Frost Resistance Of Concrete Research Articles

Possible rapid method for the determination of concrete's frost resistance

During this research, the theoretical analysis of dependence concrete's frost resistance of sample and energy, which is emitted by a sample at destruction, was carried out. The offered method includes measurement of residual deformation of a sample after the one cycle of freezing defrosting, measurement of long strength and measurement of short-term strength. Frost resistance of a sample is as the mathematical relation of these energies, and the frost resistance of concrete is calculated as arithmetic mean on samples. The offered method doesn't demand long tests, it’s high efficiency and wide scope, but special laboratory equipment is necessary.

Influence of Superplasticizer on Porosity Structures in Hardened Concretes

One of the criteria used to achieve frost resistant concrete is to obtain appropriate parameters of porosity structure in the hardened concrete. Polish requirements in this regard are not defined by standards. There is only a requirement in terms of the Spacing Factor for air-entraining admixtures contained in EN 934-2. The standard EN 206 to ensure frost resistance of concretes requires in exposure classes XF2-XF4 air content in fresh concretes at least 4% without verification of the porosity structure in the hardened concrete. The technical specifications for paving concretes and bridges usually contain requirements for parameters of porosity structures based on international requirements. Air entraining process of concrete mixtures is complex and depends on many parameters. The analysis of porosity structures in hardened concretes, despite the required frost resistance of concrete, often do not give satisfactory results. Analysis of the results indicates that the reason is inadequate pores sizes in the concretes. Thus, an attempt of explanation of influences of one of the parameters affecting the air entraining process – consistencyof concrete mixes (quantity of superplasticizer) on the porosity structure in the hardened concrete. The research programme was performed on eight series of air-entraining and non-air-entraining concretes with a variable content of superplasticizer. The basic composition and air-entraining admixtures content in air-entraining concrete mixtures were constant. The results showed that with the increase of the content of superplasticizer (with increasing fluidity) air content decreases and the pores sizes changed.

Dependence of Relative Decreasing in Strength by Rate of Strain for the New Rapid Method for Determination of Concrete Frost Resistance

The task of the project is obtaining the dependence between the relative decreasing of strength and rate of strain and substantiation of the new method for determination of concrete frost resistance. It has been analytically proved that using concrete’s rate of strain ε as a measure of damage, instead of decreasing of tensile strength R, increases freeze-thaw resistance’s accuracy of estimation a lot under otherwise equal conditions by the time of freeze-thaw cycling. Also it has been experimentally shown that ratio of relative decreasing R to ε in direction, perpendicular to compression, is assumed to be independent on values R and ε for a given concrete and on the ways of achieving them during mechanical or freeze-thaw cycling. To determine the dependence δR/R by ε (z) 8 specimens were tested by non-destructive method (RU 2 490 631) and two baths of 50 specimens by basic method (thermo cycling). Results of the non-destructive method are different from results by basic method for 6,3%. Dependence of relative decreasing in strength by rate of strain is near to linear and, therefore, value of z is constant. Taking this into account patented methods for estimation of concrete’s freeze-thaw resistance as per values R and ε received after freezing and thawing cycles of some specimens and their postlimenary failure by linear compression was substantiated.

Durability Evaluation of Frost-Resistant Concrete Modified with Additives

The article presents the influence of the addition of microsilica, finely divided sodium bentonite and air-entraining admixture for concrete frost-resistance and characteristics of examined concrete pores. Examination of frost-resistance was conducted for 150 cycles of freezing and thawing. For selected series of concrete the examination of the porosity structure of concrete composites was conducted with the use of a device for automatic image analysis and computer program Lucia Concrete. What is more, there was made a designation of: consistency of concrete mix, air content in concrete mix, compression strength, water penetration depth and concrete absorbability.

Analysis of Influence of Bubble Structure Characteristics on Frost Resistance of Concrete

By scanning the images of bubble structure made through a microscope and measuring characteristic parameters of bubble structure, the paper analyzes the influence of concrete, which is made of different proportion of mineral admixture, on bubble formation and its stability and the influence of bubble characteristics on frost resistance of concrete so as to promote people’s understanding of air-entraining agent application technology.

The Characterization of Porosity and Frost Resistance of Concrete with Fly Ashes Modified

The paper presents the influence of fly ashes for the parameters which define the characteristics of the air pore and frost resistance of aerated concrete. Concrete which was used in the maximum allowable amount of fly ashes and different amounts of air admixture have been evaluated. Test of concrete mix have been performed such as the slump cone consistency and air content with pressure method used. Compressive strength, the depth of water penetration under pressure, at 150 cycles freeze resistance and the characteristics of the air pores have been evaluated for concrete. Parameters characterizing the pore structure have been marked: the total air content in concrete A, the ratio of pores location L, the content of micropores A300. The results of the study have shown that it is possible to provide good frost resistance of concrete containing fly ashes. Air content of about 4% provides increased resistance to frost well as the use of fly ashes. The condition of frost resistance is to ensure the proper pore structure of the aircraft.

