scholarly journals Effect of Fast Freeze-Thaw Cycles on Mechanical Properties of Ordinary-Air-Entrained Concrete

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Huai-shuai Shang ◽  
Wei-qun Cao ◽  
Bin Wang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Life Prediction ◽  
Cold Region ◽  
Mathematical Formula ◽  
Laboratory Environment ◽  
Freeze Thaw ◽  
Cleavage Strength ◽  
Concrete Materials ◽  
Air Entrained Concrete

Freezing-thawing resistance is a very significant characteristic for concrete in severe environment (such as cold region with the lowest temperature below 0°C). In this study, ordinary-air-entrained (O-A-E) concrete was produced in a laboratory environment; the compressive strength, cubic compressive strength of C50, C40, C30, C25, and C20 ordinary-air-entrained concrete, tensile strength, and cleavage strength of C30 ordinary-air-entrained concrete were measured after fast freeze-thaw cycles. The effects of fast freeze-thaw cycles on the mechanical properties (compressive strength and cleavage strength) of ordinary-air-entrained concrete materials are investigated on the basis of the experimental results. And the concise mathematical formula between mechanical behavior and number of fast freeze-thaw cycles was established. The experiment results can be used as a reference in design, maintenance, and life prediction of ordinary-air-entrained concrete structure (such as dam, offshore platform, etc.) in cold regions.

Optimization Research of Mix Proportion of Frost Resistance Construction of Concrete Based on the MATLAB Language

2014 ◽  
Vol 584-586 ◽  
pp. 1917-1921
Author(s):  
Jun Jie Zhang ◽  
Rui Hong Shao ◽  
Xiang Yi Meng
Keyword(s):  
Compressive Strength ◽  
Objective Function ◽  
Frost Resistance ◽  
Unit Volume ◽  
Influence Factors ◽  
Multi Objective Optimization ◽  
Cold Region ◽  
Freeze Thaw ◽  
Performance Indexes ◽  
Mix Proportion

Analyze the influence factors of mix proportion affecting concrete freeze-thaw damage. Use the five main performance indexes of the concrete, which are compressive strength, strength of extension, impermeability grade, and frost resistance grade and per unit volume cost concrete, as the objective function of multi-objective optimization equation. Invoke the fgoalattain function in the MATLAB Optimization Toolbox to solve. The optimized parameters of mix proportion of frost resistance construction of unit concrete in cold region are: concrete 1532.6kg, water 910kg, sand 5510.6kg, 5-20mm cobblestone 3747.2kg、20-40mm cobblestone 3658.6kg、40-80mm cobblestone 4733.5kg、80-150mm cobblestone 4738.1kg, and the dosage of water reducing agent is 7.3kg.

Physical Properties of Building Blocks from Hemp Shives Aggregate and Cementitious Binder, Manufactured in the Expanded Clay (Vibro Pressing) Production Line

2017 ◽  
Vol 908 ◽  
pp. 118-122 ◽  
Author(s):  
Giedrius Balčiūnas ◽  
Viktor Kizinievič ◽  
Justinas Gargasas
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Compressive Strength ◽  
Physical Properties ◽  
Production Line ◽  
Scientific Literature ◽  
Building Blocks ◽  
Freeze Thaw ◽  
Cementitious Binder ◽  
Pressing Technology

Scientific literature mostly aims at investigation of composites with fibre hemp shives (FHS) aggregate and lime binder, although, such materials are characterised by pretty low mechanical properties. In order to obtain higher mechanical properties of a composite, it is appropriate to use cementitious binder. This work investigates physical properties of blocks from hemp shives aggregate and cementitious binder, manufactured in the expanded clay production line using vibro pressing technology. Following properties of the blocks are determined: freeze-thaw resistance, compressive strength, thermal conductivity and density. Thermal resistance according to EN ISO 6946 for the block with cavities is calculated as well. It is found that compressive strength of FHS-cement blocks may be up to 3.18 MPa when the density is of ~850 kg/m3 and thermal conductivity up to 0.135 W/(m∙K). It is found as well that the decrease of compressive strength is 8.7% after 25 freeze-thaw cycles.

