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International Concrete Abstracts Portal

Showing 1-5 of 92 Abstracts search results

Document: 

19-324

Date: 

July 1, 2020

Author(s):

Dhanushika Gunatilake Mapa, Manjriker Gunaratne, Kyle A. Riding, and A. Zayed

Publication:

Materials Journal

Volume:

117

Issue:

4

Abstract:

Jointed plain concrete pavement (JPCP) repair slabs experience high incidences of early-age cracking due to high temperature rise and increased autogenous shrinkage of high-early-strength (HES) concrete mixtures. This paper presents an investigation to evaluate early-age cracking mitigation strategies of JPCP repair slabs. Finite element analyses were performed to understand the effects of physical phenomena leading to early-age cracking in JPCP repair slabs. While the analyses indicate the importance of concrete hydration kinetics and viscoelastic behavior on the early-age stress development in slabs, concrete moisture loss to the base was found to be the most significant phenomenon. Numerical modeling of concrete slabs was found to be useful in predicting the stress development in advance of costly field trials. Therefore, the proposed modeling approach can be applied to evaluate the performance of concrete mixtures prior to slab placement and thus improve and economize the current rigid pavement maintenance practices.

DOI:

10.14359/51725780


Document: 

18-474

Date: 

March 1, 2020

Author(s):

Boyu Wang and Rishi Gupta

Publication:

Materials Journal

Volume:

117

Issue:

2

Abstract:

In recent years, the construction industry has invested a lot of effort in increasing concrete safety and in extending the service life of structures. Several test methods such as water penetration, surface/ bulk electrical resistivity, rapid chloride permeability (RCP), and half-cell potential have been proposed to study concrete durability. This study establishes the relationship between multiple durability test methods in the context of concrete repair, which was rarely selected as the object for study. By means of experimental study, this study finds that surface resistivity has a linear relation to bulk resistivity and a polynomial relation to water permeability. No relationship can be established between concrete resistivity and compressive strength, though high-strength concrete tends to have a high resistivity. RCP test results do not correlate well with resistivity measurements, which requires further study to overcome its heating and binding effect when measurements are being taken.

DOI:

10.14359/51722396


Document: 

19-012

Date: 

January 1, 2020

Author(s):

Gabriel W. Cook and Cameron D. Murray

Publication:

Materials Journal

Volume:

117

Issue:

1

Abstract:

Belitic calcium sulfoaluminate cement (BCSA) is a hydraulic, rapid-setting alternative to ordinary portland cement (OPC) with reduced energy demands and CO2 emissions. BCSA cement has numerous current and potential applications, including transportation repair and precast manufacturing. Currently, limited research exists regarding the structural performance of BCSA cement concrete, restricting its potential implementation. Thus, the purpose of this research is to provide insight into the flexural performance and behavior of reinforced BCSA concrete beams. Overall, BCSA concrete had similar cracking and loading behavior to the OPC beams, with increased moment capacity for compression-controlled specimens. Furthermore, BCSA cement concrete showed increased tensile strength and ductility when compared to OPC. Overall, the flexural strength of the BCSA cement concrete was higher than the control OPC concrete and the predicted flexural strength based on compressive strength, indicating the current flexural strength equations are applicable for BCSA reinforced concrete design.

DOI:

10.14359/51719074


Document: 

18-456

Date: 

November 1, 2019

Author(s):

Joseph J. Assaad, Najib Gerges, Kamal H. Khayat, Najib Lattouf, and Jimmy Mansour

Publication:

Materials Journal

Volume:

116

Issue:

6

Abstract:

A comprehensive research project was undertaken to evaluate the effect of styrene butadiene rubber (SBR) latex admixture on washout loss and bond strength of underwater concrete (UWC) designated for repair applications. Three UWC series possessing low to high stability levels that incorporate 5 to 15% SBR, by binder mass, were tested. A 1.5 m (4.93 ft) long specially designed channel was developed to enable the UWC to free fall from the outlet of a V-funnel apparatus, flow along an inclined surface submerged in water, then spread onto a horizontal concrete surface. Results show that underwater casting leads to reduced pulloff strengths caused by washout loss and aggregate segregation that weaken in-place properties. The incorporation of SBR was particularly efficient to reduce washout loss and improve adhesion between the repair overlay and substrate. Regression models enabling the prediction of residual bond strengths from the UWC rheological properties, washout loss, and polymer content are established.

DOI:

10.14359/51716982


Document: 

18-518

Date: 

November 1, 2019

Author(s):

M. R. Sakr, M. T. Bassuoni, and M. Reda Taha

Publication:

Materials Journal

Volume:

116

Issue:

6

Abstract:

In this study, different types of surface coatings were applied to concrete to assess their suitability for resisting physical salt attack (PSA). Concretes with different water-binder ratios (w/b) were tested and severe PSA conditions were implemented, using sodium sulfate, to obtain conclusive trends on the performance of coatings. Visual assessment and mass loss of concrete specimens were used as physical indicators to quantify the damage, while mineralogical and microstructural studies were conducted to elucidate the damage mechanisms. Epoxy, ethyl silicate, and acrylic emulsion coatings were found successful at protecting concrete from PSA regardless of the quality of the substrate concrete, while other coatings tested were highly dependent on the concrete quality. Coatings that permit a high rate of absorption and/or desorption (evaporation) led to more severe PSA damage compared with coatings with low absorption/desorption.

DOI:

10.14359/51718058


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