Civil Engineering Materials Research Articles

Influence of Aggregates in Concrete on Fiber-Optic Based Thermal Integrity Profiling Analysis of Concrete Structures

Fiber-optic sensor has drawn wide attention in the nondestructive testing and evaluation of civil engineering materials due to its high accuracy and resolution as well as cost-efficiency. Currently, using optical fiber as the temperature sensor is proposed to conduct the thermal integrity profiling (TIP) of concrete structures. However, concrete is not a thermally homogeneous material as assumed in current studies of concrete TIP. Its essential components, such as aggregates may cause thermal inhomogeneity problems when implementing fiber-optic sensors for TIP. In this paper, we use the concrete structures with different grades of aggregates to conduct numerical simulation for nondestructive thermal testing. The goal is to investigate how the thermal inhomogeneity caused by aggregates would influence the testing result. Firstly, we establish three concrete structure models with three different grades of aggregates based on the scenarios where these concrete structures will be used. Then, we numerically simulate the thermal process on these models and extract the temperature at the location where optical fiber would be installed. The influence caused by the inhomogeneity of aggregate size and distribution as well as the possible method to minimize the effect are evaluated in the paper. Overall, aggregates of concrete have a significant influence on the accuracy of TIP analysis, and defects could be veiled if no proper treatment to the data is implemented for TIP analysis.

Effect of polypropylene fibers on the mode I, mode II, and mixed-mode fracture toughness and crack propagation in fiber-reinforced concrete

Concrete is the most commonly used material in civil engineering and also the most conventional and cheap material available in the market. Concrete cracking and fracturing may cause irreparable damages to concrete structures. Hence, fiber-reinforced concretes have been introduced in recent years as a strategy to eliminate these drawbacks to a large extent. In this study, crack propagation and the fracture toughness of concrete specimens without polypropylene (PP) fibers and those containing 0.2, 0.35, and 0.5 vol% of PP fibers were investigated through testing the straight notched Brazilian disc specimens. Furthermore, crack propagation from the pre-existing cracks in the specimens was investigated, and the mode I, mode II, and mixed-mode I/II fracture toughness were also calculated. The Brazilian disc (BD) test was performed on the specimens at different inclination angles of 0, 15, 28.83, 60, 75, and 90° relative to the direction of pre-existing cracks. According to the experimental results, at angles less than 75° (0 < α less than 75), the wing cracks initiated from the tip of pre-existing cracks, and as the loading continues, the path of crack propagation and growth approaches the loading direction. At angles equal to or greater than 75°, the crack initiated with a distance d from the crack tip. This distance was larger in the fiber-free specimens than in the fiber-reinforced specimens. The results showed that the mode I, mode II, and mixed-mode I/II fracture toughness of the specimen containing 0.35 vol% of PP fibers were higher than the fracture toughness of the fiber-free specimens or those containing other PP fiber levels.

A hybrid intelligent system for designing optimal proportions of recycled aggregate concrete

The replacement of natural coarse aggregate (NCA) with recycled coarse aggregate (RCA) in concrete mixtures offers various advantages, including conservation of natural resources, reduction of CO2 emissions, and cost reduction. However, multiple related variables and objectives (e.g., mechanical, economic, and environmental objectives) need to be considered when optimizing mixtures of recycled aggregate concrete (RAC). This cannot be achieved through traditional laboratory- or statistics-based methods. This study proposes a hybrid intelligent system based on artificial intelligence (AI) and metaheuristic algorithms for designing optimal mixtures of RAC. To verify the proposed model, a data set containing 344 different RAC mixtures was collected from previous literature. A semi-supervised cotraining algorithm using two k-nearest neighbor (kNN) regressors with different distance metrics is developed to label the unlabeled data in the collected dataset. Different AI models are incorporated into the system for modeling the relationship between RAC strength and its influencing variables. A multi-objective optimization (MOO) model based on AI algorithms and on a multi-objective firefly algorithm is used to search for optimal mixtures of RAC. The results show that kNN-based semi-supervised cotraining can effectively exploit unlabeled data to improve the regression estimates. In the test set, A Random Forest and Backpropagation Neural Network achieve the best prediction accuracy for predicting, respectively, uniaxial compressive strength and splitting tensile strength of RAC, indicated by the highest correlation coefficients (0.9064 and 0.8387, respectively) and lowest root-mean-square errors (6.639 MPa and 0.5119 MPa, respectively). The Pareto fronts of the multi-objective mixture optimization problem are successfully obtained by the MOO model. The proposed system can also be used to optimize mixture proportions of other cementitious materials in civil engineering.

