• Computers and Concrete
• /
• v.9 no.5
• /
• pp.375-387
• /
• 2012

The objective of this investigation was to develop rules for automatic categorization of concrete quality using selected artificial intelligence methods based on machine learning. The range of tested materials included concrete containing a new waste material - solid residue from coal combustion in fluidized bed boilers (CFBC fly ash) used as additive. The rapid chloride permeability test - Nordtest Method BUILD 492 method was used for determining chloride ions penetration in concrete. Performed experimental tests on obtained chloride migration provided data for learning and testing of rules discovered by machine learning techniques. It has been found that machine learning is a tool which can be applied to determine concrete durability. The rules generated by computer programs AQ21 and WEKA using J48 algorithm provided means for adequate categorization of plain concrete and concrete modified with CFBC fly ash as materials of good and acceptable resistance to chloride penetration.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.11a
• /
• pp.483-486
• /
• 2005

This study investigates the effect of air contents on concrete properties, compressive strength, chloride migration coefficient and freeze-thaw resistance. Chloride migration and freeze-thawing test conducted in accordance with NT-BUILD 492 and pr-EN 12390-9, respectively. As a result, compressive strength reduced with air contents increase, but chloride migration coefficient more influenced by the water-binder ratios than air contents. Air contents of hardened concrete measured half times that of fresh concrete after mixing. Also, concrete scaling decreased with air contents increased.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.2
• /
• pp.1188-1194
• /
• 2014

The purpose of this study is to estimate Chloride Attack Resistibility and mechanical properties of quaternary concrete adding fly ash, blast-furnace slag, and silica fume. Compressive strength, modulus of elasticity, chloride migration coefficient, charge passed from Rapid chloride penetration test(RCPT), and immersion testing in 3% NaCl are tested. Chloride migration coefficient and charge passed of quaternary concrete measured $0.032{\times}10^{-12}m^2/sec$ and 650 coulomb at 17 weeks, which are in a permitted limit. Also in immersion test, depth of chloride penetration and maximum chloride ion of quaternary concrete measured 3.7 mm and $10.211kg/m^3$ respectively. From the results, quaternary concrete adding fly ash, blast-furnace slag, and silica fume denotes improvement of mechanical properties and chloride attack resistibility.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.10a
• /
• pp.787-790
• /
• 1999

To estimate durability of reinforced concrete structures located in or nearby seawater, many different kinds of accelerated tests for evaluation of chloride ion permeation in concrete were proposed. At present the only standardized test is the ASTM C 1202(RCP test). This test method is used to estimate the concrete's resistivity of the chloride penetration in concrete by using the total charges passed and sometimes used to calculate the chloride diffusion coefficients. However, this test may lead to an erroneous chloride diffusion coefficient. So this test method was compared with the modified Dhir's test and the traditional concentration diffusion test. Experimental results showed that the diffusion coefficients determined the RCP test and the PD Index gave wrongous values, but the diffusion coefficient acquired by considering a migration term was nearly the same to the CD Test.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.10 no.4
• /
• pp.600-608
• /
• 2022

This study investigates the effect of layered double hydroxide (LDH) on the healing performance of self-healing concrete by assessing the chloride penetration resistance of self-healing cement mortars using electrical chloride ion migration-diffusion test. Test results show that both mortars containing healing materials only and mortars containing healing materials and Ca-Al LDH together mostly had higher migration-diffusion coefficients right after cracking, but the migration-diffusion coefficients decreased more than that of OPC with increasing healing ages, and thus, they yielded higher healing capacities than OPC. Also, mortars containing Ca-Al LDH together with healing materials showed higher reduction of their migration-diffusion coefficients, and thus, higher healing capacities than mortars containing healing materials only. This suggests that as the self-healing product increases on the crack surface, the binding of chloride ions by LDH inside the crack increases.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.04a
• /
• pp.427-432
• /
• 1999

An electrci method for the rapid determination of chloride diffusion coefficient in concrete is proposed considering the electrical migration term in the Nernst-Plank equation. The experimental set-up for this method is basically that for PD index by Dhir, excluding some change in the experimental parameter values in consideration of reliability, simplicity and rapidity of the accelerated test method. Experimental results show that 30mm of specimen thickness, 10 volt of supplied potential, and 5M of chloride ion concentration are optimal

