Effect of sulphate attack on the flexural fatigue behaviour of fly ash–based geopolymer concrete

2018 ◽  
Vol 53 (8) ◽  
pp. 711-718 ◽  
Author(s):  
Tao Long ◽  
Hongen Zhang ◽  
Yu Chen ◽  
Zhi Li ◽  
Jiageng Xu ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fly Ash ◽  
Damage Index ◽  
Fatigue Loading ◽  
Fatigue Behaviour ◽  
Distribution Model ◽  
Geopolymer Concrete ◽  
Sulphate Attack ◽  
Flexural Fatigue ◽  
Erosion Effect

In this work, the erosion effect of sulphate solution on the flexural fatigue behaviour of fly ash–based geopolymer concrete was investigated. Under cyclic bending loading, the effect of sulphate attack on the fatigue life of geopolymer concrete was analysed using the static flexural strength as the damage index. Results revealed that the fatigue life of geopolymer concrete after sulphate erosion was significantly reduced compared with uncorroded samples under the same fatigue loading condition. And the fatigue life of corroded/uncorroded geopolymer concrete can be approximately described by the two-parameter Weibull distribution model. Since the sulphate attack would increase the actual stress level of corroded geopolymer concrete, a fatigue equation considering the damage index was deduced to predict the fatigue life of geopolymer concrete after sulphate attack.

scholarly journals Fatigue behaviour of fibre-reinforced composite T-joints

2018 ◽  
Vol 165 ◽  
pp. 07004
Author(s):  
Ying Wang ◽  
Constantinos Soutis
Keyword(s):  
Fatigue Life ◽  
Testing Machine ◽  
Fatigue Loading ◽  
Maximum Load ◽  
Fatigue Behaviour ◽  
Control Mode ◽  
Static Properties ◽  
T Joints ◽  
Pull Out ◽  
Reinforced Composite

In this paper a study was carried out on the fatigue life of fibre-reinforced composite T-joints subjected to a tensile pull-out loading. The composite T-joints have been made of glass fabric infused with epoxy resin using a vacuum assisted resin transfer moulding technique. Methods such as the use of veil layers, tufting techniques and 3D weave have been employed to improve the interlaminar fracture toughness of the composite T-joints. All the tests were conducted in an Instron testing machine using a specially designed test fixture. Fatigue tests were performed in a load control mode with a stress ratio of R = σmin/σmax = 0.1. The cyclic loading pattern was a sinusoidal wave with a frequency of 6 Hz. The specimens were cycled at a series of constant maximum load values up to failure. Fatigue loads versus life data for each T-joint type were produced at various maximum applied loads. The 3D weave T-joints were found to have the best performance in both static and fatigue loading. Increasing the static properties increases fatigue life performance; the increasing rate in fatigue life is changed with the number of stress cycles. The location for the through-thickness reinforcement plays an important role in improving fatigue life of the Tjoints. Fatigue life is significantly improved if the web is reinforced in through-thickness direction. A finite element (FE) failure model was also created using ABAQUS to determine the location where delamination is initiated and its subsequent propagation.

scholarly journals Effect of Sugarcane Bagasse Fibre on the Behavior of Geopolymer Concrete under Sulphate Attack

2021 ◽  
Vol 309 ◽  
pp. 01106
Author(s):  
T. Srinivas ◽  
Thandra Arun ◽  
N.V. Ramana Rao
Keyword(s):  
Fly Ash ◽  
Sugarcane Bagasse ◽  
Geopolymer Concrete ◽  
Sulphate Attack ◽  
Low Calcium ◽  
Considerable Impact ◽  
Hardened Properties ◽  
Bagasse Fibre ◽  
Made In ◽  
Sugarcane Industry

The use of various fibres such as steel, glass, sugarcane bagasse, and others has a considerable impact on the fresh and hardened properties of concrete. Sugarcane bagasse fibre is a byproduct from the sugarcane industry that can be reused as a concrete fibre. This paper objective is to work on the behaviour of sugarcane bagasse fibre on low calcium fly ash and slag based geopolymer concrete of G40 which is equivalent to M40 grade, when it is exposed to 5% sulphate attack with the help of experiments. The specimens were casted, GPC and GPCF Cured in an oven at 60 ° C for 24 hours, then let to cure in the atmosphere until the test is complete. After 28 days, the specimens were immersed in sulphates such as Na2SO4 and MgSO4 for 15, 45, and 75 days, and then tested according to codal standards on 15, 45, and 75 days. The comparisons were made in a controlled concrete environment (CC), controlled concrete with sugarcane bagasse fibre (CCF), geopolymer concrete (GPC) and geopolymer concrete with sugarcane bagasse fibre (GPCF). From the results it is observed that CCF and GPCF showed more resistant than CC and GPC when it is subjected to sulphate attack.

