Fiber-matrix interaction in microfiber-reinforced mortar

Betterman, L.R.; Ouyang, C.; Shah, Surendra P.

doi:10.1016/1065-7355(95)90025-x

Cited by 148 publications

(55 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…For instance, among the samples with 1.5% fibre content, the highest crack strength was obtained from the micro‐fibre containing samples. Previous studies also showed that the micro‐sized fibres strengthen the cement paste and the mortar phase in traditional concrete whereas long steel fibres strengthen the concrete 19,22 …”

Section: Resultsmentioning

confidence: 93%

See 1 more Smart Citation

The flexural strength and fracture toughness of reactive powder concrete in response to changing fibre size and pre‐setting pressure

İpek

2011

Fatigue Fract Eng Mat Struct

View full text Add to dashboard Cite

A B S T R A C T In this study, steel fibre mixtures having different compositions of fibres with various sizes were used in reactive powder concrete. The mixture composition, which would present the best performance during the flexural tests, was determined. Pre-setting pressure tests at six different magnitudes (0,5,10, 15,20, 25 MPa) were conducted on the freshly prepared reactive powder concrete mixture having the determined mixture composition. The 30-mm-long steel fibres mixed at a ratio of 4.5% provided the highest flexure strength and the fracture toughness during these tests. The highest pre-setting pressure was attained at 25 MPa and the flexural strength of the sample increased by 117% reaching 28.07 MPa at that pre-setting pressure. Ctrl = Control JSF-14 = Japan Standard L = Long LVDT = Linear Variable Differential Transformer M = Medium PC = Portland cement Q. Powder = Quartz powder Q. Sand = Quartz sand RPC = Reactive powder concrete S = Small SF = Silica fume SP = Super-plasticiser TCMA = Turkish Cement Manufacturers' Association TL = Turkish Liras TS = Turkish Standards Institute Z = Zero I N T R O D U C T I O NReactive powder concrete (RPC) is manufactured by a different method of production through hot curing than that of ordinary concrete. The aggregates were replaced by micro-sized particles and the particle distribution was arranged in such a way to enable the minCorrespondence: M.İpek.

show abstract

Section: Resultsmentioning

confidence: 93%

“…Previous studies also showed that the micro-sized fibres strengthen the cement paste and the mortar phase in traditional concrete whereas long steel fibres strengthen the concrete. 19,22 Fig. 5 Graphics of the change in fracture energy in response to the fibre type and content.…”

Section: R E S U L T S a N D Discussionmentioning

confidence: 99%

The flexural strength and fracture toughness of reactive powder concrete in response to changing fibre size and pre‐setting pressure

İpek

2011

Fatigue Fract Eng Mat Struct

View full text Add to dashboard Cite

show abstract

“…Since the 1870s, the steel reinforcing bars have been widely used to compensate for the low tensile properties of concrete. Over the past few decades, synthetic fibers (macro to micro fibers) have attracted considerable attention of researchers to control the propagation of cracks [1][2][3][4][5][6][7]. Depending on the fiber type, the contributions of fibers rely on the shape and size of the fibers, their surface textures, the interfacial bond strength between the fibers and the matrix, crack bridging ability, and energy dissipation during crack propagation [8,9].…”

Section: Generalmentioning

confidence: 99%

“…Kim et al [41] found that the density of two different types of MWCNTs having diameters of 15 and 22 nm was in the range of 1.74 ± 0.16 g/cm 3 (0.063 ± 0.006 lb/in. 3 ). Laurent et al [42] theoretically calculated the density of CNTs with respect to their diameter and the number of walls.…”

Section: Cnt Propertiesmentioning

confidence: 99%

Design and predicting performance of carbon nanotube reinforced cementitious materials : mechanical properties and dispersion characteristics.

