Properties and performance of high strength fibre reinforced concrete by using steel and polypropylene fibres

Many reinforced concrete structures suffer severe degradation due to the effect from freezing and thawing, shrinkage and expansion, aggressive environment, earthquake and drastic increase of live loads. The most common sign of deterioration in concrete is cracking. Plain or unreinforced concrete is characterised by its low tensile strength, low strain capacities and brittle in nature. The tensile strength of plain concrete is considered lost once cracking occurred. Discrete short fibre reinforcement is being considered to be used for structural applications since it can reduce cracking phenomena, improve ductility and failure mode, and to some extent improve the durability of reinforced concrete. Fibre added in concrete has also been found to be effective in controlling cracks due to plastic and drying shrinkage. Shrinkage in concrete is greatly influenced by the surrounding environment and types of fibre included. Therefore, the aim of this research is to investigate the engineering and shrinkage properties of reinforced concrete containing a combination of steel and polypropylene fibres under different exposure conditions. In this study, the physical and engineering properties of fibre reinforced concrete (FRC) are investigated by using steel fibre (SF) type hooked end and polypropylene fibre (PPF) type virgin fibrillated. The objectives of the study are to assess the effect of hybrid fibres on its engineering properties, shrinkage properties under the influence of tropical climate and finally the structural performance of the FRC beams. Laboratory testing program is first conducted to determine the physical properties of the fibres. Then, the fibre reinforced concrete were tested to determine the engineering properties include compressive strength, tensile splitting strength, flexural strength, toughness, Modulus of Elasticity and shrinkage. The desired optimum mix is evaluated by the volume fractions (Vf) of 0.5%, 1.0% and 1.5%., and the combination of SF 100% + PPF 0%, SF 75% + PPF 25%, SF 50% + PPF 50%, SF 25% + PPF 75%, SF 0% + PPF 100%. The engineering properties and structural performance are then determined based on the optimum percentage using high strength concrete grade C60 to simulate concrete strength of sample manufactured at the factory. Test on the efficiency of fibres in limiting the shrinkage deformation for indoor and outdoor exposure are performed. The results indicated that the best combination of fibres is for concrete containing SF 75% + PPF 25%. The combination of SF and PPF fibres in concrete is able to enhance the engineering properties and controlling the growth of cracks in concrete. The results also indicated that concrete with both SF and PPF produced higher tensile and flexural strengths as compared with the control by 77% and 170%, respectively. The variation in relative humidity and temperature was found to have small effect on the drying shrinkage of the FRC. Results for the FRC beam test show that the percentage proportion of SF 75% + PPF 25% give the best flexural performance compared to other beams. Thus, the use of hybrid fibres, SF 75% + PPF 25%, was found to enhance the performance of either plain concrete or reinforced concrete

Effectiveness of different curing media in self-healing process monitored by compressive strength and water absorption of cement mortar

The root cause of the majority of structural failure is attributed to cracking, there is a compelling economic incentive to develop concrete that can treat and repair the damage by itself. Even though some research has been carried out in this area a breakthrough in method to supply nutrient for effective healing are yet to materialise. For the present study, Bacillus sphaericus with diatomaceous earth as a protective vehicle was selected to determine the best performance with different curing media as an alternative method to supply a nutrient. For the growth of the bacterial, the nutrients are supplied using three different curing media which is deposition medium (controlled nutrients), runoff water (uncontrolled nutrients) and also distilled water. The performance of Bio-based cement mortar (BBCM) was evaluated by comparing the influence on compressive strength and water absorption subjected to different curing media. BBCM cured in run-off water had the best compressive strength with increment of 39.04% compared to others curing media. Also, with its great dispersal characteristics, denser BBCM with a reduction of water absorption. BBCM cured in run-off water had a 40% improvement in strength compared to normal curing. As a conclusion, run-off water is highly promising in supplying sufficient nutrients to bacteria for the biomineralization process to pro- duce CaCO3. This work also aims to apply this approach in the field especially in sewerage and drainage system

Mechanical and shrinkage properties of hybrid steel and polypropylene fibre reinforced concrete composite