Effect of Intra-Ply Hybridization of Carbon-Aramid/Epoxy Laminates under Tension-Tension Fatigue Loading

2018 ◽  
Vol 10 (6) ◽  
Author(s):  
B. Ruban Rajasekar ◽  
R. Asokan ◽  
C. Ramesh ◽  
V. Jamin Daniel Selvakumar ◽  
M. Dinesh
Keyword(s):  
Tensile Strength ◽  
Fatigue Life ◽  
Stress Ratio ◽  
Fatigue Loading ◽  
Fatigue Behaviour ◽  
Load Control ◽  
Elongation To Failure ◽  
Superior Mechanical Properties ◽  
Fibre Angle ◽  
Hybrid Carbon

The objective of the research is to investigate the fatigue life of intra-ply hybrid Carbon-Aramid laminate with Epoxy resin in on-axis and off-axis directions. Three different off-axis angles of 15, 30 and 45 degrees were considered for the present work. The intra-ply hybridization is used to combine the superior mechanical properties of Carbon fibre with excellent elongation-to-failure property of Aramid fibre in the same lamina. The fatigue test was performed using load control using a frequency of 5Hz. The fatigue behaviour was studied for Carbon/Epoxy, Aramid/Epoxy, Carbon-Aramid/Epoxy, Carbon-Aramid/Epoxy - 15, Carbon-Aramid/Epoxy - 30 and Carbon-Aramid/Epoxy - 45 with the stress ratio of R = 0.1. The ultimate tensile strength decreases progressively for Carbon/Epoxy, Carbon-Aramid/Epoxy, Aramid/Epoxy, Carbon-Aramid/Epoxy - 15, Carbon-Aramid/Epoxy - 30 and Carbon-Aramid/Epoxy - 45. The effect of off-axis loading indicates that the increase of fibre angle influences the decrease in tensile strength and fatigue life.

scholarly journals Influence of porosity on the fatigue behaviour of additively fabricated TA6V alloys

2018 ◽  
Vol 165 ◽  
pp. 02008 ◽  
Author(s):  
Viet-Duc Le ◽  
Etienne Pessard ◽  
Franck Morel ◽  
François Edy
Keyword(s):  
Fatigue Life ◽  
Additive Manufacturing ◽  
Fatigue Strength ◽  
Pore Size ◽  
Selective Laser Melting ◽  
Fatigue Loading ◽  
Fatigue Behaviour ◽  
Laser Melting ◽  
Experimental Campaign ◽  
Porosity Fraction

This work is focused on the influence of porosity when dealing with the fatigue behaviour of the TA6V alloys fabricated by the selective laser melting (SLM) process. The presence of porosity is one of the major issue facing additive manufacturing (AM) of metallic components subjected to fatigue loading. In order to study the effect of porosity on the fatigue behaviour, a vast experimental campaign has been undertaken. These materials are fabricated by the SLM process with different building directions (horizontal, vertical and diagonal) thanks to which specimen batches with different pore sizes are obtained. It is observed that despite a low porosity fraction (around 0.01%), the influence of pores on the fatigue strength of the materials is pronounced. A mapping approach is presented, which links the applied stress, the pore size and the fatigue life. This approach makes it possible to accurately characterize the effect of the porosity size, and also to construct Kitagawa-Takahashi diagrams from S-N data.

Fatigue Behaviour of GFRP Reinforced Beams

2021 ◽  
Vol 322 ◽  
pp. 163-169
Author(s):  
Ondřej Januš ◽  
Frantisek Girgle ◽  
Vojtěch Kostiha ◽  
Jan Prokeš ◽  
Petr Štěpánek
Keyword(s):  
Reinforced Concrete ◽  
Fatigue Life ◽  
Concrete Slab ◽  
Fatigue Loading ◽  
Maximum Load ◽  
Fatigue Behaviour ◽  
Constant Load ◽  
Reinforced Concrete Slab ◽  
Reinforced Beams ◽  
Constant Load Amplitude

This article deals with the influence of fatigue loading on the behaviour of GFRP (Glass Fibre Reinforced Polymers) reinforced concrete elements. The aim of the experimental programme is to quantify the effect of fatigue loading on the mechanical properties of GFRP reinforced beams subjected to flexure. The proposed element was a beam simulating the cut-out part of a reinforced concrete slab directly subjected to traffic loading. The dimensions and the amount of reinforcement were adjusted regarding the possibilities of the testing laboratory and to ensure the repeatability of the test. Two different fatigue loading schemes were experimentally verified: a) a constant load amplitude, b) a gradually increasing amplitude. The applied fatigue load with a constant amplitude was designed to achieve a fatigue life of the element ≥ 2×106 cycles. In the case of fatigue loading with an increasing amplitude, the load was increased every 50,000 cycles by 5% of the maximum load in the cycle. The resulting fatigue life was compared to the expected fatigue life determined according to Miner's rule on linear fatigue summation.

