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Current Research in Cement and Building Materials
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Current Research in Cement and Building Materials

A special issue of Coatings (ISSN 2079-6412). This special issue belongs to the section "Surface Characterization, Deposition and Modification".

Deadline for manuscript submissions: closed (10 September 2023) | Viewed by 40787

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Dr. Peng Liu

E-Mail Website
Guest Editor
School of Civil Engineering, Central South University, Changsha 410013, China
Interests: cementitious materials; concrete; durability; coating materials; building materials; damage
Dr. Lingkun Chen

E-Mail Website
Guest Editor
School of Civil Engineering, Yangzhou University, Yangzhou 225127, China
Interests: engineering; mechanical; bridge
Special Issues, Collections and Topics in MDPI journals
Dr. Ying Chen

E-Mail Website
Guest Editor
School of Civil Engineering, Central South University of Forestry and Technology, Changsha 410004, China
Interests: cementitious materials; concrete structures; structural engineering; coating materials; synthesis and preparation nano materials; concrete durability

Special Issue Information

Dear Colleagues,

Building materials are the main components of current architecture, which directly determines the quality and service life of the buildings. The field of current research in cement and building materials, with all its traditionalism and multidisciplinarity, also profited from this development. However, the specific features of this field have led to a considerable scattering of literary sources and a lack of mutual information between all relevant subjects. Moreover, the latest research achievements of cement and building materials are not summarized.

This Special Issue should help to overcome these problems. It provides an opportunity to create a compendium of novel cement and building materials, which will not only boost further scientific progress but also provide restorers and artists with a useful literary overview. It is focused on cement and building materials, publishing the most important results from different regions of the world.

I cordially invite you to submit your contribution to this issue, whose topics include but are not limited to the following:

  • Cement and building materials;
  • Design and preparation of concrete;
  • Cementitious capillary crystalline waterproofing materials;
  • Special cement including preparation, applications, and implementation issues;
  • Structural health monitoring;
  • Concrete structures;
  • Inorganic non-metal material;
  • Structural health monitoring;
  • Durability of concrete structures.

Dr. Peng Liu
Dr. Lingkun Chen
Dr. Ying Chen
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Coatings is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • cement
  • concrete
  • smart materials
  • advanced materials
  • structural health monitoring
  • intelligent system
  • durability
  • inorganic non-metal material

Published Papers (27 papers)

