scholarly journals Effect of Low Temperatures on the Mechanical Performance of GFRC Modified by Low Carbon Cement

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Meimei Song ◽  
Chuanlin Wang
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Low Temperatures ◽  
Mechanical Performance ◽  
Strain Curve ◽  
Hydration Product ◽  
Ultimate Strain ◽  
Low Carbon ◽  
Bending Performance ◽  
Freeze Thaw

Glass fibre reinforced cement (GFRC) is a composite material with great ductility but it undergoes severe strength and ductility degradation with ageing. Calcium sulfoaluminate (CSA) cement is low carbon cement, and more importantly, it exhibits great potential to produce more ductile and durable GFRC. This study focuses on mechanical performance, e.g., compressive strength, stress-strain curve, and freeze-thaw resistance of CSA/GFRC as well as its microstructural characteristics under low temperatures. XRD was applied to investigate the hydration mechanism of CSA cement under −5°C, 0°C, and 5°C. It was found out that low-temperature environments have very little effect on the type of hydration products, and the main hydration product of hydrated CSA cement cured under low temperatures is ettringite. Moreover, low-curing temperatures have an adverse effect on the compressive strength developments of CSA/GFRC but the strength difference compared with that under 20°C reduces gradually with increasing curing ages. In terms of bending performance, both ultimate tensile strength and ultimate strain value indicate considerable degradation with ageing under low temperatures after 14 d. The ultimate strain value reduces to 0.34% at −5°C, 0.39% at 0°C, and 0.44% at 5°C compared with 0.51% for that cured at 20°C for 28 d. The tensile strength of samples cured at −5°C for 28 d is only 15.2 MPa, taking up only 40% of that under 20°C. CSA/GFRC also demonstrated great capability in the antifreeze-thaw performance, and the corresponding strength remains 95.9%, 94.7%, 94.2%, and 94.3%, respectively, for that cured under 20°C, 5°C, 0°C, and −5°C after 50 freeze-thaw cycles. Microstructural studies reveal that densification of the interfilamentary space with intermixtures of C-A-S-H and ettringite is the main reason that causes the degradation of CSA/GFRC, which may result in loss on flexibility when forces are applied, therefore reducing the post-peak toughness to some extent.

Experiment on the Mechanical Performance of Fiber Lightweight Aggregate Concrete after Freeze-Thaw and Elevated Temperature

2014 ◽  
Vol 919-921 ◽  
pp. 1790-1793 ◽  
Author(s):  
Bo Cheng ◽  
Jing Huang ◽  
Wen Ting Jiang ◽  
Jian Min Wang
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Room Temperature ◽  
Mechanical Performance ◽  
Lightweight Aggregate ◽  
Splitting Tensile Strength ◽  
Lightweight Aggregate Concrete ◽  
Polyacrylonitrile Fiber ◽  
Aggregate Concrete ◽  
Freeze Thaw

Experiment on the compressive strength and splitting tensile strength of fiber lightweight aggregate concrete (FLWAC) after freeze-thaw cycling and high temperature was tested through blending polyvinyl alcohol fiber (PVAF) and polyacrylonitrile fiber (PANF) in aggregate concrete respectively. Five temperature levels, room temperature, 200°C, 400°C, 600°Cand 800°C were selected to heat the FLWAC test blocks after 25 times of freeze-thaw cycling. The micro-structure of FLWAC was observed through SEM. The experiment results show that, the cubic compressive strength of FLWAC is improved when the temperature is above 200°C, and the splitting tensile strength of FLWAC is obviously improved between the ranges from room temperature to 600°C. Blending fiber can weaken the brittle fracture performance of LWAC after freeze-thaw cycling at the peak loading state. However, the mass loss doesn’t have obvious improvement before and after 25 number of freeze-thaw cycling.

scholarly journals Tensile Performance of a Novel Glue-Laminated Cornstalk Scrimber

2020 ◽  
Vol 23 (3) ◽  
pp. 198-203
Author(s):  
Wei Tian ◽  
Yongmei Qian ◽  
Ruozhu Wang ◽  
Yiming Wang
Keyword(s):  
High Pressure ◽  
Tensile Strength ◽  
Experimental Analysis ◽  
Building Material ◽  
Mechanical Performance ◽  
Strain Curve ◽  
Cost Effective ◽  
Building Industry ◽  
Young’S Moduli ◽  
Tensile Performance

