APPLICATION OF INNOVATIVE MATERIALS IN PRECAST CONCRETE STRUCTURES

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Klaus Holschemacher
Keyword(s):  
Reinforced Concrete ◽  
Construction Industry ◽  
Precast Concrete ◽  
Cementitious Materials ◽  
Concrete Cover ◽  
Fiber Reinforced Concrete ◽  
Textile Reinforced Concrete ◽  
Construction Methods ◽  
Corrosion Risk ◽  
Innovative Materials

Construction industry contributes essentially to Germany’s gross domestic product (GDP). In 2015 construction investments amounted around 300 billion Euro corresponding to a share of 10% of total GDP. Because of the essential importance of construction industry there are many activities aiming on reduction of construction costs and improvement of durability and sustainability. Recent tendencies in precast concrete industry include application of innovative materials like self-compacting concrete, fiber reinforced concrete, textile reinforced concrete, carbon concrete composite and strain hardening cementitious materials. The report describes the material developments and first applications for precast concrete members. By the application of non-metallic reinforcement, such as carbon meshes and carbon bars, there is no corrosion risk for the reinforcement resulting in an essentially lower concrete cover and depth of structural members. However, the use of carbon reinforcement requires new design concepts and new construction methods. By solving these problems there is a big chance for precast concrete industry to enhance their market share.

scholarly journals Improving the Mechanical Performance of Shell Precast Concrete Blocks for Coastal Protection Structures of Hydraulic Works

2021 ◽  
Vol 11 (1) ◽  
pp. 6787-6791
Author(s):  
N. Viet Duc
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
High Performance ◽  
Mechanical Performance ◽  
Precast Concrete ◽  
Reference Beam ◽  
Concrete Cover ◽  
Fiber Reinforced Concrete ◽  
Bending Test ◽  
Coastal Protection

Although the use of concrete and reinforced concrete for construction has been widespread, more studies are needed on marine structures exposed directly to corrosive environments to prolong their service life. This paper proposes a new type of shell precast concrete block for coastal structures, studying a beam consisting of 15mm High-Performance Glass Fiber-Reinforced Concrete (HPGFRC) at the bottom and 45mm Traditional Concrete (TC) for the rest of the structure. Steel bar reinforcements were placed at the bottom with a concrete cover of 25mm to avoid abrupt failure. The strength classes of HPGFRC and TC were 60MPa and 30MPa respectively. A reference beam consisting of TC only was also prepared for comparison. The four-point flexural bending test results showed that the first cracking strength of the proposed beam was 20% higher, as HPGFRC performed better on tension than TC. Additionally, HPGFRC's maximum strength was 25% greater than TC's. Furthermore, HPGFRC possessed more durable characteristics such as waterproof grade, abrasion resistance, and shrinkage than TC, promising to protect the reinforcement from the aggressive marine environment and corrosion, prolonging the service life of the structure.

Fiber-reinforced concrete in precast concrete applications: Research leads to innovative products

PCI Journal ◽  
2012 ◽  
Vol 57 (3) ◽  
pp. 33-46 ◽  
Author(s):  
Nemkumar Banthia ◽  
Vivek Bindiganavile ◽  
John Jones ◽  
Jeff Novak
Keyword(s):  
Reinforced Concrete ◽  
Precast Concrete ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Innovative Products

Repair of Severely Damaged Reinforced Concrete Beams with High-Strength Cementitious Grout

2020 ◽  
Vol 2674 (6) ◽  
pp. 372-384
Author(s):  
Antoine N. Gergess ◽  
Mahfoud Shaikh Al Shabab ◽  
Razane Massouh
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Cementitious Materials ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Rc Structures

High-strength cementitious materials such as high-performance concrete are extensively used for retrofit of reinforced concrete (RC) structures. The effectiveness of these materials is increased when mixed with steel fibers. A commonly used technique for strengthening and repair of RC beams consists of applying high-performance fiber-reinforced concrete jackets around the beam perimeter. This paper investigates the jacketing method for repairing severely damaged RC beams. Four 2 m (6 ft 63/4 in.) long rectangular RC beams, 200 × 300 mm (8 ×12 in.) were initially cast and loaded until failure based on three-point bending tests. The four beams were then repaired by thickening the sides of the damaged RC beams using a commercially available high-strength shrinkage grout with and without steel fibers. Strain and deformation were recorded in the damaged and repaired beams to compare structural performance. It is shown that the flexural strength of the repaired beams is increased and the crack pattern under loading is improved, proving that the proposed repair method can restore the resistance capacity of RC beams despite the degree of damage. A method for repair is proposed and an analytical investigation is also performed to understand the structural behavior of the repaired beams based on different thickening configurations.

scholarly journals New warning sensors to detect corrosion risk in reinforced concrete

2019 ◽  
Vol 289 ◽  
pp. 06002
Author(s):  
Mahdi Khadra ◽  
Elisabeth Marie-Victoire ◽  
Myriam Bouichou ◽  
Christian Crémona ◽  
Stéphanie Vildaer
Keyword(s):  
Reinforced Concrete ◽  
Concrete Cover ◽  
Chloride Ions ◽  
Cultural Value ◽  
Original Material ◽  
Reinforcing Bars ◽  
First Results ◽  
Corrosion Risk ◽  
Deterioration Mechanism ◽  
Different Depths

Corrosion is the most frequent but also the most deleterious deterioration mechanism affecting reinforced concrete. In addition to the economic impact of the repair works, for historical concrete structures, corrosion can generate irreversible losses of original material of great cultural value. If the usual non-destructive electrochemical methods have highlighted their efficiency in evaluating on-going corrosion activity, they also have pointed out their drawbacks for accurate extrapolation and prevention. To prevent the corrosion phenomenon, by detecting the penetration of aggressive agents, a new warning sensor system has been developed. The principle of the technique is to embed thin metallic sheets (called orphan blades) in the concrete cover, at different distances from the surface to the reinforcing bars. Then the corrosion of those very reactive orphan blades is followed during the propagation of the carbonation front and/or the penetration of chloride ions using stimulated infrared thermography. The corrosion of the sensors at different depths is indicative of the ingress speed of the front and can alert about the risk of corrosion of reinforcing bars in the concrete. The purpose of this study is to present this new technique and the first results obtained in the laboratory on corroded and non-corroded sensors.

