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3 pages, 167 KiB

Open AccessEditorial

Special Issue on Green Concrete for a Better Sustainable Environment

by Waiching Tang

Appl. Sci. 2020, 10(7), 2572; https://doi.org/10.3390/app10072572 - 09 Apr 2020

Cited by 1 | Viewed by 1427

Abstract

Green concrete is defined as concrete that uses waste material as at least one of its components, or has a production process that does not lead to environmental destruction, or has a high performance and life cycle sustainability [...] Full article

(This article belongs to the Special Issue Green Concrete for a Better Sustainable Environment)

Research

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14 pages, 4203 KiB

Open AccessArticle

Thermal and Mechanical Properties of Cement Mortar Composite Containing Recycled Expanded Glass Aggregate and Nano Titanium Dioxide

by Ali Yousefi, Waiching Tang, Mehrnoush Khavarian, Cheng Fang and Shanyong Wang

Appl. Sci. 2020, 10(7), 2246; https://doi.org/10.3390/app10072246 - 26 Mar 2020

Cited by 31 | Viewed by 5396

Abstract

One of the growing concerns in the construction industry is energy consumption and energy efficiency in residential buildings. Moreover, management of non-degradable solid glass wastes is becoming a critical issue worldwide. Accordingly, incorporation of recycled expanded glass aggregates (EGA) as a substitution for [...] Read more.

One of the growing concerns in the construction industry is energy consumption and energy efficiency in residential buildings. Moreover, management of non-degradable solid glass wastes is becoming a critical issue worldwide. Accordingly, incorporation of recycled expanded glass aggregates (EGA) as a substitution for natural fine aggregate in cement composites would be a sustainable solution in terms of energy consumption in the buildings and waste management. This experimental research aims to investigate the effects of EGA on fresh and hardened properties and thermal insulating performance of cement mortar. To enhance the mechanical properties and water resistance of the EGA-mortar, nano titanium dioxide (nTiO₂) was used as nanofillers. The results showed an increase in workability and water absorption of the EGA-mortar. In addition, a significant decrease in bulk density and compressive strength observed by incorporating EGA into the cement mortar. The EGA-mortar exhibited a low heat transfer rate and excellent thermal insulation property. Furthermore, inclusion of nTiO₂ increased compressive strength and water resistance of EGA-mortar, however, their heat transfer rate was increased. The results demonstrated that EGA-mortar can be integrated into the building envelop or non-load bearing elements such as wall partition as a thermal resistance to reduce the energy consumption in residential buildings. Full article

(This article belongs to the Special Issue Green Concrete for a Better Sustainable Environment)

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12 pages, 3531 KiB

Open AccessArticle

Impact of Temperature Changes and Freeze—Thaw Cycles on the Behaviour of Asphalt Concrete Submerged in Water with Sodium Chloride

by Ángel Vega-Zamanillo, Luis Juli-Gándara, Miguel Ángel Calzada-Pérez and Evelio Teijón-López-Zuazo

Appl. Sci. 2020, 10(4), 1241; https://doi.org/10.3390/app10041241 - 12 Feb 2020

Cited by 20 | Viewed by 2296

Abstract

One of the main applications of salt in civil engineering is its use as a de-icing agent on roads in cold areas. The purpose of this research is to find out the mechanical behaviour of an asphalt concrete when it is subjected to [...] Read more.

One of the main applications of salt in civil engineering is its use as a de-icing agent on roads in cold areas. The purpose of this research is to find out the mechanical behaviour of an asphalt concrete when it is subjected to temperature changes and freeze–thaw cycles. These temperature interactions have been carried out for dry specimens, specimens submerged in distilled water and specimens submerged in salt water (5% of sodium chloride, NaCl). An AC16 Surf D bituminous mixture was evaluated under three types of temperature interaction: three reference series remained at a controlled temperature of 20 °C, another three series were subjected to five freeze–thaw cycles and the last three series have been subjected to one year outside in Santander (Spain). The mechanical behaviour of the mixture was determined by Indirect Tensile Strength Test (ITS), Water Sensitivity Test (ITSR) and Wheel Tracking Test, Dynamic Modulus Test and Fatigue Tests. The results of the tests show that, although the temperature changes have a negative effect on the mechanical properties, salt water protects the aggregate-binder adhesive, maintains the mechanical strength, increases the number of load cycles for any strain range and reduces the time that the mixture is in contact with frozen water. Full article

