• Journal of the Korean Wood Science and Technology
• /
• v.39 no.4
• /
• pp.303-310
• /
• 2011

The mechanical properties of heat-compressed Radiata pine (Pinus radiata D.Don) by compression temperature and time were investigated. The compressive strength and bending strength of heat-compressed wood increased with increasing compression temperature and time. But the compressive strength and bending strength decreased with press temperature $220^{\circ}C$. It was considered due to thermal degradation during high temperature conditions. The surface hardness of heat-compressed wood increased with increasing compression temperature. However, the effect of compression time was negligible. The nail holding power was not affected by compression temperature and time.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2002.05a
• /
• pp.335-340
• /
• 2002

By the recently, Environmental pollution is serious by the highly economic growth and expansion of lively country basic industry. Especially, in case of industrial waste and life waste leaped into a pollution source. Also, research for processing of waste and recycling countermeasure is a pressing question on national dimension because it is prohibited an ocean disposal and reclamation. In this study, it looked for fracture characteristic value of recycling a coal ash to decrease environmental pollution by picky and exhaustion of natural resources and to reduce self-weight to prepare for a tall building and earthquake. So a coal ash examined to be possible to do as construction material. It achieved compressive strength test and three points bending test with initial notch depth rate and age for variables to show a basic research data. From the basis of the three points bending test, the fracture parameters - notch sensitivity, fracture energy, initial compliance were experimentally proposed. From the results of the compressive strength test, the elastic modulus was experimentally proposed. Also on the basis of the three points bending test, the fracture parameters - notch sensitivity, fracture energy, initial compliance were experimentally proposed. The results that the strength and fracture energy value are lower than concrete or mortar is described in this paper. Also, it shows that the deflection at fracture decreases as the age increases and the notch sensitivity decrease. However, it is judged to be available to construction material if research is continuously gone forward.

• Magazine of the Korea Concrete Institute
• /
• v.11 no.2
• /
• pp.157-165
• /
• 1999

When the ultimate strength of a concrete flexural member is evaluated, the effect of member size is usually not considered. For various types of loading, however, the strength always decreases with the increment of member size. In this paper the size effect of a flexural compression member is investigated by experiments. For this purpose, a series of C-shaped specimens subjected to axial compressive load and bending moment was tested using three different sizes of specimens with a compressive strength of 528 kg/$cm^2$. According to test results the size effect on flexural compressive strength was apparent, and more distinct than that for uniaxial compressive strength of cylinders. Finally a model equation was derived using regression analyses with experimental data.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2020.11a
• /
• pp.94-95
• /
• 2020

Oyster shells are characterized by coarse and coarse grains, but similar in strength to sand, and egg shells are fine grains but weak in strength. In terms of supply and demand of raw materials, oyster shells can be supplied only in limited periods and regions in winter and south coast of the year, but egg shells have the advantage of being able to supply and supply nationwide 365 days. This study aims to study the change in strength characteristics by mixing oyster shell powder and egg shell powder with the same particle size and mixing up to 150%. The conclusions of the flexural and compressive strength tests of mortar mixed with oyster shell powder and egg shell powder are as follows. The 7-day flexural and compressive strength with ESP added and the 3-day flexural and compressive strength with OSP added were similar, which is thought to be because the strength of OSP is higher than that of ESP.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2002.05a
• /
• pp.959-964
• /
• 2002

The purpose of this study is to establish flexural behavior of high-strength concrete by means of both theoretical approach and experimental analysis of beams in which confinement stirrups have been introduced into pure bending zone. The experiment was carried out on full-scale high-strength reinforced concrete beams whose compressive strengths are 400 and 700kgf/cm$^2$, and confined with rectangular closed stirrups. The test results are reviewed in terms of flexural capacity and ductility.

• Journal of agriculture & life science
• /
• v.44 no.4
• /
• pp.21-27
• /
• 2010

This study was carried out to investigate the properties of woodceramics made from woody part of Broussonetia Kazinoki at different carbonizing temperatures of $600^{\circ}C$, $800^{\circ}C$, $1000^{\circ}C$and $1200^{\circ}C$. The physical and mechanical properties increased with increasing carbonizing temperature. The highest mean values of density, bending strength, Brinell hardness and compressive strength were $0.62g/cm^3$, $79kgf/cm^2$, $203kgf/cm^2$ and $129kgf/cm^2$, respectively. There were close correlations between density and bending strength, Brinell hardness and compressive strength and MOE and MOR.

• Korean Journal of Materials Research
• /
• v.14 no.6
• /
• pp.375-378
• /
• 2004

The samples were prepared with hydroxyapatite(HAp) powder and eugenol (Eugenol/HAp = 15, 20, 25, 30wt%). The samples were dried at room temperature. The higher mechanical properties was observed in HAp sample with 25wt% Eugenol. The average compressive and bending strength in HAp with 25wt% Eugenol are 542 kgf/$\textrm{mm}^2$ and 366 kgf/$\textrm{mm}^2$ respectively. This strength is higher compare to that of the cortical bone.

• Computers and Concrete
• /
• v.19 no.2
• /
• pp.121-126
• /
• 2017

This paper presents the effect of aggregate type on high temperature resistance of self-compacting mortars (SCM) produced with normal and lightweight aggregates like expanded perlite and pumice. Silica fume (SF) and fly ash (FA) were used as mineral additives. Totally 13 different mixtures were designed according to the aggregate rates. Mini slump flow, mini V-funnel and viscometer tests were carried out on the fresh mortar. On the other hand, bulk density, porosity, water absorption and high temperature tests were made on the hardened SCM. After being heated to temperatures of 300, 600 and $900^{\circ}C$, respectively, the tensile strength in bending and compressive strength of mortars determined. As a result of the experiments, the increase in the use of lightweight aggregate increased total water absorption and porosity of mortars. It is observed that, the increment in the usage of lightweight aggregate decreased tensile strength in bending and compressive strengths of mortar specimens exposed to high temperatures but the usage of up to 10% expanded perlite in mortar increased the compressive strength of specimens exposed to $300^{\circ}C$.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2002.10a
• /
• pp.193-196
• /
• 2002

This study is performed to examine physical and mechanical properties or neutralization treatment point and curing methods of ECO-cencrete using rice straw ash. Tests for void ratio, compressive and bending strength with neutralization treatment point and curing methods are performed. The test result shows that the void ratio is decreased with increasing content of rice straw ash. But, the compressive and bending strength is increased with increasing content of rice straw ash. The greatest strength is appeared when neutralization is treated at the curing age of 6 days.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1992.10a
• /
• pp.44-49
• /
• 1992

Selected strength characteristics of recycled concrete using crushed waste concrete were compared with those of conventional concrete using natural aggregate. Compressive strength, bonding at the interface between recycled aggregate and fresh mortar, strain and deflection under three-point bending were evaluated. Recycled concrete, in general, showed lower compressive strength, lower edlastic modulus, higher stain and higher deflection under the same loading level, compared with those of conventional concretes. However, the strength retaining ratios of recycled concretes were higher than those of conventional concretes. The compressive strength which is one of the most important load carrying capacities of concrete should be improved for successful re-use of waste concrete in structural concrete.