scholarly journals Influence of Water Pressure on the Mechanical Properties of Concrete after Freeze-Thaw Attack under Dynamic Triaxial Compression State

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Ruijun Wang ◽  
Yan Li ◽  
Yang Li ◽  
Fan Xu ◽  
Xiaotong Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Strain Rate ◽  
Water Pressure ◽  
Mass Loss Rate ◽  
Triaxial Compression ◽  
Ultimate Compressive Strength ◽  
Peak Strain ◽  
Freeze Thaw ◽  
Dynamic Triaxial Compression

This study aims at determining the effect of water pressure on the mechanical properties of concrete subjected to freeze-thaw (F-T) attack under the dynamic triaxial compression state. Two specimens were used: (1) a 100 mm × 100 mm × 400 mm prism for testing the loss of mass and relative dynamic modulus of elasticity (RDME) after F-T cycles and (2) cylinders with a diameter of 100 mm and a height of 200 mm for testing the dynamic mechanical properties of concrete. Strain rates ranged from 10−5·s−1 to 10−3·s−1, and F-T cycles ranged from 0 to 100. Three levels of water pressure (0, 5, and 10 MPa) were applied to concrete. Results showed that as the number of F-T cycles increased, the mass loss rate of the concrete specimen initially decreased and then increased, but the RDME decreased. Under 5 MPa of water pressure and at the same strain rate, the ultimate compressive strength decreased, whereas the peak strain increased with the increase in the number of F-T cycles. This result is contrary to the variation law of ultimate compressive strength and peak strain with the increase in strain rate under the same number of F-T times. With the increase in F-T cycles or water pressure, the strain sensitivity of the dynamic increase factor of ultimate compressive strength and peak strain decreased, respectively. After 100 F-T cycles, the dynamic compressive strength under all water pressure levels tended to increase as the strain rate increased, whereas the peak strain decreased gradually.

scholarly journals Degradation of Roller-Compacted Concrete Subjected to Freeze-Thaw Cycles and Immersion in Potassium Acetate Solution

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Wuman Zhang ◽  
Jingsong Zhang ◽  
Shuhang Chen ◽  
Sheng Gong
Keyword(s):  
Mechanical Properties ◽  
Weight Loss ◽  
Compressive Strength ◽  
Impact Energy ◽  
Impact Test ◽  
Potassium Acetate ◽  
Acetate Solution ◽  
Freeze Thaw ◽  
Roller Compacted Concrete ◽  
The Impact

Two sets of roller-compacted concrete (RCC) samples cured for 28 days were subjected to freeze-thaw (F-T) cycles and immersion in laboratory conditions. F-T cycles in water and water-potassium acetate solution (50% by weight) were carried out and followed by the flexural impact test. The weight loss, the dynamic elastic modulus (Ed), the mechanical properties, and the residual strain of RCC were measured. The impact energy was calculated based on the final number of the impact test. The results show that the effect of F-T cycles in KAc solution on the weight loss and Ed of RCC is slight. Ed, the compressive strength, and the flexural strength of RCC with 250 F-T cycles in KAc solution decrease by 3.8%, 23%, and 36%, respectively. The content (by weight) of K+ at the same depth of RCC specimens increases with the increase of F-T cycles. The impact energy of RCC specimens subjected to 250 F-T cycles in KAc solution decreases by nearly 30%. Microcracks occur and increase with the increase of F-T cycles in KAc solution. The compressive strength of RCC immersed in KAc solution decreases by 18.8% and 32.8% after 6 and 12 months. More attention should be paid to using KAc in practical engineering because both the freeze-thaw cycles and the complete immersion in KAc solution damage the mechanical properties of RCC.

scholarly journals Frost resistance of cement-sand and concrete beams during unilateral freezing

