Title: Cyclic Heating and Cooling Effects on Concrete Durability

Author(s): V. Ramakrishnan, Hani F. Shafai and George Wu

Publication: Symposium Paper

Volume: 126

Issue:

Appears on pages(s): 1285-1304

Keywords: concretes; cyclic heating; durability; jet exhaust; limestone; spalling; thermal shock; General

DOI: 10.14359/3747

Date: 8/1/1991

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.