Fibre Reinforced Geopolymer Concrete Research Articles

Physical & mechanical properties of fiber reinforced metakaolin-based geopolymer concrete

Research on fiber reinforced Geopolymer Concrete (GPC), as a novel type of GPC with enhanced ductility characteristics has gained interest. In this paper, mechanical and physical properties of GPC reinforced with different fiber types (Polypropylene or PP, 2-part PP, 4-part polyolefin) and volume content (0.15, 0.2 and 0.25%) is investigated. Initially, an experimental campaign on the various effective parameters of metakaolin-based GPC is performed to find the optimal mix design. The results displayed the beneficial influence of fibers in improving compressive, tensile and flexural strengths, reduction of specific density and water absorption, and negligible effect on resistance to elevated temperatures.

Behaviour of GGBS-dolomite geopolymer concrete beam-column joints under monotonic loading

Geopolymer concrete (GPC) is a cementless concrete in which polymerization gives strength to concrete. In this present study, geopolymer concrete was developed from Ground Granulated Blast furnace Slag (GGBS) and dolomite. The behaviour of GGBS-dolomite geopolymer concrete was found to be brittle in nature. Experimental investigations were conducted to evaluate the effect of the addition of steel fibres to GGBS-Dolomite geopolymer concrete. Improved engineering properties were observed for steel fibre reinforced geopolymer concrete. The performance of beam-column joints was monitored with the addition of 0.25, 0.5 and 0.75% steel fibres by volume of concrete under monotonic loading. Parameters such as ultimate load, energy absorption capacity, ductility index and crack behaviour of steel fibre reinforced geopolymer concrete were compared with geopolymer concrete (without steel fibres). Higher ductile behaviour, energy absorption and toughness were observed along with the addition of steel fibres. The Performance of beam-column joints was evaluated by finite element method and compared with experimental results. Parametric studies were done by numerical methods and concluded that the GGBS-dolomite GPC beam-column joint has an improved load carrying capacity when compared to cement concrete beam-column joints with ductile detailing as per IS-13920 2016.

Steel fibre reinforced alkali-activated geopolymer concrete slabs subjected to natural gas explosion in buried utility tunnel

Accidental gas explosions in the buried utility tunnels around the world have caused massive losses in economy and human lives. The buried utility tunnel with adequate blast resistance capacity is therefore required to withstand the possible accidental gas explosions. In this study, a novel construction material, alkali-activated steel fibre reinforced geopolymer composite is introduced and the blast resistance capacity of slabs made of this material is studied in a full-scale buried utility tunnel. Fly ash and S95 grade ground granulated blast-furnace slag powder (GGBS) were used as the major binders in this geopolymer concrete. The plain geopolymer concrete had a compressive strength of 61 MPa and the steel fibre reinforced geopolymer concrete had a compressive strength of 74 MPa. The elastic modulus of the plain geopolymer concrete was found to be lower than the conventional C30 concrete. The methane gas explosion test was conducted in a full-scale (12 m × 1.8 m × 0.6 m) tunnel segment to investigate the structural performance of selected slab specimen (1.8 m × 0.4 m × 0.09 m). The test results and numerical simulations of structural responses subjected to methane gas explosion are presented. The results indicate the fibre reinforced geopolymer concrete slab has good capacity to resist methane gas explosion load.

Seawater Exposure Effect on Fly Ash based Geopolymer Concrete with Inclusion of Steel Fiber

Concrete is widely used in construction offshore such as concrete floating bridges and sea tank. This research is providing an alternative construction material to replace ordinary Portland cement (OPC) concrete known as geopolymer. The geopolymer concrete was produced by mixing fly ash with alkaline activator and 3% of steel fibre in order to improve the properties of fiber reinforced geopolymer concrete (FRGPC). The effects of aging period in term of strength, changes in weight and carbonation of FRGPC in seawater is investigated and compared with the fiber reinforced concrete (FROPC). The compressive strength obtained for FRGPC were higher than FROPC. The highest compressive strength obtained by FRGPC is 76.87 MPa at 28 days and 45.63 MPa at 28 days for FROPC concrete. The compressive strength was decreased as the period of immersing the concrete in seawater is increased. During the immersion process of both samples in seawater up to 120 days, the carbonation was not detected even though with the existence of steel fibres.

