scholarly journals Construction Technology of Precast Pier Foundation Filled with Demolished Concrete Lumps

2021 ◽  
Author(s):  
Wengui Li ◽  
Bin Lei ◽  
Zhiyu Luo ◽  
Fuzhi Yang
Keyword(s):  
Flexural Strength ◽  
Stress Level ◽  
Strength Properties ◽  
Construction Technology ◽  
Damage Mode ◽  
Key Factors ◽  
Construction Waste ◽  
Steel Mesh ◽  
Test Pieces ◽  
Elastic Stage

Applying of demolished concrete lumps (DCLs) in the pier foundation is an effective way to improve the efficiency of construction waste resource utilization. Fifty-two cylindrical specimens with the size of ∅ 250 mm × 500 mm were fabricated by mixing of DCLs with the fresh concrete (FC) and used to investigate the influence of two key factors, the gradation of the DCLs and the height setting of layered “steel mesh,” on the uniaxial compression and flexural strength properties of the compound concrete specimens. Results indicate that the layered “steel mesh” in the specimens can restrain the settlement and segregation of the DCLs and improve the compressive and flexural strength of the specimens significantly. Normally, there are two types of failure damage mode of the test pieces, the failure of the interface between DCLs and the FC and the fracture failure of the DCLs. When the stress level is below 0.5, the test piece is in the elastic stage. Crack development occurs when stress level further increase to 0.7–0.9. The pieces with the layered pouring height of H2 and the DCLs of R3 present the optimum compressive strength and flexural strength and also best construction effect.

scholarly journals Deformation Behavior and Fracture Patterns of Laminated PEEK- and PI-Based Composites with Various Carbon-Fiber Reinforcement

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2268
Author(s):  
Pavel V Kosmachev ◽  
Vladislav O Alexenko ◽  
Svetlana A Bochkareva ◽  
Sergey V Panin
Keyword(s):  
Carbon Fiber ◽  
Flexural Strength ◽  
Laminated Composites ◽  
Flexural Modulus ◽  
Strength Properties ◽  
Fe Model ◽  
Carbon Fabric ◽  
Model Framework ◽  
Order Of Magnitude ◽  
Stress States

Laminated composites based on polyetheretherketone (PEEK) and polyimide (PI) matrices were fabricated by hot compression. Reinforcing materials (unidirectional carbon-fiber (CF) tapes or carbon fabric) and their layout patterns were varied. Stress–strain diagrams after three-point flexural tests were analyzed, and both lateral faces of the fractured specimens and fractured surfaces (obtained by optical and scanning electron microscopy, respectively) were studied. It was shown that the laminated composites possessed the maximum mechanical properties (flexural elastic modulus and strength) in the case of the unidirectional CF (0°/0°) layout. These composites were also not subjected to catastrophic failure during the tests. The PEEK-based composites showed twice the flexural strength of the PI-based ones (0.4 and 0.2 GPa, respectively), while the flexural modulus was four times higher (60 and 15 GPa, correspondently). The reason was associated with different melt flowability of the used polymer matrices and varied inter- (intra)layer adhesion levels. The effect of adhesion was additionally studied by computer simulation using a developed two-dimensional FE-model. It considered initial defects between the binder and CF, as well as subsequent delamination and failure under loads. Based on the developed FE-model, the influence of defects and delamination on the strength properties of the composites was shown at different stress states, and the corresponding quantitative estimates were reported. Moreover, another model was developed to determine the three-point flexural properties of the composites reinforced with CF and carbon fabric, taking into account different fiber layouts. It was shown within this model framework that the flexural strength of the studied composites could be increased by an order of magnitude by enhancing the adhesion level (considered through the contact area between CF and the binder).

Comparative Study on Mechanical Strength Properties of Concrete by Using Demolished Concrete Waste

2019 ◽  
Vol 1 (6) ◽  
pp. 235-239
Author(s):  
Sabarinathan K ◽  
Ashwathi R
Keyword(s):  
Comparative Study ◽  
Mechanical Strength ◽  
Coarse Aggregate ◽  
Environmental Awareness ◽  
Strength Properties ◽  
Raw Material ◽  
Construction Waste ◽  
The World ◽  
Day By Day

The growing environmental awareness and Construction waste, is increasing day by day which in turn makes the world in seeking for examining the characteristics of Construction waste and obtaining a solution by using its reliable segments such that it can be used as a raw material and Conservation the natural recourses like Coarse aggregate

scholarly journals The effect of curing conditions on the mechanical properties of SIFCON

2021 ◽  
Vol 20 (1) ◽  
pp. 37-51
Author(s):  
Kubilay Akçaözoğlu ◽  
◽  
Adem Kıllı ◽  
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Steel Fiber ◽  
Impact Resistance ◽  
Strength Properties ◽  
Fiber Reinforced Concrete ◽  
Curing Conditions ◽  
Accelerated Curing ◽  
Aspect Ratios ◽  
Curing Method

