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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 22 Abstracts search results
March 1, 2020
Steel fiber-reinforced concrete (SFRC) can be an ideal substitute for conventional steel reinforcement in railway tunnel lining construction due to its high strength and good fire resistance. On the other hand, it is still not clear whether discontinuous steel fibers can pick up and transfer stray current and lead to similar corrosive attack as that occurs in conventional steel reinforcement. These were
evaluated through voltammetry tests and electrochemical impedance spectroscopy (EIS) before and after simulated railway stray direct current (DC) and alternating current (AC) interferences. In addition to instrumental methods in electrochemistry, numerical modeling based on the boundary element method (BEM) modeling indicates that discrete steel fibers can pick up and transfer stray currents. This was validated by the electrochemical investigations conducted using both aqueous and solid (mortar) electrolytes. It can be concluded that steel fibers have high corrosion resistance to stray AC and DC interferences even with the presence of a small amount of NaCl in the electrolyte.
November 1, 2017
Zhiming Ma, Zuquan Jin, Tiejun Zhao, and Yuanchao Cao
Sacrificial concrete is a cement-based material used for fire protection purposes. It is commonly used as a protective layer in nuclear reactor core containment structures in nuclear power plants. Its purpose is to act as a protection material only. Sacrificial concrete is particularly effective in protecting nuclear reactor core containment because it possesses high temperature stability and high melt capability that can reduce or help avoid the deterioration due to ultra-high temperature exposure from nuclear reactor core accidents or meltdowns. Sacrificial concrete is used in European pressurized reactors (EPRs), as an example, to contain molten core melts by melting a sacrificial concrete layer within the containment, which helps to cool the molten core and assists in avoiding a hot melt on the load-bearing containment structure. The study of performance of sacrificial concrete in ultra-high temperature exposures is in its early stages. To investigate the behavior and properties of sacrificial concrete at the ultra-high temperature of 5430°F (3000°C), numerical modeling simulating the same environment of a nuclear accident is established. Results indicate that the water-cementitious materials ratio (w/cm) and mineral admixtures have a significant impact on compressive strength, water loss, and water content of sacrificial concrete. Mixture proportions presented in this paper possess outstanding spalling resistance and melting behavior. Even at ultra-high temperatures, the sacrificial concrete possesses good melting behavior, and the melt depth of sacrificial concrete increases proportionally with time, which can effectively reduce the detriment of a nuclear accident.
September 1, 2017
A. Gil, F. Pacheco, R. Christ, F. Bolina, K. H. Khayat, and B. Tutikian
There is still a concern regarding concrete structures’ fire safety, mostly due to the occurrence of concrete spalling. Although many tests have already been carried out, there is no clear definition about the parameters of the factors that influence its occurrence. This paper aimed to compare three different types of concrete panels, with dimensions of 300 x 315 x 10 cm (124.0 x 39.4 x 3.9 in.), composed of reinforced concrete (RC), prestressed concrete, and polypropylene microfiber RC. The panels were exposed to the standard fire curve based on ISO 834, aged 28 days, measuring the temperatures in panels’ surfaces. Prestressed concrete panels experienced explosive spalling 18 minutes after the test began. RC panels and the panels with polypropylene microfiber addition maintained their integrity and structural stability for 240 minutes, failing in the thermal insulation criteria at 210 and 140 minutes, respectively. Although polypropylene microfiber concrete panels presented no spalling of concrete, conventional concrete panels attended the standardized criteria for a longer period due to its better thermal insulation.
January 1, 2017
Martin Neuenschwander, Markus Knobloch, and Mario Fontana
This paper presents a generic uniaxial constitutive model of the complete stress-strain curve of concrete in compression, adaptable to elevated temperatures solely by temperature-dependent material parameters. The pre-peak regime is divided into an initial linear part until the point of first yielding and a subsequent nonlinear part, starting with a tangent slope equal to the elastic modulus. The post-peak regime is split into two parts by the inflection point of the descending branch and ends at a predefined degree of softening. Additionally, elastic stiffness degradation is considered in the post-peak regime. First, analytical expressions for the different parts are derived and then the model is validated against experimental data of normal-strength concrete and self-consolidating concrete at elevated temperatures, including data from specimens heated under sustained loading. Finally, the model performance is discussed with respect to existing models in the literature and to the available design code models.
March 1, 2015
Christopher R. Shearer and Kimberly E. Kurtis
In this study, biomass and co-fired fly ashes are examined for use as supplementary cementitious materials. These ash sources are not addressed in the current American standard for fly ash and natural pozzolan use in concrete (ASTM C618-12a). The influence of these ashes on early-age hydration kinetics, workability, setting time, strength, permeability, and sulfate resistance is investigated. The findings demonstrate that co-fired fly ash, when conforming to current ASTM C618 specifications, can impart similar properties to concrete as coal fly ash. Thus, the potential of an ash to be used as a supplementary cementitious material is related to the chemical and physical properties of the ash, and not necessarily to its source (that is, coal or co-firing). Current standards should consider permitting co-fired fly ash sources that meet existing ASTM C618 requirements and any additional requirements deemed necessary to ensure their satisfactory performance when used in concrete.
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