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Research

33 pages, 5482 KiB  
Article
General Curve Model for Evaluating Mechanical Properties of Concrete at Different Ages
by Qiuwei Yang, Xinhao Wang, Xi Peng and Fengjiang Qin
Coatings 2023, 13(12), 2002; https://doi.org/10.3390/coatings13122002 - 25 Nov 2023
Cited by 2 | Viewed by 748
Abstract
During the process of pouring and solidification of concrete, the compressive strength and elastic modulus of concrete exhibit dynamic growth patterns. The mechanical properties of concrete usually remain stable in the later stage (28 days after pouring). Studying appropriate curve models to accurately [...] Read more.
During the process of pouring and solidification of concrete, the compressive strength and elastic modulus of concrete exhibit dynamic growth patterns. The mechanical properties of concrete usually remain stable in the later stage (28 days after pouring). Studying appropriate curve models to accurately evaluate the changes in early mechanical properties of concrete has always been an important topic in the field of concrete materials. This work proposes a new dual parameter curve model for accurately evaluating the growth pattern of early compressive strength and elastic modulus of concrete. A comparative study was conducted between the proposed new curve model and existing curve models using 18 sets of experimental data from 10 literature sources. The research results indicate that the fitting average error and standard deviation of this new curve model are significantly smaller than the existing curve models. For some examples, the fitting error and standard deviation of the new model are only about 20%–30% of those of the existing models. The main advantages of this new curve model lie in two aspects. The first advantage is that this new curve model only contains two unknown parameters, so only a small amount of experimental data is required for data fitting and does not require complex mathematical operations. The second advantage is that this new curve model has a wide range of applications, which include compressive strength evaluation and elastic modulus evaluation and can also be extended to the evaluation of the mechanical properties of other materials similar to concrete. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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18 pages, 79583 KiB  
Article
Effect of Planting Rebars on the Shear Strength of Interface between Full Lightweight Ceramsite Concrete and Ordinary Concrete
by Hongbing Zhu, Yixue Duan, Xiu Li, Na Zhang and Jingyi Chen
Coatings 2023, 13(9), 1622; https://doi.org/10.3390/coatings13091622 - 15 Sep 2023
Viewed by 936
Abstract
The use of full lightweight ceramsite concrete (FLWCC) for the repair of ordinary concrete (OC) structures has a good application prospect in the field of engineering structural strengthening. However, the interface here is less studied at present. For this purpose, 10 sets of [...] Read more.
The use of full lightweight ceramsite concrete (FLWCC) for the repair of ordinary concrete (OC) structures has a good application prospect in the field of engineering structural strengthening. However, the interface here is less studied at present. For this purpose, 10 sets of FLWCC (new concrete)–OC (old concrete) specimens were produced for the shear test to test the bonding properties of the interface. The results showed that the damage form was changed from brittle damage to ductile damage after strengthening. It was proven that planting rebars in the interface could improve the shear performance. The interface shear strength increased with the number of rebars and it had a better effect after the number was more than 2. The strength was related to the rebar diameter and the maximum was obtained when the diameter was 8 mm. The most suitable spacing of the bars was 80 mm. The one-way analysis of variance (ANOVA) showed that the number of rebars had the greatest effect on shear strength followed by rebar diameter, while the effect of the spacing of the bars was less pronounced. Moreover, Fib’s (2010) specification of the interface shear strength formula could be used for the calculation of FLWCC–OC. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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17 pages, 1368 KiB  
Article
Study on Flexural Strength of Interface between Full Lightweight Ceramsite Concrete and Ordinary Concrete
by Hongbing Zhu, Yu Xiao, Xiu Li, Ye Wang and Siyu Wen
Coatings 2023, 13(8), 1383; https://doi.org/10.3390/coatings13081383 - 07 Aug 2023
Viewed by 827
Abstract
The efficacy of full lightweight ceramsite concrete as a restorative material has been widely acknowledged, given its light weight, strength, and durability. However, the extent of its performance in repairing existing or old concrete remains uncertain. This study examined the reparation of flexural [...] Read more.
The efficacy of full lightweight ceramsite concrete as a restorative material has been widely acknowledged, given its light weight, strength, and durability. However, the extent of its performance in repairing existing or old concrete remains uncertain. This study examined the reparation of flexural performance with full lightweight ceramsite concrete, using 14 different combinations of old and new concrete test blocks. The primary focus of the study was on investigating the flexural bond strength of the interface between the old and the new concrete. This included understanding the effects of the interfacial roughness, interfacial agent type, and concrete curing age of the concrete on the flexural strength. The test results showed that increasing the interface roughness from 0 mm to 5 mm resulted a restoration of the flexural strength of the sample by approximately 59%. Additionally, the flexural strength of the specimens was restored by 62%–78% of their original strength with the application of different types of interfacial agent. To rank the impact of these factors on the flexural strength, a univariate analysis of variance was conducted. This allowed us to establish a mathematical formula for calculating the flexural capacity of old and new concrete interfaces, taking the three aforementioned factors into account. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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15 pages, 3544 KiB  
Article
Experimental Study on Performance of Modified Cement-Based Building Materials under High-Water-Pressure Surrounding Rock Environment
by Jun Yao, Di Feng, Zhikui Wang, Chengcheng Peng, Yonggang Zhang and Lei Han
Coatings 2023, 13(3), 501; https://doi.org/10.3390/coatings13030501 - 24 Feb 2023
Viewed by 1229
Abstract
Traditional cement-based grouting materials have good reinforcement and anti-seepage effects on the surrounding rock under normal conditions, but the grouting effect is not ideal due to problems such as a long setting time, a low stone ratio, and poor crack resistance under high [...] Read more.
Traditional cement-based grouting materials have good reinforcement and anti-seepage effects on the surrounding rock under normal conditions, but the grouting effect is not ideal due to problems such as a long setting time, a low stone ratio, and poor crack resistance under high water pressure and in a dynamic water environment. In this study, we aimed to improve the physical properties, chemical properties, and microstructure of a cement-based slurry by forming a hydrogel through its chemical crosslinking with polyvinyl alcohol and boric acid as modifiers for the purpose of improving the permeability resistance of the surrounding rock grouting under high-water-pressure conditions, which can expand the function of traditional building materials. The grouting effect of the modified cementitious material on the surrounding rock was analyzed through indoor tests, the SEM testing of the performance of the modified slurry, the numerical calculation of the seepage field, and the application of the modified slurry in combination with the actual project to verify the water-plugging effect. The research findings demonstrate that (1) the additives boric acid and PVA can significantly speed up the slurry gel time, and the gel time can be controlled within 2–20 min to meet the specification requirements. (2) At a velocity of moving water > 1 m/s, the retention of the solidified modified slurry stone body reaches more than 80%. According to the SEM analysis, the structure of the solidified modified slurry stone body is dense and has good impermeability. (3) According to the numerical calculation analysis, the modified slurry can effectively change the seepage field of the surrounding rock and improve its seepage resistance. The water pressure outside the lining is reduced by 47%, 31%, and 22%, respectively, compared with no slurry, the pure cement slurry, and cement–water-glass grouting, and the indoor test and numerical simulation conclusions are consistent. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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15 pages, 5881 KiB  
