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In concrete structures, material performance is typically determined at the level of the concrete mix (the microscale) and the overall shape and dimensions of a building element (the macroscale). However, recent developments in the field of 3D Concrete Printing (3DCP) are demonstrating that the design of concrete now also can take place at a previously impossible intermediate scale involving the shaping and placement of the material at the level of the printing nozzle (the mesoscale). By focusing directly on the design of print paths, advanced surface effects and internal porous material distributions can be achieved that significantly affect the aesthetic experience and structural performance of 3DCP structures. This ability to design the distribution of concrete according to local architectural, structural, and functional design criteria is an especially interesting application of 3DCP that could be exploited to customise material performance while at the same time optimising material use and reducing the self-weight of building elements. This paper specifically examines how four different three-dimensional print patterns produce distinct material structures at the mesoscale (mesostructures) and presents an experimental procedure for evaluating their load-bearing capacity.

The reduction of vibrations in concrete has been a topic of discussion among scientists. This article presents research on designing concrete mixes for constructing ground barriers with enhanced vibration isolation using waste materials. This study discusses the design of concrete mixes for the construction of concrete partitions with increased vibration isolation, using the polish standards. The experiments were conducted at the Laboratory of Building Materials Engineering at the Cracow University of Technology as part of the project entitled “Innovative construction of vibration-insulating barriers to protect the environment from transport vibrations and similar sources”. The concrete composition utilized blast furnace cement CEM III/A 42.5 N, with mineral and chemical additives. Recycled rubber aggregate from used tires was employed to enhance vibration isolation. Measurement results demonstrated the effectiveness of the concrete in dampening vibrations, confirming its suitability for practical use.

Experimental tests, and two conventional grading curves, are used to design a dosing scheme, seeking the best way to enhance the general sustainability of certain types of low-to-medium workability concrete mixes. The aim is to achieve highly compacted aggregate gradations, thereby minimizing the need for Portland cement consumption. Several aggregate mix designs, employing fractions of both commercial limestone and recycled electric steelmaking slag, were prepared and assessed. Nine concrete mixes of structural quality (above 40 MPa as compressive strength) were manufactured to analyze their aggregate packing density and their performance as engineering concrete mixtures. The results obtained after classical testing showed excellent quality homogeneous concrete mixes, considering both the in-fresh and in-hard properties. Subsequently, a sustainability analysis of all the mixes led to the conclusion that they were of low environmental impact, due to their high aggregate content and their low cement consumption which, additionally, included other industrial co-products with hydraulic properties.

This article presents the results obtained from the execution of the project called "Characterization of stone material banks for the preparation of concrete in the cities of Tepic and Xalisco, Nayarit", developed by the academic group "Education and Innovation in Civil Engineering" of the Instituto Tecnológico de Tepic. This project was developed financed by PRODEP in the 2019 Strengthening of Academic Bodies program. The results of the analyzes carried out on the material banks registered in the Secretaría de Desarrollo Rural of Nayarit state government are presented, which were contacted to invite them to participate in the project. Analysis of?" sands and gravels were carried out, additionally a concrete design was carried out with the results obtained to verify the behavior of the materials in their final form. [ABSTRACT FROM AUTHOR]

Copyright of International Journal of Engineering Research & Development (IJERAD) is the property of International Journal of Engineering Research & Development and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper outlines effect of the mix composition on mechanical properties of high-strength concrete based on aggregate size like in of Reactive Powder Concrete (RPC) but without fiber reinforcement. The main purpose which guided the authors choosing proportion of water and superplasticizer (SP) was to achieve a similar consistency in the test slump for various concrete mix. Test results for 3 groups of superplasticizers, designated as D - with chemical base - acrylic polymer, V - with chemical base - polycarboxylate ether, P - with chemical base - modified polycarboxylates, two cement groups, designated as Cem A - with fineness Blaine 3980 cm²/g, Cem B - with fineness Blaine 4430 cm²/g and 2 types of aggregate: basalt and granite were presented. After curing for 1, 7 and 28 days samples were tested for compressive strength and flexural tensile strength. The article also presents the study of the elemental composition and structure of the SP with the use of the SEM electron microscope. The amount of solid particles in the SP was also determined by the water vaporization. The assumption of the paper was to maintain the consistency of the mixture at the S2 level according to the Eurocode standard. The paper proposes a method based on SEM analysis in order to select a superplasticizer with the best ductility parameters, and the best results of the compressive and flexural tensile strength of concrete samples were obtained. The best results for compressive strength after 28 days are obtained for concrete series with the polycarboxylate ether superplasticizer and modified polycarboxylate ether superplasticizer in combination with the use of type A cement and it is greater than for the concrete series with type B cement by 11.7%. [ABSTRACT FROM AUTHOR]

