Nanoparticles in Concrete: Application in Fresh and Hardened State

2018 ◽  
Vol 760 ◽  
pp. 3-9
Author(s):  
Jiří Němeček ◽  
Rostislav Šulc ◽  
Jitka Němečková ◽  
Jaroslav Kruis
Keyword(s):  
Electric Field ◽  
Fresh Concrete ◽  
Concrete Structures ◽  
Concrete Surface ◽  
Ionic Species ◽  
Reinforced Concrete Structures ◽  
Colloidal Solutions ◽  
Concrete Mixtures ◽  
Hardened State ◽  
Pore Liquid

The paper summarizes utilization of nanoparticles (NP) in concrete for enhancing its mechanical, transport or other properties. The first part is devoted to review of NPs used in fresh concrete mixtures that have been reported previously in the literature while the second part shows original results from utilization of nanoparticles as healing agents for reparing of existing concrete structures. In the second case, nanoparticles are delivered to concrete via electrokinetic principle by using their surface charge provided in colloidal solutions. Particles are transported in the pore liquid of concrete due to electric field applied between the concrete surface and steel reinforcement. In this way, distressed concrete can be repaired, cracks sealed and risk of corrosion diminished. The injection of NPs can be complemented with extraction of chlorides that are the main deteriorating chemicals in reinforced concrete structures. Finally, the paper shows a framework developed for the electrokinetic transport of ionic species in concrete applied to chloride extraction from concrete and how it can be modified also for transport of nanoparticles.

Experience of Using Self-Compacting Concrete Mixes in Transport Construction

2020 ◽  
Vol 992 ◽  
pp. 135-142
Author(s):  
I. Pulyaev ◽  
S. Pulyaev
Keyword(s):  
European Union ◽  
Reinforced Concrete ◽  
Concrete Structures ◽  
Tunnel Construction ◽  
Reinforced Concrete Structures ◽  
Use Of Self ◽  
The European Union ◽  
Self Compacting Concrete ◽  
Concrete Mixtures ◽  
The Creation

The creation of self-compacting concrete (SCC) is associated with the introduction of plasticizing additives based on polycarboxylate esters (PCE). The first patent for a group of substances proposed for use as superplasticizers for concrete, was declared in the early 80-ies of the last century in Japan. In the mid 90-ies superplasticizers based on esters of polycarboxylates began to be used in Europe. In Russia, the use of self-compacting concrete began much later, and in bridge and tunnel construction almost a few years ago. Currently, in the European Union, 70-80% of reinforced concrete structures are made or erected from self-compacting concrete mixtures, and concrete is commonly called self-compacting. In Russia, such concretes are sometimes called self-leveling. The volume of their use is still small.

Nanoparticle Injection into Concrete Using Electromigration

2014 ◽  
Vol 1054 ◽  
pp. 6-10 ◽  
Author(s):  
Jiří Němeček ◽  
Yun Ping Xi
Keyword(s):  
Reinforced Concrete ◽  
Electric Field ◽  
Concrete Structures ◽  
Chloride Penetration ◽  
Reinforced Concrete Structures ◽  
Testing Chamber ◽  
Chloride Profile ◽  
Nanosilica Particles ◽  
Penetration Tests ◽  
Small Voltage

This paper aims at investigation of possibilities and effectiveness of chloride extraction from concrete and nanoparticle injection into existing reinforced concrete structures by means of electromigration technique. Concrete specimens are exposed to accelerated chloride penetration tests in order to simulate a natural chloride exposure. The developed chloride profile is removed by electroextraction by reversing the polarity in the testing chamber. In a similar manner, concrete specimens are injected with different concentrations of colloidal nanosilica particles. It was shown in the paper that chlorides can be effectively extracted from the concrete using small voltage lasting for several days. Higher concentration solutions of nanosilica can also be effectively transported into concrete via the electric field. Once injected nanosilica can act as microstructure densifier and further reduce chloride penetration as demonstrated by decreased diffusivity of the treated concrete.

ON PECULARITIES OF PRODUCTION PROCESSES AND AIR POLLUTION LEVEL, BUILDING ENTERPRISES CONSIDERED TO BE THE SOURCE OF EMISSION

2014 ◽  
Vol 4 (3) ◽  
pp. 84-88 ◽  
Author(s):  
Natalia Emirovna POSPELOVA ◽  
Elmira Khamzyanovna TIMIRBULATOVA
Keyword(s):  
Air Pollution ◽  
Reinforced Concrete ◽  
Concrete Structures ◽  
Pollution Level ◽  
Reinforced Concrete Structures ◽  
Concrete Mixtures ◽  
Production Processes ◽  
Level Building ◽  
Building Enterprises

The paper describes production processes of reinforced concrete structures, bricks and bitumen-concrete mixtures. The authors stress the fact that during their experiment dust-and-gas catch systems have been installed for all production processes which allocate dust. They also examine sources of contaminants emission and their dependence on diff erent production processes. The authors succeed in using the most eff ective dust-and-gas catch systems.

