Chloride Permeability Of Concrete Research Articles

The accelerated test of chloride permeability of concrete

The availability of accelerated chloride permeability test and the effect of w/c ratio, incorporation of silica fune, maximum aggregate size and aggregate type on the chloride permeability were studied. The mathematic analysis certifies that there is a linear relationship between accelerated test and natural diffusion. Test results show that the chloride permeability of concrete increases as w/c ratio increases whilst a limited amount of replacement of cement with silica fune, the chloride permeability decreases dramatically. The maximum aggregate size in the range of 8 to 25 mm seems also affect chloride permeability but with a much less significant level. The chloride permeability of silica fume lightweight aggregate concrete is very low, especially the concrete made with dry lightweight concrete. The chloride permeability can be evaluated by this accelerated test method.

Effect of Cracking on Water and Chloride Permeability of Concrete

The goal of this research was to study the relationship between cracking and concrete permeability and to support accounting for permeability and cracking resistance to other factors besides strength, as criteria to be considered in mix design to achieve a durable concrete. The effect of material composition [normal-strength concrete (NSC) and high-strength concrete (HSC) with two different mix designs] and crack width (ranging from 50 to 400 μm) on water and chloride permeability were examined. Cracks of designed widths were induced in the concrete specimens using a feedback-controlled splitting tensile test. Chloride permeability of the cracked samples was evaluated using a rapid chloride permeability test and the water permeability of cracked concrete was then evaluated by a low-pressure water permeability test. Uncracked HSC was less water permeable than NSC, as expected, but cracking changed the material behavior in terms of permeability. Both NSC and HSC were affected by cracking, and the water perm...

Effect of Supplementary Cementing Materials on the Specific Conductivity of Pore Solution and Its Implications on the Rapid Chloride Permeability Test (AASHTO T277 and ASTM C1202) Results

The American Association of States Highway and Transportation Officials (AASHTO) Test Method T277--Rapid Determination of the Chloride Permeability of Concrete and the American Society of Testing and Materials (ASTM) C1202--Electrical Indication of Concrete's Ability to Resist Chloride Ion Penetration have specified a rapid test method to rank the chloride penetration resistance of various concretes by applying a potential of 60 V DC to a concrete specimen and measuring the charge passed through the specimen during 6 hours of testing. The method is essentially a measurement of electrical conductivity of concrete, which depends on both the pore structure and the chemistry of the pore solution. Analyses based on published results have indicated that the replacement of portland cement with supplementary cementing materials, such as silica fume, can reduce the electrical conductivity of concrete more than 90% because of the change in pore solution composition in the concrete. Chemical composition of pore solution has little to do with the transport of chloride ions in the concrete; thus, it is not correct to use passed charge to rank the chloride penetration resistance of concrete made with supplementary cementing materials.

若材齢で凍結融解を受けた普通および軽量骨材コンクリートの塩化物イオン透過性

The chloride permeability of normal weight and lightweight concretes subjected to freeze-thaw damage at the age of 3 days was evaluated by using the AASHTO T277 chloride permeability test method and the freeze-thaw test method similar to that recommended by JSCE-1986. The relative dynamic modulus of elasticity was obtained from the results of ultrasonic pulse velocity measurements for each specimen before and after the freezing and thawing test. The results showed that the chloride permeablity of the normal weight concretes having an air content of at least 7.6% changed little with the repeated cycles of freezing and thawing ranging from 18 to 44 cycles, irrespective of the presence and the type of mineral admixtures. It was found that the application of freeze-thaw cycles obviously decreased the values of the relative dynamic modulus of elasticity in the normal weight concretes, but that the reduction in the relative dynamic modulus of elasticity did not always result in an increase in the chloride permeablity of the concretes. The test results also indicated that most of lightweight concretes made with fully-saturated expanded shale aggregates exhibited an extremely high chloride permeability, when they were subjected to a single freeze-thaw cycle. Furthermore, the type of microcracks developing in the normal weight concretes under the repeated freeze-thaw cycles was discussed.

Strength and chloride permeability of concrete containing red tropical soils

Red tropical soils are produced by natural chemical weathering. They contain appreciable quantities of amorphous silica and alumina and also large proportions of very poorly ordered clay minerals. For this reason they are considered to be a good source of pozzolanic material and may be used as raw feed for the manufacture of cement or as cement replacement for the production of concrete. This Paper presents the results of an investigation into the engineering properties and performance of concrete made with a mixture of cement/pozzolan, where the pozzolan consisted of two types of red tropical soil. The Paper highlights the strength properties and chloride ion permeability characteristics of these mixtures and discusses the beneficial effects of using red tropical soils in concrete.

フライアッシュおよび高炉スラグ微粉末を使用したコンクリートにおける養生条件の塩素イオン透過性に及ぼす影響

Chloride permeability of concrete is one of the major factors that influence the corrosion of steel reinforcement in concrete. It has been confirmed that the chloride permeability of cement paste and mortar varies widely depending on the water: cement ratio, type of cement, curing condition and so on. However, there are only a few reports concerning the chloride permeability of concrete. This study aims at revealing the effect of curing condition on the chloride permeability of concrete in which Portland cement was replaced in various amounts by flyash and blastfurnace slag. The chloride permeability of concrete was determined by the accelerated chloride permeability test using a diffusion cell similar to that described in Federal Highway Administration report (FHWA/RD-81/119). In order to relate the porosity or pore size distribution of concrete to its chloride permeability, the mercury intrusion porosimetry measurements were also conducted.The experimental results showed that the chloride permeability of concrete containing flyash and blastfurnace slag was high when the concrete was exposed to a low humidity at the early stage of curing. It was also found that the chloride permeability of concrete increased proportionally with increasing volume of pores larger than 0.1μm in diameter.

Chloride Permeability Of Concrete Containing A Flyash And A Blastfurnace Slag

AbstractThe effects of curing conditions on the chloride permeability of concrete with various replacements of Portland cement by a flyash and a blastfurnace slag was investigated. In order to relate the porosity and pore size distribution of concretes to their chloride permeability, mercury intrusion porosimetry measurements were also conducted. The results showed that exposure of concretes to a relatively low humidity at early ages increased their chloride permeability. It was also found that the chloride permeability of concrete increased proportionally with increasing volume of pores larger than 0.1 μm in diameter.