Article
Experimental Study on Flexural Bearing Characteristics of Ceramsite Concrete Beams after Creep at Different Curing Ages
by Hongbing Zhu, Jingyi Chen, Yuxin Wu, Jiapeng Li, Zhenghao Fu and Peng Liu
Coatings 2023, 13(1), 158; https://doi.org/10.3390/coatings13010158 - 11 Jan 2023
Viewed by 1091
Abstract
Ceramsite concrete is increasingly used for structural applications due to its lightweight, high-strength, and high-temperature resistance advantages. However, research into the postcreep properties of ceramsite concrete has yet to keep pace with other areas. Therefore, this paper aims to investigate the flexural bearing [...] Read more.
Ceramsite concrete is increasingly used for structural applications due to its lightweight, high-strength, and high-temperature resistance advantages. However, research into the postcreep properties of ceramsite concrete has yet to keep pace with other areas. Therefore, this paper aims to investigate the flexural bearing properties of ceramsite concrete beams after creep and make recommendations for future research. To study the flexural load-bearing performance of ceramsite concrete beams after creep, a comparison test was carried out on four ceramsite concrete beams subjected to 200 d creep loading and four beams subjected to static load without creep loading for four curing ages. The results showed that, at first, the deformation capacity of the ceramsite concrete beams would increase after creep and the toughness and energy absorption capacity would also strengthen. Secondly, the creep could improve the ultimate bearing capacity of the ceramsite concrete beams. It was an approximate 10% increase after 200 d creep. Then, the stiffness, toughness, and ultimate bearing capacity of the ceramsite concrete beams would increase gradually with the increase of the curing age after the creep. In addition, the ultimate bearing capacity of the ceramsite concrete beams increased gradually with the increase of the curing age. The growth rate was faster in the early stage, slower after 120 d, and slower and more stable after 228 d. Finally, creep could cause the maximum crack width and depth of the ceramsite concrete beams decreased and the number of cracks would grow with the curing age. The conclusions obtained in the study provide a theoretical basis for the design of light aggregate structures for creep. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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18 pages, 6745 KiB  
Article
Analytical Study on Reinforced Concrete Columns and Composite Columns under Lateral Impact
by Xianhui Li, Yao Yin, Tieying Li, Xiang Zhu and Rui Wang
Coatings 2023, 13(1), 152; https://doi.org/10.3390/coatings13010152 - 11 Jan 2023
Cited by 3 | Viewed by 1994
Abstract
This study investigates the lateral impact responses of reinforced concrete (RC) and composite columns through dynamic nonlinear analysis using LS-DYNA. The simulation results were first validated against experimental results performed earlier on four different cross sections. The finite element analysis results show that [...] Read more.
This study investigates the lateral impact responses of reinforced concrete (RC) and composite columns through dynamic nonlinear analysis using LS-DYNA. The simulation results were first validated against experimental results performed earlier on four different cross sections. The finite element analysis results show that the simulation results of LS-DYNA can predict the experimental results well and can be used for further parametric analysis. The overall impact resistance of the four new composite columns is significantly better than that of RC columns. Among the composite columns, the solid concrete-filled double steel tube (S-DS) column has the best impact resistance with higher impact plateau force and smaller mid-span deflection under the same test conditions. It was found that the impact response process of all types of composite columns was similar. Finally, parametric analysis of the composite columns is performed to study the influence of load, material and other related parameters on the impact response of the composite columns. The results provide new information on the impact response of composite columns and the influence of materials and load parameters. The study provides a basis for the design and analysis of composite columns under lateral impact loading. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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14 pages, 4935 KiB  
Article
Improvement of 3D Printing Cement-Based Material Process: Parameter Experiment and Analysis
by Zihan Li, Huanbao Liu, Xiang Cheng, Ping Nie, Xianhai Yang, Guangming Zheng, Hongxing Su and Wenyu Jin
Coatings 2022, 12(12), 1973; https://doi.org/10.3390/coatings12121973 - 16 Dec 2022
Viewed by 1414
Abstract
Three-dimensional printing concrete is a digital and automating construction technology, which is expected to solve a series of problems existing in the traditional construction industry, such as low automation, high labor intensity, low efficiency and high risk. However, there are still many technical [...] Read more.
Three-dimensional printing concrete is a digital and automating construction technology, which is expected to solve a series of problems existing in the traditional construction industry, such as low automation, high labor intensity, low efficiency and high risk. However, there are still many technical and operational challenges. The purpose of this paper is to provide insights into the effects of process parameters on the geometry and stability of the printed layer. Firstly, a theoretical model is established to analyze the structure of the printed layer under different nozzle speeds, material flow rates and nozzle offset. Secondly, a slump test is carried out to select the optimal ratio suitable for 3D cement printers, and the specimen is printed under various conditions. Finally, based on the obtained parameters, multiple nozzles are used for printing, and a pressure value suitable for each nozzle in the nonlinear path is calculated. The experimental results show that theoretical model can sufficiently verify printing structure in different parameter intervals, and the process parameters (nozzle speed, material flow rate and nozzle offset) can be changed to achieve the best effect of cement-based material forming structure. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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20 pages, 3778 KiB  
Article
Research and Experimental Application of New Slurry Proportioning for Slag Improvement of EPB Shield Crossing Sand and Gravel Layer
by Yongshuai Sun and Dongjie Zhao
Coatings 2022, 12(12), 1961; https://doi.org/10.3390/coatings12121961 - 14 Dec 2022
Cited by 3 | Viewed by 1120
Abstract
Based on the construction practice of the Beijing Metro Line 10 shield tunneling project, this paper describes research on soil improvement technology for Beijing stratum characteristics (sandy gravel stratum) and covers similar engineering conditions. It also describes the development of a new type [...] Read more.
Based on the construction practice of the Beijing Metro Line 10 shield tunneling project, this paper describes research on soil improvement technology for Beijing stratum characteristics (sandy gravel stratum) and covers similar engineering conditions. It also describes the development of a new type of mud improver. Based on the laboratory tests with bentonite as the base mud and different additives, the effects of guar gum, CMC, xanthan gum, and clay medium particles on mud performance are analyzed. Then, two kinds of mud were used to conduct indoor simulated muck improvement tests (mixing test, slump test, sliding plate test, and adhesion resistance test), and the improvement effects of new mud and ordinary mud applied in pebble/round gravel and sandy soil layers were compared. The results show that xanthan gum is the best material to improve the performance of slurry, using the contrast test of bentonite-based slurry and different additives. The optimum slurry preparation scheme is 4% bentonite, 0.2% xanthan gum, 0.04% soda ash, and 1% clay particles. Using indoor simulated muck improvement tests (mixing test, slump test, slide plate test, and adhesion resistance test), the improvement effects of applying new mud and ordinary mud in pebble/round gravel and sandy soil layers are compared, and the advantages of the new mud in the application of the above two formations are verified. Among them, the new slurry has great advantages for improving the two parameters of the soil adhesion resistance coefficient and slump during shield tunneling. When the improved soil mass reaches the flowing plastic state, the proportion of new mud added to different soil mass is different. The proportion of new mud added to improved pebble/pebble soil is 28%, and that of sand and clay is 32%. It can be seen that new mud is more suitable for improving pebble/pebble soil. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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7 pages, 3956 KiB  