The development of Portland cement and concrete in the 19th and 20th centuries revolutionised the construction industry, and provided a means of achieving architectural and structural feats that were previously impossible. While reinforced concrete bridges provided a means of simultaneously spanning vast distances and carrying significant loads, the material was little understood and designs reflected this. As a result, many early reinforced concrete structures suffer from significant durability issues and there is a growing requirement for their maintenance and repair, but the extent of the issue is unclear. As such, this review of historic test data intends to provide insight into previous reinforced concrete bridge design in Scotland, compare their design to current engineering codes, and discuss the implications for maintaining and preserving these unique examples of architectural heritage. [ABSTRACT FROM AUTHOR]

At the time of completion in 1961, the roof of St. Charles Church became the largest unbalanced hyperbolic paraboloid structure in the United States and the only shell structure in Spokane, WA. Situated on an 8-acre site on the north side of the city, St. Charles is a modernist structure designed through partnership of Funk, Molander & Johnson engineers, architect William C. James and in consultation with Professor T.Y. Lin of the Structural Engineering Laboratory at the University of California, Berkeley. This asymmetric structure spans over 33.5 m (110 ft) and utilizes folded edge beams that taper from 1067 mm (42 in) at the base to a 76.2 mm (3 in) thickness at the topmost edge using regular strength reinforcing steel and concrete load carrying components. The novelty of the pre-stressed shell structure serves both architectural and structural design criteria by delivering a large, uninterrupted interior sanctuary space in materially and economically efficient manner. This structural assessment summarizes the roof’s historic design and construction according to the original construction documents, newspaper reports and historic photographs. The FEA is completed using UBC 1955 design loads and ACI 334 Concrete Shell Structures provisions.

The reduction of vibrations in concrete has been a topic of discussion among scientists. This article presents research on designing concrete mixes for constructing ground barriers with enhanced vibration isolation using waste materials. This study discusses the design of concrete mixes for the construction of concrete partitions with increased vibration isolation, using the polish standards. The experiments were conducted at the Laboratory of Building Materials Engineering at the Cracow University of Technology as part of the project entitled "Innovative construction of vibration-insulating barriers to protect the environment from transport vibrations and similar sources". The concrete composition utilized blast furnace cement CEM III/A 42.5 N, with mineral and chemical additives. Recycled rubber aggregate from used tires was employed to enhance vibration isolation. Measurement results demonstrated the effectiveness of the concrete in dampening vibrations, confirming its suitability for practical use.

