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International Concrete Abstracts Portal

Showing 1-5 of 127 Abstracts search results

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


Document: 

18-315

Date: 

March 1, 2021

Author(s):

John S. Lawler, Jonah C. Kurth, Stephen M. Garrett, and Paul D. Krauss

Publication:

Materials Journal

Volume:

118

Issue:

2

Abstract:

Reliability-based durability design of reinforced concrete structures requires a probabilistic service life modeling approach. Probabilistic service life modeling of chloride-induced corrosion should consider the statistical distributions of key parameters that influence corrosion initiation and subsequent damage. For typical reinforced concrete structures (such as bridge decks), these are chloride exposure, chloride penetration resistance of the concrete, chloride-induced corrosion threshold, depth of concrete cover, and corrosion propagation time. Assessing the impact of the use of corrosion-resistant reinforcement, such as epoxy-coated reinforcing bars (ECR), is typically performed through a selection of the chloride threshold and/or propagation time. This paper provides recommendations for statistical distributions for the chloride threshold to be used in service life modeling for structures containing carbon steel and ECR based on both experimental work reported in the literature and field investigations of existing structures conducted by the authors.

DOI:

10.14359/51730411


Document: 

19-416

Date: 

September 1, 2020

Author(s):

Ali F. Al-Khafaji, John J. Myers, and Antonio Nanni

Publication:

Materials Journal

Volume:

117

Issue:

5

Abstract:

Corrosion in reinforced concrete (RC) represents a serious issue in steel-reinforced concrete structures; therefore, finding an alternative to replace steel reinforcement with a non-corrosive material is necessary. One of these alternatives is glass fiber-reinforced polymer (GFRP) that arises as not only a feasible solution but also economical. The objective of this study is to assess the durability of GFRP bars in concrete bridges exposed to a real-time weather environment. The first bridge is Southview Bridge (in Missouri) and its GFRP bars have been in service for more than 11 years; the second bridge is Sierrita de la Cruz Creek Bridge (in Texas State) and its GFRP bars have been in service for more than 15 years. To observe any possible mechanical and chemical changes in the GFRP bars and concrete, several tests were conducted on the GFRP bars and surrounding concrete of the extracted cores. Carbonation depth, pH, and chlorides content were performed on the extracted concrete cores to evaluate the GFRP-surrounding environment and see how they influenced certain behaviors of GFRP bars. Scanning electron microscopy (SEM) was performed to observe any microstructural degradations within the GFRP bar and on the interfacial transition zone (ITZ). Energy dispersive spectroscopy (EDS) was applied to check for any chemical elemental changes. In addition, glass transition temperature (TA) and fiber content tests were carried out to assess the temperature state of the resin and check any loss in fiber content of the bar after these years of service. The results showed that there were no microstructural degradations in both bridges. EDS results were positive for one of the bridges, and they were negative with signs of leaching and alkali-hydrolysis attack on the other. Fiber content results for both bridges were within the permissible limits of ACI 440 standard. Carbonation depth was found only in one of the bridges. In addition, there were no signs of chloride attack in concrete. This study adds new evidence to the validation of the long-term durability of GFRP bars as concrete reinforcement used in field applications.

DOI:

10.14359/51725980


Document: 

18-347

Date: 

September 1, 2020

Author(s):

Song Wang and Mohamed A. ElGawady

Publication:

Materials Journal

Volume:

117

Issue:

5

Abstract:

In recent decades, concrete-filled fiber-reinforced polymer tube (CFFT) columns have gained increasing popularity in bridge construction as an alternative to conventional reinforced concrete columns. CFFT columns have excellent structural performance, which is attributed to the superior properties of the fiber-reinforced polymer (FRP) tubes. Furthermore, using FRP tubes eases the construction of CFFT columns. However, one obstacle hindering the greater acceptance of FRP as a common construction material in civil infrastructure application is the susceptibility of FRP to degradation during long-term exposure to a severe environment. The purpose of this study is to investigate the durability of CFFT columns subjected to seawater corrosion, which is the scenario for seashore bridges. CFFT stubs were immersed in simulated seawater with two different elevated temperatures for up to 450 days. Sustained axial loads were also applied to the stubs to simulate the real-life service load. Compression tests and hoop tensile tests were carried out on both pre- and post-conditioned specimens.

DOI:

10.14359/51724621


Document: 

19-322

Date: 

July 1, 2020

Author(s):

B. S. Sindu and Saptarshi Sasmal

Publication:

Materials Journal

Volume:

117

Issue:

4

Abstract:

To develop cementitious composites with improved properties, engineering has to be judiciously done at different scales. In this study, a multi-scale engineered cementitious composite (MS-ECC) with high tensile strength and strain-hardening properties is developed by incorporating nano-, micro-, and macro- (in the form of continuous fibers) fibers into it. At first, a cementitious composite is developed by individually incorporating nano- and microfibers to understand the influence of each type of fiber and to arrive at the optimum dosage level. Digital image correlation information is employed to investigate the crack properties and fracture process in the developed composite with individual scale fibers. Next, a hybrid cementitious composite, developed by incorporating nano- and microfibers, is found to demonstrate an improvement in the strength and strain hardening properties. Further improvement in higher scale is carried out by incorporating continuous fibers into it to develop MS-ECC which exhibited tensile strength of 23 MPa (3.63 ksi) and strain capacity more than 8000 micron.

DOI:

10.14359/51724625


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