Study on Melted Waste Plastic Bottles as Binder in Plastic Mortar

One of the big challenges that the solid waste management community of present and future generations will face is the proper disposal of plastic waste such as carry-bags, covers, bottles, containers, packing materials etc. They are causing health hazards to humans and animals, and polluting and damaging the environment through all the modes; air, soil and water. One of the effective reuses of plastic waste can be done by incorporating it through civil engineering materials on a large scale. This paper is about an experimental study of recycling waste plastic bottles made of polyethylene terephthalate (PETE) mixed in melted form with quarry dust into a plastic mortar. The characteristics of plastic mortar cubes such as density, uniformity and compressive strength are studied. The plastic waste and quarry dust mortar proportion of 1:3 resulted into a density of 19.3 kN/m3 , ultrasonic pulse velocity value of 1.45 km/s and compressive strength of 14.8 N/mm2. Also, the effect of adding fine material like cement as filler material in plastic mortar was studied and found that it resulted into an increase in density by 2.25 %, ultrasonic pulse velocity by 65 % and compressive strength by 52%.

Synthesis of geopolymer emulsions

The understanding of geopolymer emulsion synthesis is a major issue for several industrial applications such as the formation of hierarchically porous material for filtration, lightweight materials for civil engineering or even the conditioning of radioactive mineral oil. The aim of this paper is to study model emulsions (hexadecane dispersed in Na or K-metakaolin based geopolymer) with the highest volume fraction of C16 incorporated. The influence of the viscosity of the geopolymer paste controlled by the water content was studied and results show that emulsions are unstable for a viscosity ratio ηd/ηc lower than 0.01. Up to 70% in volume of C16 was incorporated within the K-geopolymer and hierarchical porous network was thus obtained. After oil removal by solvent extraction, a monolith with a compressive strength of around 0.5–0.6 MPa was characterized in terms of pore size distribution and specific surface area.

EVALUASI KUALITAS PASIR PADA PROYEK BANGUNAN PEMERINTAH DENGAN METODE STATISTIK INFERENSIAL

Sand is one of the key material in civil engineering, which is sometime overlooked during the construction process. In many projects, the first concern is about the structure and then the material. The improper use of material doesn’t show significant signs in the early stage of building service. Using low quality material may give significant impact after few years and when it comes to a concern, it’s always too late to be repaired. Sand has drawn many attentions in term of its quality and few works dealing with this topic have been reported. This study aims to asses the quality of sand collected from few government building projects in west Lombok. The results were analysed using statistic software, which is SPSS 16.0, to provide inferential analyses. A mixed model, namely field surveys and laboratory experiments, were employed for the research methodology. It was found that only one out of the seven project that used proper sandmin terms of quality. The rest do not meet the standards required by SNI (Indonesian Nasional Standard) for sand material. It was also found that the quality of sand used by the observed projects under this research was significantly differ from each other, in terms of their bulk density, apparent specific density, SSD specific density, water absorption, silt content, loose content weight, solid fill weight, and fine modulus. It is strongly recommended that the government should take a good control to the sand suppliers/providers as well as the builders especially when they are involving in the government projects.

