scholarly journals The Influence of Concrete Strength on the Effect of Synthetic Fibres on Fire Resistance

2017 ◽  
Vol 62 (1) ◽  
pp. 136-142 ◽  
Author(s):  
Éva Lublóy
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Pore Structure ◽  
Fire Resistance ◽  
Concrete Strength ◽  
Small Diameter ◽  
Concrete Surface ◽  
Strength Reduction ◽  
Fibre Reinforcement ◽  
Polypropylene Fibres

Numerous studies have verified that increased concrete strength reduces its resistance to fire, leads to a higher degree of strength reduction and higher chances of spalling of concrete surfaces.The risks of spalling of concrete surfaces can be reduced by adding synthetic polypropylene fibres. Numerous experiments have shown that the risk of spalling of the concrete surface is significantly lower when using short, small diameter fibres of polypropylene synthetic, because the pore structure created by the burning of fibres reduces the risk of cracking.However, the question arises whether other types of fibres of greater diameter and length are still able to prevent spalling of concrete surfaces without drastically reducing the strength and if so, in what range of concrete strength it is true.The experiments are aimed to determine the effects of micro and macro synthetic fibres on the post-fire residual compressive strength, flexural strength and porosity of concrete.Nine kinds of mixture were prepared and tested. Three of them are without fibers (reference concretes) with diverse strength, three with synthetic micro-fibres with diverse strength and three with synthetic macro-fibres of diverse strength. The experiment was conducted with three concretes with different strength. Each type had a reference concrete without fibre reinforcement, one with micro- and one with macro-fibres.

scholarly journals The Mechanical Properties of Steel-Polypropylene Fibre Composites Concrete (HyFRCC)

2015 ◽  
Vol 773-774 ◽  
pp. 949-953 ◽  
Author(s):  
Izni Syahrizal Ibrahim ◽  
Wan Amizah Wan Jusoh ◽  
Abdul Rahman Mohd Sam ◽  
Nur Ain Mustapa ◽  
Sk Muiz Sk Abdul Razak
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Volume Fraction ◽  
Concrete Strength ◽  
Fibre Volume Fraction ◽  
Fibre Volume ◽  
Polypropylene Fibre ◽  
Experimental Results

This paper discusses the experimental results on the mechanical properties of hybrid fibre reinforced composite concrete (HyFRCC) containing different proportions of steel fibre (SF) and polypropylene fibre (PPF). The mechanical properties include compressive strength, tensile strength, and flexural strength. SF is known to enhance the flexural and tensile strengths, and at the same time is able to resist the formation of macro cracking. Meanwhile, PPF contributes to the tensile strain capacity and compressive strength, and also delay the formation of micro cracks. Hooked-end deformed type SF fibre with 60 mm length and fibrillated virgin type PPF fibre with 19 mm length are used in this study. Meanwhile, the concrete strength is maintained for grade C30. The percentage proportion of SF-PPF fibres are varied in the range of 100-0%, 75-25%, 50-50%, 25-75% and 0-100% of which the total fibre volume fraction (Vf) is fixed at 0.5%. The experimental results reveal that the percentage proportion of SF-PPF fibres with 75-25% produced the maximum performance of flexural strength, tensile strength and flexural toughness. Meanwhile, the percentage proportion of SF-PPF fibres with 100-0% contributes to the improvement of the compressive strength compared to that of plain concrete.

scholarly journals TENSILE, COMPRESSIVE AND FLEXURAL STRENGTH REDUCTION OF TIMBER IN FIRE

2009 ◽  
Vol 1 (3) ◽  
pp. 148-156 ◽  
Author(s):  
Zoja Bednarek ◽  
Mečislavas Griškevičius ◽  
Gintas Šaučiuvėnas
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Reduction Rate ◽  
Strength Reduction ◽  
Timber Structures ◽  
Static Tests ◽  
Reduction Coefficient ◽  
Temperature Ranges ◽  
In Fire ◽  
Linear Expression

The present research was dedicated to investigation into the strength of timber structures under fire conditions. Two kinds of timber specimens including oak and pine were used. The carried out investigation covered static tests on tensile strength, compressive strength along the grain, compressive strength perpendicular to the grain and flexural strength. The specimens were tested under the temperatures of 50°C, 100°C, 150°C, 200°C and 230°C. The obtained results show that pine specimens have better properties over the entire temperature range in case of tests on tensile and flexural strength. Also, as for these types of strength, oak specimens show a higher strength reduction rate than those of pine specimens, whereas oak specimens have better properties over the entire temperature ranges in case of compressive strength perpendicular to the grain. Based on statistical analysis, a linear expression of the strength reduction coefficient was proposed.