Article
The Effect of Multi-Walled Carbon Nanotubes on the Compressive Strength of Cement Mortars
by Nelli G. Muradyan, Harutyun Gyulasaryan, Avetik A. Arzumanyan, Maria M. Badalyan, Marine A. Kalantaryan, Yeghiazar V. Vardanyan, David Laroze, Aram Manukyan and Manuk G. Barseghyan
Coatings 2022, 12(12), 1933; https://doi.org/10.3390/coatings12121933 - 08 Dec 2022
Cited by 4 | Viewed by 1592
Abstract
In this work, multi-walled carbon nanotubes (MWCNTs) have been synthesized using a modified method of solid-phase pyrolysis. The MWCNTs are effectively dispersed using a simple and facile method such as ultrasonic energy without and with surfactant for two different sonication times (15 min [...] Read more.
In this work, multi-walled carbon nanotubes (MWCNTs) have been synthesized using a modified method of solid-phase pyrolysis. The MWCNTs are effectively dispersed using a simple and facile method such as ultrasonic energy without and with surfactant for two different sonication times (15 min and 40 min). In the present study, the effect of MWCNT concentration (0.001, 0.01, 0.05, 0.1 wt.%) on the compressive strengths of cement mortars has been investigated. Compressive tests were carried out on an automatic pressure machine (C089) with a loading rate of 0.5 kN/s at the age of 7 days and 28 days. It is shown that the optimal value of the nanotubes’ concentration does not exist in the case of 15 min of sonication time, whereas the optimal value for 40 min of sonication time without and with surfactant is 0.01%. Moreover, in the absence of surfactants, the strength of the specimen over 7 days of hardening increased by 13%, and by 19.5% in the presence of surfactants. The compressive strength for a curing period of 28 days increased by 6.3% and 13.8%, respectively. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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19 pages, 5311 KiB  
Article
Load Transfer Mechanism and Bond–Slip Behavior of Recycled Concrete-Encased Steel (RCES) Subjected to Cyclic Loading
by Jun Gao, Guoliang Zhao and Xin Zhang
Coatings 2022, 12(12), 1806; https://doi.org/10.3390/coatings12121806 - 23 Nov 2022
Viewed by 960
Abstract
RCES composite structures, which combine the advantages of high bearing- and good anti-seismic capacity of ordinary steel reinforced concrete (SRC) with the characteristics of energy-saving and environmental protection of recycled concrete, are beneficial to promote the use of recycled concrete. However, the bond–slip [...] Read more.
RCES composite structures, which combine the advantages of high bearing- and good anti-seismic capacity of ordinary steel reinforced concrete (SRC) with the characteristics of energy-saving and environmental protection of recycled concrete, are beneficial to promote the use of recycled concrete. However, the bond–slip behavior and load transfer mechanism are essential issues of RCES composite structures. This paper primarily focused on the load transfer mechanism and bond–slip behavior of RCES composite structures subjected to cyclic loading. A total of 14 specimens, which were designed with different replacement ratios of recycled concrete, cover thicknesses of H-shaped steel, transverse reinforcement ratios, and recycled concrete strengths, were tested to investigate the load transfer mechanism and interface damage. The results indicate that the whole loading procedure can be divided into four phases and four limit points. The bonding shear damage of a specimen develops rapidly, and most damage happened during 0~0.2 mm slip. The bonding stress values of chemical bonding stress τca, friction resistance stress τf, and mechanical biting stress τm were calculated. Moreover, in order to reflect the influence of cyclic loading, a degradation factor ξ was proposed. The mean values of chemical bonding stress τca: friction resistance stress τf: mechanical biting stress τm are 1:0.187:0.696, in which the chemical bonding stress is the largest, friction resistance stress is the second, and the mechanical biting stress is the least. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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19 pages, 6616 KiB  
Communication
Blast Resistance of a Masonry Wall Coated with a Polyurea Elastomer
by Xudong Zu, Taian Chen, Youer Cai, Zhengxiang Huang and Qiangqiang Xiao
Coatings 2022, 12(11), 1744; https://doi.org/10.3390/coatings12111744 - 14 Nov 2022
Cited by 1 | Viewed by 1402
Abstract
The coating of polyurea elastomers on walls is a hotspot in the protection field. This work combines a numerical simulation with experimental validation to examine the blast resistance after coating a polyurea elastomer on a 370 mm wall under a contact explosion. Firstly, [...] Read more.
The coating of polyurea elastomers on walls is a hotspot in the protection field. This work combines a numerical simulation with experimental validation to examine the blast resistance after coating a polyurea elastomer on a 370 mm wall under a contact explosion. Firstly, the failure limit, failure mode, and failure mechanism of the 370 mm unreinforced wall under different strength loads are studied. In the case of the contact explosion, the increase in size of the 370 mm wall blasting pit gradually stops after the dose is increased to more than 1 kg. Thereafter, the energy of the explosive load wis released by splashing wall fragments as well as by the deflection and movement of the wall. Spraying double-sided polyurea reinforcement on the wall can effectively improve the resistance to damages caused by exposure to explosive loads and can inhibit the damage to the surrounding personnel and equipment caused by flying structural debris. When the polyurea thickness on the front surface is 6 mm, the optimal thickness of the back surface should be 2 mm. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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30 pages, 10249 KiB  
Article
Nonlinear Numerical Analysis and Restoring force Model of Composite Joints with Steel Reinforced Recycled Concrete Columns and Steel Beams
by Jing Dong, Changling Shen, Hui Ma, Yunhe Liu and Xiaoran Cong
Coatings 2022, 12(11), 1606; https://doi.org/10.3390/coatings12111606 - 22 Oct 2022
Viewed by 1208
Abstract
Cyclic loading tests were conducted for eight composite joints (five interior joints and three exterior joints) with steel reinforced recycled concrete (SRRC) columns and steel beams under cyclic loading. The axial compression ratio and recycled coarse aggregate (RCA) replacement percentage were considered as [...] Read more.
Cyclic loading tests were conducted for eight composite joints (five interior joints and three exterior joints) with steel reinforced recycled concrete (SRRC) columns and steel beams under cyclic loading. The axial compression ratio and recycled coarse aggregate (RCA) replacement percentage were considered as the main design parameters for the above composite joints. The seismic behavior of the composite frame joints with (SRRC) columns and steel beams were studied by numerical simulation and the constitutive models of recycled aggregate concrete (RAC), steel and reinforcement were given to the corresponding elements. The experimental results were used to validate the finite element (FE) model. The results indicated that the FE model can accurately predict the deformation and stress load-strain curves of the composite joints. Then, a FE parameter analysis was carried out on the seismic behavior of the composite joints. The RAC strength, steel strength and column steel web thickness were considered as the main parameters. Results pinpointed that the increase in RAC strength and steel web thickness of the columns significantly affected the horizontal bearing capacity of the composite joints. However, with the increase in RAC and steel strength, the deformation ability and ductility of composite joints were almost unaffected. The reasonable increase in column steel web thickness can improve the seismic ductility of composite joints, evidently. On this basis, considering the stress characteristics of joint specimens, a four broken line restoring force model for steel reinforced recycled concrete column steel beam composite frame joints was established. This model includes the skeleton curve model, the stiffness degradation pattern and hysteresis rules. The calculation curve was in good agreement with experimental curves, which can well reflect the hysteretic behavior of joints subjected to low cyclic repeated loading. The above results can be used as a reference for the seismic design of composite frame joints. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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14 pages, 2265 KiB  
