• Title/Summary/Keyword: concrete strength in structure

Search Result 1,343, Processing Time 0.033 seconds

Durability assessments of limestone mortars containing polypropylene fibres waste

  • Bendjillali, Khadra;Boulekbache, Bensaid;Chemrouk, Mohamed
    • 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 ㎛.

Experimental study of graphene oxide on wollastonite induced cement mortar

  • Sairam, V.;Shanmugapriya, T.;Jain, Chetan;Agrahari, Himanshu Kumar;Malpani, Tanmay
    • Advances in concrete construction
    • /
    • v.12 no.6
    • /
    • pp.479-490
    • /
    • 2021
  • Present research is mainly focused on, microstructural and durability analysis of Graphene Oxide (GO) in Wollastonite (WO) induced cement mortar with silica fume. The study was conducted by evaluating the mechanical properties (compressive and flexural strength), durability properties (water absorption, sorptivity and sulphate resistance) and microstructural analysis by SEM. Cement mortar mix prepared by replacing 10% ordinary portland cement with SF was considered as the control mix. Wollastonite replacement level varied from 0 to 20% by weight of cement. The optimum replacement of wollastonite was found to be 15% and this was followed by four sets of mortar specimens with varying substitution levels of cementitious material with GO at dosage rates of 0.1%, 0.2%, 0.3% and 0.4% by weight. The results indicated that the addition of up to 15%WO and 0.3% GO improves the hydration process and increase the compressive strength and flexural strength of the mortar due to the pore volume reduction, thereby strengthening the mortar mix. The resistance to water penetration and sulphate attack of mortar mixes were generally improved with the dosage of GO in presence of 15% Wollastonite and 10% silica fume content in the mortar mix. Furthermore, FE-SEM test results showed that the WO influences the lattice framework of the cement hydration products increasing the bonding between silica fume particles and cement. The optimum mix containing 0.3% GO with 15% WO replacement exhibited extensive C-S-H formation along with a uniform densified structure indicating that calcium meta-silicate has filled the pores.

Effect of Foaming Agent Content on the Apparent Density and Compressive Strength of Lightweight Geopolymers (발포제 함량에 따른 경량 다공성 지오폴리머의 밀도와 강도 특성)

  • Lee, Sujeong;An, Eung-Mo;Cho, Young-Hoon
    • Journal of the Korean Recycled Construction Resources Institute
    • /
    • v.4 no.4
    • /
    • pp.363-370
    • /
    • 2016
  • Lightweight geopolymers are more readily produced and give higher fire resistant performance than foam cement concrete. Lowering the density of solid geopolymers can be achieved by inducing chemical reactions that entrain gases to foam the geopolymer structure. This paper reports on the effects of adding different concentrations of aluminum powder on the properties of cellular structured geopolymers. The apparent density of lightweight geopolymers has a range from 0.7 to $1.2g/m^3$ with 0.025, 0.05 and 0.10 wt% of a foaming agent concentration, which corresponds to about 37~60 % of the apparent density, $1.96g/cm^3$, of solid geopolymers. The compressive strength of cellular structured geopolymers decreased to 6~18 % of the compressive strength, 45 MPa of solid geopolymers. The microstructure of geopolymers gel was equivalent for both solid and cellular structured geopolymers. The workability of geopolymers with polyprophylene fibers needs to be improved as in fiber-reinforced cement concrete. The lightweight geopolymers could be used as indoor wall tile or board due to fire resistance and incombustibility of geopolymers.

A Study on the Optimal Design of Reinforced Concrete Slab-Beam-Column Structures by Direct Method (직접설계법(直接設計法)에 의한 철근(鐵筋)콘크리트 2방향(方向) 슬래브형(型) 구조체(構造體)의 최적설계(最適設計))

  • Kim, Yong Hee;Lyu, Hong Leal;Park, Moon Ho
    • KSCE Journal of Civil and Environmental Engineering Research
    • /
    • v.5 no.1
    • /
    • pp.1-12
    • /
    • 1985
  • This study is conserned for the optimum design of reinforced concrete slab-beam-column structures with multi-storys and multi-bays by Direct Method. Flexural and shear strength, sectional size, and steel ratio etc., were considered as the design-constraints and the cost function was taken as to objective function. They became high degree nonlinear problems. Using SLP as an analytical method of nonlinear optimal problems, an optimal algorithm was developed in this study and the algorithm was applied to the optimization of reinforced concrete structure system of 5 storys. The result converged to a optimal solution with 3 to 5 iterations, and proved that economical design could be possible when compared with conventional designs.