Dispersed Reinforcement Based on Natural Fibres Used in Cement Composites

2016 ◽  
Vol 722 ◽  
pp. 216-221
Author(s):  
Jitka Peterková ◽  
Martin Sedlmajer ◽  
Magdalena Kocianova
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Thermal Insulation ◽  
Considerable Effect ◽  
Fibre Reinforcement ◽  
Cement Composites ◽  
Cellulose Fibres ◽  
Natural Origin ◽  
Waste Cellulose

One of the options for improving the mechanical properties of cement composites is the use of fibre reinforcement. Nowadays, steel or polymer fibres are most frequently used for this purpose. However, given the increasingly stricter requirements related to environmental protection, one goal is to find ways of using alternative fibres of natural origin or waste fibres for which it is difficult to find other practical use. This paper focuses on one part of the development of materials which contain natural waste fibres as dispersed reinforcement in thermally insulating cement composites. The authors aimed to observe what influence the fibres have on the material’s final mechanical properties as well as thermal insulation properties. Another important factor, which was investigated, was the quotient of mechanical and thermal insulation properties. The results of this research showed that waste cellulose fibres have a considerable effect. The best compressive strength values were found in mixture M-2-BF which contained waste basalt fibres. The highest flexural strength values were reached by mixture M-3-CF-a containing cellulose fibres.

scholarly journals Engineering Properties of Hybrid Fibre Reinforced Ternary Blend Geopolymer Concrete

2021 ◽  
Vol 5 (8) ◽  
pp. 203
Author(s):  
V. Sathish Kumar ◽  
N. Ganesan ◽  
P. V. Indira
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Modulus Of Elasticity ◽  
Engineering Properties ◽  
Ternary Blend ◽  
Geopolymer Concrete ◽  
Polypropylene Fibres ◽  
Hybrid Form ◽  
Steel Fibres

The primary aim of this research is to find an alternative for Portland cement using inorganic geopolymers. This study investigated the effect of steel and polypropylene fibres hybridisation on ternary blend geopolymer concrete (TGPC) engineering properties using fly ash, ground granulated blast furnace slag (GGBS) and metakaolin as the source materials. The properties like compressive strength, splitting tensile strength, flexural strength and modulus of elasticity of ternary blend geopolymer concrete. The standard tests were conducted on TGPC with steel fibres, polypropylene fibres and a combination of steel and polypropylene fibres in hybrid form. A total number of 45 specimens were tested and compared to determine each property. The grade of concrete considered was M55. The variables studied were the volume fraction of fibres, viz. steel fibres (0%, 0.5% and 1%) and polypropylene fibres (0%, 0.1%, 0.15%, 0.2% and 0.25%). The experimental results reveal that the addition of fibres in a hybrid form enhances the mechanical properties of TGPC. The increase in the compressive strength was nominal, and a significant improvement was observed in splitting tensile strength, flexural strength, and modulus of elasticity. Also, an attempt to obtain the relation between the different engineering properties was made with different volume fractions of fibre.

scholarly journals Fresh and Hardened Properties of Hybrid Fibre Reinforced Self Consolidating Concrete Containing Basalt and Polypropylene Fibres

2019 ◽  
Vol 8 (2) ◽  
pp. 3356-3361 ◽  
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Research Paper ◽  
Pulse Velocity ◽  
Fresh Properties ◽  
Polypropylene Fibres ◽  
Self Consolidating Concrete ◽  
Complete Filling ◽  
Hybrid Fibre ◽  
Hardened Properties

