whether a titanium dioxide waste (TiO₂ waste) can be used as a source material for geopolymers with good fire resistance properties. Samples with different proportions were prepared, replacing fly ashes with titanium dioxide waste on geopolymers (0, 20, 30, [...] Read more.

This research analyzes whether a titanium dioxide waste (TiO₂ waste) can be used as a source material for geopolymers with good fire resistance properties. Samples with different proportions were prepared, replacing fly ashes with titanium dioxide waste on geopolymers (0, 20, 30, 40 and 100% w/w). The activating solution has a Na₂O/SiO₂ molar ratio of 0.98. Physical (bulk density, moisture content and water absorption) and mechanical (superficial hardness and compressive strength) characteristics have been evaluated. In addition, their thermal behavior at high temperatures (fire resistance, compressive strength at elevated temperature and absorbed energy) has also been evaluated to see if they can be used as fire insulating materials. This work also studies the radiological activity of geopolymer materials. The replacement of FA with WTiO₂ increases the bulk density due to its higher specific bulk density. The highest compressive strength values were obtained with a TiO₂ waste content between 30 and 40% w/w. The compressive strength decreases at high temperatures, especially when more TiO₂ waste is added. When the amount of TiO₂ waste is increased, so is the plateau of evaporation, and this, in turn, increases the resistance to fire. Geopolymers containing FA and TiO₂ waste do not present radiological problems, although, when the TiO₂ waste is increased, the activity index of the geopolymer also rises. Full article

(This article belongs to the Special Issue Convergence & Sustainable Technology in Building Materials)

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18 pages, 4106 KiB

Open AccessArticle

Strength and Permeability Properties of Pervious Concrete Containing Coal Bottom Ash Aggregates

by Ji-Hun Park, Seung-Tae Jeong, Quang-The Bui and In-Hwan Yang

Materials 2022, 15(21), 7847; https://doi.org/10.3390/ma15217847 - 07 Nov 2022

Cited by 7 | Viewed by 1337

Abstract

This study investigates the strength and permeability properties of pervious concrete-containing coal bottom ash (CBA) aggregates. Two pervious concrete mixtures were fabricated with different aggregate size distributions. One mixture contained CBA aggregates with a single-type distribution and the other mixture contained CBA aggregates [...] Read more.

This study investigates the strength and permeability properties of pervious concrete-containing coal bottom ash (CBA) aggregates. Two pervious concrete mixtures were fabricated with different aggregate size distributions. One mixture contained CBA aggregates with a single-type distribution and the other mixture contained CBA aggregates with a hybrid-type distribution. The test parameters of the CBA pervious concrete included the water/cement (W/C) ratio and compaction level to investigate their effects on the properties. W/C ratios of 0.25, 0.30, and 0.35 were considered for the mixture, and compaction levels of 0.5, 1.5, and 3.0 MPa were applied to fabricate the pervious specimen. The increase in the W/C ratio reduced the strength by approximately 20% to 30% of the CBA pervious concrete. The increase in the compaction level reduced the permeability by approximately four to five times but significantly increased the strength of the CBA pervious concrete. The test results indicate that the use of single-type CBA or hybrid CBA aggregates with different size distributions affected the properties of the pervious concrete. The strength of specimens, including hybrid CBA aggregates, was 30% to 45% greater than that of the specimens containing single-type CBA aggregates. Meanwhile, the use of hybrid CBA aggregates reduced the permeability of the CBA pervious concrete by approximately 20% to 35%. Finally, relationships between the strength properties, permeability characteristics and total void ratios of the CBA pervious concrete specimens are suggested based on the test results. Full article

(This article belongs to the Special Issue Convergence & Sustainable Technology in Building Materials)

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25 pages, 1977 KiB

Open AccessArticle

Dynamics of Strength Gain in Sandy Soil Stabilised with Mixed Binders Evaluated by Elastic P-Waves during Compressive Loading

by Per Lindh and Polina Lemenkova

Materials 2022, 15(21), 7798; https://doi.org/10.3390/ma15217798 - 04 Nov 2022

Cited by 7 | Viewed by 1318

Abstract

This paper addresses the problem of stabilisation of poor subgrade soil for improving its engineering properties and stiffness. The study aim is to evaluate the effects from single and mixed binders on the gain of strength in sandy soil over the period of [...] Read more.

