• Journal of the Korea Institute of Building Construction
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• v.15 no.6
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• pp.545-551
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• 2015

The aim of this research is suggesting application method of the wasted rock obtained from the limestone quarry of raw material for cement as a coarse aggregate for high strength concrete after crushing and sieving processes. The wasted rock has been normally wasted because of its low quality as a material for cement production. In this research, the concrete using this wasted limestone coarse aggregate was evaluated the constructability based on the performances of workability, air content, and compressive strength. From the experiment, a favorable performance was achieved with a limestone coarse aggregate for high strength concrete comparing to the high strength concrete using granite coarse aggregate.

• The Journal of Engineering Geology
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• v.11 no.1
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• pp.51-62
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• 2001

Jurassic granites of three sites, Pocheon, Geochang and Habcheon, were analysed with respect to the characteristics of the rock cleavage. Microscopic analysis for the oriented thin sections of the specimens was conducted by using the scanline survey technique to measure microcrack direction, spacing and length. The results showed that the preferred orientations of microcrack developed in quartz and feldspar arc coincident with the orientation of quarry planes. The length of microcrack is related to grain size. The length of microcrack in coarse-grained granite is longer than that in relatively fine-grained granite. In all granites, microcracks related to the preferred orientations are well developed in order of rift, grain and hardway planes in number, length and density.

• Explosives and Blasting
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• v.16 no.4
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• pp.18-28
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• 1998

Effects of blasting vibrations on curing concrete have not been well studied. As a result, unreasonable and strong blasting vibration constraints have been placed on blasting when it occur in the vicinity of curing concrete. To study the effects of blasting on curing concrete blocks of $33.3{\times}27.7{\times}16.2cm$ were molded and placed on the quarry. Several sets of concrete blocks were subjected separately to peak vibrations of 0.25, 0.5, 1.0, 5.0 and 10cm/sec. The impulses of blasting vibrations were applied with thirty-minute intervals. Along with unvibrated concrete blocks, the vibrated concrete samples cored with 60.3mm in diameter were measured for elastic moduli, sonic velocity and uniaxial compressive strength. Test results can be summarized as follows; 1. The blasting vibrations between 6 and 8 hours after pour generally lowered on the uniaxial compressive strength of the concrete. 2. A low blasting vibration of 0.25cm/sec did not affect the uniaxial compressive strength. As the magnitude of the blasting vibration increases, compressive strength of concrete is decreased. 3. Physical properties of the P-wave velocity, Young’s modulus, and Poisson's ratio showed a weakly decreasing trend in the concrete blocks vibrated between 6 and 8 hours after pour.

• International Journal of Concrete Structures and Materials
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• v.7 no.3
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• pp.193-202
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• 2013

Geopolymer mortar compressed blocks were prepared using fly ash, ground granulated blast furnace slag, silica fume and metakaolin as binders and sand/quarry dust/pond ash as fine aggregate. Alkaline solution was used to activate the source materials for synthesizing the geopolymer mortar. Fresh mortar was used to obtain the compressed blocks. The strength development with reference to different parameters was studied. The different parameters considered were fineness of fly ash, binder components, type of fine aggregate, molarity of alkaline solution, age of specimen, fluid-to-binder ratio, binder-to-aggregate ratio, degree of saturation, etc. The compressed blocks were tested for compression at different ages. It was observed that some of the blocks attained considerable strength within 24 h under ambient conditions. The cardinal aim was to analyze the experimental data generated to formulate a phenomenological model to arrive at the combinations of the ingredients to produce geopolymer blocks to meet the strength development desired at the specified age. The strength data was analyzed within the framework of generalized Abrams' law. It was interesting to note that the law was applicable to the analysis of strength development of partially saturated compressed blocks when the degree of saturation was maintained constant. The validity of phenomenological model was examined with an independent set of experimental data. The blocks can replace the traditional masonry blocks with many advantages.

• Tunnel and Underground Space
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• v.20 no.3
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• pp.183-193
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• 2010

The present paper highlights some important fragmentation issues experienced in the limestone quarry blast rounds. In light of these major issues, the paper outlines influence of a few important design parameters, which bear merit to alter the blast performance in order to duly resolve the issues in field scale blast rounds. A comprehensive field based program for evaluation of such blast rounds has also been suggested. The knowledge disseminated in the paper, backed up by sufficient images, is largely based on the experience of the authors, while designing, implementing and evaluating numerous field scale blast rounds in cement grade limestone quarries.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.854-859
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• 2006