scholarly journals STRUCTURAL DESIGN OF POLYMER PROTECTIVE COATINGS FOR REINFORCED CONCRETE STRUCTURES. PART I: THEORETICAL CONSIDERATIONS

2007 ◽  
Vol 13 (1) ◽  
pp. 11-17 ◽  
Author(s):  
Zenonas Kamaitis
Keyword(s):  
Reinforced Concrete ◽  
Protective Coatings ◽  
Concrete Structures ◽  
Concrete Surface ◽  
Polymer Coatings ◽  
Concrete Cover ◽  
Reinforced Concrete Structures ◽  
Coating Materials ◽  
Barrier Materials ◽  
Mechanism Of Degradation

In a number of situations reinforced concrete structures must be protected by barrier materials to prevent contact with aggressive agents. One of the ways to protect concrete structures from corrosion is to use protective polymer coatings. Polymers as coating materials are not totally resistant and impermeable to all aggressive agents. Gases, vapors and liquids penetrate into a polymer so that the polymer mass swells and eventually disintegrates. However, the penetration/disintegration progresses at a much lower rate than that in the concrete. Surface coatings are able to reduce considerably the penetration, to slow down the rate of deterioration of concrete cover and to overcome most durability problems associated with external attack. In this article the mechanism of degradation of polymer coatings are analyzed. Methodology and predictive models for the degradation over time caused by aggressive actions of polymer coatings are presented. Proposed models can be applied to design of polymer coatings. Such a design of coatings is presented in a simple form for engineering design purposes.

Applying Ultrasound Detection Devices to Examine Pгореrties of Concrete Structures

2021 ◽  
Vol 1038 ◽  
pp. 424-429
Author(s):  
Viktor Kolokhov
Keyword(s):  
Software Package ◽  
Concrete Structures ◽  
Statistical Processing ◽  
Concrete Surface ◽  
Reinforced Concrete Structures ◽  
Ultrasonic Vibrations ◽  
Regulatory Requirements ◽  
Ultrasonic Measurements ◽  
Calibration Dependence ◽  
Ultrasonic Devices

The article considers the problems of diagnostics of reinforced concrete structures and creation the generalized calibration dependence for the use of ultrasonic devices. The results of the study of the influence of some factors on the results of measuring the dissemination time of ultrasonic vibrations are presented. The study was conducted using devices "Pulsar 1.1" and "Novotest IPSM-U" in compliance with regulatory requirements. Statistical processing of the obtained results (with visualization) was performed using the software package EXEL. Processing of the obtained data confirmed the multifactorial dependence of ultrasonic measurements on the concrete surface. The lack of clearly defined conditions for measurements reduces the reliability of the results. The use of ultrasonic measurements to obtain absolute values of the properties of concrete is not adequate. It is proposed to make changes to the regulations regarding the limits of application of ultrasonic measurements.

scholarly journals Development of Bonded/Riveted Steel Anchorages of Prestressed CFRP Strips for Concrete Strengthening

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2217
Author(s):  
Bartosz Piątek ◽  
Tomasz Siwowski ◽  
Jerzy Michałowski ◽  
Stanisław Błażewicz
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Concrete Surface ◽  
Epoxy Adhesive ◽  
Full Scale ◽  
Steel Plates ◽  
Tensile Failure ◽  
Small Scale ◽  
Reinforced Concrete Structures ◽  
Flexural Strengthening

CFRP (carbon fiber reinforced polymer) strips are currently often used to strengthen reinforced concrete structures in flexure. In order to ensure effective strengthening, proper connection between FRP material and concrete structure is needed. CFRP strips can be applied passively (only by bonding to the concrete surface) or actively (by prestressing before bonding). In the case of passive strengthening, CFRP strips connecting by bonding to the surface along the strengthened element are usually sufficient. However, active (prestressing) CFRP strips should be additionally anchored at their ends. Anchoring of unidirectional CFRP strips to the reinforced concrete is difficult because of their weak properties in transverse directions. The paper presents a development of mechanical steel anchorages used in an active CFRP flexural strengthening system for reinforced concrete structures. The anchorages were made of steel plates connected to CFRP strips with steel rivets and epoxy adhesive. They were developed within series of tests on specimens from small-scale to full-scale tested in an axial tensile scheme. The paper describes successive modifications of the anchorages as well as the results of full-scale tests. The final version of the anchorage developed during the research had a tensile failure force of 185 kN, which is sufficient value for CFRP strengthening purposes.

scholarly journals The Performance of Carbon Fibre Composites as ICCP Anodes for Reinforced Concrete Structures

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Chinh Van Nguyen ◽  
Paul Lambert ◽  
Pal Mangat ◽  
Fin O’Flaherty ◽  
Graeme Jones
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fibre ◽  
Cathodic Protection ◽  
Concrete Structures ◽  
Steel Corrosion ◽  
Concrete Surface ◽  
Reinforced Concrete Structures ◽  
Reinforcing Steel ◽  
Fibre Composites ◽  
Carbon Fibre Composites