Laboratory investigation on the synthesis and mechanical characterization of fiber reinforced geopolymer concrete

Geopolymer concrete was invented as an eco-friendly alternative of conventional concrete. The work reported in this paper is based on laboratory investigation on geopolymer concrete synthesized using locally available materials. The Class F – fly ash was used in the synthesis along with a mix of 25 mm long crimped steel and 12 mm long glass fibers as hybrid fibers. A total of 24 mix designs were investigated to obtain an optimal constituent mixes corresponding to high mechanical strength. In order to study the effect of molarity of alkaline solution on the fresh and hardened geopolymer concrete; Compressive Strength, indirect tensile and flexural strength tests were conducted on the mixes. The maximum compressive strength was explored by varying concentration of NaOH, ratio of alkaline solution to fly ash and ratio of Na2SiO3 to NaOH solution. The hybrid fiber (0.15% glass and 0.85% steel fiber) gives the maximum mechanical strength at 1% by volume. The observed strength of geopolymer concrete without and with fiber was found to be equivalent to M40 and M50 conventional cement concrete.

Effect of Combination of Alumina-Silica Rich Minerals with Fly Ash on Structural Behaviour of the Basalt Fibre Reinforced Geopolymer Concrete

Cement production is one of the major C02 emitter which contributes around 8% of the world’s carbon dioxide emissions. So the Engineers are in the need of developing alternate material for cement to reduce the effect of vulnerable climatic changes in the world. This paper aims at presenting the experimental study on effect of combination of silica rich minerals with fly ash based geopolymer concrete. Fly ash was found to be successful in enhancing the performance of geopolymer concrete. The Utilization of more industrial wastes will promisingly contribute for reducing the environmental pollution. To determine the effective admixture combination with fly ash in geopolymer concrete, industrial wastes such as silica fume, GGBS, Metakaolin, palm oil fly ash were used. The concrete mixes were designed with 60 percentile of fly ash and 40 percentile of other industrial wastes to replace the cement in Geopolymer concrete. The Concrete specimens were casted and cured at different conditions namely Oven curing, Steam curing and sunlight. The Compressive, tensile and flexural strength behaviors were determined for the designed concrete mixes and the results were presented.

Effect of Polypropylene fibers over GGBS based Geopolymer Concrete Under Ambient Curing

Geopolymer is being widely used in the construction industry in the recent years. Ground Granulated Blast Furnace Slag (GGBS) based geopolymer concrete is the most suited for ambient curing conditions. It has been perceived that geopolymer concrete is brittle in nature. This brittleness could be reduced by the augmentation of fibers. The objective of this paper is to study the effect of incorporation of polypropylene fibers in Geopolymer Concrete. The various proportions of the ingredients of Geopolymer concrete were calculated from the B.V.Rangan mix design of Geopolymer Concrete. Based on the previous research works conducted by the author, optimum molarity of the sodium hydroxide solution to be used as a part of alkaline activator solution was taken as 13M. Polypropylene fibers were added to the matrix in the ratios from 0.1% to 0.6%. Cubical, Cylindrical and Prism Specimens were casted and subjected to ambient curing. Compaction factor test was performed to measure workability of fresh concrete and tests such as compressive strength test, split tensile strength test and flexural strength test were performed to assess the mechanical properties of hardened Fiber Reinforced Geopolymer Concrete. Tests were carried after curing period of 7days & 28 days and the results were tabulated. Being a low modulus fiber, the fiberposses a good post cracking behaviour and reduce the brittleness of the Geopolymer Concrete. The incorporation of polypropylene fibers increases the compressive strength and flexural strength initially and then decreases.