Glue-laminated cornstalk scrimber is a novel composite to substitute timber. This composite can be prepared in three steps: selecting flawless cornstalks, laying them parallel to grain, and gluing the scrimbers under high pressure. Compared with ordinary timber, glue-laminated cornstalk scrimber excels in the resistance to water, damping, insect, and fire. It is therefore widely recognized as novel eco-friendly and cost- effective composite with great potential in the building industry. The tensile strength of glue-laminated cornstalk scrimber mainly depends on the parallel-to-grain strength of its fibers. The mechanical performance parallel to grain directly determines that of this composite. Hence, this paper carries out experimental analysis on the Young’s moduli and parallel-to-grain tensile strengths of cornstalk scrimber and glue-laminated cornstalk scrimber. The results show that the load-strain curve of glue-laminated cornstalk scrimber basically changed linearly parallel to grain, and the material exhibited stable Young’s modulus and good strength; the glue-laminated cornstalk scrimber had a slightly higher tensile strength than cornstalk scrimber, and could thus replace timber as a building material.

scholarly journals Influence of Partial Replacement of Micro-Silica by Fly-Ash on Strength Properties of Reactive Powder Concrete

2020 ◽  
Vol 9 (3) ◽  
pp. 2932-2937
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Fly Ash ◽  
Mechanical Performance ◽  
Cementitious Materials ◽  
Partial Replacement ◽  
Reactive Powder Concrete ◽  
Experimental Investigations ◽  
Reactive Powder ◽  
Micro Silica

Reactive powder concrete (RPC) is the ultra-high strength concrete made by cementitious materials like silica fumes, cement etc. The coarse aggregates are completely replaced by quartz sand. Steel fibers which are optional are added to enhance the ductility. Market survey has shown that micro-silica is not so easily available and relatively costly. Therefore an attempt is made to experimentally investigate the reduction of micro-silica content by replacing it with fly-ash and mechanical properties of modified RPC are investigated. Experimental investigations show that compressive strength decreases gradually with addition of the fly ash. With 10 per cent replacement of micro silica, the flexural and tensile strength showed 40 and 46 per cent increase in the respective strength, though the decrease in the compressive strength was observed to be about 20 per cent. For further percentage of replacement, there was substantial drop in compressive, flexural as well as tensile strength. The experimental results thereby indicates that utilisation of fly-ash as a partial replacement to micro silica up to 10 per cent in RPC is feasible and shows quite acceptable mechanical performance with the advantage of utilisation of fly-ash in replacement of micro-silica.

scholarly journals Attempts to Improve the Subsurface Properties of Horizontally-Formed Cementitious Composites Using Tin(II) Fluoride Nanoparticles

Coatings ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 83 ◽  
Author(s):  
Kamil Krzywiński ◽  
Łukasz Sadowski ◽  
Jacek Szymanowski ◽  
Andrzej Żak ◽  
Magdalena Piechówka-Mielnik
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Abrasion Resistance ◽  
Mechanical Performance ◽  
Reference Sample ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Cementitious Composites ◽  
Fluoride Nanoparticles

This article presents studies that were performed in order to improve the subsurface properties of horizontally-formed cementitious composites using tin(II) fluoride nanoparticles. The main aim of the study was to solve the problem of the decrease in subsurface properties caused by mortar bleeding and the segregation of the aggregate along the height of the overlay. The article also aims to highlight the patch grabbing difficulties that occur during the process of forming horizontally-formed cementitious composites. Four specimens were analyzed: one reference sample and three samples modified with the addition of 0.5, 1.0, and 1.5% of tin(II) fluoride nanoparticles in relation to the cement mass. To analyze the mechanical properties of the specimens, non-destructive (ultrasonic pulse velocity) and destructive tests (flexural tensile strength, compressive strength, abrasion resistance, pull-off strength) were performed. It was indicated that due to the addition of the tin(II) fluoride, it was possible to enhance the subsurface tensile strength and abrasion resistance of the tested cementitious composites. To confirm the obtained macroscopic results, the porosity of the subsurface was measured using SEM. It was also shown that the addition of the tin(II) fluoride nanoparticles did not reduce its flexural and compressive strength. The results show that horizontally-formed cementitious composites with the addition of 1.0% of tin(II) fluoride nanoparticles in relation to the cement mass obtained the most effective mechanical performance, especially with regard to subsurface properties.

scholarly journals Evaluation of the Performance of Bio-Based Rigid Polyurethane Foam with High Amounts of Sunflower Press Cake Particles

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5475
Author(s):  
Agnė Kairytė ◽  
Sylwia Członka ◽  
Renata Boris ◽  
Sigitas Vėjelis
Keyword(s):  
Thermal Conductivity ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Water Absorption ◽  
Polyurethane Foam ◽  
Mechanical Performance ◽  
Positive Impact ◽  
Press Cake ◽  
Rigid Polyurethane Foam ◽  
Average Cell