Life Prediction and Stiffness Degradation Modeling of Glass/Epoxy Composites Subjected to Flexural Fatigue Loading

2016 ◽  
Author(s):  
Vinod B. Suryawanshi ◽  
Evan T. Kimbro ◽  
Ajit D. Kelkar
Keyword(s):  
Fatigue Life ◽  
Prediction Model ◽  
Life Prediction ◽  
Epoxy Composite ◽  
Fatigue Loading ◽  
Stiffness Degradation ◽  
Degradation Model ◽  
Flexural Fatigue ◽  
Plain Weave ◽  
Life Prediction Model

Textile composite are extensively used as structural materials for automotive, aerospace, energy, transportation and construction applications. During their service life these structures are subjected to different types of static and cyclic loading. For structural health monitoring of these structures, it is important to know the fatigue life and damage occurred at any stage of the life of the structure. Fatigue life is generally estimated using suitable life prediction model, while fatigue damage can be predicted by monitoring measurable damage parameters such as stiffness and strength. Two mathematical models namely fatigue life prediction model and stiffness degradation model are proposed for plain weave glass/epoxy composite subjected to flexural fatigue loading. Three different functions namely linear, exponential and sigmoid are evaluated to represent S-N diagram for plain weave glass/epoxy composite. Using predicted fatigue life along with initial modulus as inputs, the stiffness degradation model can predict residual stiffness at any stage of the fatigue loading life cycle. Logarithmic function used to represent stiffness degradation in the model is derived by inverting Boltzmann sigmoid function. The results of both, fatigue life model and stiffness degradation model were found to be in good agreement with those of the experimental results.

Damage Mechanics and Critical Plane Approach to Multiaxial Fatigue

2013 ◽  
Vol 592-593 ◽  
pp. 239-245
Author(s):  
Roberto Brighenti ◽  
Andrea Carpinteri
Keyword(s):  
Fatigue Life ◽  
Damage Mechanics ◽  
Crack Nucleation ◽  
Fatigue Loading ◽  
Fatigue Behaviour ◽  
Damage Parameter ◽  
Multiaxial Fatigue ◽  
Critical Plane ◽  
Critical Plane Approach ◽  
Scalar Damage Parameter

The mechanical behaviour of structural components subjected to multiaxial fatigue loading is very important in modern design. Several approaches have been introduced in recent decades to analyse this problem. The so-called critical plane approach, based on the stresses acting on the plane where the crack nucleation is expected to occur, is widely used. This criterion can give us a fatigue damage measurement, which can be used to evaluate fatigue life. On the other hand, fatigue life under general multiaxial stress histories can also be assessed by applying the damage accumulation method. In such a method, a scalar damage parameter is quantified through the damage increments which develop during the fatigue process up to the critical damage value corresponding to the final failure of the structures. The damage increment approach to fatigue has recently been discussed and connected to the classical crack propagation approach. In the present paper, the interpretation of the critical plane approach based on the continuum damage mechanics concepts is examined. In particular, the physical meaning of the critical plane approach is shown, that is, such an approach can be interpreted as a damage method which takes into account the scalar damage parameter evaluated along preferential directions. Finally, the fatigue behaviour of a metallic material under multiaxial cyclic load histories is analysed through the two above approaches.

THE EFFECT OF FLY ASH IN GEOPOLYMER CONCRETE POLES – A THRIVING SOLID WASTE DISPOSAL MEASURE FOR ECO-FRIENDLY ENVIRONMENT

2018 ◽  
Vol 8 (2) ◽  
pp. 7
Author(s):  
R. THENMOZHI ◽  
VADIVEL T.SENTHIL ◽  
S. MUTHURAMALINGAM ◽  
V. PADMAPRIYA ◽  
◽  
...  
Keyword(s):  
Fly Ash ◽  
Solid Waste ◽  
Waste Disposal ◽  
Geopolymer Concrete ◽  
Solid Waste Disposal

scholarly journals Practical Prediction Models of Tensile Strength and Reinforcement-Concrete Bond Strength of Low-Calcium Fly Ash Geopolymer Concrete

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 875
Author(s):  
Chenchen Luan ◽  
Qingyuan Wang ◽  
Fuhua Yang ◽  
Kuanyu Zhang ◽  
Nodir Utashev ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Fly Ash ◽  
Bond Strength ◽  
Prediction Models ◽  
Splitting Tensile Strength ◽  
Geopolymer Concrete ◽  
Structural Factors ◽  
Test Results ◽  
Portland Cement Concrete ◽  
Low Calcium

There have been a few attempts to develop prediction models of splitting tensile strength and reinforcement-concrete bond strength of FAGC (low-calcium fly ash geopolymer concrete), however, no model can be used as a design equation. Therefore, this paper aimed to provide practical prediction models. Using 115 test results for splitting tensile strength and 147 test results for bond strength from experiments and previous literature, considering the effect of size and shape on strength and structural factors on bond strength, this paper developed and verified updated prediction models and the 90% prediction intervals by regression analysis. The models can be used as design equations and applied for estimating the cracking behaviors and calculating the design anchorage length of reinforced FAGC beams. The strength models of PCC (Portland cement concrete) overestimate the splitting tensile strength and reinforcement-concrete bond strength of FAGC, so PCC’s models are not recommended as the design equations.

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