Article
The Influence of Extractant Composition on the Asphaltenes Extracted from Asphalt
by Dachuan Sun, Yang Song and Feiyong Chen
Coatings 2022, 12(10), 1600; https://doi.org/10.3390/coatings12101600 - 21 Oct 2022
Cited by 2 | Viewed by 1375
Abstract
The compositions of extractants containing xylene (G) and n-heptane (P) recovered and reused in the asphaltene extraction process were determined by densimetry and the extracted asphaltenes were analyzed to study the influence of extractant composition on their elemental, spectral and structural properties. With [...] Read more.
The compositions of extractants containing xylene (G) and n-heptane (P) recovered and reused in the asphaltene extraction process were determined by densimetry and the extracted asphaltenes were analyzed to study the influence of extractant composition on their elemental, spectral and structural properties. With increasing the number of extraction, the G/P ratio in extractant increases, which dissolves more asphaltenes of higher aromaticity and causes a decrease of asphaltene yield, the polarity and aromaticity in molecular structure of the extracted asphaltenes. Asphaltenes extracted at a higher G/P ratio were found to have less fractions of N and O elements as well as higher fractions of H and S elements, a lower C/H atom ratio and molecular unsaturation. Moreover, they have a smaller fraction of aromatic rings and aromatic carbon ratio, a higher substitution rate on aromatic rings, a higher fraction of alkyl chain and free ends in their average molecular structure. Compared with the base asphalt, asphaltenes’ infrared absorptions generally move towards smaller wave numbers owing to more aromaticity in their molecules and subsequent stronger conjugative and inductive effects. The asphaltenes extracted at a higher G/P ratio have a denser packing of alkyl chains and a looser packing of aromatic rings, according to their spectra of X-ray diffraction. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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23 pages, 10923 KiB  
Article
Cyclic Performance of Prefabricated Shear Wall Connected to Columns by Rectangular Concrete-Filled Steel Tube Keys
by Zhijun Zhou, Ming Li, Qian Wu, Shuang Yuan and Li Zhang
Coatings 2022, 12(10), 1584; https://doi.org/10.3390/coatings12101584 - 19 Oct 2022
Viewed by 2813
Abstract
A prefabricated frame–shear wall structure is a major structure in an assembled building. To find a method of connecting a shear wall and columns that can both reduce the amount of wet work required and maintain adequate stiffness, we propose connecting the shear [...] Read more.
A prefabricated frame–shear wall structure is a major structure in an assembled building. To find a method of connecting a shear wall and columns that can both reduce the amount of wet work required and maintain adequate stiffness, we propose connecting the shear wall to the vertical frame using rectangular concrete-filled steel tube keys (RCFSTKs). Static tests of a cast-in-place frame–shear wall structure without keys and a prefabricated structure with RCFSTKs were conducted to compare their seismic performance. The feasibility of the new method was analyzed. Finite element models were then set up to determine if plain concrete blocks between RCFSTKs could be removed and to identify the influence of different parameters on the cyclic performance of the assembled structure. The results show that the use of RCFSTK is practical. Compared with a dimensionally similar cast-in-place shear wall–column construction, a prefabricated shear wall connected to columns by RCFSTKs has a fuller hysteresis curve, better ductility, slightly higher energy dissipation, and slightly slower degradation of stiffness and bearing capacity. The removal of inter-key concrete blocks significantly reduces bearing capacity and initial stiffness. The cyclic performance of the assembled structure is primarily influenced by the number of RCFSTKs, the thickness of the steel tube key wall, and the axial compression ratio, with less effect from key unit height, steel strength, and concrete grade in RCFSTKs. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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16 pages, 7546 KiB  
Article
Analysis of the Mechanical Properties of a Bidirectional Laminated Slab with Shear Keys
by Ming Li, Zhijun Zhou, Qian Wu, Wei Yan and Shuang Yuan
Coatings 2022, 12(10), 1542; https://doi.org/10.3390/coatings12101542 - 13 Oct 2022
Viewed by 1261
Abstract
The load-bearing capacity of a bidirectional laminated slab with shear keys arranged in a rectangular grid (BCSWSK) was investigated to determine its mechanical properties, using load tests on a fabricated laminated slab and finite element models. The shear force distribution across the shear [...] Read more.
The load-bearing capacity of a bidirectional laminated slab with shear keys arranged in a rectangular grid (BCSWSK) was investigated to determine its mechanical properties, using load tests on a fabricated laminated slab and finite element models. The shear force distribution across the shear keys was measured and analysed, and the effects of different parameters were identified. The interfaces between the cast bottom slab and the shear keys were strongly bonded, as was the interface between the precast bottom slab and the cast-in-place upper slab, despite it being a secondary concrete pouring. The shear force was distributed similarly along the X direction (columns) and the Y direction (rows) of the shear key arrangement. The shear forces along the Y direction were greater and reached a maximum value sooner, but the differences between columns were mostly less than 10%. A square cross-section is recommended for the shear keys. The number of rows, number of columns, and the cross-sectional area of the shear keys are the main factors influencing the mechanical properties of the composite slab, but as they individually increased, they reached a point at which further increase had little effect. Similarly, after a certain number of shear keys were used, the concrete grade cast in situ, the shear key concrete grade, and the friction coefficient between the precast bottom slab and the cast-in-place upper slab had little influence on the BCSWSK. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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16 pages, 6258 KiB  
Article
Experimental Research on Dynamic Response of Layered Medium under Impact Load
by Mingqing Liu and Qinyu Gan
Coatings 2022, 12(10), 1474; https://doi.org/10.3390/coatings12101474 - 05 Oct 2022
Viewed by 951
Abstract
Stress waves propagating through multiple parallel fractures are attenuated due to the multiple wave reflections and transmissions at the fractures. The dynamic response of a layered medium under an impact load is systematically studied by a model test in this paper. The effects [...] Read more.
Stress waves propagating through multiple parallel fractures are attenuated due to the multiple wave reflections and transmissions at the fractures. The dynamic response of a layered medium under an impact load is systematically studied by a model test in this paper. The effects of the impact energy, number of joints, thickness of the medium and joint layer, material properties of the cementation layer, and other factors of the dynamic stress propagation and attenuation of layered media are analyzed. Studies have shown that Sadovsky’s empirical formula fits the attenuation law of vertical peak velocity well, and the obtained attenuation coefficient k and index b can be used for reflecting the dynamic response characteristics of layered media. The attenuation coefficient k is positively correlated with the impact height and negatively correlated with the plate thickness in a single-layer plate impact test. The thickness of the medium layer is the main factor affecting the vibration response of the layered medium in the impact test of the multi-layer slab. The medium thickness, the number of medium layers, and the number of joints have little influence. The different cementation materials and the change of cementation thickness will have a great influence on the dynamic response of layered media, when the cementation layer is filled with joint surfaces for the impact test of multi-layer plates. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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20 pages, 8589 KiB  
Article
