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International Concrete Abstracts Portal

Showing 1-5 of 311 Abstracts search results

Document: 

19-444

Date: 

May 1, 2021

Publication:

Materials Journal

Volume:

118

Issue:

3


Document: 

20-222

Date: 

March 1, 2021

Author(s):

M. R. Sakr and M. T. Bassuoni

Publication:

Materials Journal

Volume:

118

Issue:

2

Abstract:

The response surface method, a statistical modeling approach, was used to assess the influence of water-binder ratio (w/b), binder content, and dosages of supplementary cementitious materials on the performance of 52 mixtures under accelerated physical salt attack (PSA). The test protocol simulated partially embedded elements. Also, the PSA damage of concrete was mapped by regression analysis based on combination of performance-based parameters. Mineralogical, thermal, and microstructural analyses were conducted to elucidate the bulk trends obtained from the models. Multi-objective optimization was also performed to determine optimal combinations of parameters (w/b; binder content; and dosages of fly ash, slag, and silica fume) producing mixtures resistant to PSA. In addition, a classification for the resistance of concrete to PSA based on performance indicators (mechanical capacity and wicking factor) was proposed.

DOI:

10.14359/51730515


Document: 

20-130

Date: 

March 1, 2021

Author(s):

Kai Wu, Jianan Xu, Feng Chen, Chuyang Chen, and Zhigang Chai

Publication:

Materials Journal

Volume:

118

Issue:

2

Abstract:

The reinforcing bar cages in concrete-encased steel (CES) structures are replaced with steel fibers to form the steel fiber-reinforced concrete-encased steel (SFRCES) structures, which can avoid common difficulties in the construction of a traditional CES structure. To study the bonding properties and interfacial damage between shaped steel and steel fiber-reinforced concrete (SFRC), the pushout tests of 16 specimens were conducted. Main parameters including steel fiber ratio (ρsf) (0, 1, 2, and 3%), thickness of concrete cover (Css), and effective bonding length (Le) of specimens were considered. In this paper, some important performance indicators are obtained, such as P-S curves, bonding strength, interfacial energy dissipation, and interfacial damage variables. The experimental results show that the P-S curves at the loading end and free end have the greatest difference under the peak load. A higher ρsf has a stronger constraint effect on concrete cracks, which leads to better post-peak bonding behavior. A bigger Css can delay the interfacial damage in the middle and late stages of the test. A larger Le means more elastic deformation energy can be stored at the interface, so the damage variable increases at a slower pace.

DOI:

10.14359/51730413


Document: 

20-166

Date: 

March 1, 2021

Author(s):

Jiayin Tao, Rita Maria Ghantous, Ming Jin, and Jason Weiss

Publication:

Materials Journal

Volume:

118

Issue:

2

Abstract:

The objective of this study is to determine whether the addition of silica fume (SF) can accelerate a reduction in the degree of saturation (DOS) of sealed cementitious materials at early ages, thereby increasing the freezing-and-thawing (F-T) resistance of the paste. This study investigated the influence of SF on the F-T resistance of cementitious materials using two techniques. The first technique consists of quantifying the DOS of cementitious materials at early ages and compares it to the critical degree of saturation (DOSCR). The second technique consists of determining the difference in the length of the cement paste sample before and after exposure to an F-T cycle at early ages. The change in length during the F-T cycle is an indicator of the development of damage caused by F-T. The DOS decreases faster when a higher amount of SF replaces cement. Consequently, the DOS of SF cement paste samples are more likely to be below DOSCR faster than plain cement paste samples when the samples are sealed.

DOI:

10.14359/51730414


Document: 

20-188

Date: 

March 1, 2021

Author(s):

Noura Sinno, Matthew Piersanti, and Medhat H. Shehata

Publication:

Materials Journal

Volume:

118

Issue:

2

Abstract:

This paper presents tests that can be used collectively to provide a qualitative assessment of residual expansion in structures affected by alkali-silica reaction (ASR). The tests are applied to bridge barriers suffering different levels of ASR deterioration. These include testing extracted cores under different lab conditions, monitoring concrete elements under field condition, damage rating index (DRI) on cores, and measuring alkali levels in the affected concrete. Expansion of barriers with low deterioration level was double that of highly deteriorated barriers at 4.5 years. Similar results were reached through testing cores under laboratory conditions at 38°C (100°F) and 100% relative humidity, although the DRI showed the same increase in damage in both cores after testing. Testing cores under laboratory conditions until expansion ceases helps in predicting the minimum residual expansion. Soaking cores in alkaline solutions of different concentrations and finding the level required to trigger expansion helps in assessing the risk of future expansion.

DOI:

10.14359/51729330


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