• Title/Summary/Keyword: Blast design

Search Result 365, Processing Time 0.028 seconds

Lightweight Properties of Matrix using Paper Ash according to Replacement Ratios of Fly Ash and Polysilicon Sludge (플라이애시 및 폴리실리콘 슬러지 혼입율에 따른 제지애시 경화체의 경량 특성)

  • Park, Sun-Gyu;Kim, Yun-Mi;Lee, Sang-Soo
    • Journal of the Korean Recycled Construction Resources Institute
    • /
    • v.2 no.2
    • /
    • pp.166-171
    • /
    • 2014
  • This experimental study considers manufacturing method of the non-portland cement matrix for the light-weight building materials using blast furnace slag, paper ash, fly ash and polysilicon sludge the industrial by-product. For the experiment, we used paper ash by means of the foaming agent and alkali activator to make non-portland cement light-weight matrix. Various specimens were prepared with different types and addition ratios of the alkali activator. Then, the properties of these specimens were investigated by compressive strength test, bulk specific gravity. As a results, it was judged that experiment results of non-portland cement matrix with specific waste resources and alkali activators were useful as basic data for mixtures design and evaluation properties of lightweight non-portland cement building material.

A Performance Evaluation of Concrete for Low-carbon Eco-friendly PC Box for Near-surface Transit System (저심도 철도시스템 구축을 위한 저탄소 친환경 PC 박스용 콘크리트의 성능 평가)

  • Koh, Tae-Hoon;Ha, Min-Kook;Jung, Ho-Jin
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.16 no.5
    • /
    • pp.3587-3595
    • /
    • 2015
  • Low-carbon eco-friendly precast concrete (PC) box structure has been recently was developed as an low-cost infrastructure of near-surface transit system. The concrete of PC box was manufactured by industrial byproducts such as ground granulated blast furnace (GGBF) slag, flyash and rapid-cooling electric arc furnace (EAF) oxidizing slag, its mechanical property and durability were estimated in this study. Based on the mechanical and durability tests, it is found that low-carbon eco-friendly concrete shows high initial compressive strength, more than 90% of design strength (35MPa), and high resistance to salt-attack, chemical- attack and freeze-thaw. Therefore, low-carbon eco-friendly PC box concrete technology is expected to contribute to the railway with low environmental impact.

Determination of homogeneity index of cementitious composites produced with eps beads by image processing techniques

  • Comak, Bekir;Aykanat, Batuhan;Bideci, Ozlem Salli;Bideci, Alper
    • Computers and Concrete
    • /
    • v.29 no.2
    • /
    • pp.107-115
    • /
    • 2022
  • With the improvements in computer technologies, utilization of image processing techniques has increased in many areas (such as medicine, defence industry, other industries etc.) Many different image processing techniques are used for surface analysis, detection of manufacturing defects, and determination of physical and mechanical characteristics of composite materials. In this study, cementitious composites were obtained by addition of Grounded Granulated Blast-Furnace Slag (GGBFS), Styrene Butadiene polymer (SBR), and Grounded Granulated Blast-Furnace Slag and Styrene Butadiene polymer together (GGBFS+SBR). Expanded Polystyrene (EPS) beads were added to these cementitious composites in different ratios (20%, 40% and 60%). The mechanical and physical characteristics of the composites were determined, and homogeneity indexes of the composites were determined by image processing techniques to determine EPS distribution forms in them. Physical and mechanical characteristics of the produced samples were obtained by applying consistency, density, water absorption, compressive strength (7 and 28 days), flexural strength (7 and 28 days) and tensile splitting strength (7 and 28 days) tests on them. Also, visual examination by using digital microscope, and image analysis by using image processing techniques with open source coded ImageJ program were performed. As a result of the study, it is determined that GGBFS and SBR addition strengthens the adhesion sites formed as it increases the adhesion power of the mixture and helps to get rid of the segregation problem caused by EPS. As a result of the image processing analysis it is demonstrated that GGBFS and SBR addition has positive contribution on homogeneity index.

