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International Concrete Abstracts Portal

Showing 1-10 of 448 Abstracts search results

Document: 

SP327-34

Date: 

November 1, 2018

Author(s):

Marco Rossini, Eleonora Bruschi, Fabio Matta, Carlo Poggi and Antonio Nanni

Publication:

Special Publication

Volume:

327

Abstract:

This paper presents a parametric analysis of the ACI 440 (2015) and AASHTO (2009) algorithms governing the flexural design of a one-way concrete member internally reinforced with glass fiber-reinforced polymer (GFRP) bars. The influence of specific design parameters on the required amount of reinforcement is investigated. The aim is to identify variables and requirements governing the design of a large-section GFRP reinforced concrete (RC) member. The member considered for this case-specific analysis is the reinforced concrete pile cap of the Halls River Bridge (Homosassa, FL), which is deemed representative of large-section GFRP-RC members operating as bent caps in short-span bridges. The influence of four critical parameters on the required amount of reinforcement is assessed. Salient analysis and design implications are discussed with respect to creep and fatigue rupture stress limits, minimum amount of flexural reinforcement, and applicable strength reduction factors. The outcomes of the parametric analysis highlight an untapped potential to reduce the required amount of reinforcement, and prioritize research areas to advance the development of rational design algorithms. Cyclic fatigue and creep rupture are identified as governing mechanisms.


Document: 

SP-329-07

Date: 

September 26, 2018

Author(s):

Manuel Ilg and Johann Plank

Publication:

Special Publication

Volume:

329

Abstract:

Concretes formulated at low water-cement ratios exhibit good material properties. Nevertheless, such concretes exhibit a honey-like consistency with a low speed of flow (“creeping behavior”) which is highly undesirable. In this paper it is shown that non-ionic small molecules can help to improve the fluidity at low water-cement ratios significantly and eliminate the “stickiness” when combined with ordinary PCE superplasticizers. For this purpose, different non-ionic glycol derivatives were screened via mini-slump testing. It was found that especially less polar species behave as very powerful co-dispersants. To gain a more profound understanding of the working mechanism, heat flow calorimetry was carried out. Additionally, concrete lab tests were performed to ascertain the impact of the non-ionic molecules on the V-funnel empty time of SCCs. Based on adsorption measurements it is inferred that the co-dispersants act as osmotic spacers which keep the cement particles apart and prevent them from agglomeration.


Document: 

SP326-78

Date: 

August 10, 2018

Author(s):

Petr Arleninov, Sergey Krylov, and Dmitry Kuzevanov

Publication:

Special Publication

Volume:

326

Abstract:

Two main novelties are proposed in this article: the first is an introduction that details deformation characteristics — long-term modulus of concrete elasticity during bending and its differentiation, and the second is the proposed simplified method for creep testing during the bending mode with the further matching of results with classic testing for compression in spring test rigs.


Document: 

SP326-60

Date: 

August 10, 2018

Author(s):

Simon S. Kaprielov, Andrey V. Sheynfeld, Igor A. Chilin, and Igor M. Bezgodov

Publication:

Special Publication

Volume:

326

Abstract:

It is known that characteristics of fiber-reinforced concrete generally depend on the volume and properties of the matrix, the type and dosage of fiber. Studies have been conducted on the influence of these factors on strength and deformation characteristics, including the modulus of elasticity, creep and frost resistance of ultra-high strength self-compacting fiber reinforced concrete (UHSFRC).

Portland cement CEM I 52.5, sand with fineness modulus of 2.5, organic-mineral modifier MB-50 and straight steel fiber were used as components for self-compacting concrete. The fiber dosage was varied in the range from 0 to 2.0% of the volume of concrete mixtures.

The tests have shown that the creep of steel fiber reinforced concrete at different levels of loading (0.3 and 0.6 of Rb) is significantly less than that of the matrix. The ratio of transverse creep deformation is significantly lower than under the short-time loading, as for the matrix and the same as for steel fiber reinforced concrete. Despite almost linear diagram of concrete deformation under compression, the value of creep deformation shows quite higher figures. It is noted that the effectiveness of steel fiber increases with the increase of stress level.

Freeze-thaw resistance was evaluated in the cyclic process of freezing at -50°C [-58°F] and thawing in 5% NaCl solution. The test results show very high frost resistance of concrete, what corresponds to the grade F2800, what is 2.7 times above the concrete requirements for transport structures in Russia.


Document: 

SP326-55

Date: 

August 10, 2018

Author(s):

Arne Spelter, Sergej Rempel, Norbert Will, and Josef Hegger

Publication:

Special Publication

Volume:

326

Abstract:

Textile reinforced concrete (TRC) is a high-performance composite material made of impregnated filaments and a concrete matrix with a longer service life compared to steel reinforced concrete. Due to the non-corrosive reinforcement it is possible to reduce the concrete cover and realize slender and architectural attractive concrete structures. In addition, resources and CO2-emissions can be saved.

Despite the non-corrosive reinforcement, a loss of strength occurs over the service life due to environmental impacts. Therefore, a testing concept is required to determine a reduction factor that takes the loss of strength during the service life into account. This enables a safe design of textile reinforced concrete structures.

A testing concept for TRC is derived from existing concepts for fiber reinforced polymers (FRP). Available concepts (e.g. ACI 440.3R-12, ASTM 7337, CSA S806-12, ISO 10406-1) differentiate between creep rupture and alkaline resistance. Therefore, a test setup was derived which combines the existing concepts and enables the determination of the long-term durability of non-metallically reinforced concrete structures. The long-term durability is defined as a constant stress on a reinforcement that can be applied during the service life without a failure of the reinforcement.