(This article belongs to the Special Issue Green Concrete for a Better Sustainable Environment)

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23 pages, 10877 KiB

Open AccessArticle

Numerical Study of Bond Slip between Section Steel and Recycled Aggregate Concrete with Full Replacement Ratio

by Chao Liu, Lu Xing, Huawei Liu, Zonggang Quan, Guangming Fu, Jian Wu, Zhenyuan Lv and Chao Zhu

Appl. Sci. 2020, 10(3), 887; https://doi.org/10.3390/app10030887 - 29 Jan 2020

Cited by 23 | Viewed by 2674

Abstract

In this paper, the bond deterioration mechanism of recycled aggregate concrete (RAC) with a full replacement ratio was studied through experimental and numerical simulations. To study the bond behavior and the bond slip between section steel and RAC, nine push-out specimens were designed [...] Read more.

In this paper, the bond deterioration mechanism of recycled aggregate concrete (RAC) with a full replacement ratio was studied through experimental and numerical simulations. To study the bond behavior and the bond slip between section steel and RAC, nine push-out specimens were designed using the control variable method. The effects of the concrete strength, the embedded length, the cover thickness, and the lateral stirrup ratio on the bond behavior and the bond slip were investigated in detail. The loading process and failure mode of the specimens were observed, and the test curves of the loading end and free end of the specimens were analyzed. Based on the experiment, the finite element method (FEM) was used to simulate the specimens, and the simulation results were analyzed by comparing the experiment data. The analysis of the results showed that the developed model is capable of representing the characteristic bond strength value between section steel and RAC with sufficient accuracy, and the main differences of bond slip between the simulation and the test results are the slippage at the limit state and the moment at which the free end starts to slip. Full article

(This article belongs to the Special Issue Green Concrete for a Better Sustainable Environment)

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14 pages, 5489 KiB

Open AccessArticle

An Experimental Strain-Based Study on the Working State of Husk Mortar Wallboards with Openings

by Xuesong Cai, Shijun Sun and Guangchun Zhou

Appl. Sci. 2020, 10(2), 710; https://doi.org/10.3390/app10020710 - 19 Jan 2020

Cited by 3 | Viewed by 1861

Abstract

Rice husks as common agricultural remnants with low density and good thermal conductivity properties have been used in infill walls in the northern area of China. Accordingly, many tests and numerical simulations were conducted to address a difficult issue, the inaccurate estimation on [...] Read more.

Rice husks as common agricultural remnants with low density and good thermal conductivity properties have been used in infill walls in the northern area of China. Accordingly, many tests and numerical simulations were conducted to address a difficult issue, the inaccurate estimation on the lateral load-bearing capacity of different types of husk mortar energy-saving (HMES) wallboards. The difficulty has not been overcome so far, implying that the novel methods are anticipated to achieve the accurate estimation. This paper tests the full-scale HMES wallboards with different openings and obtains the strains at the points distributed on the wallboard sides. The experimental strains are modeled as the approximate strain energy values to produce the characteristic parameter of the HMES wallboard’s stressing state. Furthermore, the inherent working state characteristic points of HMES wallboards are revealed from the evolution of the characteristic parameter called as the normalized approximate strain energy sum, leading to the redefinition of the failure loads for the HMES wallboards. Finally, it investigates the stressing state mode evolution of the HMES wallboard around the failure loads. The achieved results provide the reference to the accurate estimation of the bearing capacity of the HMES wallboards. Full article

(This article belongs to the Special Issue Green Concrete for a Better Sustainable Environment)

