Long-Term Development of Strength of Cement Paste with Fly Ash

2016 ◽  
Vol 722 ◽  
pp. 151-156
Author(s):  
Ondřej Zobal ◽  
Pavel Padevět
Keyword(s):  
Tensile Strength ◽  
Fly Ash ◽  
Cement Paste ◽  
Concrete Structure ◽  
Concrete Mixture ◽  
Massive Concrete ◽  
Negative Impacts ◽  
Long Term Behavior

The paper deals with the long-term development of strength of cement paste with fly ash. If the fly ash replaces the clinker in the cement or concrete mixture, the properties of the fresh and hardened material are affected. The slower increase in the strength of concrete is one of the biggest negative impacts. However, there are applications where it does not matter - e.g. massive concrete structure. It is important due to the ever increasing requirement from society for saving material and energy and durability of structures monitoring long-term behavior of such modified material. Three different mixtures were made for this experiment - cement paste without fly ash and cement paste with replacement of 40 and 50% of cement by fly ash. The evaluation of the measurement of compressive and tensile strength after 28, 90, 180 days and 5 years is presented in this paper.

scholarly journals The Implications of HIV Treatment on the HIV-Malaria Coinfection Dynamics: A Modeling Perspective

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
F. Nyabadza ◽  
B. T. Bekele ◽  
M. A. Rúa ◽  
D. M. Malonza ◽  
N. Chiduku ◽  
...  
Keyword(s):  
Hiv Treatment ◽  
Pathogen Transmission ◽  
Disease Epidemiology ◽  
Qualitative Dynamics ◽  
Potential Impact ◽  
Negative Impacts ◽  
Long Term Behavior ◽  
The Impact ◽  
Multiple Pathogens

Most hosts harbor multiple pathogens at the same time in disease epidemiology. Multiple pathogens have the potential for interaction resulting in negative impacts on host fitness or alterations in pathogen transmission dynamics. In this paper we develop a mathematical model describing the dynamics of HIV-malaria coinfection. Additionally, we extended our model to examine the role treatment (of malaria and HIV) plays in altering populations’ dynamics. Our model consists of 13 interlinked equations which allow us to explore multiple aspects of HIV-malaria transmission and treatment. We perform qualitative analysis of the model that includes positivity and boundedness of solutions. Furthermore, we evaluate the reproductive numbers corresponding to the submodels and investigate the long term behavior of the submodels. We also consider the qualitative dynamics of the full model. Sensitivity analysis is done to determine the impact of some chosen parameters on the dynamics of malaria. Finally, numerical simulations illustrate the potential impact of the treatment scenarios and confirm our analytical results.

scholarly journals Experimental Investigation on Mechanical Properties of In Situ Cemented Paste Backfill Containing Coal Gangue and Fly Ash

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Xinguo Zhang ◽  
Shichuan Zhang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Fly Ash ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Friction Angle ◽  
Coal Gangue ◽  
Cemented Paste Backfill ◽  
Paste Backfill

Cemented paste backfill containing coal gangue and fly ash (CGFACPB) is an emerging backfill technique for coal mines that allows environmentally hazardous coal gangue and fly ash to be reused in the underground goaf. Meanwhile, CGFACPB can provide an efficient ground support and reduce the surface subsidence. Due to the difference of consolidation environment between the laboratory and the field, the mechanical properties of the cemented paste backfill vary significantly. In this paper, the core specimens were collected from an underground coal mine where the CGFACPB was used for coal mining, and the mechanical properties of the collected specimens were investigated. The cores were obtained from the underground coal mine, and then the standard cylinders or discs were prepared in laboratory. The uniaxial compressive strength (UCS), Young’s modulus, and Poisson’s ratio were determined by the compression tests, and the tensile strength was achieved by the Brazilian test. Then the internal friction angle and cohesion were calculated using the improved Mohr–Coulomb strength criterion. The results showed the development of UCS can be divided into four stages, and the final long-term stable value was about 5.1 MPa. The development of Young’s modulus had similar trend. Young’s modulus had a range from 550 MPa to 750 MPa and the mean value of 675 MPa. Poisson’s ratio gradually increased with the underground curing duration and eventually approached the stable value of 0.18. The failure type of compression samples was mainly single-sided shear failure. The development of tensile strength can be divided into two stages, and the stable value of the tensile strength was about 1.05 MPa. The development of cohesion can be divided into four stages, and the stable value was about 1.75 MPa. The stable value of the internal friction angle was about 25°. This study can provide significant references for not only the long-term stability evaluation of CGFACPB in the field but also the design of optimal recipe of the cemented paste backfill (CPB).