Evidences as well as outcomes proved that the progress of self-consolidating concrete is comprehensive benchmark in the construction area. Due to its highly beneficial characteristics, self-consolidating concrete is eminently preferred and widely used all around the Globe. Self-consolidating concrete is that inventive concrete which does not need any assistance of vibration by any means in order for its placement and compaction. Its ability to flow under its self-weight allows complete filling formwork. Hence, successful results to attain full compaction, even in the existence of clogged reinforcement. Intension of this research paper is to put light on the fresh properties of hybrid fibre reinforced self-consolidating concrete (HFRSCC)such as T50cm, L-box, spread flow, V-funnel and properties of hardened like compressive strength, flexural strength and ultra-sonic pulse velocity at the period of 7 and 28 days. The properties of hardened HFRSCC is greatly improved by the process of addition of fibres.

scholarly journals Experimental Investigation of Using Recycled Plastic Aggregates in Concrete with OPC 53 Grade

2021 ◽  
Vol 9 (8) ◽  
pp. 2918-2925
Author(s):  
Chevvu Krishnaveni
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
High Performance ◽  
Coarse Aggregate ◽  
Concrete Strength ◽  
Partial Replacement ◽  
Plastic Pollution ◽  
Split Tensile Strength ◽  
Polypropylene Fibres ◽  
Waste Products

Abstract: Plastic pollution is one of the greatest causes of global warming. Disposal of large quantity of plastic waste products causes environmental & health issues .This report will discuss a solution to plastic pollution by conducting to recycle the plastic and reuse in concrete, so the waste plastic is recycled into plastic aggregates. This paper aims to enhance the concrete mechanical properties by replacement of natural coarse aggregate with recycled plastic aggregates and by adding polypropylene fibers in combination with high performance cement as a partial replacement of cement. This both combinations in concrete gave excellent values of compressive strength and tensile strength. Replacement of coarse aggregate weight by 5%, 10%, 15%, 20%, 25% of recycled plastics and for each replacement percentages polypropylene fibres of 0.5%, 1.0%, 1.5%, 2.0% with partial replacement of cement were conducted. In literature reported that the addition of recycled plastic causes the reduction of strength due to poor bonding between concrete and plastics, to overcome this problem the addition of polypropylene fibres which has a good bonding property will improve the concrete strength were added. Result shows that 15% replacement of natural aggregates with plastic aggregate achieves the maximum strength of concrete. Keywords: Re-cycled plastic aggregates, polypropylene fibres, high performance cement, compressive strength, split tensile strength.

Investigating Alternates to Flexural Beams for Airport Concrete Strength Compliance

2021 ◽  
Author(s):  
Greg White ◽  
Matthew Johnson
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Concrete Strength ◽  
Acceptance Testing ◽  
Rigid Pavement ◽  
Indirect Tensile ◽  
Curing Condition ◽  
Pavement Construction ◽  
Flexural Beam

Concrete for airport rigid pavement construction is generally specified to achieve a minimum characteristic flexural strength of 4.5 MPa and acceptance testing during construction aims to verify this key design assumption. The large flexural beam specimens are cumbersome and the testing is expensive. Consequently, industry desires a more convenient test and a laboratory-based conversion to an estimated flexural strength for acceptance testing during production. This research developed and trialed a protocol for the conversion of indirect tensile strength and compressive strength to estimate the flexural strength. The laboratory correlation was encouraging. However, when trialed on a real construction project, the conversions significantly underestimated the measured flexural strength and the risk of rejecting compliant batches of concrete was significantly higher. Further research is required to understand why the reliable conversions developed in the laboratory failed in the field. This may be related to the effect of ambient temperature on 28 day flexural strength, despite the constant curing condition.

Study on Ultra-Strength Mortar Prepared with Mineral Admixture

2011 ◽  
Vol 675-677 ◽  
pp. 1073-1076
Author(s):  
Zu Quan Jin ◽  
Peng Zhang ◽  
Tie Jun Zhao ◽  
Bao Rong Hou
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Flexural Strength ◽  
Pore Structure ◽  
Silica Fume ◽  
Mineral Admixture ◽  
Replacement Rate ◽  
River Sand ◽  
Optimum Proportion ◽  
Curing Age

