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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 71 Abstracts search results
Document:
SP126-68
Date:
August 1, 1991
Author(s):
V. Ramakrishnan, Hani F. Shafai and George Wu
Publication:
Symposium Papers
Volume:
126
Abstract:
The exhaust from the auxiliary power unit (APU) of the modern F/A-18 aircraft has caused spalls and erosion on portland cement concrete (PCC) pavements. The exhaust gas has a maximum temperature of 385 F (196 C) and a maximum velocity of 140. At this temperature, PCC seems to lose its integrity when subjected to repeated and prolonged exposure. Spills of hydraulic fluid and jet fuel on the pavement aggravate the spalling process. The main objective of this investigation was to determine effects of cyclic heating on the strength of portland cement concrete subjected to high temperature, and compare the effects of cyclic heating on concrete contaminated with hydraulic fluid and jet fuel with noncontaminated concrete. Five different concrete mixtures were investigated. Twenty-one prisms and 21 cylinders were made from each mixture and tested for compressive strength, flexural strength, pulse velocity, and dry unit weight. Within each group, specimens were tested after each of the following heating/cooling cycles: 0, 15, 30, 60, 120, 240, and 400. A heating and cooling cycle is defined as heating in an oven at 400 F (204.4 C) for 60 min and cooling at room temperature for 30 min. After every 15 heating/cooling cycles, the contaminated specimens were soaked in jet fuel or hydraulic fluid overnight before the next heating/cooling cycles. Test results indicate that jet fuel contamination is more detrimental than hydraulic fluid contamination. Compressive strength, flexural strength, and pulse velocity are adversely affected by the cyclic heating.
DOI:
10.14359/3747
SP126-69
V. Nobokshchenov
A survey was conducted of failures of prestressing steel in bridge members exposed to potentially aggressive environments. It appears that the main cause of corrosion of prestressing tendons is the ingress of moisture laden with corrosion-inducing agents. Moisture can make its way to the prestressing steel by penetrating through leaking joints from a deck slab, or by diffusion from the underside of a bridge. Moisture may penetrate through concrete cover, sheathing and grout (or grease in unbonded tendons), as well as through anchorage systems. The rate of penetration of moisture depends primarily on permeability of concrete, type of sheath employed for protection of a tendon, and condition of grout or grease inside the sheath. Brittle fracture of reinforcing steel can occur due to pitting corrosion and/or stress corrosion cracking (SCC). Two types of SCC have been identified in prestressing steel in bridges: hydrogen embrittlement and fatigue corrosion. The rate of corrosion in prestressed concrete components can be minimized by using proper preventive and remedial measures.
10.14359/3755
SP126-70
M. Marosszeky, J. G. Yu, and C. M. Ng
Discusses the findings from the study of bond that forms a part of a major laboratory evaluation of the characteristics of repair materials carried out in the Building Research Centre. The important properties of repair patching materials that can affect the bond of a repair, such as shrinkage, thermal movement, compressive, shear, and tensile strength, are evaluated. The importance of surface preparation is also discussed.
10.14359/3765
SP126-39
Jakob Sustersic, Edward Mali, and Stanislav Urvancic
The results of investigation into the erosion-abrasion resistance according to CRD-C 63-80 test method and abrasion resistance according to Bohme test method of steel fiber reinforced concrete specimens are discussed in the paper. Nine mix proportions were used. The water-cement ratios (w/c) were varied from 0.30 to 0.65. The volumetric percentage of hooked steel fibers were varied from 0.25 to 2.0 volume percent at the w/c of 0.30 and at the others the quantity of fibers was constant. In addition, mixes without fibers were made at each w/c. The results show that adding steel fibers to the concrete improves the resistances as measured by both test methods. The erosion-abrasion resistance is improved by an increase of compressive strength and an increase in fiber content. It can be correlated to improvements of abrasion resistance from the Bohme test method but only at constant w/c and different content of fibers.
10.14359/2359
SP126-35
K. Takewaka and T. Minematsu
The impressed current-type of cathodic protection was evaluated for controlling of marine concrete structures as follows: To establish criteria of cathodic protection on marine concrete structures, to develop a system that can distribute current uniformly to all reinforcement, and to investigate the over-protection problem that effects the bonding of reinforcement and durability of anode material. The application of the cathodic protection system for the rehabilitation of a harbor concrete structure in Japan was also examined.
10.14359/3797
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