The Effect of Alkaline Solution of Varying Molarity and Hookedend Steel Fibres on Split Tensile Strength(SPTS)(fct) of Fibre Reinforced Geopolymer Concrete(FRGPC)

This article mainly aims the study the effect of alkaline solution of varying molarity [1]” and the percentage of volume fraction of steel fibres[2]” of 0%, 0.5%, 0.7%, 0.9% and 1.1% (R0, R5, R7, R9 and R11),different ratios of GGBS to Flyash on Split Tensile Strength of GPC is studied. The combination of Sodium Hydraxide (NaoH) of different molarity (8M,10M and 12M) and Sodium Silicate (Na2Sio3) used are alkaline activators. The Modified Binder Index(Bmi) [3]” is introduced to express the effect of Binder Index(Bi) [4]” and hooked end Steel Fibre Effect on Split Tensile Strength (fct) of SFRGPC. In the experimental program total 180 cylinders of its size 100mm dia and 200mm length for each variation were cast and tested after 7days and 28days of ambient curing for average strength. The effect of Molarity, GGBS to Flyash ratio and Steel Fibres on the SPTS (fct) of SFRGPC is presented in this paper.

Behaviour of Fiber Reinforced Geopolymer Concrete

This paper presents the behavior of geopolymer concrete with small and big fibers. The aluminosilicate materials used for geopolymer concrete are fly ash and GGBS. For this study standard cube, cylinder and beam specimens are casted and tested to investigate compressive, split tensile and flexural strengths. The experimental results shows that incorporation of steel fibers for the geopolymer mixes improve the strength properties. Few models are generated to estimate the strengths with alliance of cube compressive strength.

Strength and Structural Properties of Geopolymer Concrete with Natural Fibers -A Review

As the infrastructure development growing worldwide, the demand for ordinary Portland cement (OPC) increases exponentially. Studies revealed that the production of one ton cement releases one ton of CO2 to the atmosphere due to the calcinations of lime stone and combustion of fossil oil. The production of cement is highly energy intensive and it consumes a substantial amount of natural resources. Davidovits (1978) proposed that binders can be produced by polymeric reaction of alkaline liquid with alumino-silicate materials such as fly ash, blast furnace slag, rice husk etc., Geopolymer also has the ability to form a strong chemical bond with rock based aggregates. Fiber reinforced geopolymer concrete is relatively a new composite material in which fibers are introduced in the matrix as micro reinforced to improve the strength properties. This paper presents a new review on various research works done in the area of geopolymer concrete and the effect of fiber on their mechanical properties.

Creep and shrinkage of synthetic fibre-reinforced geopolymer concrete

This paper presents the results of an investigation on the use of synthetic polypropylene (PP) and polyolefin (PO) fibres to improve the creep and shrinkage performance of low-calcium fly ash-based geopolymer concrete. Three PP fibres of 18, 19 and 51 mm length and two PO fibres of 48 and 55 mm length with a volume fraction of 0·5% were added to geopolymer concrete. The mechanical properties of the resulting material, such as compressive and splitting tensile strength, modulus of elasticity and modulus of rupture, have been studied. The drying shrinkage and creep of plain and fibre-reinforced geopolymer concrete were examined for a period of 1 year. The results revealed that the inclusion of PP and PO fibres in a volume fraction of 0·5% decreased the drying shrinkage and increased the compressive creep of fly ash-based geopolymer concrete at both early ages and in the long term.

Experimental Study on the Behaviour of Hybrid Fiber Reinforced Geopolymer Concrete under Ambient Curing Condition

Recent studies have shown that Geopolymer concrete is one of the emerging building materials worldwide. Various studies have been conducted on the Geopolymer concrete and the engineering properties of the material have been improved drastically. Geopolymer concrete is found to be comparatively brittle than the ordinary conventional concrete. To counteract this effect fibers are incorporated in to the Geopolymer concrete. In this research work, glass fibers and polypropylene fibers are added to the Geopolymer concrete in various proportions and its influence was studied over the fresh and hardened properties of concrete such as workability, compressive strength, split tensile strength, flexural strength and ductility factor. The Geopolymer concrete in this study is GGBS based as it involves ambient curing. The various materials were proportioned based on the Rangans mix design. Fair results have been obtained in the study and it was found that the brittleness could be controlled in the Geopolymer concrete by appropriate proportioning of fiber.