  • PDF

An Experimental Study on the Fatigue Behaviors Strengthened by Ventilation-Glass Fiber Plate of Reinforced Concrete Beams (철근콘크리트 보의 통기성 유리섬유판 보강에 따른 피로거동에 관한 실험적 연구)

  • Kim, Woonhak;Kang, Seokwon;Shin, Chunsik
    • Journal of the Society of Disaster Information
    • /
    • v.8 no.4
    • /
    • pp.391-400
    • /
    • 2012
  • Recently, the construction industry commonly uses FRP as a reinforcement material because of its material advantages. FRP attached reinforcement has various advantages such as high strength, stiffness, excellent durability and construction practicability comparing to its weight. However, external attachment of FRP is water-tighted with low water permeable material, not draining water, probably causing damages on a permanent structure. The study manufactured it through pultrusion and examined GP(glass fiber panel) of which material-mechanical properties are almost same as the existing FRP but durability and attachment performance are better by stationary experiments, testing load-deflection curve, destruction types and load-deflection relation under repetitive loading test. As a result of 2,000,000 fatigue tests, it did not result in the destruction and showed excellent permanent attachment and durability as it displays significantly low compressive strain of concrete.

Influence of Various Replacing Ratios of SCMs on Properties of High Fluidity Concrete (광물질 혼화재의 치환율 변화가 고유동 콘크리트의 특성에 미치는 영향)

  • Han, In-Deok
    • Journal of the Architectural Institute of Korea Structure & Construction
    • /
    • v.35 no.12
    • /
    • pp.165-172
    • /
    • 2019
  • The aim of the research is to evaluate the influence of various replacing ratios of supplementary cementitious materials(SCMs) such as fly ash(FA), blast furnace slag(BS), and both FA and BS on general properties including segregation resistance as a powder based high fluidity concrete of normal strength grade with water-to-cement ratio 0.40. Specifically, by replacing the SCMs with low density powders, it was assessed that the decreased segregation resistance due to the decreased viscosity by J-ring test. As a result of the experiment, from the general test, the mixtures with SCMs showed increased segregation resistance by increased viscosity as the references, while some segregation was shown from J-ring test due to the decreased density of fresh state mixture related with the capacity of delivering coarse aggregate.

Evaluation of the Septic Tank Performance in the Sewage Treatment Area and Suggestion of an Optimum Model (하수처리구역내 단독정화조의 성능평가 및 최적 모형의 제안)

  • Lim, Bong-Su;Jung, Keum-Hee;Wang, Ze-Jie
    • Journal of Korean Society on Water Environment
    • /
    • v.23 no.3
    • /
    • pp.403-409
    • /
    • 2007
  • This study was carried out to recommend the systematic improving practice for the effective operation of septic tank, and the evaluation of its BOD and nutrient removal efficiency depending on process, the survey of characteristics of FRP material, and the suggestion of optimum septic tank model within sewage treatment area. The average BOD concentration and BOD removal efficiency of septic tank which was carried out the cleaning periodically in 63.9 mg/L and 77.8%, shows good quality better than the septic tank which was not carried out the cleaning regularly. Maximum load of tensile, flexural and compressive strength increased in proportion to its thickness, and the contents standard 25% of glass fiber required upgrade over than 30%. Configuration and performance for the optimum of the septic tank suggests that over $0.75m^3$ of the effective total volume, adding to over $0.25m^3$ a man for more than 5 men of the treated person, retention time should be within one day. Improving plans about facility and materials quality of the septic tank have an obligation that protective wall ought to install on the concrete bottom and side faces to prevent crumble or transform from loading of the ground or upper part of the structure on the tank setting. And it is eliminated the uneffective resisting pressure and it keeps off circulate imperfect products by strengthening of the test methods such as stretching strength, pressing strength, glass fiber contents and thickness.