Fiber-reinforced polymer (FRP) reinforcing bars have been demonstrated as a viable substitute to steel-reinforced reinforcing bars owing to their favorable properties of non-corrosive and magnetic neutrality. Design code and guidelines for concrete members reinforced with these reinforcing bars have been proposed by the Canadian Standards Association (CSA) and ACI. Recent researches suggest that these methods do not account for some of the shear design parameters appropriately. One of them is the shear span-depth ratio (a/d), which has a significant effect on the shear capacity of FRP-reinforced members. This paper presents the assessment of the shear design methods of CSA and ACI for calculating the shear strength of FRP-reinforced concrete members. The accuracy of these methods for predicting shear capacity are assessed using 328 test results of rectangular beams and slabs that were studied in existing publications. The samples were reinforced for flexure only using FRP reinforcing bars, and there were no shear reinforcements. It was seen that the shear capacities predicted by applying the CSA and ACI procedures are conservative and widely scattered, mainly for deep beams (a/d < 2.5) due to the lack of proper implementation of this parameter. This is partly due to the arch action for this type of beam. The variations of shear strength for these beams are investigated. Based on this investigation, modifications of CSA and ACI guidelines have been proposed for members with a/d < 2.5 using a data set of 38 specimens. The proposed modifications have been verified using a data set of an additional 65 specimens. The proposed modifications were found to improve the results significantly for beams with a/d < 2.5 and provide uniform predictions over a wide range of d and a/d. [ABSTRACT FROM AUTHOR]

In this research, aimed to study the behavior of simply supported steel concrete composite beams with normal and high compressive strength of the concrete slab under the action of a span mid-point external load. The steel I-section beam is located at the bottom of reinforced concrete slab and connected with it by stud shear connectors. Eight composite beams were tested under the action of a monotonic load, half of them had a normal strength concrete slab while the others with a high strength concrete slab. Four degrees of shear connection interaction (100%, 80%, 60%, and 40%) were used for both groups of the tested beams. It was noticed that there are no essential differences between the modes of failure that occurred in the tested beams with normal strength concrete and those with high strength concrete. It was also found that there is an increase in the initial stiffness of the beams when the concrete changed from normal to high strength for different degrees of shear connections, but this increment reduced with increasing the degree of the shear connection. It was noted that the ultimate capacity of the tested beams was increased with enhancement of the strength of the adopted concrete from normal to high strength. The results showed that, when the concrete compressive strength was increased from 32.6 MPa to 72.8 MPa, the ultimate moment capacity of the specimens was increased from 28% for 100% shear connection, and it is increased to 38% for specimens with 40% shear connection.

Experimental tests, and two conventional grading curves, are used to design a dosing scheme, seeking the best way to enhance the general sustainability of certain types of low-to-medium workability concrete mixes. The aim is to achieve highly compacted aggregate gradations, thereby minimizing the need for Portland cement consumption. Several aggregate mix designs, employing fractions of both commercial limestone and recycled electric steelmaking slag, were prepared and assessed. Nine concrete mixes of structural quality (above 40 MPa as compressive strength) were manufactured to analyze their aggregate packing density and their performance as engineering concrete mixtures. The results obtained after classical testing showed excellent quality homogeneous concrete mixes, considering both the in-fresh and in-hard properties. Subsequently, a sustainability analysis of all the mixes led to the conclusion that they were of low environmental impact, due to their high aggregate content and their low cement consumption which, additionally, included other industrial co-products with hydraulic properties. [ABSTRACT FROM AUTHOR]

Copyright of Online Journal of Art & Design is the property of Online Journal of Art & Design and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Advancement in the field of construction has given rise to the modification of conventional materials in order to utilize the full potential of their components to achieve high durability, strength, and other engineering characteristics. Construction materials should ideally be environmental friendly. These diverse requirements resulted in the invention of high strength concrete (HSC). A rapidly increasing use of HSC in most of the construction projects has encouraged researchers to identify its behavior at elevated temperatures. This has led to the recognition of an inadequate understanding of elevated temperatures' effects on the behavior of HSC. This paper initially provides necessary information about HSC and relates its benefits. A number of different design standards for the preparation of HSC are also presented and compared. Previous research activities performed on HSC to identify the effect of elevated temperatures on the properties of HSC are reviewed. Findings showed that the mechanical properties of NSC decreases at a 10% to 20% higher rate than HSC ranging between ambient temperature and approximately 350°C, depending upon the mix proportions and initial compressive strength of the concrete. The differences become narrower at temperature above 350°C. Major failure modes are identified and future recommendations are presented. [ABSTRACT FROM AUTHOR]

