Freeze-thaw Performance Research Articles

A Numerical Test of Air Void Spacing Equations

Air void spacing equations have been proposed in the literature by a number of authors: Powers; Philleo; Attiogbe; and Pleau and Pigeon. Each proposed spacing equation attempts to characterize the true “spacing” of entrained air voids in concrete. While efforts have been made to correlate these spacing equation calculations to freeze-thaw performance, no test has been performed to assess the geometrical accuracy of these spacing equations. Herein is a computerized accuracy test of these proposed spacing equations. A computer model of air void systems is used, and various “spacings” are measured in the model system. The results of these measurements are then compared to the appropriate spacing equation prediction, along with equations developed by Lu and Torquato.

Evaluation of Type C Fly Ash in Cold In-Place Recycling

The Kansas Department of Transportation has developed an innovative method of rehabilitating low-volume pavements using cold in-place recycling (CIR) and Type C fly ash. Previous field test sections have indicated that fly ash improves constructability and moisture sensitivity. However, the same field test sections have exhibited increased cracking with increased fly ash content and a drop in pavement modulus with time. A laboratory study was undertaken to evaluate the effect of fly ash content on CIR. Reclaimed asphalt pavement (RAP) was mixed with 3, 7, 11, and 15 percent Type C fly ash and the fatigue life, durability, freeze-thaw resistance, and thermal cracking potential of laboratory-compacted samples were evaluated. RAP mixed with asphalt emulsion and asphalt emulsion with hydrated lime were evaluated as well. The results indicated that 7 to 11 percent Type C fly ash provided optimal laboratory freeze-thaw and moisture sensitivity performance. Increasing the fly ash content resulted in a brittle fatigue behavior as well as an increased thermal fracture temperature. AASHTO T283 is recommended for selecting the optimum fly ash content.

Impact of Concrete Placing Method on Air Content, Air-Void System Parameters, and Freeze-Thaw Durability

Approximately 76 m3 (100 yd3) of ready-mixed, air-entrained concrete were placed in a parking lot and driveway at the Schwing America Manufacturing facility in White Bear, Minnesota, on June 21, 1994. This concrete was placed by means of a pump, crane and bucket, and truck-mounted conveyor, and came directly from the chute of ready-mix trucks. Pump configurations were used that allowed unrestricted free-fall of the concrete; a kink in the rubber hose at the end of the line created a slight back pressure and slowed the descent of the concrete. After placement, the concrete was consolidated by an immersion vibrator in some locations and struck off with no further consolidation in other locations. Air content of the fresh concrete was measured by ASTM C231 pressure meters at the truck chutes and at the point of placement. Air content and air-void system parameters of the hardened concrete were determined in accordance with ASTM C457. Actual freeze-thaw performance was evaluated by ASTM C666 for concrete sampled from the truck chute and sampled from the pavement after placement by the various methods. Twenty-four tests of the air content of concrete from six successive truckloads of concrete showed that the variation in truck-to-truck air content was frequently greater than the within-truck variation because of different methods of handling the concrete. Tests of the fresh concrete after pumping, conveying, chuting, and free-fall from the concrete bucket showed reduced air content. From analysis of the hardened concrete, it was observed that the air bubbles remaining in the pumped concrete were smaller than in the concrete as delivered. The air-void spacing factor was not significantly altered by pumping. In ASTM C666 freezing and thawing tests, the specimen experiencing the greatest loss of air content as a result of pumping was determined to have the lowest total air content of all specimens tested (before vibration), yet had the highest durability of all specimens tested.

Evaluation of Frost Resistance Tests for Carbonate Aggregates

D-cracking is a progressive distress associated primarily with the use of coarse aggregates that deteriorate when they are critically saturated and subjected to repeated cycles of freezing and thawing. The present study was undertaken to consider better acceptance criteria for concrete aggregates and to allow for the use of more local Minnesota aggregates through selected aggregate beneficiation techniques. Condition surveys of concrete highway pavements were performed to document the field freeze-thaw performance of selected aggregate sources representing a range of frost resistance. Cores were obtained from these sections for laboratory testing and evaluation, and coarse aggregates were obtained from the original sources for use in performing environmental simulation tests [i.e., variations of ASTM C666 and the Virginia Polytechnic Institute (VPI) single-cycle slow-freeze test] and correlative tests (i.e., absorption and bulk specific gravity, Portland Cement Association absorption and adsorption tests, Iowa pore index test, acid insoluble residue test, X-ray diffraction analysis, X-ray fluorescence analysis, thermogravimetric analysis, and the Washington hydraulic fracture test). The tests that provided the best correlation with field performance included a modification of ASTM C666 Procedure B (specimens prepared with salt-treated aggregates), the VPI single-cycle slow-freeze test, and the Washington hydraulic fracture test. Other test procedures were correlated with field performance to lesser extents. It was noted that petrographic examination of pavement cores can help to distinguish between D-cracking and other conditions that can produce distresses with similar appearances (e.g., distresses caused by secondary mineralization, embedded shale, poor mix design, and alkali-aggregate reaction).