Behavior of Shear Yielding Thin Steel Plate Wall with Tib (리브로 보강한 전단 항복형 강판벽의 거동)

  • Yun, Myung Ho;Wi, Ji Eun;Lee, Myung Ho;Oh, Sang Hoon;Moon, Tae Sup
    • Journal of Korean Society of Steel Construction
    • /
    • v.13 no.5
    • /
    • pp.503-511
    • /
    • 2001
  • Structures are designed against earthquakes and reinforced concrete shear walls or steel bracings are usually used as aseismic resistant element. However their hysteretic characteristics in plastic region ductility and capacity of energy absorption are not always good. Besides their stiffness is so rigid that structure designed by static analysis is occasionally disadvantageous. when dynamically analized. Generally a steel plate subjected to shear force has a good deformation capacity Also it has been considered to retain comparative shear strength and stiffness Steel shear wall can be used as lateral load resistant element for seismic design. However there was little knowledge concerning shear force-deformation characteristics of steel plates up to their collapse state In this study a series of shear loading tests of steel plate collapse state. In this study a series of shear loading tests of steel plate surrounded by vertical and horizontal ribs were conducted with the parameters of D/H ratios rib type and the loading patterns. The test result is discussed and analyzed to obtain several restoring characteristics. that is shear force-deformation stiffness and yield strength etc.

  • PDF

An Experimental Study on the Durability Evaluation of Polymer Cement Restoration Materials for Deteriorated Reinforced Concrete Structures (성능저하된 철근콘크리트구조물 폴리머시멘트계 보수용 단면복구재의 내구성 평가에 관한 실험적 연구)

  • Kim, Moo-Han;Kim, Jae-Hwan;Cho, Bong-Suk;Park, Jong-Ho
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.10 no.1
    • /
    • pp.123-130
    • /
    • 2006
  • The duties of the restorative materials are to bear up against stress and to protect reinforcement corrosion. So the restorative materials are estimated by various kinds of strength, permeability and etc, But, in case of existing performance evaluation of restorative materials, because various deterioration factors are separately acted, the system of performance evaluation is different from that of combined deterioration of real structure and it is difficult to evaluate the exact performance of restorative materials. In this study, to evaluate Performance of restorative materials, we compare their korea standard properties in terms of compressive and bending strength and permeability of water and air with real durability for carbonation, salt damage and actual reinforcement corrosion like ratio of corrosion area. weight reduction and corrosion velocity of steel bar under environment of combined deterioration. The results showed that strength and permeability of restorative materials are similar but their resistance to carbonation, salt damage and actual reinforcement corrosion are very different.

Performance Evaluation of Fiber-Reinforced Concrete Compression Members Transversely Constrained by BFRP (BFRP로 횡구속된 섬유 보강 콘크리트 압축부재의 성능평가)

  • Lee, Gyeong-Bok;Lee, Sang-Moon;Jung, Woo-Young
    • KSCE Journal of Civil and Environmental Engineering Research
    • /
    • v.42 no.5
    • /
    • pp.607-616
    • /
    • 2022
  • Corrosion and degradation of reinforced structures due to abnormal climates and natural disasters further accelerate the aging of structures. Coping with the decrease in structure performance, many old structures are being repaired and reinforced with low-weight and high-strength materials such as glass fiber composite material (GFRP). To further contribute, this paper focus on a more economical and eco-friendly material, basalt fiber composite (BFRP), which provide a more effective lateral constraint effect for seismic reinforcement. The main variables considered in this study are the curing temperature during the manufacturing of BFRP and the material characteristics of the target concrete member. The lateral constraint reinforcement effect was investigated through the evaluation of the performance of normal concrete and those with improved durability through fiber reinforcement. The reinforcement effect was 3.15 times for normal concrete and 3.72 times for fiber reinforced concrete, and the difference in reinforcement effect due to the improvement of the durability characteristics of the compression member was not significant. Lastly, the performance of the BFRP was compared with the results of the GFRP reinforcement from the previous study. The effect of the BFRP reinforcement was 1.18 times better than that of the GFRP reinforcement.