Abstract This work presents topology-optimized design of plain concrete beams using a density-based approach and subsequent construction and experimental evaluation. Three elastic design cases are considered to allow investigation of the effect of using different topology optimization problem formulations and different safety factors on the material strengths. Specifically (i) the compliance is minimized under a limit on the material use, and (ii) stress limits are imposed with a Drucker-Prager criteria while the material use is minimized. Imposing stress limits on the design problem considered in this work is found to create solutions that require significant levels of post-processing prior to construction. This heuristic post-processing is demonstrated to have had a significant effect on the behavior of one of the design cases; leading to large variations in the experimental observations. In line with common design engineering practices, the most robust experimental behavior is found in the design with the highest safety factor on the concrete's tensile strength. Highlights • Two topology optimization algorithms are used to design constructible concrete beams. • The optimized performance is experimentally validated in the elastic range. • The objective properties are controlled in a design and robust across tested samples. • Non-controlled properties vary significantly between tested samples of a design. • Heuristic post-processing is demonstrated to alter the optimality of a design. [ABSTRACT FROM AUTHOR]

• Concept of raw-crushed wind-turbine blade as waste material defined. • Solution for recycling wind-turbine blades to be dismantled in the next years. • Waste composed of glass fibers and spherical particles of balsa wood and polyurethane. • Good concrete workability by five-stage mixing process and plasticizer adjustment. • Waste provided load-bearing capacity to concrete, and reduced its carbon footprint. Many of the first wind-turbine installations are reaching the end of their useful life, so their blades have to be replaced. Inexpensive, sustainable, and straightforward recycling solutions are therefore needed. The conversion of turbine blades into raw materials for concrete solutions is proposed in this paper, through a novel recycling process entailing non-selective cutting, crushing, and sieving of the blade walls, without component separation. The material, Raw-Crushed Wind-Turbine Blade (RCWTB), consists of fiberglass-composite fibers, polyurethane, and balsa-wood particles. It serves as concrete fibers and aggregates, according to its physical and microscopic characterizations. A customized concrete mix design and a five-stage mixing procedure with up to 6% RCWTB achieved suitable workability levels. The compressive strength of the RCWTB concrete was 40 MPa, and it had a higher load-bearing capacity and a lower carbon footprint than ordinary concrete. The results encourage research on the overall performance of RCWTB concretes. [Display omitted] [ABSTRACT FROM AUTHOR]

Copyright of Kufa Journal of Engineering is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The design of large concrete structures is a very complex area which requires specialized skills and specialized tools. Tools are available to design these structures efficiently. However, these design tools are based on inconsistency between what is assumed in the structural analysis and the sectional design. This inconsistency is believed to be conservative, but is such an approach always safe and cost-effective? In light of this, a design tool has been developed to eliminate this inconsistency. The program is called ShellDesign and the new method is called the 'consistent stiffness method'. The method can be used in practical design and is a more efficient alternative to running non-linear analysis programs. In order to obtain a more rational and consistent design method for transverse shear, implementation of the modified compression field theory (MCFT) in ShellDesign is almost finished. The main advantages of developing ShellDesign are to increase the competitiveness of concrete structures, contribute to increased safety and also to increase operability and document robustness in existing structures. [ABSTRACT FROM AUTHOR]

Abstract: The structure design problems of simulation inspection detector on ground are researched in this paper. The general design scheme is proposed based on the design task requirements of simulation inspection detector with a synthetic consideration on the requirements of the whole mass and the real grounded force. Detailed design for the concrete mechanical strcture has been carried out. The prototype of simulation inspection detector meets the test requirements, which can also provide important reference for the detector improvement [Copyright &y& Elsevier]

The paper presents the development of an adaptable strut-and-tie model that can be applied to the design or analysis of four-pile caps that support axial compression and biaxial flexure from a supported rectangular column. Due to an absence of relevant test data, the model is validated using non- linear finite element analyses (NLFEA). The results indicate that the use of the proposed model would lead to safe and economical designs. The proposed model can be easily extended to any number of piles, providing a rational procedure for the design of wide range of pile caps. [ABSTRACT FROM AUTHOR]