• Proceedings of the Korea Concrete Institute Conference
• /
• 2002.10a
• /
• pp.17-22
• /
• 2002

Chloride ions have a tendency to penetrate into concrete and proceed the corrosion by depassivating rebar surface. Thus the deteriorated concrete is subject to experience severe degrading of durability under marine environment. Physical properties of mortar, such as, compressive strength and penetration depth of chloride ion were investigated. And to investigate the effect of containing SG, FA in mortar, the diffusion coefficient of chloride was measured through an electro - migration test. The diffusion coefficient of chloride was decreased with the increase of replacement ratio of SG compared with plain specimen.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.11a
• /
• pp.793-796
• /
• 2001

Physical properties of concrete, Such as, compressive strength, permeable pore and penetration depth of chloride ion were investigated. And to investigate the effect of containing GGBF in concrete, the diffusion coefficient of chloride was measured through an electro- migration test. The diffusion coefficient of chloride was decreased with increase of replacement ratios of GGBF when compared to OPC. Relation coefficients between physical properties of concrete and diffusion coefficient of chloride were more than 0.9.

• Advances in concrete construction
• /
• v.7 no.2
• /
• pp.87-96
• /
• 2019

Self-compacting concretes (SCC) are highly fluid concrete which can flow without any vibration. Their composition requires a large quantity of fines to limit the risk of bleeding and segregation. The use of crushed sand rich in limestone fines could be an adequate solution for both economic and environmental reasons. This paper investigates the influence of quarry limestone fines from manufactured crushed sand on rheological, mechanical and durability properties of SCC. For this purpose, five mixtures of SCC with different limestone fines content as substitution of crushed sand (0, 5, 10, 15 and 20%) were prepared at constant water-to-cement ratio of 0.40 and $490kg/m^3$ of cement content. Fresh SCC mixtures were tested by slump flow test, V-funnel flow time test, L-box height ratio, segregation resistance and rheological test using a rheometer. Compressive and flexural strengths of SCC mixtures were evaluated at 28 days. Regarding durability properties, total porosity, capillary water absorption and chloride-ion migration were studied at 180 days. For the two test modes in fresh state, the results indicated compatibility between slump flow/yield stress (${\tau}_0$) and V-funnel flow time/plastic viscosity (${\mu}$). Increasing the substitution level of limestone fines in SCC mixtures, contributes to the decrease of the slump flow and the yield stress. All SCC mixtures investigated achieved adequate filling, adequate passing ability and exhibit no segregation. Moreover, the inclusion of limestone fines as crushed sand substitution reduces the capillary water absorption, chloride-ion migration and consequently enhances the durability performance.

• Journal of the Korea Institute of Building Construction
• /
• v.16 no.4
• /
• pp.321-329
• /
• 2016

The use of ternary blended cement consisting of Portland cement, granulated blast-furnace slag (GGBFS) and fly ash has been on the rise to improve marine concrete structure's resistance to chloride attack. Therefore, this study attempted to investigate changes in chloride attack resistibility of concrete through NT Build 492-based chloride migration experiments and test of concrete's ability to resist chloride ion penetration under ASTM C 1202(KS F 2271) when 1.5-2.0% of alkali-sulfate activator (modified alkali sulfate type) was added to the ternary blended cement mixtures (40% ordinary Portland cement + 40% GGBFS + 20% fly ash). Then, the results found the followings: Even though the slump for the plain concrete slightly declined depending on the use of the alkali-sulfate activator, compressive strength from day 2 to day 7 improved by 17-42%. In addition, the coefficient from non-steady-state migration experiments for the plain concrete measured at day 28 decreased by 36-56% depending on the use of alkali-sulfate. Furthermore, total charge passed according to the test for electrical indication of concrete's ability to resist chloride ion penetration decreased by 33-62% at day 7 and by 31-48% at day 28. As confirmed in previous studies, reactivity in the GGBFS and fly ash improved because of alkali activation. As a result, concrete strength increased due to reduced total porosity.