Experiment Study on the Effect of GGBFS on Frost Resistance of Concrete

High volume utilization of industrial wastes and by products is the solution for high disposal coast. The anti-frost of high performance concrete is a key factor for safe utilization of concrete structure containing industrial wastes under severe environment. In this paper, to understand the property on anti-frost of high performance containing ground granulated blast furnace slag (GGBFS) under cold marine environment. Some comparison studies were conducted on plain concrete by rapid freeze-thaw cycle test. During the rapid freeze-thaw cycle test, the mass loss and relative elastic modulus were measured regularly at the prescribed conditioning ages. The development of microstructure in concrete was analyzed through scanning electron microscopy (SEM) and X-ray diffraction (XRD). The rapid freeze-thaw cycle test results show that the plain concrete was destroyed severely at 150 freeze-thaw cycles. After 225 freeze-thaw cycles, the mass loss and the relative dynamic modulus of elasticity of GGBFS concrete decrease 1.3% and 26.11%, respectively, that indicates that GGBFS significantly improve the anti-frost performance of concrete; The addition of GGBFS can accelerate the cement hydration reaction, promote more Ca (OH)2 crystals shift to C-S-H gel and help to increase the density of the micro-structure of concrete, which can prevent the formation of micro-cracks and suppress the propagation of cracks and thus effectively improve the durability of concrete. KEY WORDS: GGBFS; freeze-thaw durability; microstructure; scanning electron microscopy; X-ray diffraction.

Quality Evaluation of Air Entraining Agent Based on Air Void Parameters of Fresh Concrete

In order to evaluate the quality of air entraining agent quickly and effectively. Air void parameters of fresh concrete with different air entraining agents were studied by Air Void Analyzer (AVA). The spacing factor and durability index of hardened concrete were tested and the relationship between the surface tension of air entraining agent and frost resistance of concrete was compared. The results showed that, the quality of air entraining agent can be evaluated quickly and effectively by diameter distribution of air bubbles in fresh concrete and spacing factor of fresh concrete. AEA2 introduced much more big air bubbles into concrete which is bad for the frost resistance of concrete. The quality of AEA2 was the worst, so the durability index of hardened concrete was 58.7%. Quality of air entraining agent cannot be characterized by properties of air entraining agent, but air entraining ability can be characterized by surface tension of air entraining agent. Keywords: air entraining agent (AEA), air void parameter, fresh concrete

Research on Frost Resistance of Recycled High Performance Concrete

Experimental research on the frost resistance of recycled high performance concrete (RHPC) was carried out, in which three kinds of replacements were considered including recycled coarse or fine aggregate to natural coarse or fine aggregate and together. The results showed that RHPC had the lower dynamic modulus and mass loss than natural aggregate concrete when the replacement of recycled coarse or fine aggregate ranged 30-70% or 10-50%. The best frost resistance of RHPC appeared to the simultaneous replacements of 50% and 10% for recycled coarse and fine aggregate.

Influences of Polypropylene Fiber on Properties of Foam Concrete with Iron Tailings

Iron tailings are mineral wastes obtained from industrial processing and magnetic separation of iron ore. Foam concrete with iron tailings can be made with iron tailings, cement, fly ash, silica fume, polypropylene fiber, superplasticizer, early strength agent, accelerating agent and foaming agent. The influences of polypropylene fiber on the crack resistance and frost resistance of foam concrete have been investigated in this study. Further, the microstructure of foam concrete was observed. This result demonstrates that polypropylene fiber has greatly increased the crack resistance and frost resistance of foam concrete. The pore structure of foam concrete is improved obviously by polypropylene fiber. Due to the uniformly distributed pores, high porosity and rather complete pore wall, the mechanical properties and thermal properties of foam concrete are excellent. The foam concrete with high-strength and excellent thermal insulation property develops a new route for the comprehensive utilization of iron tailings.

The Analysis of Nano SiO<sub>2</sub> Impacting on the Frost Resistance of EPS Lightweight Concrete

Styrofoam (EPS) lightweight concrete, a new type of lightweight aggregate concrete, whose superior thermal performance and remarkable economic benefit earns more and more attention from the engineering. Adding nanoSiO2into it can improve the frost resistance of EPS lightweight concrete, so that it can improve the microstructure and mechanical properties of concrete. The research on the nanomaterials has the vital significance to the frost resistance of EPS lightweight concrete. The wide application of this technology will greatly promote the development of construction industry, and has very important engineering practical value and social economic benefits.

Research on Frost Resistance of Recycled High Performance Concrete

The influence of recycled aggregates on the frost resistance of concrete was studied by rapid freezing-thawing test. Results showed that there was an important effect of aggregate gradation on frost resistance of recycled coarse aggregate concrete. Frost resistance of recycled fine aggregate concrete was deteriorated with increasing the content of recycled fine aggregate, and recycled fine aggregate had a greater influence on the frost resistance of recycled aggregate concrete than recycled coarse aggregate when adding both together. Test showed that the mass loss rate and the relative dynamic elastic modulus loss are not consistent as evaluation indexes of the frost resistance for recycled concrete, and whether the mass loss rate is suitable as an indicator of frost resistance durability needs to be further studied.