This paper addresses the problem of stabilisation of poor subgrade soil for improving its engineering properties and stiffness. The study aim is to evaluate the effects from single and mixed binders on the gain of strength in sandy soil over the period of curing. We propose an effective non-destructive approach of using P-waves for identifying soil strength upon stabilisation. The growth of strength and stiffness is strongly dependent on time of curing and type of the stabilising agents which can include both single binders and their blended mixtures. The diverse effects from mixed binders on the properties of soil were evaluated, compared and analysed. We performed the experimental trials of five different binders for stabilisation of sandy soil using cement, lime, Ground Granulated Blast Furnace Slag (GGBFS), energy fly ash and bio fly ash. The methodology included soil stabilisation by binders during a total period of 90 days, strength test for the Unconfined Compressive Strength (UCS) and seismic tests on the stabilised samples. The dynamics of soil behaviour stabilised by different binders for days 7, 14, 28 and 90 was statistically analysed and compared. The optimisation of binder blending has been performed using mixture simplex lattice design with three binders in each case as independent variables. Using P-waves naturally exploited strength characteristics of soil samples and allowed us to compare the effects from the individual and blended binders over the complete period of curing with dominating mixes. The results indicate that strength growth in stabilised soil samples is nonlinear in both time and content of binders with dominating effects from slag which contributed the most to the compressive strength development, followed by cement. Full article

(This article belongs to the Special Issue Convergence & Sustainable Technology in Building Materials)

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20 pages, 7344 KiB

Open AccessArticle

Influences of Efficient Spraying of Cement-Based Slurries on Recycled Coarse Aggregate

by Jinming Yin, Aihong Kang, Peng Xiao, Zhengguang Wu, Changjiang Kou, Yongfan Gong and Chenghui Xiao

Materials 2022, 15(21), 7730; https://doi.org/10.3390/ma15217730 - 02 Nov 2022

Viewed by 989

Abstract

The inferior property is usually one of the major problems of recycled coarse aggregate (RCA), and the utilization of the RCA is limited. Strengthening the RCA is being widely explored. Immersing the RCA in the cement-based slurry is an effective approach. However, lots [...] Read more.

The inferior property is usually one of the major problems of recycled coarse aggregate (RCA), and the utilization of the RCA is limited. Strengthening the RCA is being widely explored. Immersing the RCA in the cement-based slurry is an effective approach. However, lots of slurry and time are required, and it is difficult to integrate the immersing method into the production line of the RCA. In this paper, a circular spraying method was proposed to treat the RCA using cement-based slurry. The immersing method was also conducted to verify the feasibility of the spraying method. The crushing value (CV), 24 h water absorption (WA), apparent density (AD) and dynamic water absorption (DWA) were tested, and the micro-morphology was also observed to explore the strengthening mechanism. Results showed that the CV and the WA decreased by up to 30.0% and 14.3% when the spraying method was used. The AD was slightly influenced by the cement-based slurry regardless of the treatment method. Considering the CV, WA and AD, the comprehensive grade of the RCA could be enhanced from III to II by using the spraying method. It was worth noting that the effects of the spraying method and the immersing method were basically equivalent. When the spraying method was adopted, only about 1 min and a small amount of slurry (about 5% of the RCA mass) were required to treat the RCA. Full article

(This article belongs to the Special Issue Convergence & Sustainable Technology in Building Materials)

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13 pages, 2629 KiB

Open AccessArticle

Mechanical Properties and Damage Layer Thickness of Green Concrete under a Low-Temperature Environment

by Dongsheng Zhang, Tianhao Zhang and Qiuning Yang

Materials 2022, 15(21), 7409; https://doi.org/10.3390/ma15217409 - 22 Oct 2022

Cited by 4 | Viewed by 938

Abstract

To study the influence of mineral admixtures on concrete’s mechanical properties after a low-temperature exposure, green concrete was prepared by mixing fly ash and slag at different replacement rates. By analysing the changes to concrete’s mechanical properties and the damage layer thickness under [...] Read more.

