• Structural Engineering and Mechanics
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• v.67 no.6
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• pp.579-585
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• 2018

Masonry walls are of a complex (anisotropic) structure in terms of their mechanical properties. The mechanical properties of the walls are affected by the properties of the materials used in wall construction, joint thickness and the type of masonry bond. The carried-out studies, particularly in the seismic zones, have revealed that the most of the conventional masonry walls were constructed without considering any engineering approach. Along with that, large-scale damages were detected on such structural elements after major earthquake(s), and such damages were commonly occurred at the brick-joint interfaces. The aim of this study was to investigate the effect of joint thickness and also type of mortar on the mechanical behavior of the masonry walls. For this aim, the brick masonry walls were constructed through examination of both the literature and the conventional masonry walls. In the construction process, a single-type of brick was combined with two different types of mortar: cement mortar and hydraulic lime mortar. Three different joint thicknesses were used for each mortar type; thus, a total of six masonry walls were constructed in the laboratory. The mechanical properties of brick and mortars, and also of the constructed walls were determined. As a conclusion, it can be stated that the failure mechanism of the brick masonry walls differed due to the mechanical properties of the mortars. The use of bed joint thickness not less than 20 mm is recommended in construction of conventional masonry walls in order to maintain the act of brick in conjunction with mortar under load.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.3
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• pp.55-62
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• 2010

This is an experimental research in order to judge the applicability of sewage sludge incineration ash having applied the mixing proportion needed to manufacture bricks and to do plaster work with addition of hwangtoh and slaked lime as a part of the methods for utilizing the wastes produced from sewage sludge incineration ash. Based on the results from experiment and analysis, it is judged that, in case of mixing proportion of 1:2 for the purpose of plastering and masonry work, the cement mortar produced by using a 10% addition ratio of sewage sludge incineration ash with mixture of hwangtoh covering all range of addition ratio, and also the cement mortar produced by using a 20% of sewage sludge incineration ash together with 0% and 10% addition ratio of hwangtoh, was possible to be applied to the practical use. In case of mixing proportion of 1:7 for manufacture of bricks and blocks, if such brick and block products are produced with 10% and 20% addition ratio of sewage sludge incineration ash having added aggregate fines or stone dust that has been actually used in brick and block manufacturing, it is judged that these bricks and blocks could be practically used in the job sites, although strength development is a little bit lower.

• Journal of Conservation Science
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• v.19
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• pp.43-56
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• 2006

We checked the conditions and material properties after producing the lime finishing layers with a mortar mix of processed lime. In addition, we reproduced the lime finishing layers of the Koguryo Tomb Murals, colored the layers with a few different techniques and identified the characteristics for each painting technique. As a result of the experiment, we could infer the producing techniques as well as teaming the conditions and properties of the lime finishing layers of the Koguryo tomb murals, and examined the maintenance of the lime finishing layers. Of those samples produced under various conditions, the layers of slaked lime, which were obtained after being hydrated underground for a long time, showed quite a good condition. Thus the slaked lime mixes produced through particular hydration methods are judged to increase the maintenance of the lime finishing layers of the Koguryo Tomb Murals. Mostly, the paints of Koguryo Tomb Murals indicated that they have similar conditions with the samples produced with a secco method. In addition, Considering the compositional forms of the painting layers and the boundary layers which formed between the painting layers and the finishing layers, we can verify that, in some cases, the conditions of the painting layers of the Koguryo tomb murals are similar to those which were produced with a combination of fresco and secco.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.89-92
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• 1999

The purpose of this study is to evaluate the capability to use with cement admixture materials because Paper Sludge Ash consists of Si, Ca and Al which are chief content in Pozzolan. For the derivation of Pozzolanic reaction in Paper Sludge Ash, it is measured compressive strength on cement mortar which is replaced mixing of Paper Sludge Ash and inorganic admixture ; ie, gypsum, lime and slaked lime, regularly. In the result of test, the strength decrease remarkably when cement is only replaced with Paper Sludge Ash, but the strength is almost equal when cement is replaced with Paper Sludge Ash is mixed with inorganic admixture material in proportions of 5~15%. Consequently, It is possible to use Paper Sluge Ash with admixture materials of cement.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.232-235
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• 2004

This study aims to manufacture non-sintering cement(NSC) by adding phosphogypsum(PG) and waste lime(WL) to granulated blast furnace slag(GBFS) as sulfate and alkali activators. This study also investigates the basic physical properties and hydration reaction of NSC, and evaluates its reusing possibility as construction material. Results obtained from this study have shown that GBFS was affected by $So_4^{2-}$ in waste PG and stimuli under wet condition, left slag components, created Ettringite and CSH gels, and eventually started being hydrated. These hydrated creations formed dense structures like CSH based on Ettringite and contributed in allowing the mortar to reveal high strength.