Document: 

SP326-41

Date: 

August 10, 2018

Author(s):

Nicola Buratti, Anna Lisa Vinciguerra, Andrea Incerti, Stefania Manzi, Elisa Rambaldi, Maria Chiara Bignozzi, and Claudio Mazzotti

Publication:

Special Publication

Volume:

326

Abstract:

The paper describes part of the preliminary results of the of the MATERSOS project, funded by the Emilia Romagna Region, Italy. This research project aims at implementing circular economy processes in the constructions industry, through the usage of secondary raw materials. The present paper focuses on structural concrete. After an analysis of locally available waste materials, those with the highest potential as concrete components were identified. Normal and self-compacting concrete mixes containing powder from ceramic tile grinding, shell powder, and construction demolition waste aggregates, were then developed. Ceramic powders were used both as replacement for a fraction of cement and as filler while shell powders were used as filler only. The paper presents the results of various experimental tests that were carried out to evaluate the mechanical properties of these concretes. In particular, their compressive and flexural-tensile strengths, elastic moduli, shrinkage and creep deformations were evaluated and compared with traditional concretes. The results of the experimental tests indicated that the mechanical properties of some of the concretes containing secondary raw materials were comparable to those of traditional concretes suggesting that their adoption in real world applications is possible.


Document: 

SP319-03

Date: 

June 1, 2017

Author(s):

Salah Altoubat and Klaus-Alexander Rieder

Publication:

Special Publication

Volume:

319

Abstract:

This paper presents results of an ongoing experimental program to study the effectiveness of macro synthetic fibers to control cracking in composite metal slabs. Both short- and long-term performance is being investigated in this experimental program. Two types of experiments for composite slabs on corrugated steel deck are conducted: restrained shrinkage tests and large-scale loaded composite continuous slabs. The restrained shrinkage test provides data on crack width caused by shrinkage, while the large- scale continuous slab was intended to monitor the crack width development across the middle support caused by the load, shrinkage and creep. The crack width measurements of both experiments indicate that the investigated fiber can provide comparable performance in terms of long-term crack control to conventional steel mesh reinforced concrete specified by the standards. Crack width measurements in the restrained shrinkage test over a period of 250 days of drying suggest that macro synthetic fibers at the minimum dosage specified by the ANSI/SDI can provide similar crack control as the minimum steel mesh. Long-term monitoring of load-induced cracking in the slab at the middle support over a period of up to 5 years indicate that the crack width for both reinforcing systems (fibers and steel mesh) increased asymptotically with loading time and stabilized thereafter. The results indicated that creep across the crack occurred for both reinforcing systems suggesting that the creep deformation across the crack is not only related to the type of reinforcing materials and the creep of the fiber/cement paste interface but also by creep of concrete section in compression.


Document: 

SP314-05

Date: 

March 1, 2017

Author(s):

Michael Berry, Bethany Kappes, and David Schroeder

Publication:

Special Publication

Volume:

314

Abstract:

This paper documents research focused on evaluating the feasibility of using minimally processed reclaimed asphalt pavement (RAP) as aggregate replacement in concrete pavements. A statistical experimental design procedure (response surface methodology – RSM) was used to investigate proportioning RAP concrete mixtures to achieve desired performance criteria. Based on the results of the RSM investigation, two concrete mixtures were selected for further evaluation: a high RAP mix with fine and coarse aggregate replacement rates (by volume) of 50 and 100 percent respectively, and a “high” strength mix with one half of the RAP used in the high RAP mix. These two concrete mixtures were subjected to a suite of mechanical and durability tests, and were used in a field demonstration project to evaluate their potential use in pavements. Mechanical properties tested were compressive and tensile strength, elastic modulus, shrinkage, and creep. Durability tests included alkali-silica reactivity, absorption, abrasion, chloride permeability, freeze-thaw resistance, and scaling. Overall, both mixes performed adequately in these mechanical and durability tests, although the inclusion of RAP negatively impacted most of the tested properties relative to those of control mixes made with 100 percent conventional aggregates.


Document: 

SP304-02

Date: 

October 27, 2015

Author(s):

Fatmir Menkulasi, Doug Nelson, Carin L. Roberts Wollmann and Tommy Cousins

Publication:

Special Publication

Volume:

304

Abstract:

Composite concrete bridges are widely used because they combine the advantages of precast concrete with those of cast-in-place concrete. However, because of the difference in shrinkage properties between the girder and the deck and because of the sequence of construction, the deck is subject to differential shrinkage tensile stresses. These tensile stresses may lead to excessive cracking. This paper demonstrates how the likelihood of deck cracking due to differential shrinkage can be reduced and how consequently the resistance of composite concrete bridges against time dependent effects can be enhanced by choosing a deck mix with low shrinkage and high creep. An experimental study on the long term properties of seven deck mixes is presented to identify a deck mix with the aforementioned properties. A comparison of three composite concrete bridge systems used for short-to-medium-span bridges is performed to identify the bridge system that is most resistant against time dependent effects. The mix with saturated lightweight fine aggregates appears to best alleviate tensile stresses due to differential shrinkage and the bridge system with precast inverted T-beams and tapered webs appears to be the most resistant.


Document: 

CI3710Elkady

Date: 

October 1, 2015

Author(s):

Mohamed Elkady, Maher K. Tadros, Mark Lafferty, George Morcous, and Doug Gremel

Publication:

Concrete International

Volume:

37

Issue:

10

Abstract:

For insulated wall panels, a common practice is to connect the two concrete wythes with a solid concrete block through the insulation at the corbel location. The resulting thermal bridge significantly reduces the energy efficiency of the wall panel. Depending on the climate and building use, the accumulation of moisture on the surfaces can lead to degradation of indoor air quality or the appearance of the panel. These effects are the main reasons for the research summarized in this article.


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