• Applied Chemistry for Engineering
• /
• v.9 no.6
• /
• pp.811-816
• /
• 1998

Rebar corrosion in cement mortar containing chloride ions was investigated by electrochemical AC impedance spectroscopy. Corrosion of mild steel bar was accelerated by an acceleration test equipment in short period. Impedance values obtained from AC-impedance method could be adapted to the proposed electrochemical equivalent circuit model and they were consistent with calculated values obtained by CNLS fitting method. The weight loss of rebar could be calculated by charge transfer resistance($R_2$) with time and it was close to real value.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.49 no.5
• /
• pp.23-30
• /
• 2007

This research was to evaluate the shrinkage and durability performance of latex modified repair mortar and to improve the service lift of the agricultural concrete structures. The shrinkage characteristics of the repair material creates the delamination of repair materials and existing concrete. It may reduce the service life of structures. Also the reduction of durability performance of the repair materials induces the destruction of the repaired concrete structures at early stage. In this research, plastic and drying shrinkage, thermal expansion coefficient for shrinkage properties, durability performance, permeability, repeated freezing and thawing, and resistance of chemical solution test were performed. Test results showed that the latex modified repair mortar indicated the shrinkage amount which the delamination does not happen, and the latex modified repair mortar appeared excellent long-term durability performance which can increase the service life.

• Journal of the Korea Institute of Building Construction
• /
• v.18 no.2
• /
• pp.185-193
• /
• 2018

In this study, using Granulated Blast Furnace Slag (GBFS), an industrial byproduct, and Phosphogypsum (PG), and Waste Lime (WL) as activator, non-sintering binder (NSB) which does not require a sintering process was produced, and the chemical penetration resistance was evaluated through a seawater resistance experiment. The result of the experiment showed that the inside of NSB mortar saw almost no influence from the ions in seawater due to its dense structure. Also, as it appears that only the surface reacts with ions in seawater while spreading inward is suppressed, the high seawater resistance of NSB could be confirmed.

• Advances in concrete construction
• /
• v.10 no.2
• /
• pp.171-183
• /
• 2020

The main objective of this study is the assessment of the ability of limestone mortars to resist to different chemical attacks. The ability of polypropylene (PP) fibres waste used as reinforcement of these concrete materials to enhance their durability is also studied. Crushed sand 0/2 mm which is a fine limestone residue obtained by the crushing of natural rocks in aggregates industry is used for the fabrication of the mortar. The fibres used, which are obtained from the waste of domestic plastic sweeps' fabrication, have a length of 20 mm and a diameter ranging between 0.38 and 0.51 mm. Two weight fibres contents are used, 0.5 and 1%. The durability tests carried out in this investigation included the water absorption by capillarity, the mass variation, the flexural and the compressive strengths of the mortar specimens immersed for 366 days in 5% sodium chloride, 5% magnesium sulphate and 5% sulphuric acid solutions. A mineralogical analysis by X-ray diffraction (XRD) and a visual inspection are used for a better examination of the quality of tested mortars and for better interpretation of their behaviour in different solutions. The results indicate that the reinforcement of limestone mortar by PP fibres waste is an excellent solution to improve its chemical resistance and durability. Moreover, the presence of PP fibres waste does not affect significantly the water absorption by capillarity of mortar nether its mass variation, when exposed to chloride and sulphate solutions. While in sulphuric acid, the mass loss is higher with the presence of PP fibres waste, especially after an exposure of 180 days. The results reveal that these fibres have a considerable effect of the flexural and the compressive behaviour of mortar especially in acid solution, where a reduction of strength loss is observed. The mineralogical analysis confirms the good behaviour of mortar immersed in sulphate and chloride solutions; and shows that more gypsum is formed in mortar exposed to acid environment causing its rapid degradation. The visual observation reveals that only samples exposed to acid attack during 366 days have showed a surface damage extending over a depth of approximately 300 ㎛.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.12 no.1
• /
• pp.102-109
• /
• 2024

In order to use limestone powder as a material for concrete, the mechanical and durability characteristics of cement matrices manufactured by varying the substitution rate were evaluated. In general, limestone powder did not contribute to the cement hydration reaction, so as a result of the compressive strength test of cement mortar using it, the compressive strength decreased as the substitution rate increased. However, as a result of evaluating the durability performance of cement mortar using limestone powder, such as chloride ion penetration resistance, carbonation resistance, and chemical attack resistance, small particles of limestone powder showed superior results compared to the unsubstituted control mortar due to the micro-filler effect of filling the fine pores inside the cement matrix. Therefore, limestone powder is expected to be used as an effective method for improving the durability of concrete. In this study, the durability was evaluated by changing the mixing amount of limestone powder to 0 %, 5 %, 10 %, and 15 %, but it is judged that it is necessary to study in more detail the effect on the durability by changing the end and mixing amount of limestone powder to various levels in the future.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.9 no.4
• /
• pp.235-242
• /
• 2005

