Evaluation of freeze-thaw damage on concrete material and prestressed concrete specimens (original) (raw)

Stress Analysis for Concrete Materials under Multiple Freeze-Thaw Cycles

Journal of Advanced Concrete Technology, 2015

Once ice forms in highly saturated concrete material, internal tensile stress will be generated and causes damage to the material, which is a serious problem for concrete structures in cold and wet regions. On one hand, each component (porous body, ice and liquid) should satisfy the compatibility of stress and strain, which has been discussed by the poromechanical theories. On the other hand, if some empty voids exist, the hydraulic pressure will release when liquid water escapes from the expanded area according to Darcy's law. Recent closed freeze-thaw tests on the saturated mortar showed a consistent tendency: as the number of freeze-thaw cycles (FTC) increases, the deformation changes from the expansion to the contraction. In order to make clear the physical and mechanical changes during this process, a more comprehensive hydraulic model is developed, which combines both the mechanisms mentioned above. The estimated strain behavior by this model is in a good agreement with experimental measurements, and also, it has good potential and is more flexible to be applied to different cases such as different saturation degrees and cooling rates. The permeability change can be also considered in this model as a reflection of frost damage level.

Effect of Freezing-Thawing Cycles on the Physical and Mechanical Characteristics of Concrete

2010

Concrete is the most used construction material in practically all of civil engineering fields due to its economical and technical advantages. However, its microstructure is porous and may be completely or partially water saturated. In severely cold climates, this water freezes and degradations develop gradually with the freezing-thawing cycle’s number, in forms of internal cracking, chipping and scaling. Frost behaviour is based on the coupling between the 9% volumetric increase during water transformation into ice, the cryo-suction phenomena, the non frozen water transport within the porous network and the thermo-mechanical behaviour of each component of the frozen media. It is thus obvious that the frost resistance depends on the microstructure (pore size distribution and permeability) and the mechanical characteristics of the material. In this paper, physical and mechanical characteristics evolution during freezing-thawing cycles was followed. The results show that the reduction...

Advanced Evaluation of the Freeze–Thaw Damage of Concrete Based on the Fracture Tests

Materials, 2021

This paper presents the results of an experimental program aimed at the assessment of the freeze–thaw (F–T) resistance of concrete based on the evaluation of fracture tests accompanied by acoustic emission measurements. Two concretes of similar mechanical characteristics were manufactured for the experiment. The main difference between the C1 and C2 concrete was in the total number of air voids and in the A300 parameter, where both parameters were higher for C1 by about 35% and 52%, respectively. The evaluation of the fracture characteristics was performed on the basis of experimentally recorded load–deflection and load–crack mouth opening displacement diagrams using two different approaches: linear fracture mechanics completed with the effective crack model and the double-K model. The results show that both approaches gave similar results, especially if the nonlinear behavior before the peak load was considered. According to the results, it can be stated that continuous AE measurem...

Freeze-Thaw Resistance of Concrete: Insight from Microstructural Properties

2018

Composite cements offer low carbon alternatives to conventional CEM I. These also generally tend to perform better than CEM I in aggressive chemical environments. However, the freeze-thaw resistance, evident through surface scaling and internal damage is usually impaired. Postulated theories on freeze-thaw induced damage do not fully explain the origin of this weakness in composite cement concretes. This contribution systematically presents the phase assemblage changes associated with the freeze-thaw of concrete specimen made from composite cements with and without limestone. The freeze-thaw test was performed on concrete according to CIF method based on CEN/TR 15177 and the corresponding cement pastes characterized by X-ray powder diffraction (XRD) and thermogravimetric analysis (TGA). In all investigated composite cements, portlandite was already depleted after the 7d capillary suction. The implications of this and other modified assemblages during the conditioning and the freeze-...

Freeze-thaw resistance of concrete with porous aggregate

Procedia Engineering, 2010

This paper deals with the influence of periodic freezing on lightweight concrete characteristics. Sets of lightweight concrete prismatic specimens are cyclically frozen in range from +20°C to-20°C and non-destructively tested after every 25 cycles. Freeze-thaw resistance is determined from measurement of the frost-attacked and non-frost-attacked (referential) specimens. The referential specimens are air/water-cured. Non-destructive methods, especially ultrasonic impulse method and resonance method are used for determination of specimen's degradation. Experiments are finished with destructive test in order to determine the static modulus of elasticity.

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...

Mechanical and durability properties of concrete subjected to early-age freeze-thaw cycles

Materials and structures, 2021

Early-age frost damage to concrete used in winter construction or in cold environments negatively affects the development of the hydration process and the performance of the concrete, thereby reducing the service life of the building structure. Experimental research was carried out to investigate the compressive strength, resistance to chloride penetration and resistance to freeze-thaw of concrete specimens subjected to earlyage freeze-thaw cycles (E-FTCs). The effects that different pre-curing times of concrete and mineral admixtures have on the properties of early-age frostaffected concrete were also analyzed. Results show that the earlier the freeze-thaw cycles (FTCs), the poorer the later-age performance. Later-age water-curing cannot

Stress-Strain Model of Concrete Damaged by Freezing and Thawing Cycles

Journal of Advanced Concrete Technology, 2004

This study investigates the dependence of the mechanical behavior of concrete, such as strength, stiffness, and deformation capacity on the damage caused by freezing and thawing cycles (FTC). A stress-strain model for concrete damaged by freezing and thawing prior to the application of mechanical loading was proposed based on plasticity and fracture of concrete elements. The FTC fracture parameter was introduced to explain the degradation in initial stiffness of concrete resulting from freezing and thawing damage. Based on experimental data, the FTC fracture parameter was empirically formulated as a function of plastic tensile strain caused by freezing and thawing with the assumption that the plastic strain was caused by the combined effects of FTC and mechanical loading damage. The stress-strain relationships obtained by the proposed model were compared with the experimental data.

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.

Freeze-Thaw Durability of High-Strength Concrete

1997

This report presents freeze-thaw durability results of an investigation regarding the application of high performance concrete (HPC) to prestressed bridge girders. This study included a total of 30 concrete mixes and more than 130 specimens, with the following variables: aggregate type: round river gravel, partially-crushed gravel, granite, high-absorption limestone, and low-absorption limestone; cementitious material composition: Type III portland cement only, 20% fly ash, 7.5% silica fume, and combination of 20% fly ash with 7.5% silica fume replacement by weight of cement; and curing condition: heat-cured or seven-day moist-cured. No air-entraining agents were used in the study's initial phase to simulate the production of precast/prestressed bridge girders. Results indicate that it is possible to produce portland cement concrete with high strength and freeze-thaw durability without the use of air-entraining agents. Overall, the moist-cured concrete specimens exhibited better...