Cathodic protection has been proven to be one of the most widely applicable and cost-effective solutions for tackling steel corrosion in reinforced concrete. In this study, the possible use of carbon fibre composites, which are primarily used to strengthen concrete members, has been investigated as impressed current cathodic protection anodes. Carbon fibre anodes have been assessed in both concrete and calcium hydroxide solution. Two bonding mediums incorporating epoxy and geopolymer have also been investigated. The results demonstrate that epoxy resin can be used for bonding carbon fibre fabric anodes to reinforced concrete structures while geopolymer is more effective for bonding carbon fibre reinforced polymer (CFRP) rod into preformed grooves in the concrete surface. The dissolution of carbon fibre anode appears to stablise after a period of time, dependent upon the size and shape of the anode and applied voltage and current. Based on the present results, a maximum current density of 128 mA/m2 of reinforcing steel area is recommended for the operation of CFRP fabric anode and 64 mA/m2 of reinforcing steel area for that of CFRP rod anode.

scholarly journals RESEARCH OF WAYS TO INCREASE CORROSION RESISTANCE IN REINFORCED CONCRETE CONSTRUCTIONS. PART 2

2020 ◽  
Vol 10 (3) ◽  
pp. 15-20
Author(s):  
Nadezhda V. KONDRATYEVA ◽  
Alexandra Yu. ALFIMENKOVA
Keyword(s):  
Corrosion Resistance ◽  
Reinforced Concrete ◽  
Nitric Acid ◽  
Concrete Structures ◽  
Concrete Surface ◽  
Formaldehyde Resin ◽  
Reinforced Concrete Structures ◽  
Two Component ◽  
Resin Binder ◽  
Increase Corrosion Resistance

The article presents the results of the fi nal series of tests on the study of ways to increase the corrosion resistance of reinforced concrete structures with primary protection in the form of an addition of acetone-formaldehyde resin ACF-75 and with secondary protection with a two-component resin Binder EP 11 Tikso. An analysis of the change in the adhesion strength of secondary protection elements with a concrete surface after exposure to sulfuric and nitric acid, as well as the eff ect of the presence of a preliminary primer on a concrete surface on the intensity of adhesion change is presented. Conclusions are drawn about the possibility of using a two-component resin Binder EP 11 Tikso as a secondary protection against corrosion destruction of concrete in the process of reinforcing reinforced concrete structures operating in environments containing sulfuric and nitric acids.

scholarly journals Experimental Testing of the Effects of Fine Particles on the Properties of the Self-Compacting Lightweight Concrete

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Sandra Juradin ◽  
Goran Baloević ◽  
Alen Harapin
Keyword(s):  
Compressive Strength ◽  
Fine Particles ◽  
Lightweight Concrete ◽  
Fresh Concrete ◽  
Experimental Testing ◽  
Concrete Surface ◽  
The Self ◽  
Hardened Concrete ◽  
Hardened State ◽  
Low Mass

The self-compacting lightweight concrete (SCLC) is a combination of the Self compacting concrete (SCC) and the Lightweight concrete. It combines all the good properties of those two materials and is extremely convenient for the construction of buildings that require low mass and do not require high compressive strength, for example restoration works in old structures (e.g., replacement of wooden floors), prefabricated elements that require transportation, and for structures and elements where the concrete surface should be visible. In this paper the effect of the amount of fine particles on the properties of the self-compacting lightweight concrete (SCLC) in the fresh and hardened state was explored. For this purpose, sets of specimens with different combinations of admixtures of silica fume, fly ash, and filler were prepared and tested. Slump flow and flow time of fresh concrete, as well as the dynamic elastic modulus and compressive strength of hardened concrete, were measured at different ages of concrete. The processes of manufacturing and methods of testing are described, as well as the obtained results.

Design of precast reinforced concrete structures of frame buildings: a new set of rules

2019 ◽  
pp. 4-9 ◽  
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Building Frames ◽  
Fine Grained ◽  
Rigid Frame ◽  
Floor Slabs ◽  
Frame Buildings ◽  
Spatial System ◽  
Precast Elements

Currently, prefabricated reinforced concrete structures are widely used for the construction of buildings of various functional purposes. In this regard, has been developed SP 356.1325800.2017 "Frame Reinforced Concrete Prefabricated Structures of Multi-Storey Buildings. Design Rules", which establishes requirements for the calculation and design of precast reinforced concrete structures of frame buildings of heavy, fine-grained and lightweight structural concrete for buildings with a height of not more than 75 m. The structure of the set of rules consists of eight sections and one annex. The document reviewed covers the design of multi-story framed beam structural systems, the elements of which are connected in a spatial system with rigid (partially compliant) or hinged joints and concreting of the joints between the surfaces of the abutting precast elements. The classification of structural schemes of building frames, which according to the method of accommodation of horizontal loads are divided into bracing, rigid frame bracing and framework, is presented. The list of structural elements, such as foundations, columns, crossbars, ribbed and hollow floor slabs and coatings, stiffness elements and external enclosing structures is given; detailed instructions for their design are provided. The scope of the developed set of rules includes all natural and climatic zones of the Russian Federation, except seismic areas with 7 or more points, as well as permafrost zones.

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