• Advances in concrete construction
• /
• v.7 no.2
• /
• pp.75-85
• /
• 2019

The present study is focused on the mechanical and durability properties of ternary blended cement concrete mix of different grades 30 MPa, 50 MPa and 70 MPa. Three mineral admixtures (fly ash, silica fume and lime sludge) were used as a partial replacement of cement in the preparation of blended concrete mix. The durability of ternary blended cement concrete mix was studied by exposing it to acids HCl and $H_2SO_4$ at 5% concentration. Acid mass loss factors (AMLF), acid strength loss factor (ASLF) and acid durability factor (ADF) were determined, and the results were compared with the control mix. Chloride ions penetration was investigated by conducting rapid chlorination penetration test and accelerated corrosion penetration test on control mix and ternary blended cement concrete. From the results, it was evident that the usage of these mineral admixtures is having a beneficiary role on the strength as well as durability properties. The results inferred that the utilization of these materials as a partial replacement of cement have significantly enhanced the compressive strength of blended concrete mix in 30 MPa, 50 MPa and 70 MPa by 42.95%, 32.48% and 22.79%. The blended concrete mix shown greater resistance to acid attack compared to control mix concrete. Chloride ion ingress of the blended cement concrete mix was low compared to control mix implying the beneficiary role of mineral admixtures.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.04a
• /
• pp.415-420
• /
• 1999

Dam concrete should have sufficient durability in wet and dry repetition and abrasion due to water lever variance and also in freezing and thawing resistance as well as water penetration capacity. This study presents various experimental performance to enhance the durability of face slab concrete in concrete face rockfill dam by varying the fly ash substitution of 0%, 10%, 15% and 20% in cement quantity. The effect on durability corresponding to the increasing amount of fly-ash was evaluated and the optimum quantity of fly-ash subtitution was finally recommended. The results show that 15% fly-ash substituion was found out to be an optimum quantity and demonstrated an excellent performances in durability.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2007.04a
• /
• pp.147-150
• /
• 2007

As recent buildings often use low-quality concrete materials, are constructed defectively, and are put in extreme environmental conditions, many of them show the shortening of life resulting from the corrosion of reinforcing rods by salt damage, carbonization, freezing and thawing, cracking. This in turn raises the cost of repair and maintenance, so it is required to extend the life of structures through enhancing the durability of concrete. In response to the demand, researches on high-durability concrete are being made actively focused on the maximum water-cement ratio, the maximum unit quantity, the minimum cover thickness, the addition of mineral admixtures, etc. With this background, the present study examined the basic physical properties of concrete containing admixtures for enhancing the durability of concrete.

• Journal of the Korean Society of Safety
• /
• v.22 no.3 s.81
• /
• pp.51-56
• /
• 2007

In recent years, many research works have been carried out in order to obtain a more controlled durability and long-term performance of concrete structures in chloride containing environments. In particular, the development of new procedures for probability-based durability analysis/design has proved to be very valuable. Although there is still a lack of relevant data, this approach has been successfully applied to some new concrete structures. In this paper, the equation used for modelling of the chloride penetration was based on Fick's Second Law of Diffusion in combination with a time dependent diffusion coefficient. The probability analysis of the durability performance was performed by use of a Monte Carlo Simulation. The procedure was applied to an example based on limited data gathered in this country. The influences of each parameter on the durability of concrete structures are studied and some comments for durability design are given. The new procedure may be very useful in designing an important concrete structures in chloride containing environments. Also it may help to predict the service life of concrete structures under a given probability of failure.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2002.05a
• /
• pp.755-760
• /
• 2002

The concrete structures in marine environment has been used type V cement(sulfate-resisting Portland cement), but according to the study results reported recently, the question has been raised for effect of the resistance to salt attack of the concrete using type V cement. It is increased the demands on the use of mineral admixtures such as fly ash, ground granulated blast-furnace slag instead of type V cement in order to improve the durability of concrete structures. Therefore, this study focused on the durability evaluation of concrete containing fly ash under marine environment, and the tests such as salt attack, carbonation, sulfate attack, and freezing-thawing were performed. Test results showed t]hat the resistance to salt attack, sulfate attack and freezing-thawing was improved, and the carbonation was in some disadvantage compared with normal concrete. Nevertheless, the durability of fly ash concrete would be maintained during the service life of structures.

