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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 40 Abstracts search results
Document:
22-206
Date:
December 1, 2023
Author(s):
Rita Maria Ghantous, Margaret N. Goodwin, Mehdi Khanzadeh Moradllo, Sean Quinn, Vahit Aktan, O. Burkan Isgor, Steven Reese, and W. Jason Weiss
Publication:
Materials Journal
Volume:
120
Issue:
6
Abstract:
Carbonatable calcium silicate cement (CSC) is a promising approach to reducing the carbon footprint associated with concrete production. Carbonatable CSC gains strength by reacting with carbon dioxide (CO2). While the concept of carbonation is well known, more information on the curing process is needed. This study focuses on studying the impact of drying time, carbonation duration, and degree of saturation (DOS) on the carbonation reaction of CSC mortar. Samples were exposed to different drying durations at controlled environmental conditions to reach various DOSs ranging from 100 to 0%. The samples were then exposed to carbonation under the same environmental conditions for different durations. Neutron radiography (NR) was performed on the samples during drying to determine the DOS corresponding to various drying durations. NR was also used during the carbonation period to determine the degree of carbonation (DOC) in real time. The impact of carbonation on the diffusivity of water vapor (Dh) and pore size distribution of CSC-based samples was examined using dynamic vapor sorption (DVS). It was concluded that the carbonation reaction increased as the DOS decreased from 100 to 40%. The carbonation reaction ceased for samples with DOS values less than 6% DOS. It was also concluded that as the DOC increased, the pore structure was refined, which led to a decrease in the Dh of the CSC mortar samples.
DOI:
10.14359/51739146
22-277
July 1, 2023
Keshav Bharadwaj, O. Burkan Isgor, and W. Jason Weiss
4
As the number of potential supplementary cementitious materials (SCMs) increase, there is a need to determine their reactivity. Most recent methods to assess pozzolanic reactivity are based on measuring certain outputs such as heat release (Q), calcium hydroxide (CH) consumption, and nonevaporable water. This paper uses thermodynamic modeling to aid in the interpretation of these tests and the quantification of reactivity. It is shown that pozzolanic reactivity should be interpreted based on the SCM type. The presence of sulfates and carbonates during reactivity quantification alter the reaction of the Al2O3 phases, making the interpretation of the reactivity test results challenging. The reactivity of commercial SCMs should be interpreted specific to the type of SCM as described by ASTM International/AASHTO. A proposed interpretation for commercial SCMs is provided in this paper.
10.14359/51738817
21-495
September 1, 2022
L. Bouchelil, R. M. Ghantous, G. Clark, M. N. Goodwin, W. J. Weiss, and M. Khanzadeh Moradllo
119
5
Relatively limited work has been performed to quantify how internal curing influences curing specifications. This paper examines the performance of internally cured mixtures (made using fine lightweight aggregates) compared to conventional concrete cured with wet burlap and curing compounds. Mortar mixtures were prepared using ordinary portland cement (OPC), fly ash, and silica fume (SF) with water-cementitious materials ratios (w/c) of 0.35 and 0.45. Neutron radiography (NR) was used to determine the nonevaporable water content as a function of curing time and distance from the exposed surface. The curing-affected zone (CAZ) was determined using the nonevaporable water profiles. The CAZ was used to develop equivalent curing durations for conventionally cured and internally cured samples. Internally cured mixtures reduced the depth of the CAZ, especially in the samples with limited external curing durations (reduction up to 15 mm [0.6 in.]). The application of internal curing in all mixtures reduced the duration of external curing by 50 to 60%, except for the internally cured SF samples, which showed a slight reduction. This dramatically impacts the construction schedule.
10.14359/51735980
21-118
March 1, 2022
Jie Zhao, Jian-Jun Zheng, Gai-Fei Peng, and Meng-Qi Wang
2
High-strength concrete (HSC) is susceptible to spalling at high temperatures. One reason for this is that vapor pressure builds up in concrete and plays a key role in spalling under certain conditions. However, vapor pressure modeling is still insufficient so far. Steam tables, which bear the actual states of water steam, have never been applied in vapor pressure modeling. In this paper, a meso-scale vapor pressure modeling approach using steam tables is presented. The effects of the thermal decomposition of the cement paste matrix and the vapor phase transfer driven by the gradient of vapor pressure are considered. By applying the theory of poromechanics, the Biot modulus is deduced and the mechanical effect of vapor pressure is modeled. Finally, the distribution and mechanical effect of vapor pressure in a 100 mm (3.94 in.) HSC cube specimen exposed to fire are modeled, and the applicability and effectiveness of the model are presented.
10.14359/51734441
19-432
November 1, 2020
Manar A. Al Fadul and Kevin R. Mackie
117
A model that simulates the two-dimensional (2-D) coupled heat and mass transfer phenomena in heated concrete is proposed. A fully implicit finite difference (FD) method was used in the discretization of the partial differential equations in both domain and time. The control volume approach was employed in the formulation of the FD equations, ensuring both local and global conservation properties are satisfied by the numerical solution. The solid, liquid, and gaseous (both air and vapor) phases are considered, including evaporation, condensation, and dehydration. The discretized equations of all species along with the temporal discretization of an interior node, surface node, and corner node are presented. Numerical case studies based on an object-oriented code for extremely rapid heating of concrete and nonsymmetric boundary conditions are validated against experimental results. Temperature, pressure, and moisture contours indicate the model’s ability to capture the complex 2-D behaviors of fire-exposed concrete over the entire flow domain.
10.14359/51728122
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