Pull-Out Strength of Hooked Steel Fiber Reinforced Geopolymer Concrete

Pull-out strength of fly ash steel fiber reinforced geopolymer concrete was studied. Fly ash steel fiber reinforced geopolymer concrete was produced by mixing of Class F fly ash which taken from Manjung power station, Lumut, Perak, Malaysia with alkaline activator which are combination of sodium hydroxide and sodium silicate. Steel wool fiber were added into the geopolymer concrete as reinforcement with different weight percentage vary from 0 % - 5 %. Chemical compositions of Malaysian fly ash was first analyzed by using X-ray fluorescence. All geopolymer concrete samples with inclusion of hooked steel fiber with different volume percentage which are 0 %, 0.5 %, 1.0 %, 1.5 %, and 2.0 % were tested in terms of microstructure, flexural strength, flexural toughness, and pull-out strength. Microstructure of steel fiber reinforced geopolymer concrete shows a good degree of bonding between geopolymer binder and hooked steel fibers. Flexural strength of samples increased with the addition of hooked steel fibers until at 3 % and will slightly decrease when amount of fibers addition over than 3 %. Meanwhile, addition of hooked steel fibers shows significantly improvement to the toughness of samples. However, there is no improvement of toughness with addition of fibers over than 3 %. Pull-out strength of samples shows an excellent result where maximum result of 505 N can be achieved that indicates a good degree of bonding between geopolymer matrix and fibers.

Experimental study on early strength of polymer concrete reinforced by basalt fiber content and age

In order to study the modification effect of basalt fiber in the address polymer concrete, three groups of basalt fiber reinforced geopolymer concrete (BFRGC) with volume content of 0.1%, 0.2% and 0.3% respectively were selected, for its early mechanical properties test. The test adopts HYY series hydraulic servo test system, and the test piece is tested for quasi-static mechanical properties by standard curing to 3 d, 7 d, and 28 d. The test results show that the addition of basalt fiber in the enhanced geologic concrete can effectively improve its early quasi-static mechanical properties. The early compressive strength, flexural strength and tensile strength of basalt fiber reinforced geopolymer concrete were greatly improved, and the degree of improvement was positively correlated with the curing time of the test piece, which was 1.67 times higher than that of 3.3 d for 7 d and 28 d. For each strength, the compressive strength is the most improved, the tensile strength is the smallest, and the flexural strength is moderate. At the same time, in the concrete with the basalt fiber, the addition of the enhanced geopolymer can further improve the concrete mechanics. Performance, and the optimal blend of basalt fiber is 0.1%.

Experimental study on the effect of matrix on the flexural behavior of beams reinforced with Glass Fiber Reinforced Polymer (GFRP) bars

This experimental work presents results on the effect of different concrete types on the flexural behavior and deflection of beams reinforced with Glass Fiber Reinforced Polymer (GFRP) bars. Four different types of concretes namely; ordinary Portland concrete (OPCC), fiber reinforced concrete (FRC), geopolymer concrete (GPC), and fiber reinforced geopolymer concrete (FRGC) were used. A total of eight beams were subjected to four-point static bending tests. The parameters studied were load capacities, deflection, and strain development in concrete and rebars, while cracking patterns and failure modes were also observed. All tested beams exhibit comparable flexural and deflection characteristics. The results indicate that GPC and FRGC beams were more effective for a GFRP reinforced system than ordinary concrete. The ACI 440-R1-06 equations gave conservative estimates for both the flexural capacity and the deflection of the members and therefore may be used irrespective of the concrete type. Finally, results from flexural capacities normalized for concrete strength, cross-section and reinforcement ratio of GFRP (ρf/ρb) indicate that increase in the ρf/ρb ratio does not proportionally increase the flexural strength of the beams.