In this study, the effect of curing conditions on the mechanical properties of slurry infiltrated fiber reinforced concrete (SIFCON) was investigated. For this purpose, SIFCON samples containing 4% and 8% steel fiber with two different aspect ratios were produced. The samples were subjected to three different curing types, namely standard, dry and accelerated curing methods. Ultrasonic wave velocity, flexural strength, fracture toughness, compressive strength, impact resistance and capillary water absorption tests were performed on the samples. The highest flexural strength was found to be achieved in the samples with an aspect ratio of 55 and a content of 8% steel fiber. The most suitable curing method was determined as the standard curing method and the best flexural strength was achieved at the rate of 8%. According to the test results, the best strength properties were achieved in the samples exposed to the standard curing method. In addition, the samples exposed to the accelerated curing method showed satisfactory values. The accelerated curing method can be used as an alternative in SIFCON production especially in applications requiring mass production.

scholarly journals Rheology, fresh and hardened properties of self-consolidating concrete utilizing metal and PVA polymer fibers

2021 ◽  
Author(s):  
Moustafa M Sammour
Keyword(s):  
Flexural Strength ◽  
Fracture Energy ◽  
Strength Properties ◽  
Fiber Reinforced Concrete ◽  
Fiber Types ◽  
Fiber Reinforced ◽  
Segregation Index ◽  
Self Consolidating Concrete ◽  
Funnel Flow ◽  
Energy Absorbing

Fiber reinforced self-consolidating concrete (FRSCC) has a tremendous potential to be used in construction industry as it combines the advantagees of both self-consolidating concrete (SCC) and fiber reinforced concrete (FRC). 18 concrete mixtures were developed by incorporating differenct volumes (0 to 0.3) of polyvinyl alchohol (PVA) and metallic fibers. Fresh, rheological, mechanical and durability (in terms of chloride penetration resistance) properties of all FRSCC mixtures were evaluated. The influences of fiber types/size/ dosages and fiber combination (used in hybrid mixes) on fresh (slump flow, L-box passing ability, V-funnel flow time and segregation index), rheological (plastic viscosity and yield stress) and hardened (fracture energy and compressive/flexural/splitting tensile strength) properties were critically analyzed to examine the relationships among various properties as well as to suggest suitable FRSCC mixtures. The fibers (especially metallic ones) wre more effective in increasing the fracture energy of FRSCC than compressive/splitting tensile/flexural strength. A fracture energy gain of about 730% was observed (which is substantial) compared to 10% of compressive strength, 39% of splitting tensil strength and 124% of flexural strength. The improved strength and fracture energy of FRSCC mixtures can significantly reduce the amount of tensile reinforcement and subsantially increase the energy absorbing capacity of concrete structures.

scholarly journals Steel scrap added roller compacted concrete

2019 ◽  
Vol 10 (1) ◽  
pp. 7
Author(s):  
Kemal Armagan ◽  
Sadık Alper Yıldızel ◽  
Yusuf Arslan
Keyword(s):  
Flexural Strength ◽  
Steel Slag ◽  
High Volume ◽  
Strength Properties ◽  
Promising Material ◽  
Steel Scrap ◽  
Freeze Thaw ◽  
Roller Compacted Concrete ◽  
Local Roads ◽  
Mechanical Performances

The purpose of this paper is to investigate the benefits of using steel slag as an additive in Roller Compacted Concrete (RCC) which is a promising material can be used in streets, local roads, residential streets, high-volume roads, industrial access roads, airports...etc. The mechanical performances of steel scrap added reinforced cementitious composites produced with an industrial punch scrap. In specimen mixtures two types of scraps with diameters of 5 mm and 7 mm were used. The additive was mixed with 1%, 1.5% and 2% ratios by weight. Due to the results of the study, it was obtained that flexural strength properties of the specimens have increased up to 11%. In addition, freeze thaw effect of the specimens was investigated and found that 2% percent of scrap usage was given the best results.

scholarly journals Construction waste processing management and demolition of five-storey apartment blocks in Moscow

2018 ◽  
Vol 193 ◽  
pp. 05008
Author(s):  
Vitaliy Chulkov ◽  
Myhammet Fachratov
Keyword(s):  
Raw Materials ◽  
Strength Properties ◽  
Waste Processing ◽  
Construction Waste

Data on waste processing management is presented in the article. Processing of scrap concrete waste, which is similar to traditional raw materials in composition and condition, is economically and ecologically feasible. The research suggests that concrete with scrap concrete waste shows strength properties similar to primary concrete and helps organizing waste-free production.

scholarly journals The Analysis of the Influence of the Polystyrene Patterns Shaping Parameters on the Resistance Properties

2012 ◽  
Vol 12 (2) ◽  
pp. 227-234
Author(s):  
T. Pacyniak ◽  
K. Buczkowska ◽  
W. Bogus
Keyword(s):  
Flexural Strength ◽  
Strength Properties ◽  
Sintering Process ◽  
Research Results ◽  
Foam Plastics

The Analysis of the Influence of the Polystyrene Patterns Shaping Parameters on the Resistance Properties This work presents the technology of making foam plastics patterns used in casting as well as the final shaping stand. The analysis of the sintering process was carried out aiming at determining the influence of the pressure and the time of sintering on the flexural strength properties. The analysis of the research results confirmed that when the sintering pressure grows to the value of Pa =1,7 bar the flexural strength also increases, when the pressure value is higher than that, the degradation of the material takes place and the strength properties decrease.