DEM Analysis and Prediction for the Lateral Interaction of Monopile in Gravel Soil

Gravel is a common geotechnical material in civil engineering. To investigate the lateral bearing behavior of monopile in gravel materials and deeply understand the microscopic mechanisms, parametric three-dimensional discrete element analyses are performed to study the lateral interaction between the single pile and gravel. First, using the experimental data of two typical gravel samples, the discrete element methods (DEM) for monopile in gravel materials are investigated. A discrete particle flow model of pile segments that allows for the construction of p–y curves at various depths is proposed. The lateral mechanical behaviors (p–y curves) between monopile and different gravel material are then studied. The effects of gravel porosity, distribution and grain-size on both the strength and shape of the p–y curves are investigated. The results show that the influences of porosity and depth on the p–y behaviors of gravel are significantly different from those of sand. Furthermore, the obvious differences in p–y behaviors between the coarse gravel and fine sand are the effects of grain size and size distribution. Based on these results, corresponding equations for the estimation of the p–y curves are proposed and further validated by independent field test data. It is concluded that the proposed p–y curve is capable of modeling both different grain sizes and size distributions in gravel-monopile interaction analyses during lateral loading.

Study on the Accelerated Aging Test Method in the Development of a Self-Cleaning Topcoat for Cool Roofs

The heat island phenomenon in urban areas has become a problem in the recent years. One measure to overcome this, which has been attracting attention, is painting the cool roof with a paint that has high solar reflectance. However, the solar reflectance has been reported to decrease over time owing to staining from the paint. Our investigations reveal that a self-cleaning paint, based on an acrylic silicone polymer, is effective in maintaining a high solar reflectance and preventing dirt from adhering. These evaluations have been conducted on the cool roof of an actual building by conducting a pollution test under outdoor exposure conditions. In this study, we investigated an accelerated aging test and reported the results. ASTM D7897-15 (ASTM method) is an accelerated pollution test method for cool roofs, which has been established in the United States. In Japan, a similar accelerated pollution test method exists for antifouling civil engineering materials introduced by the Public Works Research Institute in Japan (PWRI method). The ASTM method and PWRI method were compared by conducting a stain acceleration test using a self-cleaning- and conventional-type cool-roof coating. The substitutability of the exposure test, correlation with the exposure test, performance evaluation of the paint, and the effect of the difference in the pretreatment conditions were verified. The results of these tests were reported.

Preface

After successfully held for four times, the 2020 5th International Conference on Minerals Source, Geotechnology and Civil Engineering (MSGCE 2020) was also a big success by holding via online platform on April 17-19, 2020. Organized by AEIC Academic Exchange Information Centre and supported by Sichuan University, MSGCE 2020 was held online due to the pandemic of COVID-19. In light of the prevention and control of COVID-19 and travel restrictions worldwide, the organizer could not hold the conference physically, that’s why we have to adjust the format to online meeting to avoid personnel gatherings, so that the conference could go ahead as scheduled. Online MSGCE 2020 aims to provide a flexible platform for experts and practitioners in the field of Minerals Source, Geotechnology and Civil Engineering to disseminate the latest research achievements, discuss the industrial challenges, and enhance the cooperation between them.We were honored to invite Prof. Zhengshan Luo from Xi’an University of Architecture &Technology to chair this international conference. Prof. Luo does a wide range of research areas, covering (1) Risk assessment theory, evaluation system, modeling and technical research of oil and gas pipeline; (2) Management information system theory, data storage technology and methods study of safety management; and (3) Mining systematic engineering. The rest of the committee was composed of around twenty experts in this field around the globe. During the conference, we invited two sophisticated professors to present their excellent talks. Prof. LIEW, Kim Meow from City University of Hong Kong talked about Nanomaterials and Their Use as Civil Construction Materials. Prof. Jian-Guo Dai, representing Hong Kong Polytechnic University, held a speech on Innovative Materials and Structural Systems for Sustainable Concrete Structures. Both of their marvelous speeches gained applaudable compliments and triggered a heated discussion.The model adopted during this virtual conference included plenary and delivery talks with allocated time. The conference was divided into two parts. In the first part, keynote talks and oral presentations were delivered in 30 and 20 minutes respectively, all of which were conducted via Zoom. The second part was held through a communication group via WeChat for experts and scholars to discuss more about the talks and presentations.Here we would like to present this excellent proceeding compiled by a bunch of qualified papers. These papers were solicited from the conference, covering the following topics but are not limited to: Civil Engineering, Geotechnical Engineering, Architecture Design, Construction Technology, Structural Engineering, Engineering Materials, Mineral and Mineralogy, and other related topics. All the papers have been through rigorous review and process to meet the requirements of International publication standard.We were happy to have 106 participants attended the conference. The virtual format of the conference was a first and novel attempt in this difficult time, but we are glad that we have made it a great success. Although there are some difficulties, for example, unstable network might occur, we have minimized the challenges, so that the conference was not interrupted. Thanks to the supports of all distinguished speakers, Chairman, and participants, this conference was a big success. We hope this conference can greatly promote research and developmental activities in Minerals Source, Geotechnology and Civil Engineering and make it an ideal platform for people to share views and experiences in these fields. We hope readers who are interested in these areas could enjoy and gain what they want in this proceeding.The Organizing CommitteeList of Committee member are available in the pdf.