Effect of cooling on the residual mechanical properties and cracking of plain and fibrous geopolymer concretes at elevated temperatures

AbstractThis paper presents the effects of various cooling methods on residual mechanical properties of geopolymer concrete and fiber reinforced geopolymer concretes (FRGC) after exposure to 200, 400, 600, and 800°C temperatures. Three types of cooling methods are considered namely, ambient air cooling, water spray cooling and rapid water cooling. Results show that irrespective of cooling methods, the compressive strength of geopolymer concrete decreases significantly after exposure to 400, 600, and 800°C temperatures compared to 200°C where only 10–15% reduction is observed. Among the three cooling methods, the compressive strength loss is slightly higher in rapid cooling and water spray cooling than the ambient air cooling at 400 to 800°C. However, at 200°C that loss is about 20–25%. In the case of indirect tensile strength, however, at 200°C no reduction in strength is observed due to rapid cooling and water spray cooling compared to ambient air cooling. Significant reduction in indirect tensile strength is observed in those two cooling methods at 400, 600, and 800°C. Strong correlations between indirect tensile strength and compressive strength of geopolymer concretes at all cooling methods are also observed. Rapid cooling and water spray cooling methods do not cause any significant cracking in geopolymer concretes at 200 and 400°C, followed by minor and significant cracking at 600 and 800°C, respectively. However, at 800°C the rapid cooling caused more cracking than those two cooling methods. Rapid cooling also showed higher reduction in compressive strength than ambient air cooling in both steel fiber reinforced geopolymer concrete (steel‐FRGC) and polyvinyl alcohol fiber reinforced geopolymer concrete (PVA‐FRGC) after exposure to 400 and 600°C temperatures. PVA‐FRGC exhibited more brittle failure behavior in compression than steel‐FRGC irrespective of cooling methods. The existing Eurocode overestimates the residual compressive and indirect tensile strengths of geopolymer concrete at 400 and 600°C temperatures compared to other temperatures. The same is also true in PVA‐FRGC. However, in steel‐FRGC the Eurocode 4 overestimates at 400°C but underestimates at 600 and 800°C.

Flexural performance of reinforced concrete beams strengthened with fibre reinforced geopolymer concrete under accelerated corrosion

The use of additional Reinforced Concrete (RC) layers or jackets is one of the most commonly used techniques for the strengthening of existing structural elements. A crucial parameter for these applications is the durability and the corrosion resistance of the RC layers. However, to date there are not any published studies on the use of novel cementitious materials for the improvement of the durability of the strengthened elements. In this study, a novel strengthening technique is proposed using additional high performance Fibre Reinforced Geopolymer Concrete (FRGC) layers and jackets reinforced with steel bars. The main goal of this technique is the improvement of the structural performance of the existing elements and at the same time the improvement of the durability and corrosion resistance of the strengthening layers. RC beams strengthened with reinforced FRGC layers were examined under standard and accelerated corrosion conditions. Accelerated corrosion tests were performed using the induced current technique followed by flexural tests. The results indicate superior performance for beams strengthened with FRGC and improved performance of the interface between the additional layer and the initial RC beam.

English

English

Comparative Study of Strength of Fibre Reinforced Geo polymer Concrete and Conventional OPC Concrete

Comparative Study of Strength of Fibre Reinforced Geo polymer Concrete and Conventional OPC Concrete

Mechanical and flexural performance of synthetic fibre reinforced geopolymer concrete

A comprehensive experimental program was undertaken to analyse the structural and material characteristics of synthetic fibre reinforced geopolymer concrete. This study focused on the effect of monofilament and fibrillated polypropylene fibres and monofilament structural polyolefin fibres on mechanical and flexural performance of fly ash based geopolymer concrete. Five types of synthetic fibres at a 0.5% volume fraction were added to geopolymer concretes. The specimens’ compressive strength, indirect tensile strength, modulus of elasticity, modulus of rupture, flexural toughness and fracture energy were determined. Where possible, comparative analyses where conducted to assess the performance of fibre reinforced geopolymer concrete against conventional Portland cement based systems. The flexural toughness parameters were obtained using procedure laid down in ASTM C1018, JCI-SF4 and ASTM C1609. The results indicated that the macro polyolefin fibres exhibited the largest fracture energy which is likely due to high mechanical bonding and low fibre aspect ratio. Relationships are established to predict the compressive and tensile strengths, modulus of elasticity, compressive stress–strain curve and relation between the deflection and CMOD of synthetic fibre reinforced geopolymer concrete.