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14 pages, 3021 KiB

Open AccessArticle

MSWI Bottom Ash Application to Resist Sulfate Attack on Concrete

by Yongzhen Cheng, Yun Dong, Jiakang Diao, Guoying Zhang, Chao Chen and Danxi Wu

Appl. Sci. 2019, 9(23), 5091; https://doi.org/10.3390/app9235091 - 25 Nov 2019

Cited by 11 | Viewed by 2997

Abstract

This research provides a strategy for partially replacing cement with municipal solid waste incineration (MSWI) bottom ash (BA) to improve the performance of concrete against sulphate attack. Mortar strength tests were performed firstly to evaluate the hydration activity of the ground BA. Concrete [...] Read more.

This research provides a strategy for partially replacing cement with municipal solid waste incineration (MSWI) bottom ash (BA) to improve the performance of concrete against sulphate attack. Mortar strength tests were performed firstly to evaluate the hydration activity of the ground BA. Concrete specimens were cured in standard conditions and immersed in a solution that contained 10% sodium sulfate. Then, the compressive strength of these specimens was measured to investigate the mechanical properties and durability of the concrete. Next, the capillary porosity of the concrete was determined from the volume fractions of water lost in specimens. Finally, the transport of the sulphate solution in concrete was analyzed using capillary rise, crystallization rate, and solution absorption tests. The results indicated that BA had a certain hydration activity. The equivalent replacement of cement by BA decreased the compressive strength of the specimens but increased the durability of the concrete. There was an excellent correlation between capillary rise height, sulfate solution absorption amount, crystallization rate, and coarse capillary porosity. The addition of BA can decrease the coarse capillary porosity and further slow the capillary transport and crystallization of sulfate solution in concrete. Overall, the replacement of cement with BA can improve the durability of concrete and actualize the utilization of MSWI residues as a resource. Full article

(This article belongs to the Special Issue Green Concrete for a Better Sustainable Environment)

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22 pages, 8584 KiB

Open AccessArticle

Experimental Study on Seismic Behavior of Steel Frames with Infilled Recycled Aggregate Concrete Shear Walls

by Lijian Sun, Hongchao Guo and Yunhe Liu

Appl. Sci. 2019, 9(21), 4723; https://doi.org/10.3390/app9214723 - 05 Nov 2019

Cited by 8 | Viewed by 2608

Abstract

Experiments were performed on four specimens of steel frames with infilled recycled aggregate concrete shear walls (SFIRACSWs), one specimen of infilled ordinary concrete wall, and one pure-steel frame were conducted under horizontal low cyclic loading. The influence of the composite forms of steel [...] Read more.

Experiments were performed on four specimens of steel frames with infilled recycled aggregate concrete shear walls (SFIRACSWs), one specimen of infilled ordinary concrete wall, and one pure-steel frame were conducted under horizontal low cyclic loading. The influence of the composite forms of steel frames and RACSWs (namely, infilled cast-in-place and infilled prefabricated) on the failure modes, transfer mechanisms of lateral force, bearing capacity, and ductility of SFIRACSWs is discussed, and the concrete type and connecting stiffness of beam–column joints (BCJs) are also considered. Test results showed that infilled RACSWs can increase the bearing capacity and lateral stiffness of SFIRACSWs. The connecting stiffness of BCJs slightly influences the seismic behavior of SFIRACSWs. In the infilled cast-in-place RACSWs, the wall cracks mainly extended along the diagonal direction. The bearing capacity was 2.4 times higher than in the pure steel frame, the initial stiffness was 4.3 times higher, and the displacement ductility factors were 2.44–2.69 times higher. In the infilled prefabricated RACSWs, the wall cracks mainly extended along the connection between the embedded T-shape connectors and walls before finally connecting along the horizontal direction. Moreover, shear failure occurred in the specimens. The bearing capacity was 1.44 times higher than that of the pure steel frame, the initial stiffness was 2.8 times higher, and the displacement ductility factors were 3.32–3.40 times higher. The degradation coefficients of the bearing capacity were more than 0.85, indicating that the specimens demonstrated a high safety reserve. Full article

