Investigation into Freezing-Thawing Durability of Low-Permeability Concrete with and without Air Entraining Agent (original) (raw)
Related papers
EFFECT OF FREEZING-THAWING ON SELF CONSOLIDATED CONCRETE INCLUDING FLY ASH
This paper presents the effect of freezing-thawing on self consolidated concrete that contain different percentages of fly ash (FA) and air entraining agents. Self consolidated concretes (SCC) containing four different contents of FA as a replacement of cement (0, 15, 30 and 45 by weight), and containing three different contents of air entraining agent (0, 0.15 and 0.30%) were prepared. All concrete mixtures have the same superplasticizer content as 1.3% of cementitious materials by weight. The fresh properties of the SCCs were observed through, slump flow time and diameter, air content, V-funnel flow time, L-box height ratio, setting time and segregation ratio. The hardened properties included the compressive strength, ultrasonic pulse velocity, permeability evaluation (absorption, sorptivity and rapid chloride permeability tests) and freezing-thawing tests up to 300 cycles. Following the ASTM C 666 standard test method and for this purpose, to determine the dynamic modulus of elasticity value of concrete specimens; the resonant frequency test apparatus was developed.
Concrete is one of the most widely used construction materials for several structures such as buildings, homes, dams, roads, and bridges. Concrete performance is generally based on the mix design, material properties in the mixture, curing conditions, and environmental conditions during the service life of the structure. Cracking and spalling of concrete are the most common damage caused by expansion of the cement paste matrix under the effect of freeze-thaw cycles.The purpose of this paper is to explore the feasibility of use of high strength concrete in cold weather environments and assess its durability in that environment both with and without entrained air. The development and subsequent widespread use of high range water reducing admixtures or superplasticizers has ensured strength of concrete upto 100-120 MPa as a common occurrence in many parts of the country.In this study, targeting HSC in cold weather conditions, Super Absorbent Polymer(SAP) SHN 2120 have been experimentally compared with Polypropylene fibre (Recron 3S 12mm) and air entraining agent to gauge their relative performance under the parameters of mechanical properties like slump, compressive strength for a duration of 1/7/14/28 days for numbers of freeze thaw cycles as per BAW code of practice on freeze thaw of concrete.
Effect of freezing-thawing on concrete behavior
Challenge Journal of Concrete Research Letters, 2018
This study aims to determine the effect of change of temperature (freezing-thawing cycles) on the behavior of the mortar and the concrete. Also, the evaluation of the effect of air entering for improving the durability of the mortar and concrete was discussed. 23 mixes were cast to evaluate the purpose of this study. Cement types (Portland cement and limestone cement), aggregate types (dolomite and gravel), dosages of air entering 0.01, 0.1, 0.15 and 0.2% of cement weight and freezing thawing cycles (50, 100, 150, 200, 300 and 400 cycles) were considered. Relative dynamic modules of elasticity which is illustrated the internal cracks growth, durability factor and losses of weight were evaluated. Empirical correlations were formulated. The results showed that; 0.15% air entrained of cement weight improve the durability in term of freezing-thawing; where the durability factor for the mixes was ≥ 85% that exposed to freezing-thawing cycles in range 0-200. Up to 200 cycles of freezing-t...
The effect of antifreeze additives on fresh concrete subjected to freezing and thawing cycles
Cold Regions Science and Technology, 2016
This study focused on the effect of antifreeze additives on the microstructural changes and physical and mechanical properties of fresh concrete subjected to freezing-thawing cycles produced by cold weather. For this purpose, antifreeze additives, urea and calcium nitrate, were used at the level of 6% by weight of cement dosage and were compared with control samples. After casting, one group of control samples was cured in moist curing conditions for 1 day and then cured in lime-saturated water at 23 ± 1°C for 28 days. Another group of controls, urea and calcium nitrate mixtures, were subjected to freezing-thawing cycles 1, 3, 5, 7, 10, 15 and 28 times. Scanning electron microscopic (SEM) images, ultrasonic pulse velocity (UPV), water absorption and compressive strength tests were conducted. The results showed that the lowest water absorption value after 28 freezing-thawing cycles was 5.8% for the calcium nitrate mixes. The 28-day compressive strength of the control, calcium nitrate and urea mixes subjected to freezing-thawing 28 times was reduced by 72.0%, 27.8% and 52.9% compared to those of the control samples cured in lime-saturated water at 23 ± 1°C for 28 days. The SEM images showed that the samples containing calcium nitrate had a more compact and denser micro-structure compared to urea and the control.
Freeze-Thaw Resistance of Concrete: Effect of: Curing Conditions, Moisture Exchange and Materials
2001
Research on freeze-thaw resistance of concrete in general and on curing and moisture conditions in particular is motivated from an economic and product sustainability point of view. Specifically, it is argued for the importance of considering the effect of curing and test exposure conditions on the moisture uptake and performance during freeze-thaw. Due to the demonstrated importance of moisture conditions on performance, they should be related to those of field service conditions when choosing a test procedure in a particular case. This is vital for adequate testing of newand more sustainable concrete materials.
