Tensile Strength Of Geopolymer Concrete Research Articles

Effect of GBFS ratio and recycled steel tire wire on the mechanical and microstructural properties of geopolymer concrete under ambient and oven curing conditions

In this study, the effects of waste steel wire ratios, granulated blast furnace slag (GBFS) ratios, and different curing methods on geopolymer concrete (GPC) were investigated. For this purpose, 12 mixtures were produced and eight of them were cured under ambient conditions and the remaining four were cured in an oven. Steel wire ratios and GBFS ratios were added to GPC as 0–1–2–3 % and 0–10–20 % by volume and weight, respectively. As a result of the mixtures, cubes, cylinders, and beams were obtained and these elements were subjected to compression, tensile, and flexural tests. As a result of the tests, the compressive strengths of the specimens were obtained as 8.5 %, 19.7 %, and 24.9 % for ambient curing and 10.4 %, 23.2 %, and 32.2 % for oven curing, respectively, as the steel wire fiber increased from 0 % to 3 %. The maximum compressive strength of the oven-cured specimen with 3 % steel wire fiber was measured as 42.56 MPa. The tensile strength of GPC also increased as the steel wire increased. The highest tensile strength was obtained with 3 % steel wire. In addition, oven curing conditions increased the tensile strength more than ambient curing. The flexural strength (FS) increased by 21.3 %, 29.4 %, and 33.8 % with increasing steel wire ratios of 1 %, 2 %, and 3 %, respectively. The FS was further increased by oven curing conditions and the maximum FS was achieved with 3 % steel wire. In ambient curing conditions, a successful geopolymerization was achieved due to the high calcium content in the samples containing 20 % GBFS. This allowed to obtain similar strengths between ambient curing and oven curing. Although the oven curing values were higher, similar results were obtained for the samples cured in an ambient containing 20 % GBFS. As a result of the study, mixtures containing 3 % steel wire and 20 % GBFS provided sufficient strength without oven curing and increased the usability of GPC under ambient conditions.

Strength properties of Fly Ash based Geopolymer Concrete cured at different temperatures

This paper presents the results of an experimental study of the effect of curing temperature on the compressive strength and split tensile strength of Geopolymer concrete (GPC) which is made using fly ash produced at Norochcholai coal power plant. A relationship between splitting tensile strength and compressive strength also is also developed using test data. The results are then compared with some expressions published in international literature. A mixture of Sodium Silicate and Sodium Hydroxide solutions was used to activate low calcium class F fly ash to form Geopolymers. All specimens were oven cured for 48hours where curing temperature was varied from ambient temperature to 80oC at 20oC intervals. One day of rest period was given to every sample before curing. Test results showed that curing temperature has a significant effect on rate of strength gaining of GPC. The output of this study has provided a better understanding of the correlation between splitting and compressive strengths of GPC, which has therefore helped to generate a new expression with better accuracy for GPC prepared using locally available fly ash.

Behavior of geopolymer concrete deep beams containing waste aggregate of glass and limestone as a partial replacement of natural sand

The geopolymer concrete has outstanding physical properties and positive impact on environment compared to conventional concrete. Present endeavor highlights a strategy for management of glass and limestone waste to recycle them in geopolymer concrete deep beams. In this study, 126 geopolymer concrete samples were made for investigating the mechanical properties of geopolymer concrete with the sand replacement ratio of 0–15% by weight in increments of 5%. In addition, seven Reinforced geopolymer concrete deep beams of 600,150,150 mm were casted with respect to the concrete mix and their performance was examined in four-point bending test as per ASTM C78/C78M considering sand replacing ratio of 0–15%. Moreover, proper material constitutive relationships were selected to simulate the performance of geopolymer concrete incorporating waste aggregate. Consequently, a nonlinear finite element solution in ANSYS 11.0 was developed using these constitutive models to predict the behavior of beams. Experimental observations revealed that the use of waste lime and waste glass aggregates reduced the compressive and tensile strength of geopolymer concrete. Furthermore, the loss in strength using waste glass aggregate was less than 15% when compared to geopolymer concrete with waste limestone. Whereas, 5–15% sand replacing with waste aggregate resulted in an average reduction of 19% in loading capacity of the deep beams. The degradation in the ultimate load of the beams with limestone aggregate was 46.6% lower than that for members containing waste glass aggregate. The strain energy of the deep beams containing waste limestone was enhanced by increasing the waste aggregate content from 5% to 15%. Whilst increasing the ratio of replacement for glass mixes led to a decrease in final compressive strain. The outputs of the numerical analysis, in terms of loading capacity of the geopolymer concrete deep beams, were in good matching with the experimental results.