2021 ◽  
Vol 2 (1) ◽  
pp. 64-74
Author(s):  
Nepomyach Alexander Nikolaevich ◽  
Vyrovoy Valeriy Nikolaevich ◽  
Chistyakov Artem Aleksaedrovich
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Frost Resistance ◽  
Bending Strength ◽  
Concrete Beams ◽  
Transmission Rate ◽  
Beam Structure ◽  
Freeze Thaw ◽  
Damage Coefficient ◽  
Negative Temperatures

Abstract The work investigates changes in the beam structure under the action of local freezing, which leads to a change of the mechanical properties of the material and, consequently, of the beam structure. Two types of beam samples were used: from cement-sand mortar and from concrete. The work investigates the change in the development of deformations depending on the conditions of freezing of samples. The second accelerated method for assessing frost resistance was chosen according to DSTU B В.2.7-47-96. An accelerated method was chosen for assessing frost resistance at the temperature of -20 ±2 C°. After every five freeze-thaw cycles, the following changes were monitored: mass, water absorption, ultrasound transmission rate, damage coefficient, tensile bending strength, splitting strength, compressive strength, carbonization depth. The results showed that both in concrete and in mortar samples, the compressive strength after freezing was lower by 8% and 15% accordingly. The experimental results obtained confirm the assumptions made that the frost resistance of the material depends on the conditions of exposure of negative temperatures on products and structures and it can be used in a wider range of construction which will push regional development.

Frost resistance of roller compacted concrete in airport runway subjected to ethylene glycol solution

2019 ◽  
Vol 66 (1) ◽  
pp. 40-44 ◽  
Author(s):  
Wuman Zhang ◽  
Jingsong Zhang ◽  
Shuhang Chen
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Ethylene Glycol ◽  
Immersion Test ◽  
Bending Test ◽  
Content Type ◽  
Freeze Thaw ◽  
Roller Compacted Concrete ◽  
Practical Engineering ◽  
Airport Runway

Purpose Ethylene glycol (EG) solution is a common deicing fluid of the aircrafts. Roller compacted concrete (RCC) used in the runway and the parking apron will be subjected to freeze-thaw cycles in EG solution. The purpose of this study is to find whether RCC can be damaged by the action of freeze-thaw cycles or long-term immersion in EG solution. Design/methodology/approach Freeze-thaw cycles test and immersion test in EG solution by weight were used to accelerate the degradation of RCC. A compression test and a three-point bending test were carried out in the laboratory to evaluate mechanical properties of RCC. The changes of microstructure were monitored by using scanning electron microscopy and energy-dispersive X-ray analysis. Findings The results show that RCC specimens have little weight change in both freeze-thaw cycles test and immersion test. The dynamic modulus of elasticity, the compressive strength and the flexural strength of RCC with 250 freeze-thaw cycles in EG solution are decreased by 4.2, 15 and 39 per cent, respectively. The compressive strength is decreased by 35 per cent after 12 months of immersion in EG solution. Micro-cracks occur and increase with the increase in freeze-thaw cycles and immersion test. Originality/value The mass ratio of the elements in the crystal is very close to the proportion of elements in CaC2O4 (C:O:Ca = 1:1.26:1.6). More attention should be paid to using EG in practical engineering because both the freeze-thaw cycles and the complete immersion in EG solution damage the mechanical properties of RCC.

scholarly journals Effect of Metallic Inclusions on the Compressive Strength of Cement-Based Materials

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Tomáš Ficker
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Mechanical Stability ◽  
Transition Zones ◽  
Metallic Inclusions ◽  
Cement Based Materials ◽  
Concrete Materials ◽  
Materials Used ◽  
The Stability ◽  
Critical Limits

In the concrete foundations, materials come into contact with bedrocks. The surfaces of bedrocks are often covered by sharp protrusions called asperities. Although geotechnical engineers have developed a reliable theory for assessing the mechanical stability of rocky terrains, the stability of transition zones between concrete and sharp asperities remains unsolved. Due to the large pressures that exist in these transition zones, the invasive influence of sharp asperities on the integrity of the concrete raises a question about possible changes of the mechanical properties of concrete materials used in foundations. These circumstances have inspired experiments in which metallic needles of various lengths have been embedded into cement-based materials to assess the influence of the needles on the compressive strength. This influence has been quantified, and the critical limits identifying the changes of material integrity have been determined. It has been conjectured that sharp rock asperities or needle-like rods of steel reinforcement in concrete may cause similar changes of material integrity as the metallic needles used in the experiments performed.