Effect of the Location of Broken Wires on Prestressed Concrete Cylinder Pipes under Working Pressure
by Zhu Zhang, Tongchun Li, Lanhao Zhao and Huijun Qi
Coatings 2022, 12(9), 1361; https://doi.org/10.3390/coatings12091361 - 18 Sep 2022
Cited by 1 | Viewed by 1637
Abstract
The precise analysis of the overall mechanical performance of prestressed concrete cylinder pipes (PCCPs) with broken wires is a complicated problem. In this article, powerful finite element numerical means are applied to solve this problem. Firstly, the advantages and shortcomings of the current [...] Read more.
The precise analysis of the overall mechanical performance of prestressed concrete cylinder pipes (PCCPs) with broken wires is a complicated problem. In this article, powerful finite element numerical means are applied to solve this problem. Firstly, the advantages and shortcomings of the current prestress simulation methods in the finite element analysis (FEA) literature are discussed, and the initial stress method based on a novel single-spring joint element method to model the pre-stress of wires is proposed. Then, different distributions of broken zones, including random broken distributions, are developed for two typical PCCP pipes with different wire-wrapped layers. The established nonlinear FEA model considers actual service processes such as manufacturing, installation and operation to investigate the mechanical behavior of two typical PCCP pipes with different breakage distribution regions and breakage ratios, and in particular, the overall mechanical behavior of a pipe with random breakage is determined first. To verify the accuracy of the proposed pre-stress simulation method and the established nonlinear finite element model, the overall mechanical response of a pipe before wires broke is compared with the results obtained via the specifications. The computed results under the corresponding breakage assumptions are consistent with the conclusions in the existing literature, providing important guidance for pipeline management and operation. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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13 pages, 5553 KiB  
Article
Experimental Study on Shear Performance of Post-Tensioning Prestressed Concrete Beams with Locally Corroded Steel Strands
by Rihua Yang, Yiming Yang, Peng Liu and Xinzhong Wang
Coatings 2022, 12(9), 1356; https://doi.org/10.3390/coatings12091356 - 17 Sep 2022
Cited by 1 | Viewed by 1450
Abstract
To study the effect of the local corrosion of prestressed steel strands on the shear failure mode and shear bearing capacity of concrete beams, unilateral steel strands in four post-tensioning prestressed concrete (PC) beams are corroded, and the shear test of four PC [...] Read more.
To study the effect of the local corrosion of prestressed steel strands on the shear failure mode and shear bearing capacity of concrete beams, unilateral steel strands in four post-tensioning prestressed concrete (PC) beams are corroded, and the shear test of four PC beams are performed. Moreover, a simplified calculation method for the shear bearing capacity of concrete beams with diagonal steel bars is proposed considering the effect of cross-sectional reduction of steel bars, the degradation of mechanical properties, and the cross-sectional damage of concrete. Results shows that the crack propagation mode and failure mode are unrelated to the corrosion of prestressed steel bars when the shear span ratio of beam is the same. The shear capacity of the beam decreases with the increase of corrosion rate, but the decreasing rate is lower than the increasing rate of the corrosion rate. The growth rate of stirrup stress is much greater than that of load after concrete tension and compression loss cracking, and the yield of stirrup can be used as a sign of the ultimate bearing capacity of the beam. In addition, by comparing the experimental and numerical simulation results, the proposed simplified calculation method for the shear bearing capacity of concrete beams is of high accuracy. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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19 pages, 1777 KiB  
Article
On Strain Gradient Theory and Its Application in Bending of Beam
by Anqing Li, Qing Wang, Ming Song, Jun Chen, Weiguang Su, Shasha Zhou and Li Wang
Coatings 2022, 12(9), 1304; https://doi.org/10.3390/coatings12091304 - 05 Sep 2022
Cited by 3 | Viewed by 1654
Abstract
The general strain gradient theory of Mindlin is re-visited on the basis of a new set of higher-order metrics, which includes dilatation gradient, deviatoric stretch gradient, symmetric rotation gradient and curvature. A strain gradient bending theory for plane-strain beams is proposed based on [...] Read more.
The general strain gradient theory of Mindlin is re-visited on the basis of a new set of higher-order metrics, which includes dilatation gradient, deviatoric stretch gradient, symmetric rotation gradient and curvature. A strain gradient bending theory for plane-strain beams is proposed based on the present strain gradient theory. The stress resultants are re-defined and the corresponding equilibrium equations and boundary conditions are derived for beams. The semi-inverse solution for a pure bending beam is obtained and the influence of the Poisson’s effect and strain gradient components on bending rigidity is investigated. As a contrast, the solution of the Bernoulli–Euler beam is also presented. The results demonstrate that when Poisson’s effect is ignored, the result of the plane-strain beam is consistent with that of the Bernoulli–Euler beam in the couple stress theory. While for the strain gradient theory, the bending rigidity of a plane-strain beam ignoring the Poisson’s effect is smaller than that of the Bernoulli–Euler beam due to the influence of the dilatation gradient and the deviatoric stretch gradient along the thickness direction of the beam. In addition, the influence of a strain gradient along the length direction on a bending rigidity is negligible. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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23 pages, 8272 KiB  
Article
Test and Mesoscopic Analysis of Chloride Ion Diffusion of High-Performance-Concrete with Fly Ash and Silica Fume
by Huang Tang, Yiming Yang, Jianxin Peng, Peng Liu and Jianren Zhang
Coatings 2022, 12(8), 1095; https://doi.org/10.3390/coatings12081095 - 02 Aug 2022
Cited by 3 | Viewed by 1331
Abstract
High performance concrete (HPC) is a kind of concrete with mineral admixtures, which has better resistance ability to chloride ions diffusion than ordinary concrete. In the present study, the authors carried out a chloride ion diffusion experiment for the HPC with fly ash [...] Read more.
High performance concrete (HPC) is a kind of concrete with mineral admixtures, which has better resistance ability to chloride ions diffusion than ordinary concrete. In the present study, the authors carried out a chloride ion diffusion experiment for the HPC with fly ash and silica fume. The influence of the water–binder ratio (W/B), binary (Portland cement–Fly ash (PC-FS) and Portland cement–Silica fume (PC-SF) and ternary (Portland cement–Fly ash–Silica fume (PC-FA-SF)) combinations on the concrete compressive strength and chloride ion diffusion was investigated. It was found that the compressive strength of normal concrete and HPC increase with the decrease in the W/B, the ratio of W/B deceasing value to strength increasing value for normal concrete is 0.74, and for the HPC is 0.20, so the influence of the W/B on the concrete strength for normal concrete was obviously more than the HPC. The influence of the contents of the SF or FA on developing the concrete strength was limited. The concrete compressive strength of ternary combination specimens decreases with the increase in FA or SF when the content of the other mineral admixture SF or FA remained unchanged. The ternary combination was more efficient in prohibiting chlorides ingress insider the specimens than the binary combination. The mesoscopic simulation and the tested value of the chloride ion under the same depth was close, the average ratio of simulation value to tested value was 0.91. The aggregate shape and distribution also had a negligible influence on chloride diffusivity in the HPC, but the chloride ion concentration increased with the increase in aggregate size. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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17 pages, 7714 KiB  
Article
Research on Bending Performance of Concrete Sandwich Laminated Floor Slabs with Integrated Thermal and Sound Insulation
by Peng Liu, Sisi Xie, Lei Liu, Ao Luo, Ning Zhang, Sasa He, Yingye Wu, Wen Xu, Ying Chen and Zhiwu Yu
Coatings 2022, 12(8), 1075; https://doi.org/10.3390/coatings12081075 - 30 Jul 2022
Cited by 3 | Viewed by 1320
Abstract