Multiple effects of nano-silica on the pseudo-strain-hardening behavior of fiber-reinforced cementitious composites

  • Hossein Karimpour;Moosa Mazloom
    • Advances in nano research
    • /
    • v.15 no.5
    • /
    • pp.467-484
    • /
    • 2023
  • Despite the significant features of fiber-reinforced cementitious composites (FRCCs), including better mechanical, fractural, and durability performance, their high content of cement has restricted their use in the construction industry. Although ground granulated blast furnace slag (GGBFS) is considered the main supplementary cementitious material, its slow pozzolanic reaction stands against its application. The addition of nano-sized mineral modifiers, including nano-silica (NS), is an alternative to address the drawbacks of using GGBFS. The main object of this empirical and numerical research is to examine the effect of NS on the strain-hardening behavior of cementitious composites; ten mixes were designed, and five levels of NS were considered. This study proposes a new method, using a four-point bending test to assess the use of nano-silica (NS) on the flexural behavior, first cracking strength, fracture energy, and micromechanical parameters including interfacial friction bond strength and maximum bridging stress. Digital image correlation (DIC) was used for monitoring the initiation and propagation of the cracks. In addition, to attain a deep comprehension of fiber/matrix interaction, scanning electron microscope (SEM) analysis was used. It was discovered that using nano-silica (NS) in cementitious materials results in an enhancement in the matrix toughness, which prevents multiple cracking and, therefore, strain-hardening. In addition, adding NS enhanced the interfacial transition zone between matrix and fiber, leading to a higher interfacial friction bond strength, which helps multiple cracking in the composite due to the hydrophobic nature of polypropylene (PP) fibers. The findings of this research provide insight into finding the optimum percent of NS in which both ductility and high tensile strength of the composites would be satisfied. As a concluding remark, a new criterion is proposed, showing that the optimum value of nano-silica is 2%. The findings and proposed method of this study can facilitate the design and utilization of green cementitious composites in structures.

Numerical Modelling of Tunnel Blasting (터널발파의 수치해석적 모델링)

  • 이인모;최종원;김상균;김동현
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • 2000.03b
    • /
    • pp.133-140
    • /
    • 2000
  • Drilling and blasting method for excavating rock mass is generally used in underground construction; but this technique has some shortcomings. For instance, rock mass damage is inevitable during drilling and blasting, and blast-induced vibration frequently causes some problems. Until now, field measurement method is used to predict the overbreak and vibration; but it has many limitations. Therefore, numerical analysis method is needed to overcome such limitations, and to estimate and predict damage and vibration due to tunnel blasting in the design stage. In this study, damage zone of rock mass due to stoping and contour blasting is compared based on standard tunnel blasting pattern, and the propriety of the standard tunnel blasting pattern is estimated. Then, blasting pattern is optimized so that the damage zone due to sloping blasting with reduced charge is consistent with that due to contour blasting.

  • PDF

A Field Application of the Self-Compaction Concrete for Shrinkage Compensation (수축보상을 위한 자기충전 콘크리트의 현장적용)

  • Lee, Sang-Soo;Won, Cheol;Park, Sang-Joon;Kim, Dong-Seok
    • Proceedings of the Korean Institute of Building Construction Conference
    • /
    • 2002.05a
    • /
    • pp.7-12
    • /
    • 2002
  • The purpose of this study is to design and to apply the self-compaction concrete mixture to field, having not only high strength but also compensation for shrinkage without thermal crack under 4 sides outer restraint of the member. In the experimental mix, replacement ratio of limestone Powder, CSA expansive additives, and unit water were selected as parameters, using portland blast-furnace slag cement. And, bleeding test, expansibility test, hydration heat analysis were performed. As a results, when Cement is replaced with 35% limestone Powder, 6% CSA expansive additives at unit water 175kg/$m^3$, demanded performances of fresh and hardened self-compaction concrete are accomplished in the field application.