This study is on the evaluation of performance of polymer cement mortar which is used for pre-wetting spray method. Pre-wetting spray method is an epoch-making method to repair concrete structures damaged, which is added a small quantity water preciously to dry mortar to reduce dust and rebound and spray mortar mixed with fixed quantity water at nozzle before spray. The result showed that physical performance such like compressive, flexural and adhesive strength of polymer cement mortar, TS 100 used for pre-wetting spray method was superior to other repair mortar. Also durable performance such as resistance on permeability of chloride ion, carbonation, chemical and freezing-thawing was excellent.

• International Journal of Concrete Structures and Materials
• /
• v.9 no.2
• /
• pp.241-254
• /
• 2015

A lot of reinforced concrete (RC) structures in Syria went out of service after a few years of construction. This was mainly due to reinforcement corrosion or chemical attack on concrete. The use of blended cements is growing rapidly in the construction industry due to economical, ecological and technical benefits. Syria is relatively rich in scoria. In the study, mortar/concrete specimens were produced with seven types of cement: one plain Portland cement (control) and six blended cements with replacement levels ranging from 10 to 35 %. Rapid chloride penetration test was carried in accordance with ASTM C 1202 after two curing times of 28 and 90 days. The effect on the resistance of concrete against damage caused by corrosion of the embedded steel has been investigated using an accelerated corrosion test by impressing a constant anodic potential. The variation of current with time and time to failure of RC specimens were determined at 28 and 90 days curing. In addition, effects of aggressive acidic environments on mortars were investigated through 100 days of exposure to 5 % $H_2SO_4$, 10 % HCl, 5 % $HNO_3$ and 10 % $CH_3COOH$ solutions. Evaluation of sulfate resistance of mortars was also performed by immersing in 5 % $Na_2SO_4$ solution for 52 weeks. Test results reveal that the resistance to chloride penetration of concrete improves substantially with the increase of replacement level, and the concretes containing scoria based-blended cements, especially CEM II/B-P, exhibited corrosion initiation periods several times longer than the control mix. Further, an increase in scoria addition improves the acid resistance of mortar, especially in the early days of exposure, whereas after a long period of continuous exposure all specimens show the same behavior against the acid attack. According to results of sulfate resistance, CEM II/B-P can be used instead of SRPC in sulfate-bearing environments.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.47 no.6
• /
• pp.27-34
• /
• 2005

The purpose of this study is to improve the durability performance of polymer modified cement composites for repair of concrete under combined aging conditions. The experimental procedure was divided into three parts. First, the replacement level of mineral admixtures in polymer modified cement composites were determined in an experimental study based on a Box Behnken design. Second, the flow value, compressive strength and chloride permeability test of sixteen types of mixtures were conducted. Test results show that the polymer modified cement composites were effected on the improvement of the compressive strength and permeability performance. Third, the effects on the replacement level of silica fume mixture was evaluated by the compressive strength, chloride permeability, chemical resistance and repeated freezing and thawing cycles test. They demonstrated that the polymer modified cement composites using mixture of silica fume, fly ash, and blast furnace slag improved the durability performance.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.7 no.3
• /
• pp.262-270
• /
• 2019

Ferronickel slag, which is an industrial byproduct, is activated by mechanochemical reaction as a nonferrous metal and can be used as an admixture. Therefore, ferronickel slag is used as a substitute resource of admixture. In this study, to evaluate the effect of mixed of ferronickel slag powder and admixture, a mortar using a mixture of ferronickel slag powder, quicklime, gypsum and calcium chloride was fabricated by vibrated and rolled manufacturing method. Strength were evaluated by flexural and compressive strength tests, and durability was evaluated by performing chlorine ion penetration resistance and chemical resistance test. When the substitution ratio of ferronickel slag powder is constant, it is considered that the mixed use of quicklime, gypsum and calcium chloride as admixtures increases the performance.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1997.10a
• /
• pp.375-380
• /
• 1997

The purpose of this study is to examine the properties of polymer-modified mortars using asphalt emulsion. The polymer-modified mortars using asphalt emulsion with various asphalt-cement ratios are prepared, and tested for flexural and compressive strengths, water absorption and permeability, carbonation, Cl ion penetration and chemical resistance. From the test results, the flexural and compressive strengths, water absorption and permeability, carbonation and Cl ion penetration depths of polymer-modified mortars using asphalt emulsion tend to be decreased with increasing asphalt-cement ratio, and chemical resistance is improved. It is evident that polymer-modified mortars using asphalt emulsion having an excellent properties as a waterproof and finish materials can be produced.