The density of coarse grained materials which is used in rock-fill dam or the piling the ground are used as $1.85\sim2.10g/cm^3$. Hereupon, the effect of variation of density on shear strength of ones was analyzed from the results of large scale shear test. The sample for the test was obtained from the local quarry sites. The test conditions are that density(1.85 versus $2.10g/cm^3$), material size range$(76.3\sim2.0\;mm)$, water content(air dry condition) and uniformity coefficient(5.0) Test result shows that the shear strength of $2.10g/cm^3$ is relatively larger than that of $1.85g/cm^3$.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.878-883
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• 2005

This paper describes the effect of acid rock drainage(ARD) produced from the cut slope on the slope structures. Acid rock drainage is originated from a rock quarry located in coal mine zone and mineralization belt of Chosen Supergroup and Ogcheon group, andesite with the pyrite, and acid sulfate soils of Tertiary in Korea. The cut slope, where acid rock drainage comes out, almost has been constructed by shotcrete and planting works. According to the field observation results, in most cases, the acid rock drainage has an adverse effect on slope structures. The shotcrete, anchors and rock bolts produced corrosive action, and bad germination and growth diseases of covering plants of the slope planting construction due to ARD.

• Korean Journal of Crystallography
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• v.12 no.4
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• pp.216-221
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• 2001

Artificial stone plates were hydrothermally prepared in order to utilize the stone powder sludge which were generated from stone quarry . Calcium hydroxide and silica were added to sludge of which main phases were quartz and alumina, and the effect of vapour pressure, reaction time and added amount on the properties of plates were investigated. The compressive strength, water absorp-tion and apparent specific gravity of the plates, which were prepared from the mixture of 70% stone sludge, 20% calcium hydroxide and 10% silica for 3 hours at the conditions of pressing pressure of 200kg/㎠ and vapour pressure of 20 kg/㎠, were 614kg/㎠, 0.48%, 1.88 respectively. It was also possible to produce various colours and appearances by adding inorganic pigments.

• Safety and Health at Work
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• v.2 no.3
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• pp.243-249
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• 2011

Objectives: Cement contains hexavalent chromium, which is a human carcinogen. However, its effect on cancer seems inconclusive in epidemiologic studies. The aim of this retrospective cohort study was to elucidate the association between dust exposure in the cement industry and cancer occurrence. Methods: The cohorts consisted of male workers in 6 Portland cement factories in Korea. Study subjects were classified into five groups by job: quarry, production, maintenance, laboratory, and office work. Cancer mortality and incidence in workers were observed from 1992 to 2007 and 1997-2005, respectively. Standardized mortality ratios and standardized incidence ratios were calculated according to the five job classifications. Results: There was an increased standardized incidence ratio for stomach cancer of 1.56 (27/17.36, 95% confidence interval: 1.02-2.26) in production workers. The standardized mortality ratio for lung cancer increased in production workers. However, was not statistically significant. Conclusion: Our result suggests a potential association between cement exposure and stomach cancer. Hexavalent chromium contained in cement might be a causative carcinogen.

• Explosives and Blasting
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• v.22 no.2
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• pp.1-11
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• 2004

일반적으로 국내 석회석 광산에서의 발파는 20ms나 25ms 시차를 가지는 지발발파로 시행되어지고 있다. 국외에서는 전자뇌관을 사용하여 암반의 지질학적인 특성에 따라 지발 시차를 사용자의 현장에 따라 선정하여, 주변 보안 물건에 따른 진동 및 소음을 경감하면서, 1회 발파의 생산량을 증대할 수 있으며, 2차 파쇄 비용 및 적재비용을 절감하는 최적의 시차를 적용하여 발파 규모를 줄이지 않는 발파패턴을 적용하고 있다. 본 연구는 해외에서 사용되고 있는 전자뇌관을 국내 현장 석회석 광산(단양)에 적용함으로 최적지연시차를 찾아내는 방법과 초시의 오차에 따른 문제점과 향후 국내 적용성을 판단하고자 하였다. 대규모 석회석 광산을 대상으로 최적시차를 판단하고자 동일 패턴에서 시차를 6ms ~ 30ms로 시험발파를 시행하여 4가지 요소 발파진동속도, 주 주파수특성, 파쇄입도, 암석 이동 및 버력의 상태를 분석하여 각 시차에 따른 배점을 두어, 당 현장에 요구되는 개별 가중치를 선정하여 분석하였다. 분석 결과 당 현장에서의 발파결과에 따른 요소별 가중치를 발파진동속도(20), 주 주파수 특성(20), 파쇄입도(40), 암석 이동(10) 및 버력의 상태(10)로 하여 분석한 결과 15ms가 최적시차로 나타냈다. 향후 각 현장에 적합한 요소별 가중치를 선정하여 현장별 최적시차를 도출한다면 최적의 발파효과를 있을 것으로 판단된다.