Study on soil mechanics and frost resistance of fly ash–metakaolin geopolymer

Aiming at the economic and environmental protection of fly-ash-metakaolin-based polymer concrete, the frost resistance of fly-ash-metakaolin-based polymer concrete is studied. Concrete polymers were prepared by mixing 1:1 mass ratio fly ash with metakaolin and using potassium silicate excitation. According to the content of fly ash and metakaolin, water-binder ratio, sand ratio, and bone cement ratio, the soil-cement concrete blocks were divided into 7 groups. The effects of saturation volume absorption of vacuum water, mass loss of freeze-thaw cycle, and relative dynamic elastic modulus on the frost resistance of concrete specimens were tested. The results show that after curing for 3 days and 7 days, the compressive strength of soil polymer concrete increases by 93.7% and 134.4% respectively. The increase of metakaolin content of fly ash can effectively improve the structural compactness of soil-polymer concrete. When the water-cement ratio is 0.4%, the sand ratio is 0.25–0.30%, and the bone cement ratio is 3.5%, the compressive strength and splitting tensile strength of geopolymer concrete are better. The incorporation of fly ash and metakaolin can effectively reduce the vacuum saturation volume absorption rate and the freezing-thawing water content of geopolymer concrete.

Strength Development Properties Of Sugar Cane Bagasse Ash Blended Geopolymer Concrete Containing Waste Steel Fibers

This research paper deals the two different mixture of GGBS/SCBA have been used for preparing the geopolymer alkali-activated concrete, by using NaOH (12 M solution), sodium silicate (12 M solution in Na+ and SiO2/Na2O molarity ratio of 0.3) and KOH (12 M solution) as activating solutions. Replacements of 10%, 20% and 30% of GGBS by SCBA were carried out for various mixes. It is observed that 20% replacement of GGBS showed better strength enhancement in the range 25-40 MPa at 3 days curing. However, the addition of waste steel fibers up to 1.5% by volume fraction (Vf) showed a reasonable improvements on the compressive strength and split tensile strength of geopolymer concrete. Further test results showed drastic improvement in flexural strength of geopolymer concrete for various mixes. The various comparative assessments were made for different geopolymer mixtures and the reinforcing effects of steel fibers were investigated in different concrete matrix.

An Experimental Study on Fibre Reinforced Geopolymer Concrete Composites- Glass Fibre, Copper Slag

The major problem of the world is facing today is environmental pollution. It is well known that for the production of 1-ton of cement consumes more energy and exhibit 0.8-ton of CO2 .On the other hand Fly ash is a residue from the combustion of pulverized coal from the flue gases of thermal power plant. Recently, the fly ash is not effectively used and a large part of it is disposed in landfill. Due to this problem the various researchers have sort for a new binder to minimize the consumption of OPC. This study evaluates the strength of geopolymer concrete having fly ash as the major binding material and the sand a fine aggregate was replaced with copper slag of 40% and glass fiber to enhance the mechanical properties have been presented. This paper analyses on the mechanical properties of eopolymer concrete composites such as compressive strength, split tensile strength and water absorption in heat curing at 60˚C for 24 hrs in hot air oven. Glass fibers were added in the mix in the volume fraction of 0.5%, 1.0%, 1.5% and 2.0% volume of the concrete. The influence of fiber content in terms of volume fraction on the compressive, split tensile strength of geopolymer concrete is presented. The result shows the elevated performance of the properties exhibited by the geopolymeric concrete with and without fibres.

Correlations between Mechanical Properties of Low-Calcium Fly Ash Geopolymer Concretes

This paper reports the correlation between existing standards for concrete and the major mechanical properties of geopolymer concrete produced from a range of low-calcium, Class F fly ashes. The data were collected at set points over a 1-year period and include four different sources of fly ash used in the manufacturing of geopolymer concrete. New relationships between mechanical properties and compressive strength were derived using statistical regression analysis. The applicability of current relationships of portland cement (PC) concrete as specified in Australian standards and American Concrete Institute codes for geopolymer concrete have been critically examined. The results indicated that the flexural strength of geopolymer concrete is higher than those predicted using current design equations for PC concrete with a similar compressive strength. However, the splitting tensile strength of geopolymer concrete is comparable to that predicted using the current design equation for PC concrete with similar compressive strength. It was also observed that the ACI 363 R equation significantly overestimates the splitting tensile strength of geopolymer concrete. Similarly, AS 3600 overvalues the elastic modulus of geopolymer concrete. Both of these overestimations may be critical when compressive strength is below 40 MPa.

Low carbon building: Experimental insight on the use of fly ash and glass fibre for making geopolymer concrete

Abstract Due to the environmental impacts resulting from the production of Ordinary Portland cement (OPC), the drive to develop alternative binders that can totally replace OPC is gaining huge consideration in the construction field. In the current study, attempt was made to determine the strength characteristics of glass fibre-reinforced fly ash based geopolymer concrete. Sodium hydroxide (NaOH) and sodium silicate (Na 2 SiO 3 ) were used as alkaline solutions (for activation of geopolymer reaction) at 12, 16, 20 M. Glass fibres were added to the geopolymer concrete in varying proportions of 0.1–0.5% (in steps of 0.1%) by weight of concrete. A constant weight ratio of alkaline solution to fly ash content of 0.43 was adopted for all mixes. British standard concrete test specimens were cast for measuring compressive strength, split-tensile strength, and flexural strength. Concrete specimens were cured by heating in oven at 90 °C for 24 h and natural environment, respectively. From the results, thermally cured concrete samples had better mechanical properties than the ambient (natural) cured samples. Thermally cured concrete specimen, containing 0.3% glass fibre and 16 M NaoH, achieved a maximum compressive strength of 24.8 MPa after 28 d, while naturally cured samples achieved a strength of 22.2 MPa. There was substantial increase in tensile strength of geopolymer concrete due to the addition of glass fibres. Split tensile strength increased by 5–10% in glass fibre-reinforced geopolymer concrete, containing 0.1–0.5% glass fibre and 16 M NaoH when compared to the unreinforced geopolymer concrete (1.15 MPa).