In the current study, rigid polyurethane foam (PUR) was modified with 10–30 wt.% sunflower press cake (SFP) filler, and its effect on performance characteristics—i.e., rheology, characteristic foaming times, apparent density, thermal conductivity, compressive strength parallel and perpendicular to the foaming directions, tensile strength, and short-term water absorption by partial immersion—was evaluated. Microstructural and statistical analyses were implemented as well. During the study, it was determined that 10–20 wt.% SFP filler showed the greatest positive impact. For instance, the thermal conductivity value improved by 9% and 17%, respectively, while mechanical performance, i.e., compressive strength, increased by 11% and 28% in the perpendicular direction and by 43% and 67% in the parallel direction. Moreover, tensile strength showed 49% and 61% increments, respectively, at 10 wt.% and 20 wt.% SFP filler. Most importantly, SFP filler-modified PUR foams were characterised by two times lower water absorption values and improved microstructures with a reduced average cell size and increased content in closed cells.

scholarly journals The Synergy between Bio-Aggregates and Industrial Waste in a Sustainable Cement Based Composite

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6158
Author(s):  
Cătălina Mihaela Grădinaru ◽  
Adrian Alexandru Șerbănoiu ◽  
Radu Muntean ◽  
Bogdan Vasile Șerbănoiu
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Fly Ash ◽  
Splitting Tensile Strength ◽  
Partial Replacement ◽  
Cement Matrix ◽  
Freeze Thaw ◽  
Corn Cobs ◽  
Study Results ◽  
Sunflower Stalks

The effects of the fly ash and of the sunflower stalks and corn cobs within a cement-matrix composite were studied under the aspects of density, compressive strength, splitting tensile strength, elasticity modulus, and resistance to repeated freeze-thaw cycles. In the research were developed 20 recipes of cement-based composite, including the reference composite. Fly ash was used as partial cement replacement (10, 20 and 30% by volume), and the vegetal aggregates made by corn cobs and sunflower stalks as partial replacement of the mineral aggregates (25 and 50% by volume). The study results revealed that a lightweight composite can be obtained with 50% of vegetal aggregates, and the fly ash, no matter its percentage, enhanced the compressive strength and splitting tensile strength of the compositions with 50% of sunflower aggregates and the freeze-thaw resistance of all compositions with sunflower stalks.

scholarly journals Influence of the Composition of the Activator on Mechanical Characteristics of a Geopolymer

2020 ◽  
Vol 10 (10) ◽  
pp. 3349 ◽  
Author(s):  
Adelino V. Lopes ◽  
Sergio M.R. Lopes ◽  
Isabel Pinto
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Carbon Dioxide Emissions ◽  
Sustainable Construction ◽  
Low Carbon ◽  
High Durability ◽  
Strength Tests

Geopolymer materials are characterized by their high durability and low carbon dioxide emissions, when compared with more traditional materials, like concrete made from ordinary Portland cement. These are interesting advantages and might lead to a more sustainable construction industry. The aim of this study is the characterization of the mechanical behavior of the materials obtained by the activation of metakaolin. The activator is a mixture of sodium hydroxide with sodium silicate in different proportions. The influence of the composition of activator is studied. For the analysis of the mechanical properties of the different mixtures two different types of tests were performed, bending tensile strength tests and compressive strength tests. The results show that an activator with not less than 300 g of sodium hydroxide and not exceeding 600 g of sodium silicate per 750 g of metakaolin gives the best results, for both tensile strength and compressive strength.

scholarly journals Mechanical and Fracture Parameters of Ultra-High Performance Fiber Reinforcement Concrete Cured via Steam and Water: Optimization of Binder Content

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2016
Author(s):  
Avan Ahmed Mala ◽  
Aryan Far H. Sherwani ◽  
Khaleel H. Younis ◽  
Rabar H. Faraj ◽  
Amir Mosavi
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
High Performance ◽  
Mechanical Performance ◽  
Binder Content ◽  
Splitting Tensile Strength ◽  
Steam Curing ◽  
Flexural Tensile Strength ◽  
High Performance Fiber ◽  
Curing Methods