Ramezani¹

2020

Preprint

View full text Add to dashboard Cite

Recently, Carbon Nanotubes (CNTs) are drawing considerable attention of researchers for reinforcing cementitious materials due to their excellent mechanical properties and high aspect ratio (length-to-diameter ratio). However, CNTs might not disperse well within the cement matrix, resulting in little improvement or even degradation of concrete properties. The uncertainty in producing the consistent results in different studies might be attributed to multiple interactions between the experimental variables affecting the nanotube dispersion and the final properties of CNT-cement nanocomposites. Therefore, this research mainly focused on proposing equations that can reliably capture these interactions in order to correlate CNT dispersion with the mechanical properties. The main experimental variables studied included CNT concentration, aspect ratio, ultrasonication energy, ultrasonication amplitude, surfactant-to-CNTs ratio, water-to-cement ratio, sand-to-cement ratio, and hydration age of specimen. The study reported in this research was conducted in two parts: experimental program and modeling. In the experimental part of this research, a total of 63 different mix proportions were used to evaluate the flowability, mechanical properties, and durability characteristics of cement pastes and mortars containing CNTs. Using experimental test results reported in this study and the literature, three critical relations were proposed to consider the CNT dispersion, cement matrix composition, and hydration age of cement. The proposed critical relations were then added to available theoretical models in the literature. The flexural strength and elastic modulus of CNT-cement nanocomposites were predicted through a state-of-the-art probabilistic model using a Bayesian methodology. Finally, the developed probabilistic models were used to identify the optimum ranges of the experimental variables to maximize the mechanical properties. This was done through computing the conditional probability of not meeting the specified design requirement. The experimental results indicated that addition of CNTs could significantly improve different properties of cementitious materials, if the optimum range of each variable was used. Also, to achieve the desired mechanical properties, various combinations of the experimental variables might be used. The proposed prediction models were shown to capture the interactions between the experimental variables for predicting the mechanical properties within ±15% and ±18% of the experimental test results for flexural strength and elastic modulus, respectively. Based on the findings of this research, contour plots were developed to provide practical guidelines for future engineers to design CNT-cement nanocomposites.

show abstract

“…Justification of sample size After examination of journal papers reviewed below with regard to acceptable population size, to establish peer reviewed validity of published results, it was noted most concrete researchers described what was produced for testing and subsequent results discovered from the tests, but many omitted to clearly state the population size per sample type. Researchers who stated their population size clearly were Betterman et al (1995) who used a population size of ten, Qian and Stroeven (2000) used a population size of eight, Mu et al (2002) used a population size of two and Leung (2003) used a population size of five. The problem with testing concrete cubes is that they are very heavy to move in and out of a furnace and therefore a reduced population sample of five was used to facilitate the practical aspect of testing.…”

Section: Thermal Stability Test For Fibresmentioning

confidence: 99%

The effect of polypropylene fibres within concrete with regard to fire performance in structures

Richardson

Dave

2008

Structural Survey

View full text Add to dashboard Cite

Purpose -The purpose of this paper is to examine the effect of various polypropylene fibre additions (types and volume) to concrete with regard to explosive spalling when subject to high temperatures similar to those experienced in building or tunnel fires. Design/methodology/approach -Medium strength concrete was manufactured with varying proportions of polypropylene fibres. Plain control samples were used to determine the original concrete strength and this was used as a benchmark following high temperature heat tests to evaluate the surface condition and final compressive strength. A pilot study was used to determine an appropriate heat source for the test. This was three Bunsen burners, however sufficient heat could not be generated within 150mm concrete cubes and the concrete was shown to be a significant insulator and fire protection for structural members. The concrete test cubes were tested in a saturated condition which may reflect conditions where concrete is used in an external environment and thus is subject to soaking.Findings -One hundred and fifty millimetre concrete cubes with and without fibres were placed into a furnace at 1,000 8 C. Explosive spalling was shown to be reduced with the use of polypropylene fibres but the final compressive strength of concrete was significantly reduced and had little residual structural value after a two hour period of heating. Research limitations/implications -As the concrete tested was saturated, this condition provided a worst case scenario with regards to the build up of hydrostatic and vapour pressure within the cube. A range of percentage moisture contents would produce a more evenly balanced view of the effects of fibres in concrete. A single grade of concrete was used for the test. As the permeability of concrete influences the rate at which steam can escape from the interior of a saturated concrete cube, testing a range of concrete strengths would show this aspect of material performance with regard to spalling and final residual strength. Further research is recommended with regard to moisture contents, strengths of concrete and a range of temperatures.Practical implications -This research has significance for the designer, in that buildings subject to terrorist activity may suffer from impact damage and an outbreak of fire following the initial attack.Originality/value -The use of polypropylene fibres in concrete to provide anti spalling qualities is relatively new and this research adds to the knowledge regarding fibre type and volume with regard to first spall time, total area and number of areas subject to spalling and the final compressive strength of concrete following two hours of raised temperatures.

show abstract

Fiber-matrix interaction in microfiber-reinforced mortar

Cited by 148 publications

References 7 publications

The flexural strength and fracture toughness of reactive powder concrete in response to changing fibre size and pre‐setting pressure

The flexural strength and fracture toughness of reactive powder concrete in response to changing fibre size and pre‐setting pressure

Design and predicting performance of carbon nanotube reinforced cementitious materials : mechanical properties and dispersion characteristics.

The effect of polypropylene fibres within concrete with regard to fire performance in structures

Contact Info

Product

Resources

About