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Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 36 Abstracts search results
Document:
18-380
Date:
May 1, 2020
Author(s):
Nicholas Omoding, Lee S. Cunningham, and Gregory F. Lane-Serff
Publication:
Materials Journal
Volume:
117
Issue:
3
Abstract:
In the last four decades, numerous investigations have been undertaken on abrasion-erosion of concrete using various test methods. These have suggested the existence of different abrasion mechanisms, limitations of existing test methods, and inconsistencies on the importance of compressive strength to abrasion resistance of concrete. The objective of this review is to understand the mechanisms of concrete abrasion-erosion, assess the suitability of existing test methods to simulate field conditions, and investigate the relationship between abrasion resistance and compressive strength. It is found that concrete abrasion mechanisms are dependent on both transport modes of abrasive charge and the ratio of coarse aggregate to matrix hardness. The ASTM C1138 (underwater) test method appears to simulate all the critical modes of sediment-induced abrasion expected in field conditions and specific energy can be used as a framework to correlate ASTM C1138 test results with field measurements. With the exception of concrete with rubber aggregates, abrasion loss is found to fit a simple power function of its compressive strength, and no significant improvements in abrasion resistance can be gained by using concretes with compressive strengths exceeding 60 MPa (8.70 ksi). Also, the influence of cementitious additives and coarse aggregate properties is only significant at compressive strengths below the optimal value of 60 MPa (8.70 ksi).
DOI:
10.14359/51724592
18-456
November 1, 2019
Joseph J. Assaad, Najib Gerges, Kamal H. Khayat, Najib Lattouf, and Jimmy Mansour
116
6
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.
10.14359/51716982
18-243
May 1, 2019
Ronaldo A. Medeiros-Junior, Patrícia Schnepper Gans, Eduardo Pereira, and Elias Pereira
Correlations between compressive strength and electrical resistivity of concretes exposed to different aggressive conditions were sought to evaluate concrete quality. Concrete specimens were cast with four water-cement ratios (w/c) and exposed to five different conditions of water, chloride, and sulfate solutions. Electrical resistivity and compressive strength tests were performed from 28 to 189 days. The results were statistically analyzed and supported by SEM and XRD analyses. When correlating both properties, higher coefficients of determination were found for conditions of underwater and wetting and drying cycles in water. In general, 71.4% of the coefficients of determination were greater than 0.700. The lowest correlations were found for concrete exposed to chloride solutions because the electrical resistivity of the specimens in these conditions tends to remain constant over time.
10.14359/51714464
15-163
September 1, 2016
Amr I. I. Helmy and Michael P. Collins
Structural Journal
113
5
Laboratory equipment was designed and implemented to study the effect of water pressure on reinforced concrete structures. They included a pressure vessel, a video monitoring system, and a pressurizing system. Then, the hydraulic testing facility at the University of Toronto was brought into operation. The facility is capable of testing model offshore structures under high water pressure. A one-seventh-scale model of a buoyancy compartment of a small offshore oil platform was designed and constructed as a pilot specimen. Two pilot tests were carried out using the same pilot specimen to study its behavior. The failure water pressure was approximately three times the design pressure. At failure pressure, a major circumferential crack in the cylindrical shell near the slab-shell connection was formed. At this pressure, uncontrollable water leakage through large concrete cracks associated with steel yielding occurred. The concrete in compression was capable of preventing water flow through concrete cracks until the steel yielded. Post-yielding capacity of a section was unreliable in preventing water flow.
10.14359/51689025
110-S41
May 1, 2013
Joseph J. Assaad and Camille A. Issa
110
Limited studies have been undertaken to investigate the bond properties of reinforcing steel bars embedded in underwater concrete (UWC). Approximately 60 pullout tests were carried out to evaluate the effect of washout loss (W) on residual compressive and bond strengths. Washout was determined using the CRD C61 test and by simulation using a newly developed air-pressurized tube. Reference mixtures sampled in dry conditions were also tested. Test results showed that bond between steel and UWC is affected by a combination of parameters that complement those documented in the literature for concrete cast and consolidated above water. These include the level of W, degree of segregation, hydrostatic water head (H), and interfacial concrete-water velocity. The bond-stress-versus-slip behavior of UWC is remarkably different from the one obtained using reference mixtures. Initially, the linear response is less stiff due to a coupled effect related to lower strength and increase in the relative coarse aggregate concentration. The slip at ultimate bond strength was found to decrease for UWC mixtures exhibiting higher levels of W.
10.14359/51685608
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