Recycling contaminated marine sediments as filling materials by pilot scale stabilization/solidification with lime, organoclay and activated carbon

Nowadays, stabilization/solidification (S/S) applied to the treatment of contaminated marine sediments (CMSs) represents a key technology for the production of new materials for civil engineering. Literature has shown the feasibility of CMSs recycling, although sediment needs pre-treatments for the removal of organic matter and to improve the mechanical properties of the product post S/S. In view of the full-scale applicability where it is essential to reduce any additional phase (i.e., pre-treatments), this study is aimed at demonstrating the technical feasibility of recycling CMSs as filling materials by S/S treatments with lime, organoclay and activated carbon. The original sediments are contaminated with heavy metals, PCBs, and PAHs, exceeding limits values prescribed by law. Different mixtures were tested on the STABSOL-P pilot scale plant. The absence of specific CMSs pre-treatments resulted in failure to comply with the 28-days leaching test only for copper; greater air curing with 56-days allowed it to be complied with for all the investigated metals. The organic contamination, while slowing down the process of chemical stabilization, allowed in any case to get a product environmentally compatible. The unconfined compression strength tests showed values (>28 kPa) that would allow potential CMSs recycling for environmental enhancement. The mass balance of the case study of the Mar Piccolo of Taranto (Southern Italy) showed potential recycling of marine sediments (the production of 974 kg filling materials per 1000 kg of dredged sediment) with a consequent missed disposal in landfills of 0.65 m3/1000 kg of sediment.

Smart ZnO decorated optimized engineering materials for water purification under natural sunlight

Developing and designing smart civil engineering materials for environmental depollution in our daily life is a major issue. ZnO nanostructures implemented onto civil engineering material surfaces by low cost hydrothermal growth could be one of the most promising solutions, and already showed a good water purification efficiency by photocatalysis under UV light. Nevertheless, there are two main factors to work out in order to simplify and intensify the photocatalyst production on engineering materials. The first one is the reduction of the growth time. The second one is the use of sunlight, which is the most abundant, clean, and renewable light source available. However, reducing the growth time might have an impact on the photocatalytic efficiency due to the surface/volume ratio modification. In this work, a short and efficient hydrothermal synthesis (2 h or 1 h 30 min vs 4 h) was used to grow ZnO nanostructures directly on non-conventional substrates such as tiling and concrete, demonstrating an excellent photocatalytic activity for organic pollutant degradation in water under natural sunlight, even during cloudy days. Decreasing the growth time showed no significant influence on tiling samples and even increased their photocatalytic efficiency until the optimal value obtained with a growth time of 2 h. A strong impact of the shorter growth time was observed on concrete samples, as reducing the growth time leads to complex ZnO nanosheet structures with a lower gap value (3.11 eV for 1 h 30 min against 3.17 eV for 4 h) due to a possible influence of the surface pH value and the complex chemical composition of concrete.

Mechanical Behavior of Printed Strain Hardening Cementitious Composites.