An experimental study had been carried out to investigate the mechanical properties, expansion and shrinkage of fibre reinforced concrete composite (FRC). However, instead of using single type fibre of either steel (SF) or polypropylene (PPF), this study also combined the two types in one mix.The mechanical properties investigated in this study include compressive strength, splitting tensile strength and flexural strength. Three different FRC mix proportions and one normal concrete (control) were casted which includes (a) 75% SF, (b) 75% SF + 25% PPF, (c) 25% PPF, and (d) 0% fibre for control (PC). Meanwhile, the volume fraction, Vf for the FRC was fixed at 1.5% and the concrete strength was designed to achieve grade C60 at 28 days. The results show that the use of fibres in concrete decreased the workability of concrete. In addition, concrete mix with both SF and PPF produced the highest splitting tensile and flexural strengths by an increase of 75.9% and 86.5%, respectively as compared with the control. Furthermore, expansion and shrinkage of FRC was found to be less than the control. It can be concluded that the combined SF and PPF in concrete gives the most appropriate combination as regards to the highest flexural and splitting tensile strengths, and also reduced the shrinkage strain

Flexural behaviour of reinforced concrete beams with discrete steel - Polypropylene fibres

This paper discusses the experimental results on the flexural test of concrete containing different proportions of steel fibre (SF) and polypropylene fibre (PPF). The flexural test was carried out under 4-point bending load and followed the relevant standards to FRC. Hooked-end deformed SF fibre with 60 mm length and fibrillated virgin PPF fibre with 19 mm length were used in this study. Meanwhile, the concrete was designed for high strength concrete of C60. The mixture included both single SF and PPF, and also the combination of both fibres; Control beam (PC), beam with 75%SF, beam with 75%SF + 25%PPF and beam with 25%PPF. The total fibre volume fraction (Vf) was fixed at 1.5%. The experimental results show that the percentage proportion of combined SF-PPF at 75-25% had the best performance for its flexural capacity. Mixture with single PPF was also found not effective in delaying the onset of tension cracks and to increase the tensile strength of the concrete. Experimental result also shows beam with 75%SF +25%PPF had their structural stiffness improved the most as compared with the others. For the compressive strength, beam with 75%SF + 25%PPF also revealed comparable performance with the control for high strength composite concrete

Soil reinforcement with synthetic and natural fibres: a review

Problematic soil is a common issue in construction activities, particularly when dealing with peat and clay soils of poor geotechnical properties. Such soils are non-homogeneous, and their properties vary greatly from place to place or, in some cases, even at one place. The growing development demand and insufficient suitable ground have forced the development to use problematic soil. It is therefore important that the soil properties are improved so that any construction thereon is stable and safe. Soil improvement methods are of several different kinds and ways, but the reinforcement of fibre-based approaches have recently gained increasing interest in the field of geotechnical engineering. This technique is currently used in six main areas worldwide, including pavement, road and railway embankment, foundation, slope, and bridge. The main focus of this paper is to examine the feasibility, potential and efficacy of different types of natural and/or synthetic fibres in soil reinforcement by critically reviewing past researches. The pros and cons of natural versus synthetic fibres will also be discussed

Soil reinforcement with synthetic and natural fibres: a review

Problematic soil is a common issue in construction activities, particularly when dealing with peat and clay soils of poor geotechnical properties. Such soils are non-homogeneous, and their properties vary greatly from place to place or, in some cases, even at one place. The growing development demand and insufficient suitable ground have forced the development to use problematic soil. It is therefore important that the soil properties are improved so that any construction thereon is stable and safe. Soil improvement methods are of several different kinds and ways, but the reinforcement of fibre-based approaches have recently gained increasing interest in the field of geotechnical engineering. This technique is currently used in six main areas worldwide, including pavement, road and railway embankment, foundation, slope, and bridge. The main focus of this paper is to examine the feasibility, potential and efficacy of different types of natural and/or synthetic fibres in soil reinforcement by critically reviewing past researches. The pros and cons of natural versus synthetic fibres will also be discussed

The study on used of tropical wood sawdust as a replacement fine aggregates in concrete mix