International Journal of Engineering and Technology, 2013
This paper presents the effect of curing conditions on freeze-thaw durability of self-consolidating concrete. In order to determine the effect of curing conditions on the durability properties of self-consolidating concrete, some specimens were cured in air and the others in water. Moist-cured (M-C) specimens were kept in water for 14 days at a temperature of 23±2°C before they were subjected to freeze-thaw cycles. Air-cured (A-C) specimens were however left in ambient laboratory conditions and were saturated in water for a day before they were subjected to the same freeze-thaw cycles. From the permeability tests, it was concluded that air cured specimens have higher permeability. Furthermore, an increase in fly ash content resulted in a reduction in the permeation properties of self-consolidating concrete. On the other hand, more variations were observed in permeability results since only two specimens were used for permeability tests. During the freezing-thawing test, it was observed that air cured specimens were not affected by freezing-thawing and did not indicate any degradation since they were not totally saturated because of the lack of the saturation period that was employed.
The Cement Type Effect on Freeze – Thaw and Deicing Salt Resistance of Concrete
Procedia Engineering, 2013
This paper analyzes the effect of the four types of cement (Portland cement, blast-furnace Portland cement, limestone Portland cement and blast-furnace cement) on freeze-thaw and deicing salt resistance of concrete. Eight compositions of concrete with different cements were tested. Four compositions contained hydration retarder added at 0.3 wt% and 0.5 wt% by mass of cement and four compositions were without the retarder. All compositions contained 0.6 wt% of superplasticizer. 3% NaCl solutions was used as a freezing agent in freeze-thaw tests. The mass loss (the weight of scaled material), ultrasonic pulse velocity and residual deformations were measured every seven freeze-thaw cycle. The test results showed that the highest freeze-thaw and deicing salt resistance is observed in concrete made of blast-furnace cement (CEM III/B 32.5 N -LH) and the lowest freeze-thaw resistance is observed in concrete made of Portland cement (CEM I 42.5 R) and Portland blast -furnace cement (CEM II/A-S 42.2 N). Cement hydration retarder was found to have a negative effect on freeze-thaw and deicing salt resistance of concrete.
Pulverized fuel ash concrete: air entrainment and freeze/thaw durability
Magazine of Concrete Research, 1999
The paper describes a study undertaken to determine the effect of pulverized fuel ash (PFA) and its characteristics on air entrainment, the air void system and the freeze/thaw durability of concrete. The results demonstrate that the admixture demand of PFA concrete was higher than that of Portland cement (PC) concrete and greatly influenced by the type of air-entraining admixture, the level of air required and the characteristics of the PFA used. While PFA fineness had little influence on admixture demand, PFA with high loss on ignition required dosages in excess of two times that of PC. However, PFA was found to have little influence on the rate of air loss with handling and reduced the variability of air content at a given admixture dosage when combined with PC from different sources. Tests to assess the reliability of the ASTM method for examining the air void system confirmed this. The results indicate that improvements in air void parameters were obtained with increasing air content in the concrete. However, similar or slightly enhanced parameters were measured for PFA concrete compared to those of PC concrete. In this case, the characteristics of the PFA had no effect. Following on from this, tests for freeze/thaw durability (ASTM C666: Procedure A) indicated that the critical factors influencing deterioration were the air content and design strength of the concrete. In this respect, no difference was observed between PC and PC/PFA concrete, and all concretes, irrespective of design strength, exhibited very good freeze/thaw resistance above an air content of 3·5%. A nomogram was developed to demonstrate possible routes to material selection/admixture dosages for the practical achievement of durable concrete in freeze/thaw conditions.
Cement and Concrete Research, 2004
This study aims to introduce new information on freezing and thawing resistance when air-entrained or non-air-entrained concrete is used as recycled coarse aggregate into air-entrained concrete. The laboratory produced air-entrained and non-air-entrained concretes with a water/ cement (w/c) ratio of 0.45 were recycled at the crushing age of 1 year to obtain the coarse aggregates used in the investigations. The recycling process was performed in three stages to produce recycled coarse aggregates with different adhered mortar contents. The results showed that recycled coarse aggregate produced from non-air-entrained concrete caused poor freezing and thawing resistance in concrete even when the new system had a proper air entrainment. Microstructural studies indicated that non-air-entrained adhered mortar caused disintegration of the recycled coarse aggregate in itself and disrupted the surrounding new mortar after a limited number of freezing and thawing cycles. Minimizing non-air-entrained adhered mortar or enhancing the performance of new surrounding matrix could not give satisfactory results for a long freezing and thawing exposure. D