scholarly journals Experimental study and modeling of the mechanical behavior of recycled aggregates-based high-strength concrete

2021 ◽  
Vol 15 (56) ◽  
pp. 203-216
Author(s):  
Kheira Camellia Nehar ◽  
Dalila Benamara
Keyword(s):  
Sustainable Development ◽  
High Strength Concrete ◽  
High Efficiency ◽  
Raw Materials ◽  
High Strength ◽  
Recycled Aggregates ◽  
Concrete Aggregates ◽  
Strength Concrete ◽  
Construction And Demolition Wastes ◽  
Natural Aggregates

Concrete, a material of prime importance, is widely used in various works. Among the raw materials composing concrete, aggregates come first. It is widely acknowledged that the consumption of natural aggregates increases with the growth in the amount of concrete needed. It has recently emerged that concrete waste can be recycled and reused in civil engineering works after a series of treatments. Moreover, in order to protect the environment and based on the principles of sustainable development, it was considered urgent to produce a High Strength Concrete incorporating recycled materials in addition to silica fume and a high-efficiency superplasticizer. This would certainly help to establish a harmonious sustainable development that guaranties the ecological balance and environmental protection, and prevents the depletion of natural resources. This study is part of a larger research program that that seeks to recover, recycle and valorize construction and demolition wastes. The main objective sought in this article is firstly to use aggregates from demolition concrete in the manufacture of a new concrete with high mechanical and rheological performance, and secondly, to model the behavior of this type of concrete using the Finite Element Method. This modeling aims to evaluate the maximum compressive strengths and compare them with those obtained experimentally.

scholarly journals Transverse Deformations and Structural Phenomenon as Indicators of Steel Fibred High-Strength Concrete Nonlinear Behavior

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Iakov Iskhakov ◽  
Yuri Ribakov
Keyword(s):  
High Strength Concrete ◽  
High Efficiency ◽  
Limit State ◽  
Nonlinear Behavior ◽  
High Strength ◽  
Steel Fibers ◽  
Ultimate Limit State ◽  
Strength Concrete ◽  
Brittle Behavior ◽  
Ductile Behavior

As known, high-strength compressed concrete elements have brittle behavior, and elastic-plastic deformations do not appear practically up to their ultimate limit state (ULS). This problem is solved in modern practice by adding fibers that allow development of nonlinear deformations in such elements. As a rule, are applied steel fibers that proved high efficiency and contribute ductile behavior of compressed high-strength concrete (HSC) elements as well as the desired effect at long-term loading (for other types of fibers, the second problem is still not enough investigated). However, accurate prediction of the ULS for abovementioned compression elements is still very important and current. With this aim, it is proposed to use transverse deformations in HSC to analyze compression elements' behavior at stages close to ultimate. It is shown that, until the appearance of nonlinear transverse deformations (cracks formation), these deformations are about 5-6 times lower than the longitudinal ones. When cracks appear, the tensile stress-strain relationship in the transverse direction becomes nonlinear. This fact enables to predict that the longitudinal deformations approach the ultimate value. Laboratory tests were carried out on 21 cylindrical HSC specimens with various steel fibers content (0, 20, 30, 40, and 60 kg/m3). As a result, dependences of transverse deformations on longitudinal ones were obtained. These dependences previously proposed by the authors’ concept of the structural phenomenon allow proper estimation of the compressed HSC state up to failure. Good agreement between experimental and theoretical results forms a basis for further development of modern steel fibered HSC theory and first of all nonlinear behavior of HSC.

scholarly journals Production of Greener High-Strength Concrete Using Russian Quartz Sandstone Mine Waste Aggregates

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5575
Author(s):  
Aleksandr Tolstoy ◽  
Valery Lesovik ◽  
Roman Fediuk ◽  
Mugahed Amran ◽  
Murali Gunasekaran ◽  
...  
Keyword(s):  
High Strength Concrete ◽  
Raw Materials ◽  
Mine Waste ◽  
Natural Radionuclides ◽  
High Strength ◽  
Morphological Properties ◽  
Cement Matrix ◽  
Natural Activity ◽  
Strength Concrete ◽  
The Cost

Quartz sandstone (QS) is a mine waste; therefore, its use in construction allows for both reducing the cost of the concrete and contributing to the utilization of waste. The scientific originality of this study is the identification of models of the effect of QS aggregate on the physicomechanical, durability characteristics, and eco-safety of greener high-strength concrete. The study used an energy-efficient method of non-thermal effects of electromagnetic pulses on the destruction mechanisms of quartz-containing raw materials. The characteristics of quartzite sandstone aggregates, including the natural activity of radionuclides, were comprehensively studied. The features of concrete hardening, including the formation of an interfacial transition zone between the aggregate and the cement matrix, were studied, taking into account the chemical and morphological features of quartzite sandstone. In addition, the microstructural and morphological properties of concrete were determined after a 28 day curing. In this study, the behaviors of the concrete with QS aggregate were investigated, bearing in mind the provisions of geomimetics science on the affinity of structures. The results obtained showed that the QS aggregate had the activity of natural radionuclides 3–4 times lower compared to traditional aggregates. Efficient greener concrete with a 46.3 MPa compressive strength, water permeability grade W14, and freeze–thaw resistance of 300 cycles were also obtained, demonstrating that the performance of this greener concrete was comparable to that of traditional concrete with more expensive granite or gabbro diabase aggregates.