The amount of wastage produced in the construction industry is increases. The revolution making alterations to conventional concrete had been introduced. Industrial wastage such as fly ash, sawdust, and sludge are often used to replace material in the concrete mix, by that, the value of sustainability increase. Reusing waste materials can reduce renewable and non-renewable resources such as sand and water. This study emphasis the mechanical properties of the lightweight concrete regarding the replacement of material, sawdust into the concrete mix by 0% (control sample), 10%, 20% and 40% for grade 30 N/mm2. The objectives for this study are to determine the mechanical behavior of concrete mix with partial replacement of recycled fine aggregates, to determine the concrete properties consolidating recycled tropical wood sawdust, and to identify the optimum percentage partial replacement of recycled tropical wood sawdust in the concrete mix. For fresh concrete, slump test were performed to determine the workability of the concrete while for hardened concrete tests were compressive strength test, water absorption test and density test. The tests were carried out at the age of 7 days and 28 days. The result shown that 10% of sawdust replacement in the concrete mix recorded the highest amount of compressive strength, lowest water absorption and highest density compared to the control sample

Concrete brick properties incorporating EPS and POFA as replacement materials

The implementation of sustainable construction and green building becomes the main attention of construction industries in Malaysia as it has been introduced by the government in the Construction Industry Transformation Programme (2016-2020). Therefore, this study focuses on the development of sustainable concrete bricks containing Expanded Polystyrene (EPS) and Palm Oil Fuel Ash (POFA) as sand and cement substitute materials. The percentage of replacement is 20%, 30%, 40% and 50% for EPS and 5%, 10%, 15%, 20% and 25% for POFA. There are 30 different mix designs of brick have been produced and their properties have been identified. Hardened brick density, compressive strength, water absorption and initial rate of absorption are the brick properties identified in this study. Based on the experimental results, it was found that the hardened brick density and compressive strength of the brick decreased as the replacement percentage increased. On the other hand, the water absorption and initial rate of absorption of the brick decreased as the percentage of EPS increased and increased as the percentage of POFA increased. Based on the findings, it shows that EPS and POFA has significantly contributes to the reduction of brick density. Next, for the compressive strength all the bricks have satisfied the minimum strength requirement of non-load bearing brick. Finally, for water absorption and initial rate of absorption, it has been found that majority of the bricks have an acceptable value based on standard requirements for brick. This can be concluded that EPS and POFA could be potential substitute materials for the manufacture of sustainable bricks

A simulation model of reinforced concrete beam containing expanded polystyrene beads (EPS) and palm oil fueled ash (POFA) using finite element method

In this study, Expanded Polystyrene bead (EPS) and Palm Oil Fuelled Ash (POFA) will be used to replace several percents of cement and aggregate in reinforced concrete beam construction. EPS can produce lightweight concrete, and the use of POFA can produce high strength concrete and can also reduce waste disposal. The reinforced concrete beams were analysed using computer software called ABAQUS. The main reason Abaqus software is used as analytics software for this project is that the software is designed specifically for analyzing advanced structural and heat transfer. It is designed for both linear and nonlinear pressure analyses for both tiny and huge structures. This software can also be used to analyze the proposed reinforced concrete beam failure pattern of EPS and POFA. The percentage of EPS and POFA were 40% to 60% in concrete as replacement material. The information obtained from Abaqus is then used to verify the experimental results. The data also contains the appropriate percentage of EPS and POFA in the reinforced concrete beam where performance in terms of bending, pressure, and failure pattern is at maximum. The result shows decrease performance of RC beam containing 40-60% EPS and POFA

Flexural behaviour of reinforced concrete beams with discrete steel – polypropylene fibres

This paper discusses the experimental results on the flexural test of concrete containing different proportions of steel fibre (SF) and polypropylene fibre (PPF). The flexural test was carried out under 4-point bending load and followed the relevant standards to FRC. Hooked-end deformed SF fibre with 60 mm length and fibrillated virgin PPF fibre with 19 mm length were used in this study. Meanwhile, the concrete was designed for high strength concrete of C60. The mixture included both single SF and PPF, and also the combination of both fibres; Control beam (PC), beam with 75%SF, beam with 75%SF + 25%PPF and beam with 25%PPF. The total fibre volume fraction (Vf) was fixed at 1.5%. The experimental results show that the percentage proportion of combined SF-PPF at 75-25% had the best performance for its flexural capacity. Mixture with single PPF was also found not effective in delaying the onset of tension cracks and to increase the tensile strength of the concrete. Experimental result also shows beam with 75%SF +25%PPF had their structural stiffness improved the most as compared with the others. For the compressive strength, beam with 75%SF + 25%PPF also revealed comparable performance with the control for high strength composite concrete