In this paper, preparation, property study of ultra-strength mortars with mineral admixture and clear river sand was carried out. The mineral admixture include fly ash, ultra-fine GGBS and silica fume. The experimental results show that the compressive strength of mortar improves with increasing amount of silica fume or ultra-fine GGBS. When the content of silica fume or ultra-fine GGBS is 30~35%, the compressive strength and flexural strength of mortar in curing age of 7 days are 100 MPa and 20MPa, respectively. But strength of mortar decreases with the increase replacement rate of fly ash. When the mortar mixes with combined of silica fume and ultra-fine GGBS, the optimum proportion of siliaca fume to ultra-fine GGBS is 2:3. And the compressive strength of mortar in curing age of 7 days is 75~100MPa when the mixed mineral admixture is 40~60%. The compressive strength of mortar is about 90MPa as it mix 60% of cement, 15% of silica fume, 15% of GGBS and 10% of fly ash. Moreover, the ultra strength mortar refines its pore structure and its capiliary pore (≥100nm) amount reduces by 78% compared to ordinary mortar.

Mechanical Characteristics of Concrete Exposed to External Flexural Load, De-Icing Salt and Freeze-Thaw Cycles

2011 ◽  
Vol 250-253 ◽  
pp. 33-39
Author(s):  
Xiao Lu Yuan ◽  
Bei Xing Li ◽  
Shang Chuan Zhao ◽  
Shi Hua Zhou
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Flexural Strength ◽  
Ordinary Portland Cement ◽  
Mechanical Characteristics ◽  
Concrete Strength ◽  
Mineral Admixtures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Freeze Thaw

This paper investigates mechanical characteristics of concrete exposed to external flexural load, de-icing salt and freeze-thaw cycles. Concrete specimens made with ordinary Portland cement or ordinary Portland cement incorporating fly ash with the replacement of 10% or 20%, or 0.7/10000 air-entraining agent and 20% fly ash, or ground blast furnace slag with the replacement of 15% or 30%, were made and exposed to flexural load, freeze-thaw and de-icing salt environment. Mechanical properties of concrete including compressive strength and flexural strength were measured. Phase composition of samples was determined by means of x-ray diffraction (XRD). Results indicate that increasing flexural stress ratios reduced compressive strength and flexural strength of concrete, and presented higher improvement of mineral admixtures in concrete strength. Incorporation of mineral admixtures and air-entraining agent decreased the loss of concrete strength. X-ray diffraction analysis showed the presence of abundant calcium chloroaluminate and ettringite in paste samples.

scholarly journals Strength Characteristics of Cement-Rice Husk Ash Stabilised Sand-Clay Mixture Reinforced with Polypropylene Fibers

2018 ◽  
Vol 13 (4) ◽  
pp. 447-474 ◽  
Author(s):  
Ali Ghorbani ◽  
Maysam Salimzadehshooiili ◽  
Jurgis Medzvieckas ◽  
Romualdas Kliukas
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Rice Husk ◽  
Unconfined Compressive Strength ◽  
Rice Husk Ash ◽  
Indirect Tensile Strength ◽  
Polypropylene Fibres ◽  
Indirect Tensile ◽  
Improvement Index

In this paper, stress-strain behaviour of sand-clay mixture stabilised with different cement and rice husk ash percentages, and reinforced with different polypropylene fibre lengths are evaluated. Mixtures are widely used in road construction for soil stabilisation. It is observed that replacing half of the cement percentage (in high cement contents) with rice husk ash will result in a higher unconfined compressive strength. In addition, the presence of 6 mm polypropylene fibres will help to increase the unconfined compressive strength of stabilised samples, while larger fibres cause reverse behaviour. In addition, introducing a new index for assessing the effect of curing days. Curing Improvement Index it is obtained that larger fibres show higher Curing Improvement Index values. Results gained for the effects of curing days, and fibre lengths are further discussed and interpreted using Scanning Electron Microscopy photos. Based on the conducted Unconfined Compressive Strength, Indirect Tensile Strength, and Flexural Strength tests and using evolutionary polynomial regression modelling, some simple relations for prediction of unconfined compressive strength, indirect tensile strength, and flexural strength of cement-rice husk ash stabilised, and fibre reinforced samples are presented. High coefficients of determination of developed equations with experimental data show the accuracy of proposed relationships. Moreover, using a sensitivity analysis based on Cosine Amplitude Method, cement percentage and the length of polypropylene fibres used to reinforce the stabilised samples are respectively reported as the most and the least effective parameters on the unconfined compressive strength of specimens.

Sign in / Sign up

Export Citation Format

Share Document