The Effect of Corrosive Environment on Geopolymer Concrete Tensile Strength

This study has the purpose to explore the potential of geopolymer concrete tensile strength in particular on the effects of corrosive environments. Geopolymer concrete, concrete technology used no OPC that has advantages, one of which is durability, especially for corrosive seawater environment. In addition, geopolymer concrete with polymerization mechanism does not require large energy consumption or an environmentally friendly concept. Geopolymer concrete in this study is using a type C fly ash from PT. International Power Mitsui Operation & Maintenence Indonesia (IPMOMI) Paiton. The type of alkaline activator used NaOH (14 molar) and Na 2 SiO 3 . Coarse and fine aggregate used are local aggregate. Geopolymer concrete molded test specimen with dimensions of (10 × 20) cm cylinder, further heating and without heating, then maintained at room temperature and seawater up to 28 days. Then to determine the mechanical properties, the tensile strength testing is done with reference. This result of study indicates the curing of geopolymer concrete at 60 ° C for 24 hours to raise the tensile strength of geopolymer concrete.

Mechanical Properties of Geopolymer Concrete Exposed to Combustion

This paper presents the change of material properties, such as decreasing of the compressive strength, splitting tensile strength, and porosity. The main objective of this paper is to analyze the mechanical properties of fly ash-based geopolymer concrete after being exposed to high temperature. The 28 th -day test specimens were burned for one hour at specified temperature variation of 200°C, 400°C, 600°C, and 800°C. Ordinary Portland Cement (OPC) concrete was used as a comparison. After burning at 400°C, the compressive strength of geopolymer concrete was surprisingly increased up to 27% of its normal strength. On the other hand, the compressive strength of OPC concrete decreased 67% from its normal strength. The splitting tensile strength of geopolymer concrete also decreased at the range of 50-70%. The porosity of concrete has a sufficient effect to compressive strength and splitting strength. X-Ray Diffraction (XRD) test of geopolymer concrete at temperature 400°C until 600°C showed some minerals change. Geopolymer concrete is proved to have better fire resistance compares to Portland Cement Concrete.

Discussion: Effect of strain rate on splitting tensile strength of geopolymer concrete

Discussion: Effect of strain rate on splitting tensile strength of geopolymer concrete

Effect of Alkaline Activator Ratio to Mechanical Properties of Geopolymer Concrete with Trass as Filler

This paper describes the effect of alkaline activator ratio (Na2SiO3/NaOH) to mechanical properties of geopolymer concrete. The mechanical properties of geopolymer concrete were assessed by setting time, split tensile strength and porosity. Fly ash was used as a cement substitute, and trass used as filler. While, Natrium hydroxide (NaOH) and Sodium Silicate (Na2SiO3) was applied as alkaline activator. In this study, NaOH concentration eight and ten molar with an alkaline activator ratio Na2SiO3/ NaOH by mass: 0.5, 1, 1.5, 2 and 2.5 were used. The test result showed that setting time, porosity and split tensile strength of geopolymer concrete were hardly influenced by NaOH concentration and the alkaline activator ratio. The alkaline activator ratio of Na2SiO3/NaOH has an optimum value at 2 and 2.5. Test result showed that the fastest setting time was 25 minute, the highest amount of closed porosity was 9.035 % and the highest split tensile strength was 2.86 MPa.

Effect of strain rate on splitting tensile strength of geopolymer concrete

The splitting tensile strengths of geopolymer concrete and geopolymer mortar under strain rates from 10−7 s−1 to 25 s−1 were investigated. Five mixes – one ordinary Portland cement (OPC) concrete, three geopolymer concrete and one geopolymer mortar – were considered. A Shimadzu AG-X 300 kN testing machine and a split Hopkinson pressure bar were used to conduct the tests. The dynamic increase factors of the splitting tensile strength (DIFft) of the geopolymer concretes were measured and compared with modified CEB recommendations. The results show that alkaline activators have a significant influence on the quasi-static splitting tensile strength of geopolymer concrete. For low strain rate loadings, the geopolymer concrete with low compressive strength had a larger DIFft and the viscous effect was found to be the main cause for an increase in DIFft. With high strain rate loadings, crack inertia was found to be responsible for the improvement in DIFft of geopolymer concretes. The existing formula for OPC concrete underestimates the DIFft of geopolymer concrete and therefore new empirical equations are proposed. In addition, the failure modes under various strain rate loadings were found to be similar due to the confinement of splitting tensile test on the crack path.