To study the influence of mineral admixtures on concrete’s mechanical properties after a low-temperature exposure, green concrete was prepared by mixing fly ash and slag at different replacement rates. By analysing the changes to concrete’s mechanical properties and the damage layer thickness under different ambient temperatures (20, −10, −20, −30, and −40 °C), the change rule of concrete at low temperatures was explored. The results revealed that the compressive strength of concrete, containing either fly ash or slag, peaked at 30 °C; moreover, the slag concrete’s flexural and splitting tensile strength peaked at −40 °C. The best mechanical properties were observed for a fly ash-to-slag ratio of 1:2 (F10S20; i.e., 10% fly ash and 20% slag) and its compressive strength at different temperatures was higher than that of concrete, containing 30% fly ash (F30) or 30% slag (S30), but the flexural and splitting tensile strength was lower than S30. Further, as the temperature decreased, the fly ash concrete’s damaged layer thickness gradually increased. When the content of fly ash and slag were both 15% (F15S15), the damaged layer thickness was minimal at different low temperatures, especially at −30 °C, where the thickness was only 8.31 mm. Full article

(This article belongs to the Special Issue Convergence & Sustainable Technology in Building Materials)

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14 pages, 3441 KiB

Open AccessArticle

Effects of Capsule Type on the Characteristics of Cement Mortars Containing Powder Compacted Capsules

by Se-Jin Choi, Sung-Ho Bae, Dong-Min Ji and Sung-Hoon Kim

Materials 2022, 15(19), 6773; https://doi.org/10.3390/ma15196773 - 29 Sep 2022

Cited by 1 | Viewed by 1175

Abstract

Several studies have been reported on self-healing concrete using bacteria, admixtures, and microcapsules. Among these self-healing techniques, encapsulating cement-based materials is advantageous in that large amounts of self-healing material can be contained in a capsule and released at the cracked site for a [...] Read more.

Several studies have been reported on self-healing concrete using bacteria, admixtures, and microcapsules. Among these self-healing techniques, encapsulating cement-based materials is advantageous in that large amounts of self-healing material can be contained in a capsule and released at the cracked site for a targeted reaction. This study produced a powder compacted capsule (PCC) using the droplet and blended manufacturing methods to encapsulate cementitious materials. This study refers to the PCCs as droplet-PCC (D-PCC) and blended-PCC (B-PCC) according to the manufacturing method used. The fluidity, compressive strength, carbonation, drying shrinkage, and water permeability of cement mortar with PCCs were evaluated. The test results show that the flow of the mortar sample using D-PCC was slightly higher than that of the mortar using B-PCC. The compressive strength of the mortar sample with B-PCC was generally higher than that of the mortar sample with D-PCC. The compressive strength of the B-PCC2 sample (with 0.2% of B-PCC) was the highest at all curing ages. This may be because the B-PCC fracture load was higher than that of the D-PCC. In addition, more hydrates were observed in the B-PCC sample than in the D-PCC sample. A crack healing effect was observed in the samples with PCC, regardless of the PCC type. The effect was the greatest in the B-PCC6 sample (with 0.6% of B-PCC). The results of this study provide a reference for the PCC type and mix ratio that would yield the best mechanical properties and crack healing effect. Full article

(This article belongs to the Special Issue Convergence & Sustainable Technology in Building Materials)

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15 pages, 4329 KiB

Open AccessArticle

Preparation and Properties of Foam Concrete Incorporating Fly Ash

by Dongsheng Zhang, Sen Ding, Ye Ma and Qiuning Yang

Materials 2022, 15(18), 6287; https://doi.org/10.3390/ma15186287 - 09 Sep 2022

Cited by 9 | Viewed by 2074

Abstract

Foam concrete is fire resistant and durable and has broad applicability as a building insulation material. However, cement has high energy consumption and causes pollution, necessitating an environment-friendly cementitious material to replace the cement used to prepare foam concrete. In this study, foam [...] Read more.

Foam concrete is fire resistant and durable and has broad applicability as a building insulation material. However, cement has high energy consumption and causes pollution, necessitating an environment-friendly cementitious material to replace the cement used to prepare foam concrete. In this study, foam concrete was prepared through chemical foaming. The influence of the foaming agent material, foam stabiliser, and fly ash on the basic properties of the foam concrete, including the dry bulk density, compressive strength, and thermal conductivity, was studied, and the pore structure was characterised. The results show that with an increase in the hydrogen peroxide (H₂O₂) content, the dry bulk density, compressive strength, and thermal conductivity of foam concrete decreases, whereas the pore diameter increases (0.495 to 0.746 mm). When the calcium stearate content is within 1.8%, the pore size tends to increase (0.547 to 0.631 mm). With increase in the fly ash content, the strength of foam concrete gradually decreases, and the dry bulk density first decreases and then increases. When the blending ratio of fly ash is 10–40%, the thermal conductivity gradually decreases; an extreme thermal conductivity of 0.0824 W/(m·K) appears at the blending ratio of 40%, and the dry bulk density is 336 kg/m³. Full article