Effect of Fly Ash Content on Mechanical Properties of Cement-Fly Ash Stabilized Crushed Stones

2014 ◽  
Vol 548-549 ◽  
pp. 228-232 ◽  
Author(s):  
Xiao Chen ◽  
Ji Wei Liu ◽  
Ming Kai Zhou
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Crack Resistance ◽  
Unconfined Compressive Strength ◽  
Resilient Modulus ◽  
Ash Content ◽  
Mechanical Parameters ◽  
Cleavage Strength ◽  
The Impact

To improve the impact of fly ash on the properties of cement-fly ash stabilized crushed stone, and promote it popularize and apply better. This paper investigated the effect of fly ash content on unconfined compressive strength, cleavage strength and resilient modulus of cement-fly ash stabilized crushed stones, and those relationships between mechanical parameters. The results showed that with increasing of the fly ash content, the unconfined compressive strength and cleavage strength increased at first, then decreased, the resilient modulus decreased, and The brittleness index increased. We can conclude that the optimal fly ash content is between 10% and 15%, and increment of fly ash content can improve its crack-resistance.

Effect of concrete specifications and inspection practices on freeze–thaw resistance: a field study

1990 ◽  
Vol 17 (2) ◽  
pp. 271-276
Author(s):  
M. A. Ward ◽  
B. W. Langan
Keyword(s):  
Compressive Strength ◽  
Statistical Analysis ◽  
Field Study ◽  
Key Words ◽  
Freeze Thaw ◽  
Air Content ◽  
Rigorous Statistical Analysis ◽  
Metropolitan Center ◽  
Concrete Materials ◽  
Job Site

In the late sixties significant durability problems were encountered in a major metropolitan center in Canada. A review of prevailing construction practices was undertaken, together with a rigorous statistical analysis of the air content and compressive strength results. The main outcome of that study was a conclusion that a significant amount of the concrete placed on the job site had an unacceptably low air content. It is understood that these results, coupled with a review of specifications used in other metropolitan centers, provided the basis for revising the concrete materials specification in 1970. A similar review of strength and air content results was carried out at the end of that year. It was evident that an increase of approximately 1% had occurred in the average measured air content together with a small increase in compressive strength as the result of the specification changes. To assess the effect of this specification and further changes that have occurred since 1970, a third review was carried out in 1987. It was noted that during the intervening period a further increase in air content had taken place. Reasons for these changes are reviewed with respect to current construction practices. Also included is a review of the current specifications for this class of concrete in use in Canada. Key words: air content, compressive strength, specifications, inspection, statistics, durability.

Effect of Fly Ash Content on Mechanical Properties of Cement-Fly Ash Stabilized Crushed Stones

2010 ◽  
Vol 168-170 ◽  
pp. 1881-1885
Author(s):  
Xiao Chen ◽  
Ming Kai Zhou ◽  
Jia Liu
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Crack Resistance ◽  
Unconfined Compressive Strength ◽  
Resilient Modulus ◽  
Ash Content ◽  
Brittleness Index ◽  
Mechanical Parameters ◽  
Cleavage Strength

This paper investigates the effect of fly ash content on unconfined compressive strength, cleavage strength and resilient modulus of cement-fly ash stabilized crushed stones. The relationships between mechanical parameters were also studied. The results show that with fly ash content increasing, the unconfined compressive strength and cleavage strength were increasing firstly but decreased then, and the resilient modulus were decreasing. The brittleness index was increased by the increment of fly ash content. It can be concluded that the optimal fly ash content in cement-fly ash stabilized crushed stones is between 10% and 15%, and increment of fly ash content can improve its crack-resistance.

Sign in / Sign up

Export Citation Format

Share Document