In this study, a full-scale test on the bending performance of concrete sandwich laminated floor slabs with integrated thermal and sound insulation was carried out, and the effects of different reinforcement ratios on the bending performance of concrete sandwich laminated floor slabs were [...] Read more.
In this study, a full-scale test on the bending performance of concrete sandwich laminated floor slabs with integrated thermal and sound insulation was carried out, and the effects of different reinforcement ratios on the bending performance of concrete sandwich laminated floor slabs were investigated as well as the variation law of the failure modes, characteristic loads, load-mid span deflection, load-rebar strain curves, and anti-slip performance. The results indicate that the concrete sandwich laminated floor slabs present typical bending failure characteristics. According to bending failure characteristics, the damage process can be divided into three stages, i.e., elasticity, cracking, and failure. The bearing capacity significantly increases with the increase in reinforcement ratio. The normal service, yield, and ultimate loads of bearing capacity of the floor slabs with a larger reinforcement ratio increase by 54.55%, 52.94%, and 46.46%, respectively. Moreover, the mid-span deflection decreases significantly with the increase in reinforcement ratio, and the cracking expansion is also delayed. Before cracking, the prefabricated layer and laminated layer can realize load bearing together, and the floor slab is in a state of complete interaction. When the floor slabs reach the ultimate state, the superimposed surface produces a sliding effect, and the floor slab is in a state of partial interaction. The finite element analysis software ABAQUS (with the version number of ABAQUS 2020, the chief creator of David Hibbitt, and the sourced location of the United States) was used to perform nonlinear numerical simulation. The test results accord well with the simulation results, which verifies the correctness of the finite element model. Based on finite element simulation, the influence of post-cast concrete strength on the ultimate load can be ignored. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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15 pages, 3352 KiB  
Article
Influence of Volume-to-Surface Area Ratio on the Creep Behavior of Steel Fiber Ceramsite Concrete Beams
by Xiu Li, Hongbing Zhu, Zhenghao Fu, Peng Liu and Changhuang Xia
Coatings 2022, 12(7), 977; https://doi.org/10.3390/coatings12070977 - 10 Jul 2022
Cited by 2 | Viewed by 1262
Abstract
To explore the influence of the volume-to-surface area ratio (V/S) on the creep of ceramsite concrete beams, the creep performance of ceramsite concrete beams with different V/S was studied through a long-term deformation observation test, theoretical derivation analysis and finite element modeling. First, [...] Read more.
To explore the influence of the volume-to-surface area ratio (V/S) on the creep of ceramsite concrete beams, the creep performance of ceramsite concrete beams with different V/S was studied through a long-term deformation observation test, theoretical derivation analysis and finite element modeling. First, by observing the creep deflection of ceramsite concrete beams with five different V/Ss for 180 days, the relationship between creep deflection and loading time as well as the influence of V/S on creep deflection were obtained. Then, referring to the ACI209 and ACI435 creep coefficient calculation formula, the creep theory of ceramsite concrete beams involving V/S was established. Finally, the numerical model was built according to the test parameters. The results showed that the growth rate of the creep of ceramsite concrete beams increased rapidly in the early stage, but gradually slowed down with the passage of time and tended to be stable after 120 days of loading. The V/S had a significant impact on the creep of ceramsite concrete beams. In the first 7 days, the creep growth rate of each beam was approximately the same. Thereafter, the higher the V/S was, the lower the creep became. After 28 days, the creep of ceramsite concrete beams with varied V/Ss showed sharp differences. After the V/S exceeded 30, the increasing V/S could effectively reduce the creep value and the creep growth rate under a long-term load. The calculated results were in good agreement with the measured values, which fully reflected its creep variation. The finite element simulation further verified the influence of V/S on the creep of ceramsite concrete beams and the reliability of the creep calculation formula. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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15 pages, 4950 KiB  
Article
Dynamic Strain Response of Hot-Recycled Asphalt Pavement under Dual-Axle Accelerated Loading Conditions
by Jin Li, Yingyong Li, Chongsheng Xin, Haoyu Zuo, Ping An, Shen Zuo and Peng Liu
Coatings 2022, 12(6), 843; https://doi.org/10.3390/coatings12060843 - 16 Jun 2022
Cited by 3 | Viewed by 1364
Abstract
Accelerated pavement testing (APT) is an effective method to study the long-term performance of pavement. Therefore, the dynamic strain behavior analysis of asphalt pavement has important guiding significance in the study of pavement failure modes. To explore the dynamic response of a high-content [...] Read more.
Accelerated pavement testing (APT) is an effective method to study the long-term performance of pavement. Therefore, the dynamic strain behavior analysis of asphalt pavement has important guiding significance in the study of pavement failure modes. To explore the dynamic response of a high-content plant-mixed hot-reclaimed asphalt mixture under a dynamic load of vehicles, a full-scale test road was paved, and ALT biaxial accelerated loading test equipment was used to simulate the dynamic loads of vehicles. Based on parameters such as axle load, temperature, speed, and loading times, the development law for the bottom strain of the three pavement structures was analyzed. The test results show that the most unfavorable position of the asphalt pavement load is located just below the centerline of the wheel track on one side, and the damage effect of a single double-axle wheel load is far greater than that of two single-axle wheel loads. Then, the longitudinal tensile strain of the pavement bottom always maintains the alternating state of compression-tension and compression. The longitudinal tensile strain of the pavement bottom is larger than the transverse tensile strain, and transverse fatigue cracks appear first. Under normal temperature conditions, the bottom tensile strains of the three composite pavement structures under different axial loads are close, and the pavement performance of the hot-recycled asphalt pavement of structure A and structure B can meet the specification requirements. The relationship between the bottom strain and axle load is nonlinear and is directly related to the tire ground pressure, and the difference in the tensile and compressive strain values of the bottom of the three composite pavement structures is small. Under high temperature conditions, the bottom layer temperature of structure A and structure B is lower than that of structure C, and the thermal heat transfer efficiency of hot-recycled asphalt pavement is lower than that of ordinary asphalt pavement. Additionally, the longitudinal tensile strain is about 1–1.5 times that of the transverse tensile strain. Based on the Boltzmann function, the accumulative tensile strain prediction model was established to reflect the relationship between the cumulative strain at the bottom and the number of loads. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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13 pages, 4226 KiB  
Article
Experimental Analysis of Bearing Capacity of Basalt Fiber Reinforced Concrete Short Columns under Axial Compression
by Xinzhong Wang, Yiming Yang, Rihua Yang and Peng Liu
Coatings 2022, 12(5), 654; https://doi.org/10.3390/coatings12050654 - 11 May 2022
Cited by 34 | Viewed by 1967
Abstract
Adding basalt fiber to concrete can improve the mechanical properties of concrete, and it is also one of the best ways to enhance the ultimate bearing capacity of concrete structure. In this paper, the construction performance and the compressive strength of basalt-fiber-reinforced concrete [...] Read more.