(This article belongs to the Special Issue Convergence & Sustainable Technology in Building Materials)

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14 pages, 20270 KiB

Open AccessArticle

Strength Characteristics and Microstructure Analysis of Alkali-Activated Slag–Fly Ash Cementitious Material

by Chenhui Zhu, Yuanyuan Wan, Lei Wang, Yuchen Ye, Houjun Yu and Jie Yang

Materials 2022, 15(17), 6169; https://doi.org/10.3390/ma15176169 - 05 Sep 2022

Cited by 8 | Viewed by 1612

Abstract

Modifying the admixture of alkali-activated cementitious materials using components such as fly ash and fine sand may reduce CO₂ emissions and conserve natural resources and energy. This study adopted strength testing, scanning electron microscopy, and mercury intrusion porosimetry to investigate the influence [...] Read more.

Modifying the admixture of alkali-activated cementitious materials using components such as fly ash and fine sand may reduce CO₂ emissions and conserve natural resources and energy. This study adopted strength testing, scanning electron microscopy, and mercury intrusion porosimetry to investigate the influence of different admixtures on the compressive strength and flexural strength of alkali slag cementing materials and the microstructure characteristics of hardened slurry under the action of load. The flexural strength of alkali slag cement slurry and mortar was reduced by replacing slag powder with fly ash. Content of fine sand less than 20% had little effect on the strength of alkali slag cement mortar; however, when the content of fine sand exceeded 30%, the strength decreased significantly. The hydration degree at 3 d was large, and the density of slurry increased with the extension of age. Increased fly ash or fine sand content decreased the density of the slurry, and increased fly ash resulted in a large number of unhydrated fly ash particles in the cementitious materials. Addition of fine sand resulted in a large number of microcracks in the slurry, which gradually decreased with the extension of hydration age. Full article

(This article belongs to the Special Issue Convergence & Sustainable Technology in Building Materials)

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9 pages, 5605 KiB

Open AccessArticle

Effect of Cementitious Materials on the Engineering Properties of Lightweight Aggregate Mortars Containing Recycled Water

by Jae-In Lee, Sung-Ho Bae, Ji-Hwan Kim and Se-Jin Choi

Materials 2022, 15(5), 1967; https://doi.org/10.3390/ma15051967 - 07 Mar 2022

Cited by 5 | Viewed by 1773

Abstract

With the trend toward taller and larger structures, the demand for high-strength and lightweight cement concrete has increased in the construction industry. Equipment for transporting ready-mixed concrete is frequently used to bring concrete to construction sites, and washing this equipment generates a large [...] Read more.

With the trend toward taller and larger structures, the demand for high-strength and lightweight cement concrete has increased in the construction industry. Equipment for transporting ready-mixed concrete is frequently used to bring concrete to construction sites, and washing this equipment generates a large amount of recycled water, which is an industrial by-product. In this study, we recycled this water as the pre-wetting water for lightweight aggregate and as mixing water, and we substituted blast furnace slag powder (BS) and fly ash (FA) as cementitious materials (Cm). In addition, we evaluated the fluidity, compressive strength, tensile strength, drying shrinkage, and accelerated carbonation depth of lightweight ternary cementitious mortars (TCMs) containing artificial lightweight aggregate and recycled water. The 28-day compressive strengths of the lightweight TCM specimens with BS and FA were ~47.2–51.7 MPa, except for the specimen with 20% each of BS and FA (40.2 MPa), which was higher than that of the control specimen with 100% OPC (45.9 MPa). Meanwhile, the 28-day tensile strengths of the lightweight TCM specimens containing BS and FA were ~2.81–3.20 MPa, which are ~13.7–29.5% higher than those of the control specimen. In this study, the TCM specimen with 5% each of BS and FA performed the best in terms of the combination of compressive strength, tensile strength, and carbonation resistance. Full article

(This article belongs to the Special Issue Convergence & Sustainable Technology in Building Materials)

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