Impact of Concrete Placing Method on Air Content, Air-Void System Parameters, and Freeze-Thaw Durability

Approximately 76 m3 (100 yd3) of ready-mixed, air-entrained concrete were placed in a parking lot and driveway at the Schwing America Manufacturing facility in White Bear, Minnesota, on June 21, 1994. This concrete was placed by means of a pump, crane and bucket, and truck-mounted conveyor, and came directly from the chute of ready-mix trucks. Pump configurations were used that allowed unrestricted free-fall of the concrete; a kink in the rubber hose at the end of the line created a slight back pressure and slowed the descent of the concrete. After placement, the concrete was consolidated by an immersion vibrator in some locations and struck off with no further consolidation in other locations. Air content of the fresh concrete was measured by ASTM C231 pressure meters at the truck chutes and at the point of placement. Air content and air-void system parameters of the hardened concrete were determined in accordance with ASTM C457. Actual freeze-thaw performance was evaluated by ASTM C666 for concrete samp...

Evaluation of Frost Resistance Tests for Carbonate Aggregates

D-cracking is a progressive distress associated primarily with the use of coarse aggregates that deteriorate when they are critically saturated and subjected to repeated cycles of freezing and thawing. The present study was undertaken to consider better acceptance criteria for concrete aggregates and to allow for the use of more local Minnesota aggregates through selected aggregate beneficiation techniques. Condition surveys of concrete highway pavements were performed to document the field freeze-thaw performance of selected aggregate sources representing a range of frost resistance. Cores were obtained from these sections for laboratory testing and evaluation, and coarse aggregates were obtained from the original sources for use in performing environmental simulation tests [i.e., variations of ASTM C666 and the Virginia Polytechnic Institute (VPI) single-cycle slow-freeze test] and correlative tests (i.e., absorption and bulk specific gravity, Portland Cement Association absorption and adsorption tests, Iowa pore index test, acid insoluble residue test, X-ray diffraction analysis, X-ray fluorescence analysis, thermogravimetric analysis, and the Washington hydraulic fracture test). The tests that provided the best correlation with field performance included a modification of ASTM C666 Procedure B (specimens prepared with salt-treated aggregates), the VPI single-cycle slow-freeze test, and the Washington hydraulic fracture test. Other test procedures were correlated with field performance to lesser extents. It was noted that petrographic examination of pavement cores can help to distinguish between D-cracking and other conditions that can produce distresses with similar appearances (e.g., distresses caused by secondary mineralization, embedded shale, poor mix design, and alkali-aggregate reaction).

A three-year field and laboratory evaluation of linseed oil as a concrete sealer

Sealers are used to enhance concrete durability through their ability to prevent moisture penetration and chloride intrusion, and, consequently, improve the freeze–thaw performance of the concrete and prevent corrosion of the steel reinforcement, respectively. This paper summarizes the results of three years of comprehensive field and laboratory investigations, undertaken at The University of Manitoba, to study the effectiveness of boiled linseed oil and mineral spirits in comparison to a silane and a siloxane sealer. The field investigation examined the performance of the sealers applied to the concrete pavements of a city street, a provincial highway, and an airport apron in Winnipeg, Manitoba. The laboratory investigation included sealer penetration, salt-water absorption and vapour transmission, abrasion, chloride ion intrusion, surface scaling resistance, and rapid freeze–thaw cycling. Test results of the field and laboratory investigation indicated that boiled linseed oil and mineral spirits was the most effective sealer at reducing chloride ion intrusion. It was found that boiled linseed oil and mineral spirits was comparable to siloxane and much more effective than the silane at reducing salt-water absorption. The results also indicated that boiled linseed oil and mineral spirits was most effective at reducing surface scaling and remained effective when subjected to salt-water absorption after abrasion. Key words: concrete sealers, linseed oil, silane, siloxane, absorption, scaling, chloride intrusion.