Prodution of Concrete Aggregates with High Strength by Using the Wastes

2010 ◽  
Vol 163-167 ◽  
pp. 1651-1654 ◽  
Author(s):  
Jin Bang Wang ◽  
Zong Hui Zhou
Keyword(s):  
Water Absorption ◽  
Apparent Density ◽  
Raw Materials ◽  
Steel Slag ◽  
High Strength ◽  
National Standards ◽  
Concrete Aggregates ◽  
Natural Aggregates ◽  
Different Content ◽  
Furnace Slag

Several series of concrete aggregates with different content of steel slag, blast furnace slag, coal gangue and fly ash were prepared. The reasonable ratio of raw materials and process parameters to prepare the aggregates were determined by measuring the water absorption, crush indicators and apparent density of the aggregates. The mineral composition and morphology of the aggregates were analyzed by XRD, SEM and EDS. The results showed the aggregate with about 30% steel slag, 50% slag, 20% gangue, and calcined at 1300°C for 90 minutes had the best performance. The water absorption of the aggregate is about 1.55% which is lower than that of the natural aggregates (about 2.2% on average). Both the crushing index (about 11.39%) and the apparent density (2672 kg/m3) of the aggregate meet the requirements of national standards.

A NEW KIND OF CEMENT AS A SOLUTION TO THE ENVIRONMENTAL CHALLENGES OF MODERNITY

2021 ◽  
Author(s):  
G Kasimova
Keyword(s):  
Fly Ash ◽  
High Strength Concrete ◽  
Fresh Concrete ◽  
Raw Materials ◽  
Road Construction ◽  
High Strength ◽  
Strength Concrete ◽  
Cement Replacement ◽  
Air Content ◽  
Concrete Mix

The article presents studies on the production of high-strength concrete for road construction for a given 28-day strength on local raw materials. As a cement-replacement additive, fly ash was used. It was found out that the fresh concrete mixture had adequate workability, the air content of the concrete mix withthe sperplastifizer, the 28-day strength of the base mixture, which corresponded to the required strength.

Effective Elements of Building Structures from Pipe Concrete

2019 ◽  
Vol 945 ◽  
pp. 80-84
Author(s):  
O.E. Sysoev ◽  
A.Y. Dobryshkin ◽  
Ye.O. Sysoyev
Keyword(s):  
Cross Sections ◽  
High Strength Concrete ◽  
High Efficiency ◽  
High Strength ◽  
Strength Properties ◽  
Building Structures ◽  
Strength Concrete ◽  
Concrete Pipe ◽  
Bending Load ◽  
Concrete Elements

The article is devoted to the investigation of pipe-concrete prestressed structural elements with high efficiency. This is due to a more complete use of the strength properties of structural materials in the pipe-concrete beam. The article presents various methods for calculating pipe-concrete elements. The design of a concrete tube with a prestressed element using high-strength concrete is presented. The results of calculations of various designs are shown and the cross-sections of beams for perception of the same bending load are selected. A comparison is made between the consumption of beam materials of various designs. The effectiveness of the use of pipe-concrete elements for receiving bending loads made of high-strength concrete with prestressed reinforcement is shown in comparison with the construction of beams of traditional high-strength concrete, high-strength concrete pipe-concrete with no prestressing of reinforcement and metal beam, mass of the element, consumption of metal and concrete.

Experimental Study on Rebound Curve of High-Strength Concrete

2021 ◽  
Vol 881 ◽  
pp. 137-141
Author(s):  
Cao Li ◽  
Wang Qing Gao
Keyword(s):  
High Strength Concrete ◽  
Raw Materials ◽  
Engineering Application ◽  
Basic Research ◽  
High Strength ◽  
Detection Accuracy ◽  
Concrete Technology ◽  
Strength Concrete ◽  
Strength Curve ◽  
Important Basis

As the application of high-strength concrete in civil engineering becomes more and more extensive in our country, it needs to cooperate with the popularization and application of new high-strength concrete technology so as to solve the practical problems of high-strength concrete in the engineering application of the strength detection and master the national strength measurement curve of high-strength concrete. A representative commercial concrete manufacturer in Guangzhou was selected for the detection accuracy of this area. And the general raw materials in Guangzhou were used to make concrete specimens. The 4.5J high-strength rebound tester and 5.5J high-strength rebound tester were used for testing the rebound value of the specimen and the compressive strength of the specimen at different ages. The basic research results can be used as an important basis for establishing the strength curve of high-strength concrete areas.