An investigational study is conducted to examine the effects of different amounts of binders and curing methods on the mechanical behavior and ductility of Ultra-High Performance Fiber Reinforced Concretes (UHPFRCs) that contain 2% of Micro Steel Fiber (MSF). The aim is to find an optimum binder content for the UHPFRC mixes. The same water-to-binder ratio (w/b) of 0.12 was used for both water curing (WC) and steam curing (SC). Based on the curing methods, two series of eight mixes of UHPFRCs containing different binder contents ranging from 850 to 1200 kg/m3 with an increment of 50 kg/m3 were produced. Mechanical properties such as compressive strength, splitting tensile strength, static elastic module, flexural tensile strength and the ductility behavior were investigated. This study revealed that the mixture of 1150 kg/m3 binder content exhibited the highest values of the experimental results such as a compressive strength greater than 190 MPa, a splitting tensile strength greater than 12.5 MPa, and a modulus of elasticity higher than 45 GPa. The results also show that all of the improvements began to slightly decrease at 1200 kg/m3 of the binder content. On the other hand, it was concluded that SC resulted in higher mechanical performance and ductility behavior than WC.

scholarly journals Mechanical Performance of Recycled Aggregate Concrete Containing Lathe Waste Steel Fibre

2021 ◽  
Vol 17 (4) ◽  
pp. 306-311
Author(s):  
S.A. Alabi ◽  
C. Arum
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Building Materials ◽  
Steel Fibre ◽  
Mechanical Performance ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Aggregate Concrete

The increasing demand, diminishing supplies, and growing pressure on natural resources have necessitated recycling and reusing waste. Several kinds of research have been done on the reuse and recycling of debris from building projects. Thus, with a view to the reuse of waste materials, the elimination of environmental contamination, the reduction of overhead costs of concrete, and the extension of the service life of concrete structures, this research aimed to study the feasibility of utilizing recycled concrete aggregate (RCA) with constant inclusion of waste steel fibre (LWSF) in concrete by evaluating its workability, compressive and splitting tensile strengths. A concrete mix ratio of 1:2:4 by weight of cement, sand, and granite was adopted with a water-cement ratio of 0.45. Five different concrete mixes were prepared in this study; one normal aggregate concrete (NAC) and four (4) other mixes with 25%, 50%, 75%, and 100% recycled aggregate content with a constant 1.5% addition of LWSF. The result of workability shows a reduction with an increase in the percentage replacement level. The recycled aggregate concrete (RAC) was characterized by lower compressive strength as compared with the NAC. When the replacement ratio increased from 25% to 50%, a significant reduction of about 14% and 30% were observed in the compressive strength at 7-days, but at 28-days slight increase in the compressive strength was observed. Also, a decrease in splitting tensile strength as the percentage replacement of crushed granite (CG) with RCA is increased was observed. Overall, the findings showed that the RAC-containing LWSF is environmentally sustainable and would significantly reduce the global greenhouse impact and building materials' overall quality. Keywords: Recycled concrete, lathe waste, steel fibre, compressive strength, tensile strength

The Effect of Chemicalattack of some Organic Acidic Solutions to Self Compacting Concrete (SCC)

2012 ◽  
Vol 587 ◽  
pp. 67-76
Author(s):  
Jabbar Abbas Jabir Al Khafaji ◽  
Najah Mahdi Lateef Al Maimuri ◽  
Abdul Hadi Meteab Hassan Al Sa'adi
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Acid Solution ◽  
Mechanical Performance ◽  
Acidic Solution ◽  
Splitting Tensile Strength ◽  
Self Compacting Concrete ◽  
Acidic Solutions ◽  
Reduction Percentage

A study of a mechanical performance(Compressive strength, flexural strength, and splitting tensile strength)of self-compacting (SCC) and conventional (NCC)concretemixes and some physical properties of the mixes made of Portland cement under the effect of acidic solution attackare made. Trichloroacetic and Salicycilic acids are selected and used in this study. It is found that the reduction percentage in compressive strength is about 6% and 3% under the effect of Trichloroacetic acidic solution whereas itisabout 8% under the effect the salicycilic acidic solution attackfor both SCC and NCC mixes after 62 days of treatment for bothSCC and NCC mixes respectively. The reduction percentage in flexural strengthisabout 27% and 37% under the effect of the Trichloroacetic acidic solution attack whereas itis about 59% and 79% under the effect the salicycilic acidic solution attackfor both SCC and NCC mixes respectivelyafter 62 days of treatment. The reduction percentage in splitting tensile strength is about 60% and 63% under the effect the Trichloroacetic acidic solution attack whereas it is 70% and 88% under the effect of the salicycilic acidic solution attack% for both SCC and NCC mixes after 62 days of treatment. At the age 90 days, the SCC and NCC mixes have a reductionpercentage in the cubes weight of 3% and 4% whereas there is an increasing in volume of 0.3% and 0.4% respectively under the effect of salicyclic acid solution attack.It is observed that SCC mixes offer more resistant and less deterioration against acidic solutions attack.

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