• Advances in concrete construction
• /
• v.12 no.5
• /
• pp.367-375
• /
• 2021

This study experimentally investigated the improvement of bond strength and durability of concrete containing high volume fly ash. Concrete mixtures made with 0%, 25% and 60% replacement of cement with class F fly ash were prepared. Water-binder ratios ranged from 0.28 to 0.72. The compressive, flexural and pullout bond strength, the resistance to chloride-ion penetration, and the water permeability of concrete were measured and presented. Test results indicate that except for the concretes at early ages, the mechanical properties, bond strength, and the durability-related chloride-ion permeability and water permeability of concrete containing high volume (60% cement replacement) fly ash were obviously superior to the concrete without fly ash at later ages of beyond 56 days. The enhanced bond strength for the high volume fly-ash concrete either with or without steel confinement is a significant finding which might be valuable for the structural application.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.1431-1438
• /
• 2007

This paper presents a refined design model for current railroad design code on concrete structures exposed to marine environment. A time-varying diffusion coefficient(D) as well as surface chloride$(C_S)$ and chloride threshold level$(C_{lim})$ are studied. Averaging value of the D with time over exposed duration were used to refined durability design model to consider time dependent characteristic of D. The values for $C_S$ and $C_{lim}$ for the seashore in Korea revised for realistic durability design. The proposed model was verified by the so-called performance-based durability design, which is widely used in recent durability design code. Results show that the current standard specification underestimates durability performances of concrete structures exposed to marine environment, so that the cover depth design using current durability evaluation in the standard specifications is very much conservative. Thus, it is found that proposed durability design models for the railroad design code for railway concrete structures can be used effectively for service life design of concrete structures in marine environment.

• Journal of the Korea Institute of Building Construction
• /
• v.7 no.4
• /
• pp.117-124
• /
• 2007

Focused on the material-related aspect for enhancing the durability of concrete, the present study analyzed the effect of glycol ether admixture, which is a chemical admixture that can compact the structure of concrete by entraining air inside the concrete, on the basic physical properties and durability characteristic of the concrete. In analyzing the results of experiment, we examined the basic physical properties and durability characteristic of concrete according to addition rate based on OPC and selected the optimal addition rate. In addition, with the optimal addition rate, we added glycol ether admixture to concrete, which contained fly ash used as binder and high-performance water reducing agent for reducing the unit quantity, and examined changes in the characteristics of the concrete. According to the result, the optimal addition rate of glycol ether admixture was 3% of the unit quantity of cement, and the addition of binder and chemical admixture did not have a significant effect on unhardened concrete but reduced the air content. In addition, concrete showed resistance performance of around 30% to carbonation and around 40% to drying shrinkage. In addition, as for resistance to freezing and thawing, the relative dynamic modulus of elasticity was over around 85% through atmospheric curing. These performances prove the effect.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.11a
• /
• pp.82-85
• /
• 2003

This study is to investigate durability in concrete containing slag powder and limestone power. The variables are the substitution ratio of slag powder and limestone powder. In order to study the effect of slag powder and limestone powder, all mixtures were prepared at a fixed water/cement ratio, slump, and entrained air quantity. When concrete containing slag powder is mixing rate 40%, durability appeared the highest in general. When concrete containing limestone powder is mixing rate 10% in all experiments, the most suitable result appeared.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1991.10a
• /
• pp.5-10
• /
• 1991

This study was performed to find out the effect about the spacing factor and durability factor to evaluate the durability of concrete in high-strength concrete with freezing and thawing as following each condition, 1) unit cement content : 500kg/$\textrm{m}^3$, 550kg/$\textrm{m}^3$ 2) water/cement ratio : 25%, 30%, 35% 3) air content : below 1.5%, 1.6~3.5%, 4~6%, over 7% From the results tested, a variation of air content was more effective to the durability of concrete than that of water/cement ratio and unit cement content.