Extrusion based additive manufacturing of cementitious materials has demonstrated strong potential to become widely used in the construction industry. However, the use of this technique in practice is conditioned by a feasible solution to implement reinforcement in such automated process. One of the most successful ductile materials in civil engineering, strain hardening cementitious composites (SHCC) have a high potential to be employed for three-dimensional printing. The match between the tailored brittle matrix and ductility of the fibres enables these composites to develop multiple cracks when loaded under tension. Using previously developed mixtures, this study investigates the physical and mechanical performance of printed SHCC. The anisotropic behavior of the materials is explored by means of mechanical tests in several directions and micro computed tomography tests. The results demonstrated a composite showing strain hardening behavior in two directions explained by the fibre orientation found in the printed elements. Moreover, the printing technique used also has guaranteed an enhanced bond in between the printed layers.

Integrating Team-Based Learning Modules to Improve Civil Engineering Students’ Technical Writing Skills

AbstractThis study investigates the effectiveness of role assignment in team-based learning (TBL) modules to improve technical writing skills in an undergraduate civil engineering (CE) materials la...

Effect of Heat-Treatment Remediation on the Mechanical Behavior of Oil-Contaminated Soil

The heat treatment of oil-contaminated sites is widely carried out for the purposes of remediation. However, heat treatment changes the physical and chemical properties of soil. Before the soil can be reused as a construction material in civil engineering, such as in backfill or road base materials, the changes to its physical properties must be understood. Therefore, this study investigates the changes in the physical and chemical properties of oil-contaminated soil after heat treatment. In this investigation, experimental samples of soil with added oil from a refinery plant are used to investigate the removal rate of total petroleum hydrocarbons (TPHs) by thermal desorption and incineration. The physical properties of the soil, including water permeability and mechanical properties, are compared before and after heat treatment. The results of this study are as follows. (1) Particle size analysis reveals that heat treatment makes soil particles finer. (2) In the burning reduction test, heat treatment at 900 °C removes more than 90% of THP. (3) In the direct shear test, the friction angle (ϕ) increases with the removal rate. (4) In the hydraulic test, as the removal rate increases, the permeability coefficient increases after heat treatment.

Experimental Study on Behaviour of Concrete by Replacement of Aggregate and Sand with Rubber Tyre Chips and Foundry Sand

Concrete is the most important civil engineering material in construction buildings and industries because increase the strength properties. Rubber and foundry sand are produced excessively worldwide every year. In such a case the reuse of rubber and foundry sand would be a better choice. In order to reuse rubber wastes, rubber tyre chips was added to concrete as coarse aggregate and In order to reuse foundry sand, foundry sand was added to concrete as fine aggregate and its different properties like compressive strength. As a result it was found that rubberized and foundry sand concrete is durable, less ductile, has greater crack resistance but has a low compressive strength when compared with ordinary concrete. Due to rapid growth in automobile industry use of tyre increase day to day and there is no reuse of the same to decrease the environmental pollution .in this paper we will study about physical and mechanical properties of concrete containing recycled tyre or rubber material aggregate. This study present the information about the civil engineering application of foundry sand, which is technically sound and is environmental safe. Foundry sand can be used as a partial replacement of fine aggregate and rubber tyre chip partial replacement coarse aggregate .foundry sand can be used in concrete to improve its strength and other durability factor. Foundry sand is high silica sand that is a by – product from the production of both ferrous and non-ferrous metal casting. The fresh &amp; hardened properties of concrete such as workability, compressive strength, are the identified.

Photogrammetric determination of 3D crack opening vectors from 3D displacement fields

This publication presents a procedure for the determination of all three components of crack opening vectors from stereoscopic image sequences of a specimen under load in civil engineering material testing. The method is based on analyzing stereoscopic image sequences of a concrete specimen with a surface texture, which is suitable for applying image matching techniques. Spatio-temporal correspondences are established by applying sub-pixel accuracy area based image matching techniques to a grid of surface points. Data acquisition starts at zero load. The load is stepwise or continuously increased during the experiment. The surface points are matched between the stereo images and tracked through each camera image sequence. As an intermediate result, we obtain a set of 3D object surface points for each epoch by spatial intersection. These 3D object points are triangulated into a mesh. Then, the mesh triangles are tested for deformations by transforming the triangles into 2D space and computing the norm of the 2D relative translation vector. Connected components of deformed triangles are determined and crack normals are computed. In the next step, the 3D relative translation vector can be derived for each deformed triangle. Defining local crack opening coordinate systems for the deformed triangles, the three components of the crack opening vectors can be computed. The method has been tested and validated in practical experiments. The technique is capable of quantitatively analyzing cracks with a width of less than one pixel in image space.