Effectiveness of Second-generation Light-emitting Diode (LED) Light Curing Units

2007 ◽  
Vol 8 (2) ◽  
pp. 35-42 ◽  
Author(s):  
Fabrício Aulo Ogliari ◽  
Ulisses Bastos Campregher ◽  
Susana Maria Werner Samuel ◽  
Carmen Beatriz Borges Fortes ◽  
Alberth David Correa Medina ◽  
...  
Keyword(s):  
Flexural Strength ◽  
Second Generation ◽  
Light Emitting Diode ◽  
Strength Properties ◽  
Knoop Hardness ◽  
Curing Time ◽  
Light Emitting ◽  
Led Light ◽  
Three Samples ◽  
Light Curing

Abstract Aim The purpose of this study was to evaluate the effectiveness of three commercially available light emitting diode (LED) light curing units (LCU) (Elipar FreeLight - 3M ESPE; UltraLume LED2 - Ultradent; and Single V - BioArt) for polymerizing Z250-A3 composite (3M ESPE) using Knoop hardness, polymerization depth, and flexural strength properties. Methods and Materials The XL 2500 (3M ESPE) LCU, which is a conventional halogen unit, was used as a control. In all cases the curing time was 20 seconds. Hardness was determined 24 hours after composite cure for 10 samples of 8 mm diameter and 2 mm height for each LCU tested. Samples were stored dry in a lightproof container prior to testing. The depth of cure of the composite was measured immediately after composite polymerization for each LCU using three samples 4 mm in diameter and 6 mm in height. Flexural strength was determined for five samples 24 hours after immersion in distilled water at 37°C. Each sample measured 25 mm in length, 2 mm in width, and 2 mm in height for each LCU tested. Conclusion The results were treated statistically for comparison of the LCUs. In all cases the results obtained by LED LCUs were not different or were higher than a conventional halogen LCU. Clinical Significance Second generation LED LCUs were as effective as/or more effective than a halogen LCU for polymerization of the used composite. The present study shows second generation LEDs have the potential to replace halogen LCUs. Citation Campregher UB, Samuel SMW, Fortes CBB, Medina ADC, Collares FMC, Ogliari FA. Effectiveness of Second-generation Light-emitting Diode (LED) Light Curing Units. J Contemp Dent Pract 2007 February;(8)2:035-042.

Biaxial Flexural Strength and Estimation of Size on the Strength Properties of FRP Composites

1990 ◽  
Vol 40 (2) ◽  
pp. 171-181
Author(s):  
M. N. Saraf ◽  
R. K. Gupta ◽  
B. Vishwanath ◽  
A. D. Manohar
Keyword(s):  
Flexural Strength ◽  
Strength Properties ◽  
Frp Composites ◽  
Biaxial Flexural Strength

Flexural and Morphology Properties of Kenaf Fibre Reinforcement Unsaturated Polymer Composite

2017 ◽  
Vol 888 ◽  
pp. 193-197 ◽  
Author(s):  
Nurul Wahida Rusli ◽  
Mohamad Bashree Abu Bakar ◽  
Mohd Zharif Ahmad Thirmizir ◽  
Muhammad Azwadi Sulaiman ◽  
Mohamad Najmi Masri
Keyword(s):  
Flexural Strength ◽  
Polymer Composite ◽  
Unsaturated Polyester ◽  
Strength Properties ◽  
Morphological Properties ◽  
Fibre Reinforcement ◽  
Fiber Fracture ◽  
Kenaf Fibre ◽  
Unsaturated Polymer ◽  
Polyester Composite

This study focus on the preparation of kenaf fibre reinforced unsaturated polyester composite through the compressing molding technique. The composite characterizations in flexural and morphological properties. Flexural test revealed that the incorporation of multiple layers of kenaf mat into unsaturated polymer composite (UPE) resulted in the increase of flexural strength. Nevertheless, the UPE alone still showed superior flexural strength since the presence of natural filler/fibre in polymer tends to reduce strength properties. The results proved that the UPE revealed the formation of microcracks. Thus, it has been noticed that the fiber fracture, fiber debondings and holes are some of the defects, which are observed due to the application of the load on the specimen.

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