scholarly journals FINE-GRAINED HIGH-STRENGTH CONCRETE

2020 ◽  
Vol 3 (1) ◽  
pp. 39-43 ◽  
Author(s):  
A. Tolstoy
Keyword(s):  
Structure Formation ◽  
Mineral Composition ◽  
Production Technology ◽  
High Strength Concrete ◽  
Raw Materials ◽  
Stable State ◽  
High Strength ◽  
Economic Feasibility ◽  
Strength Concrete ◽  
Fine Grained

the article discusses the possibilities of improving the strength characteristics of fine-grained concrete. Modification of compositions and production technology of fine-grained high-strength concrete is possible with the use of natural and man-made raw materials of various chemical and mineral composition. It is shown that it is possible to increase the economic feasibility of high-strength fine-grained concretes with the preservation of performance characteristics due to the use of man-made raw materials and production waste. The issues of controlling the processes of structure formation and identifying a potentially stable state of hardening compositions are considered, possibly on the basis of modification and design methods for the composition of construction objects with improved properties.

scholarly journals Optimum Sustainable Mix Proportions of High Strength Concrete by Using Taguchi Method

2020 ◽  
Vol 14 (54) ◽  
pp. 211-225
Author(s):  
M.A. Warda ◽  
H.S. Khalil ◽  
Seleem Ahmad ◽  
I.M. Mahdi
Keyword(s):  
Fly Ash ◽  
High Strength Concrete ◽  
Design Methodology ◽  
Steel Fiber ◽  
Raw Materials ◽  
Aggregate Size ◽  
High Strength ◽  
Maximum Aggregate Size ◽  
Strength Concrete ◽  
Technical Requirements

In this study, mix proportion parameters of high strength concrete (HSC) were analyzed by using the Taguchi’s experiment design methodology for optimal design. For that purpose, mixtures are designed in a L27 orthogonal array with six factors, namely, ‘Silica Fume’, ‘Steel Fiber’, ‘Super-Plasticizer’, ‘Maximum Aggregate Size (AG)’, ‘Water / cementitious material (W/C) ratio’, ‘Fly Ash’. The mixtures were extensively tested to meet technical requirements of HSC. The experimental results were analyzed by using the Taguchi experimental design methodology. The best possible levels for mix proportions were determined for maximization of compressive strength at 7, 28, 56, 90 days, splitting tensile strength at 28 days, flexural strength at 28 days, and the slump. Also the best possible levels for mix proportions were determined for minimization of the production cost. It was found that steel fibers and fly ash are the most dominant factors in the process of optimization. The advantage of using steel fiber and fly ash was the reduced energy and cost associated with the raw materials which meant more sustainable concrete could be attained. It was also found that there is a necessity to apply a multi- response optimization to get the best mix proportions.

scholarly journals DEVELOPMENT OF COMPOSITIONS OF FILLED INSULATORS BASED ON SECONDARY RAW FOR MONOLITHIC HIGH-STRENGTH CONCRETE

2019 ◽  
Vol 46 (3) ◽  
pp. 129-138
Author(s):  
A. Kh. Alaskhanov ◽  
T. S. Murtazaeva ◽  
M. S.-A. Saidumov ◽  
A. O. Omarov
Keyword(s):  
Structure Formation ◽  
High Strength Concrete ◽  
Raw Materials ◽  
High Strength ◽  
Recycled Materials ◽  
Strength Concrete ◽  
Regulatory Documents ◽  
Concrete Mixtures ◽  
Technogenic Raw Materials ◽  
Mineral Fillers

Objectives Development of compositions filled with binders based on recycled materials for monolithic high-strength concrete.Method The research methods adopted in the work are based on the theoretical principles and laws of designing and optimizing polydisperse multicomponent systems, the phase and structure formation of clinker minerals, the logic of mathematical calculations, the technological features of the structure formation of composite masses, the theoretical principles of controlling the rheological processes of mixes. All experimental data presented in the work were obtained according to the methods of current regulatory documents (GOST, recommendations, etc.).Result The paper provides an analysis of the experience of using recycled materials in the form of products of demolition of buildings and structures, the technology for producing secondary raw materials for concrete on their basis. Formulations filled with binders with an activity of 60-71 MPa with finely dispersed mineral fillers from concrete scrap and brick combat with a ratio of 70:30%, respectively, were developed and investigated.Conclusion The optimal formulations of highly mobile concrete mixtures were designed using local natural and technogenic raw materials with a grade of P5 cone sediment and persistence for more than 8 hours to obtain high-strength classes of compressive strength up to B60-B80 with unique operational properties. 

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