Study on Adding Super Absorbent Polymer to Improve the Frost Resistance of Concrete

Internal curing was especially beneficial to improve concrete performance. The super absorbent polymer and fly ash were used in the concrete and the frost resistance of concrete was studied. The result indicated that the super absorbent polymer changed the pore structure, increased the quantity of the pore, decreased the strength loss 5-10% after 250 freeze-thaw cycles and improved the frost resistance of concrete.

Experimental Study of Frost-Resistance Properties of Silica Fume Concrete

The frost resistance of low strength concrete is researched. In order to evaluate the effect of different content of silica fume on frost resistance，the quality of the cement 6%, 9%, 12% silica fume are respectively added into concrete. Freezing-thawing test results show that: the silica fume concrete has good frost resistance. Content of silica fume on concrete is not almost effect to quality loss rate. In 0-250 times of freezing-thawing cycle range, it is smaller that relative dynamic elastic modulus change rate. Relative dynamic elastic modulus of ordinary concrete decreases rapidly after 250 times of freezing-thawing cycle while dynamic elastic modulus decrease rate of the silica fume concrete tends to slow. The freezing -thawing cycles up to 350 times, silica fume concrete relative dynamic elastic modulus is 1.5 times that of ordinary concrete that show the silica fume concrete frost resistance is better than that of ordinary concrete.

The Frost Resistance of LYTAG Concrete

This article studies the frost resistance of LYTAG concrete and ordinary concrete respectively used the RILEM recommended test method (CIF) about frost resistance of concrete. The results indicate that the single surface's frost resistance of Lytag concrete with mineral admixture is much better than normal density concrete's. And the rank of the single surface's frost resistance at 56 cycles of Lytag concrete with different mineral admixture is: silica fume and slag> silica fume and fly ash>slag and fly ash>silica fume>fly ash>slag. The important reasons why LYTAG concrete has good frost resistance is that the scope of blending interfacial transition zone of LYTAG concrete between aggregate ceramsite and cement stone was significantly smaller than ordinary concrete.

Optional reference method to determine frost resistance of concrete

The main purpose of this research is to create the new reference method to determine the freeze-thaw resistance of concrete that is characterized by small labor inputs, high efficiency and a wide scope application. The offered method is based on the measurement of long strength by a nondestructive method. During this research, the theoretical analysis of concrete specimen dependence on freeze-thaw resistance and energy, which is emitted by a specimen during destruction, has been carried out. Freeze- thaw resistance of a specimen is calculated as the mathematical relation of these energies, and the freeze-thaw resistance of concrete is calculated as an arithmetic mean across specimens. Correctness of the offered method is proved by experiments. The offered method doesn't demand long tests. It is highly efficient and has a wide scope, but special further laboratory test duration is needed.

Recycling of Glass Wastes in Latvia – Its Application as Cement Substitute in Self-Compacting Concrete

The rate of treated waste glass within the last 10 years has risen up to 25% due to improved waste glass collecting system in Latvia, however the glass waste recycling infrastructure is still up to date issue due to absence of local recycling companies. Application of glass wastes as cement substitute has significant effect on the properties of concrete making it eco-friendly construction material with several benefits like: decrease of accumulated glass wastes in landfills, the reduction of non-renewable natural resource consumption, the reduction of cement content up to 20-30% and the reduction of greenhouse gas emission. In the present investigation was evaluated the effectiveness of ground soda-alkaline earth-silicate glass coming from low pressure mercury-discharge lamp waste chips, borosilicate glass coming from incandescent light bulb waste chips, soda-lime glass cullet coming from beverage containers on workability, compressive strength and frost resistance of self-compacting concrete. DOI: http://dx.doi.org/10.5755/j01.sace.6.1.6127

Application acoustic emission method during concrete frost resistance

Frost resistance is one of the most frequent characteristics of concrete. It is a very complex subject and the test methods themselves are still in development and the international consensus on methodology is still sought, too. The determination concrete frost resistance takes several weeks, months or even more than a year. However micro-structural changes as micro-cracks have not been described sufficiently. Acoustic Emission Method as unusual Non-Destructive Methods can help to monitor structural changes during common frost resistance measuring. Note the Acoustic Emission Method detects only active “defects” into monitored structure. Thus when e.g. crack grows some acoustic waves spread from crack place, i. e. from acoustic emission source. The method does not detect geometric discontinuities and “passive” defects. Selected Non-Destructive Methods as Ultrasound, Non-Linear Ultrasonic Spectroscopy, Impact Echo etc. are used to confirm micro-structural changes. The article describes the first experiment with its imperfections, difficulties and possibilities.

Experimental Study on Frost Resistance of Concrete in Seawater

The experiments of concrete in seawater under 0, 25, 50, 75 and 100 freezing-thawing cycles were performed using fast freezing and thawing method. Appling large concrete static and dynamic triaxial test system, the influence of freezing and thawing cycles on compressive strength and strain at peak stress point of concrete in seawater were detected, and then simple mathematical expressions were established.

パルプ配合によるコンクリートの耐凍害性の改善

パルプ配合によるコンクリートの耐凍害性の改善