This paper presents and discusses the applications of neural networks in concrete structures. It aims at introducing neural networks applications in structural design. The paper covers two applications of neural networks in concrete structures. Backpropagation networks are chosen for the proposed network, which is written using the programming package MAT-LAB. The overall results are compared and observed for the performance of the networks. Based on the applications it was found that neural networks are comparatively effective for a number of reasons, which include the amount of CPU memory consumed by neural networks is less than that consumed by conventional methods and their ease of use and implementation, neural networks provide both the users and the developers more flexibility to cope with different kinds of problems. [Copyright &y& Elsevier]

The application of Eurocode EN 1992-1-1 in revising the South African standard for structural concrete design SABS 0100-1:1992 will require the determination of partial factors in accordance with the reliability requirements of the revised South African loading code SANS 10160:2010. The partial material factors γs for steel and γc for concrete are proposed in analysing the reliability of reinforced concrete slabs and short centrically loaded columns. It appears that the partial factors γs = 1,10 and γc = 1,40 are a suitable set of factors to be considered in the foreseen revision of the code. Further research is required on the model uncertainty for different structural members (flexural members, shear, columns, walls) and the theoretical models of basic resistance variables related to quality control.

• Type and intensity of frost damage were affected by freezing conditions. • Amount and size of air voids were changed depending on the type of admixture. • Importance of strength of concrete concerning frost damage was investigated. • A severe scaling tests can be conducted by applying a slow freezing rate and exposure time at minimum temperature. • Microstructural examinations indicated the location and depth of the damage. Repeated freezing and thawing (F-T) cycles are the major reason for the frost damage and premature failure in concrete structures. Frost damage can be evaluated by its effects on formation of internal cracks and scaling at the surface of concrete. Both internal frost damage and surface scaling mechanisms depend on several environmental factors such as the rate of freezing, minimum temperature and the duration at the minimum temperature. The objective of this study is to investigate the effects of freezing conditions on the type and intensity of damage, and on microstructure of concrete. Investigations, within the scope of this research, indicated that freezing conditions significantly affect the F-T resistance assessment of the concrete mixtures. Microstructural examinations also revealed the severity of the scaling under slower freezing rate and longer exposure time at the minimum temperature. Therefore, examination of the local freezing and thawing regime is crucial for designing durable and sustainable concrete structures. [ABSTRACT FROM AUTHOR]

Artificial marine infrastructures now cover large stretches of the available natural shoreline in many parts of the world. This is having a substantial impact on the local marine ecosystems as biodiverse natural hard substrata are being replaced with man-made structures, which have been shown to support lower levels of biodiversity. The ecological value of artificial coastal structures could be enhanced through careful design of pre-fabricated ecologically engineered units. Material selection is a critical parameter in the design of these units. To maximise the potential of concrete units to support and increase biodiversity, this paper explores the impact of binder composition, aggregate type and plasticizer on surface chemistry and early biofilm formation which influence subsequent colonisation. Experiments in the current study have shown that the addition of ground granulated blast-furnace slag (GGBS) to the mix can increase the levels of biodiversity supported while maintaining engineering performance requirements in terms of strength, chloride resistance and alkalinity. Conversely the aggregate type and use of a plasticizer have a minor influence. In particular, the addition of GGBS was shown to increase the biomass of diatoms, cyanobacteria and green algae and barnacle abundance one month after immersion on both sheltered surfaces and those exposed to wave action. Results suggest that concrete composition can alter the surface chemistry of artificial structures and thereby can improve the ecological value of these structures as habitats for marine life. • Effect of various binder, aggregate and plasticizer mixes of concrete were tested on engineering and biological performance • Variation in concrete mix design is shown to have a clear impact on concrete chemistry and biofilm development • Binder type is shown to influence the concrete alkalinity and early colonisation of concrete tiles • Additionally, the CEM I/GGBS mixtures are found to have lower surface alkalinity and higher growth of biofilm [ABSTRACT FROM AUTHOR]