(This article belongs to the Special Issue Green Concrete for a Better Sustainable Environment)

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17 pages, 4008 KiB

Open AccessArticle

Experimental Study on the Seismic Performance of Recycled Concrete Hollow Block Masonry Walls

by Chao Liu, Xiangyun Nong, Fengjian Zhang, Zonggang Quan and Guoliang Bai

Appl. Sci. 2019, 9(20), 4336; https://doi.org/10.3390/app9204336 - 15 Oct 2019

Cited by 5 | Viewed by 3088

Abstract

This paper aims to manufacture recycled concrete hollow block (RCHB) which can be used for the masonry structure with seismic requirements. Five RCHB masonry walls were tested under cyclic loading to evaluate the effect of the axial compression stress, aspect ratio, and the [...] Read more.

This paper aims to manufacture recycled concrete hollow block (RCHB) which can be used for the masonry structure with seismic requirements. Five RCHB masonry walls were tested under cyclic loading to evaluate the effect of the axial compression stress, aspect ratio, and the materials of structural columns on the seismic performance. Based on the test results, the failure pattern, hysteresis curves, lateral drift, ductility, stiffness degradation, and the energy dissipation of the specimens were analyzed in detail. The results showed that with the increase of aspect ratios, the ductility of RCHB masonry walls increased, but the horizontal bearing capacity and energy dissipation of RCHB masonry walls decreased. With the increase of compressive stress, the bearing capacity and energy dissipation performance of RCHB masonry walls were improved, and the stiffness degraded slowly. The results also demonstrated that the RCHB masonry walls with structural columns, depending on whether the structural columns were prepared by ordinary concrete or recycled concrete, could increase the bearing capacity, ductility, and energy dissipation of specimens. The research confirmed that RCHB masonry walls could meet the seismic requirements through thoughtful design. Therefore, this study provided a new cleaner production for the utilization of construction waste resources. Full article

(This article belongs to the Special Issue Green Concrete for a Better Sustainable Environment)

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11 pages, 1061 KiB

Open AccessArticle

Experimental Study on a Prediction Model of the Shrinkage and Creep of Recycled Aggregate Concrete

by Zhenyuan Lv, Chao Liu, Chao Zhu, Guoliang Bai and Hao Qi

Appl. Sci. 2019, 9(20), 4322; https://doi.org/10.3390/app9204322 - 14 Oct 2019

Cited by 16 | Viewed by 3159

Abstract

The significant difference between recycled aggregate and natural aggregate is the content of the attached mortar layer. With the increase of the replacement rate of recycled aggregate, the shrinkage and creep of recycled aggregate concrete is significantly increased. In this paper, 180-day shrinkage [...] Read more.

The significant difference between recycled aggregate and natural aggregate is the content of the attached mortar layer. With the increase of the replacement rate of recycled aggregate, the shrinkage and creep of recycled aggregate concrete is significantly increased. In this paper, 180-day shrinkage and creep tests of recycled aggregate concrete with different water–cement ratios were designed in order to analyze the effect of the substitution rate and water–cement ratio on shrinkage and creep properties. The results show that the shrinkage strain of recycled aggregate concrete with a substitution rate of 50% and 100% at 180 days is 26% and 48% higher than that of ordinary concrete, respectively, and the growth of group II is 22% and 47%, respectively. When the load was 180 days old, the creep coefficient of recycled aggregate concrete with a substitution rate of 50% and 100% in group I increased by 19.6% and 39.6%, respectively compared with ordinary concrete, and group II increased by 23.6% and 44.3%, respectively. Based on the difference of adhering mortar content, the creeping increase coefficient and shrinkage increase coefficient of the attached mortar were proposed, and a shrinkage and creep model of recycled aggregate concrete was established. When compared with the experimental results, the model calculation results met the accuracy requirements. Full article

(This article belongs to the Special Issue Green Concrete for a Better Sustainable Environment)

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