Techniques for the effective use of recycled asphalt pavement material as a civil engineering material

Techniques for the effective use of recycled asphalt pavement material as a civil engineering material

Experimental Analysis of Cold-Formed Steel C-Sections with the Notch Subjected to Axial Compression

Studies on the use of cold-formed steel (CFS) C-section, which is a civil engineering material, in building and civil engineering work are still on-going. The advantages of the CFS C-section are becoming so interesting that it is often being used as a roof truss system, storage rack, and wall framing. In order to have a roof truss system with a strong, safe, and stable condition, a study on truss member was carried out using the cut-curving process. Before the CFS C-section was curved, the process started by cutting the section in a proper way. A parametric study was conducted to determine the suitability of the cut pattern which recognised as a notch in the section and find out whether or not the notch depth would affect the ultimate load of the CFS C-section column. The study of CFS C-section was separated into two parts; firstly, to investigate the mechanical behaviour of the column in different notch depths and secondly, to investigate the behaviour in different column height with fixed notch depth. The notch width of 3 mm and notch spacing of 100 mm for both parts were fixed. Total specimen for both parts were 15 specimens. The results of the study showed that the reduction of the ultimate load was about 56–65% of the variation of notch depth section when compared with the normal section. Therefore, the ultimate load of the section with the notch decreased when the notch depth increased. In addition, the study illustrated that the reduction of the ultimate load was 64–82% of the variation of column height between 100 mm to 500 mm. Finally, the average percentage of the column height was 72% which can use in the modification of CFS C-section without notch to CFS C-section with notch calculation.

Chemical Characterisation of Construction and Demolition Waste in Skopje City and Its Surroundings (Republic of Macedonia)

In the Republic of Macedonia, construction and demolition (C&amp;D) waste is often dumped, underestimating the potential recycling and re-use as raw materials for civil engineering works and/or cement/ceramic industries. SAMCODE (Sustainable Approach to Managing Construction and Demolition Waste) is a know-how exchange program, the focus of which is chemical characterisation in terms of major and trace elements in order to evaluate the possible Macedonian C&amp;D waste recycling. Thirty-nine C&amp;D waste samples were collected from different dumps in Skopje and surroundings. X-ray fluorescence analyses, carried out on powdered samples, show i) highly variable concentrations, indicative of the heterogenous nature of C&amp;D waste, and ii) high concentration in Cr, Ni, and Zn with respect to Italian, Chinese, and Dutch tolerance limits, probably due to the presence of these elements in ophiolitic rocks and sulphide-bearing deposits, used as raw material in building activity. Inductively coupled plasma mass spectrometry analyses of leachates, performed to assess the mobility of heavy metals, show significant concentrations of Cr, and to a lesser extent, Ni. Results suggest that homogenisation processes of the recycled materials should be implemented and preliminary screening of C&amp;D waste should be performed to eliminate heavy metals-bearing components.

Research on Teaching Reform of Civil Engineering Materials Based on Individuation and Interactivity

Teachers should take the initiative to develop specialties of students and drive the progress of the curriculum. The traditional course of civil engineering materials has some obvious problems such as redundant course content, unreasonable scoring assessment mechanism, and low output of post-class practice. As a result, students in the classroom are less motivated and do not get insight into the understanding of this course. To conquer these limitations, this paper aims to optimize the traditional teaching system from three aspects: (1) the teaching method of course teaching, (2) the course evaluation system and (3) the extracurricular practice output. In addition, it also helps to carry out teaching activities for students based on the perspective of individuality and interaction as well as cultivate applied talents. This paper also provides a reference for the innovative teaching model.