Adding basalt fiber to concrete can improve the mechanical properties of concrete, and it is also one of the best ways to enhance the ultimate bearing capacity of concrete structure. In this paper, the construction performance and the compressive strength of basalt-fiber-reinforced concrete (BFRC) with five kinds of fiber lengths and eight kinds of fiber volume content subjected to an axial load are systematically investigated. The optimum fiber length and fiber volume content are obtained by comprehensively considering the construction performance and compressive strength. Moreover, the prediction model and finite element analysis method of the ultimate bearing capacity of basalt-fiber-reinforced concrete are developed. The results show that the optimum fiber length is about 12–24 mm and the fiber volume content is 0.15%. Adding an appropriate amount of basalt fiber can effectively improve the ultimate bearing capacity of concrete short columns, with maximum and average increases of 28% and 24%, respectively. In addition, the comparison with the experimental results shows that both the proposed prediction method and the finite element modeling method have good applicability, and they can be used to predict the ultimate bearing capacity of the BRFC short columns in practical engineering. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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17 pages, 5551 KiB  
Article
Research on Dynamic Response and Construction Safety Countermeasures of an Adjacent Existing Line Foundation under the Influence of a New Railway Line
by Shen Zuo, Tianyu Li, Jin Li, Peng Liu and Xinzhuang Cui
Coatings 2022, 12(5), 641; https://doi.org/10.3390/coatings12050641 - 07 May 2022
Cited by 1 | Viewed by 1400
Abstract
The excavation of a new high-speed railway causes the side slope adjacent to the existing line foundation to become airborne, and the excessive dynamic deformation or cumulative deformation caused by the dynamic load of trains will affect the normal service of the subgrade, [...] Read more.
The excavation of a new high-speed railway causes the side slope adjacent to the existing line foundation to become airborne, and the excessive dynamic deformation or cumulative deformation caused by the dynamic load of trains will affect the normal service of the subgrade, even leading to its instability. To date, there are no relevant experimental data regarding this, and there is also a lack of corresponding specifications. The only available numerical simulation research results need to be verified in practice. Therefore, this study relies on the Shanghai–Nanjing intercity high-speed railway construction project adjacent to the existing Beijing–Shanghai line to carry out a subgrade dynamic response test to ensure the safe operation of the existing line. The test obtained the vibration displacement, frequency, acceleration, and other parameters of the existing subgrade construction in three stages: subgrade excavation, pile formation, and subgrade filling. From the test results: During the test period, the vertical surface vibration displacement and vibration acceleration have a certain attenuation along the depth direction. In the stage of subgrade excavation, the vibration displacement and vibration acceleration generated are the largest. The vertical vibration displacement amplitude reaches 1.9 mm, and the horizontal vibration displacement amplitude reaches 0.15 mm. The vibration frequency of the roadbed under the action of the train load is concentrated in the range of 0–50 Hz, and the vibration energy at the peak value is relatively large, which reflects the load action frequency of the train, and the peak value is mainly concentrated in the range of 20–40 Hz. These results show that the maximum vibration response peak appears in the subgrade excavation stage, that is, the most dangerous stage of the existing subgrade. The vibration acceleration and vibration displacement of each dynamic response parameter are important in that they reflect the dynamic performance of the subgrade and establish the index control standard, which can be used as a control index for roadbed dynamic stability monitoring. The dynamic test of the subgrade state provides data support for the reasonable opening of the construction skylight and the protection of the excavation slope. Taking into account the impact of piling vibration, technical measures such as static pressure, jumping construction, and setting up stress relief holes are adopted. The test results and engineering measures ensure the safe operation of the existing subgrade, and have important theoretical significance for guiding the construction of the new subgrade adjacent to the existing line. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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19 pages, 2806 KiB  
Article
Shear Behavior of Stud-PBL Composite Shear Connector for Steel–Ceramsite Concrete Composite Structure
by Hongbing Zhu, Zhenghao Fu, Peng Liu, Yongcan Li and Benlu Zhao
Coatings 2022, 12(5), 583; https://doi.org/10.3390/coatings12050583 - 24 Apr 2022
Cited by 7 | Viewed by 2214
Abstract
For steel–concrete composite structure, a new type of stud–PBL composite shear connector can improve the shear resistance of steel–concrete interface, and polypropylene fiber ceramsite concrete can reduce the self-weight. Therefore, investigating the shear behavior of stud–PBL composite shear connectors for steel–ceramsite concrete composite [...] Read more.
For steel–concrete composite structure, a new type of stud–PBL composite shear connector can improve the shear resistance of steel–concrete interface, and polypropylene fiber ceramsite concrete can reduce the self-weight. Therefore, investigating the shear behavior of stud–PBL composite shear connectors for steel–ceramsite concrete composite structures bears significance. In this study, static testing and numerical simulation of the composite shear connector push-out specimen of polypropylene fiber ceramsite concrete were first conducted. The influencing factors of the shear bearing capacity were then analyzed. The formula for determining the shear bearing capacity of the steel–ceramsite concrete composite structure stud–PBL composite shear connectors was ultimately established. The results indicated that the new composite shear connector exhibited excellent shear resistance and good deformation ability. In addition, increasing concrete’s strength, stud’s diameter, and perforated plate’s thickness could significantly improve the shear bearing capacity of the composite shear connector. The calculated value of the shear bearing capacity of the composite shear connector was well correlated the measured value of the test. Overall, the stud–PBL composite shear connector could effectively improve the interfacial shear bearing performance of the steel–ceramsite concrete composite structure. Moreover, the established formula demonstrated broad applicability. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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16 pages, 4411 KiB  
Article
Long-Term Performance of Recycled Asphalt Pavement with Recycled Engine Oil Bottom Based on Accelerated Loading Test
by Jin Li, Li Zhu, Miaozhang Yu, Shen Zuo, Xinzhuang Cui and Peng Liu
Coatings 2022, 12(4), 522; https://doi.org/10.3390/coatings12040522 - 12 Apr 2022
Cited by 7 | Viewed by 1852
Abstract
The practical performance of recycled asphalt obtained from recycled engine oil bottom (REOB) was evaluated by paving a test road of base asphalt and REOB-recycled asphalt mixture in a laboratory, where accelerated loading tests with 700,000 cycles were conducted. During accelerated loading, pavement [...] Read more.
The practical performance of recycled asphalt obtained from recycled engine oil bottom (REOB) was evaluated by paving a test road of base asphalt and REOB-recycled asphalt mixture in a laboratory, where accelerated loading tests with 700,000 cycles were conducted. During accelerated loading, pavement temperature, layer bottom strain, pavement skid resistance, and rutting were monitored. The performance of pavement core material was tested after loading to analyze the index change of binder and the compaction degree of the mixture. The results show that the long-term anti-rutting ability of REOB-recycled asphalt pavement is approximately 10% higher than that of the base asphalt pavement, although the long-term anti-sliding force and anti-fatigue performance are poor. A developed model of rut with loading time can better predict the development trends of these parameters with loading cycles. The performance test of the pavement material after loading shows that 700,000 cycles can only degrade the performance of the test pavement, not damage it. The recycled asphalt pavement with 7% REOB has basically the same performance as the base asphalt under 700,000 cycles, indicating that REOB-recycled asphalt pavement can ensure basic road performance, while providing economic and environmental advantages. These results provide a reference for the application and form optimization of REOB-recycled asphalt pavement. Full article
(This article belongs to the Special Issue Current Research in Cement and Building Materials)
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