• Korean Journal of Agricultural Science
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• v.7 no.2
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• pp.119-130
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• 1980

This study was conducted to determine the effect of curing temperature on the strength of briquette ash mortar hardened by cement. The six different kinds of briquette ash mortars were made by mixing the cement : briquette ash, ((cement (90%)+lime (10%)) : briquette ash and cement : standard sand at the ratio of 1:2, 1:3, 1:4, 1:5, 1:7, and 1:9, respectively and the cu ring temperatures were $20^{\circ}C$, $30^{\circ}C$, and $35^{\circ}C$. The strength of compression, bending and tensile were measured at ${\sigma}_7$ and ${\sigma}_{28}$. The summarized results were as follows. 1. At the ${\sigma}_7$ of 1:2 the compressive strength of the cement : briquette ash and (cement+lime) : briquette ash were 69.3% and 75.1%, respectively of the mortar made of the standard sand. At the ${\sigma}_{28}$ the strength of those materials were 56.4% and 49.0%, respectively. 2. At the ${\sigma}_7$ of 1:2 the tensile strength of the cement : briquette and (cement+lime) : briquette ash were 64.4% and 47.1%, respectively of the mortar made of standard sand. At the ${\sigma}_{28}$ the tensile strength of those materials were 69.6% and 64.8%, respectively. 3. At the ${\sigma}_7$ of 1:2 the bending strength of the cement : briquette ash and (cement+lime) : briquette ash were 46.3% and 65.9%, respectively of the mortar made of the standard sand. At the ${\sigma}_{28}$ the strength of those materials were 89.9% and 96.7%, respectively. 4. The increment of strength per $1^{\circ}C$ increase of curing temperature were on the average $0.92{\sim}1.75kg/cm^2$ of compressive strength, $0.12{\sim}0.16kg/cm^2$ of the tensile strength and $0.21{\sim}0.38kg/cm^2$ of the bending strength.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.607-610
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• 2005

If cement can be manufactured with industrial byproducts such as granulated blast furnace slag(GBFS), phosphogypsum(PG), and waste lime(WL) instead of clinker as its counterproposal, there would be many advantages, including maximum use of these industrial byproducts for high value-added resources, conservation of natural resources and energy by omitting the use of clinker, minimized environmental pollution problems caused by $CO_2$ discharge, and reduction of the production cost. This research investigates the chemical resistance of NSC mortar added PG and WL to GBFS as sulfate and alkali activators. The result of experiment of chemical resistance, showed that NSC is very excellent in acid resistance and seawater resistanc. Such a reasons are that the hydrate like CSH gel and ettringite formed dense pore structure of NSC matrix.

• Structural Engineering and Mechanics
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• v.20 no.1
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• pp.21-43
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• 2005

Masonry is a composite non-homogeneous structural material, whose mechanical properties depend on the properties of and the interaction between the composite components - brick and mortar, their volume ratio, the properties of their bond, and any cracking in the masonry. The mechanical properties of masonry depend on the orientation of the bed joints and the stress state of the joints, and so the values of the shear modulus, as well as the stiffness of masonry structural elements can depend on various factors. An extensive testing programme in several countries addresses the problem of measurement of the stiffness properties of masonry. These testing programs have provided sufficient data to permit a review of the influence of different testing techniques (mono and bi-axial tests), the variations caused by distinct loading conditions (monotonic and cyclic), the impact of the mortar type, as well as influence of the reinforcement. This review considers the impact of the measurement devices used for determining the shear modulus and stiffness of walls on the results. The results clearly indicate a need to re-assess the values stated in almost all national codes for the shear modulus of the masonry, especially for masonry made with lime mortar, where strong anisotropic behaviour is in the stiffness properties.

• Corrosion Science and Technology
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• v.21 no.2
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• pp.100-110
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• 2022

Corrosion of steel reinforcement is the most important mode of concrete structures damages. It strongly depends on the composition and physicochemical properties of the cementitious medium. The use of waste materials as lightweight aggregates in concrete is environmentally recommended in polluted environments such as marine and/or industrial atmospheres in order to reduce its porosity and ensure the requested protection of reinforcing steel. The present study investigated the effect of waste cork addition on corrosion resistance of steel rebar in mortar specimen prepared in the laboratory. The main objective of this study was to improve the corrosion resistance of reinforcing steel. Another objective of this study was to valorize this ecological product and preserve the environment. Results obtained from various electrochemical tests indicated that the presence of a fine cork powder substantially improved the corrosion resistance of steel in the mortar contaminated by chloride ions. This improvement was reflected by a notable decrease in corrosion current density and a shift of corrosion potential of the steel towards more noble values. Moreover, the presence of a fine cork powder in the mortar had no adverse effect on its mechanical properties.

• Journal of the Korean Ceramic Society
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• v.40 no.7
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• pp.702-708
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• 2003

Cement paste, mortar or concrete specimens, substituting the content of Portland cement with fly ash up to 50 wt%, were prepared to investigate the effect of fly ash on the temperature, free lime content and strength etc. of mortar/concrete. Being compared with the concrete made of ordinary Portland cement, temperature increment of the concrete containing 50 wt% fly ash reduced, according to appropriate conversion formulae, to about 45％ at the 7 days curing time: the temperature increment of the former amounted to 33.4$^{\circ}C$, while that of the latter only to 18.7$^{\circ}C$. On the other hand, it is better to control the content of fly ash in the cement that is used for reinforced concrete not to exceed 30 wt％. In this study, more than 28 days curing time is necessary in order that the strength of concrete made of fly ash cement will be higher than that of pure Portland cement. In addition, 28-days concrete strength higher than 360 kg/$\textrm{cm}^2$ could be easily achieved even with 50 wt% fly ash cement.