BEHAVIOR OF HIGH STRENGTH FIBER REINFORCED CONCRETE SQUARE COLUMNS WITH HYBRID BARS

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Saad Al-Taan ◽  
Abduljalil Aldoski
Keyword(s):  
Reinforced Concrete ◽  
Weight Ratio ◽  
High Strength ◽  
Concrete Cover ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Test Results ◽  
Fiber Reinforced ◽  
High Strength Fiber ◽  
And Behavior

The paper presents test results on 20 high-strength fiber reinforced concrete square columns subjected to concentric and eccentric loading. The study aim was to examine the effect of the weight of steel fibers on the strength and behavior of HSC columns under concentric and eccentric loading. All columns were longitudinally reinforced with 4 GFRP bars 6 mm diameter, and two steel bars 10 mm diameter, making the reinforcement ratio (ρg = 0.0181), and steel ties at 64 mm spacing. The studied test variables included the steel fiber weight ratio and the eccentricity. To prevent premature spalling in the concrete cover, it was discovered that it helps to add steel fibers to HSC mixtures in concrete columns. In addition, this also increases the strength of eccentrically loaded reinforced columns compared to that for concentrically loaded columns. The strength and behavior were predicted also by the proposed method. The predicted and the experimental results found to be in a good agreement.

scholarly journals Ultra high Performance Concrete - Materials Formulations and Serviceability based Design

2018 ◽  
Author(s):  
Barzin Mobasher ◽  
Yiming Yao ◽  
Aashay Arora ◽  
Narayanan Neithalath
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Cementitious Materials ◽  
Fiber Reinforced Concrete ◽  
Analytical Models ◽  
Tension Stress ◽  
Optimization Approach ◽  
Cement Composites ◽  
Ultra High Performance Concrete

Materials and mechanical design procedures for ultra-high performance cement composites (UHPC) members based on analytical models are addressed. A procedure for the design of blended components of UHPC is proposed using quaternary cementitious materials. The blending procedures are used using a packing and rheology optimization approach to blend high performance mixtures using non-proprietary formulations. Closed-form solutions of moment-curvature responses of UHPC are derived based on elastic-plastic compressive model and trilinear strain hardening tension stress strain responses. Tension stiffening behavior of UHPC due to fiber toughening and distributed cracking is then incorporated in the cross-sectional analysis. Load-deflection responses for beam members are obtained using moment-area, and direct integration approach. The proposed models provide insights in the design of SHCC to utilize the hardening properties after cracking. Using proper parameters, generalized materials model developed are applicable to both SHCC and strain softening cement composites such as steel fiber reinforced concrete (SFRC), textile reinforced concrete (TRC) and ultra-high performance concrete (UHPC).DOI: http://dx.doi.org/10.4995/HAC2018.2018.8263

scholarly journals Strength Calculation Features and Tests Results on Bearing Capacity and Operational Serviceability of Hollow-Core Floor Slabs of Formwork-Free Shaping in Seismic Areas

2020 ◽  
Vol 9 (1) ◽  
pp. 2219-2225
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Construction Industry ◽  
Precast Concrete ◽  
Concrete Strength ◽  
Concrete Structures ◽  
High Strength ◽  
Reinforced Concrete Structures ◽  
Hollow Core ◽  
Wide Range

The technology of manufacturing reinforced concrete structures of long-line systems of formwork-free shaping is widely used lately in construction industry in many countries. Using this technology, industrial construction can be carried out in accordance with the requirements of modern regulatory documents that allow projects to be developed individually, and production can be reoriented in a very short time in accordance with emerging needs. This means that on the same production line it is possible to produce various structural elements of buildings and structures. Also, this technology allows the production of structures according to a wide range of products that meet operational requirements, and increases the possibility of their use in design of buildings and structures with various architectural, planning and structural decisions. Prestressed hollow-core slabs of formwork-free shaping reinforced with high-strength wire reinforcement are widely used due to the simplicity of construction and their relatively low cost, as well as their high bearing capacity, large spans and better quality. The problem of their introduction into construction industry of Uzbekistan is that the issues of designing, manufacturing and using them in construction have not been studied. Besides, the production technology of such slabs is mostly associated with the construction in non-seismic areas, and the country does not have an appropriate regulatory framework for the possibility of slab designing and production. The aim of the study is to assess the strength and serviceability of hollow-core slabs of formwork-free shaping, designed on the basis of the proposed structural solution of the slab cross section and intended for construction in seismic areas. Therefor the issues of optimizing the main reinforcement consumption (prestressed high-strength wire reinforcement) at class B30 concrete strength without using the non-stressed reinforcement (reinforcing products) for the product range under consideration were addressed. Theoretical and constructive solutions of the slabs were developed in accordance with the standard requirements of Uzbekistan KMK 2.03.01-96 “Concrete and reinforced concrete structures”, KMK 2.01.03 “Construction in seismic areas” and considering the Euronorm EN 1168-2005 requirements “Precast concrete. Hollow-core slabs”.

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