  • PDF

A Case Study of Constructions as Quality Improvement of the FLAT SLAB Mass Concrete (FLAT SLAB 매스 콘크리트의 품질향상에 따른 시공 사례 연구)

  • Hong, Sang-Hee;Lee, Pil-Hwan;Lee, Seong-Woo;Ryu, Hyun-Gi
    • Journal of the Korea Institute of Building Construction
    • /
    • v.7 no.4
    • /
    • pp.133-138
    • /
    • 2007
  • This research goes into the field application cases about Flat slab concrete divide placing construction for the Multi-purpose Apartment. It is important to investigate sufficiently when mass concrete is applied to the substituted divide placing and admixture(blast furnace slag and fly ash). In addition, it is improved on the concrete quality by the job mix design which can decrease cracks caused by the heat of hydration, by the good compactability and the substitution of admixture that can prevent segregation when concrete is poured, and by the good conditioned fluidity which makes the efficiency of building construction. After considering the stated above, the sufficient prior consideration is important for a quality Improvement plan at the field use concrete of the Mass Concrete when divide placing and admixture are substituted and applied.

Design, Fabrication and Performance Testing of a High-impulse, Low-Power Microthruster using Liquid Propellant with High Viscous Fluid Plug (저전력소비, 고출력, 연발형 마이크로 분사기의 설계, 제작 및 성능 시험)

  • Kim, Sang-Wook;Kang, Tae-Goo;Cho, Young-Ho
    • Proceedings of the KSME Conference
    • /
    • 2001.06c
    • /
    • pp.59-63
    • /
    • 2001
  • A high-impulse, low-power, continuous-shot microthruster has been developed using low boiling temperature liquid-propellant with high viscous fluid-plug. The viscous friction force of the fluid-plug increases the blast pressure and the low boiling temperature liquid-propellant is intended to reduce input power consumption. The three-layer microthruster has been fabricated by surface micromachining as well as bulk micromachining in the size of $7{\times}13{\times}1.5mm^{3}$. A continuous output impulse bit of $6.4{\times}10^{-8}N{\cdot}sec$ has been obtained from the fabricated microthruster using perfluoro normal hexane (FC72) propellant and oil plug, resulting in about ten times increase of the impulse bit using one hundredth electrical input energy compared to the conventional continuous microthruster.

  • PDF

An experimental study for developing of silencer to be adapted large gun (대구경 화포용 소음기 개발을 위한 실험적 연구)

  • Lee, Hae suk;Park, Sung ho;Kim, Sang min;Kang, Tae yeop;Kim, Heung soo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2014.04a
    • /
    • pp.558-563
    • /
    • 2014
  • To reduce the transmission of large gun-generated noise from the firing test range to the community, we have tested a silencer to be used with howitzer(155mm KM114A2) after simulation. Numerical analysis was conducted by using a commercial CFD code, FLUENT. To analyze complex blast flow fields, the Spalart-Allmaras model was applied under 2 dimensional and axisymmetric conditions. Firing tests were also performed with the KM114A2 howitzer while the silencer was installed. This paper describes a result of comparison between results of computer analysis and test outcomes which were gotten by firing 155mm projectiles at the testing range. This paper will also be informative to the muffler design which will be adapted to 155mm large gun in the future.

  • PDF

Role of ingredients for high strength and high performance concrete - A review

  • Parande, A.K.
    • Advances in concrete construction
    • /
    • v.1 no.2
    • /
    • pp.151-162
    • /
    • 2013
  • The performance characteristics of high-strength and high-performance concrete are discussed in this review. Recent developments in the field of high-performance concrete marked a giant step forward in high-tech construction materials with enhanced durability, high compressive strength and high modulus of elasticity particularly for industrial applications. There is a growing awareness that specifications requiring high compressive strength make sense only when there are specific strength design advantages. HPC today employs blended cements that include silica fume, fly ash and ground granulated blast-furnace slag. In typical formulations, these cementitious materials can exceed 25% of the total cement by weight. Silica fume contributes to strength and durability; and fly ash and slag cement to better finish, decreased permeability, and increased resistance to chemical attack. The influences of various mineral admixtures such as fly ash, silica fume, micro silica, slag etc. on the performance of high-strength concrete are discussed.