scholarly journals Assessment of the influence of fly ash additive on the tightness of concrete with furnace cement CEM IIIA 32,5N

2017 ◽  
Vol 66 (4) ◽  
pp. 153-164
Author(s):  
Anna Szcześniak ◽  
Jacek Zychowicz ◽  
Adam Stolarski
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Fly Ash ◽  
Concrete Strength ◽  
Concrete Compressive Strength ◽  
Water Penetration ◽  
Laboratory Investigations ◽  
Concrete Testing ◽  
Water Tightness

The analysis of influence of fly ash additive to concrete on the basis of cement CEM IIIA 32,5 N on the tightness and strength was presented in the paper. Researches were carried out for three types of concrete made with the use of CEM IIIA 32,5N LH HSR NA cement. The basic recipe of concrete does not contain the additive of fly ash, while two other concretes contain the fly ash additive in an amount of 25% and 33% of the cement mass. Laboratory investigations of the concrete samples were carried out under conditions of long-term maturation in the range of the water tightness and the depth of water penetration in concrete, compressive strength and tensile strength of concrete at splitting. Keywords: concrete testing, furnace cement, fly ash additive, water tightness of concrete, strength of concrete.

scholarly journals Effect of Carboxylic Acid (Benzene Crystallable) in Cement Concrete and Geopolymer Concrete

2020 ◽  
Vol 9 (7) ◽  
pp. 472-475
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Fly Ash ◽  
Carboxylic Acid ◽  
Geopolymer Concrete ◽  
Cement Concrete ◽  
Split Tensile Strength ◽  
Sealing Capacity ◽  
Time Period

The present study appraises the recitals of carboxylic acid- based admixture to increase concrete water tightness and self-sealing capacity of the cement and geopolymer concrete. Outcomes of the previous studies in particular, adding 1% by cement mass of the carboxylic polymer reasons for reduction in the water dispersion under pressure of 7-day wet cured concrete by 50% associated to that of the conforming reference concrete. At 7 days, M4 mix compressive strength is about 43.5% less than M3 mix. The compressive strength of M4 increases and is about 37.6% less than M3 mix at 28 days of curing. At 7 days, M4 mix split tensile strength is about 17.5% less than M3 mix (cement concrete with 0.45 w/c ratio). The split tensile strength of M4 declines and is about 42.3% less than M3 mix at 28 days of curing. The strength of the geopolymer concrete tends to increase as the time period increases due to the presence of fly ash in it. So it is expected that geopolymer concrete will give more strength than cement concrete in long term with the presence of carboxylic acid

scholarly journals Effect of Filler Particle Size on the Recyclability of Fly Ash Filled HDPE Composites

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2836
Author(s):  
Mohammed N. Alghamdi
Keyword(s):  
Particle Size ◽  
Tensile Strength ◽  
Fly Ash ◽  
High Performance ◽  
Filler Particle ◽  
Tensile Modulus ◽  
Filler Particle Size ◽  
Recycled Composites ◽  
Multiple Recycling

Fly ash polymer composites are innovative high-performance materials that reduce the environmental worries and disposal complications of heavy industry produced fly ash. This study developed and characterized such composites of high-density polyethylene (HDPE) matrices and found that the use of small (50–90 µm) particles of fly ash could give rise to the tensile modulus (~95%) and tensile strength (~7%) of their reinforced composites when compared to neat HDPE materials. While these results themselves convey a strong message of how fly ash can be effectively utilized, this was not the key aim of the current study. The study was extended to examine the effect of fly ash particle size on the recyclability of relevant HDPE composites. The extrusion-based multiple recycling of composites gave slightly lower mechanical properties, primarily due to filler/matrix delamination when large fly ash particles were used. Compared to freshly made fly ash-filled HDPE composites, although using small (50–90 µm) fly ash particles reduced the tensile modulus and tensile strength of recycled composites, the values were still far above those from neat HDPE materials. This novel insight directs the effective utilization of fly ash and provides long-term sustainable and economical solutions for their practical applicability.

Influence of Fly Ash Type on Material Properties of Cement Paste

2014 ◽  
Vol 969 ◽  
pp. 212-217 ◽  
Author(s):  
Pavel Padevět ◽  
Tereza Otcovská ◽  
Ondřej Zobal
Keyword(s):  
Tensile Strength ◽  
Fly Ash ◽  
Cement Paste ◽  
Compression Strength ◽  
Material Properties ◽  
Modulus Of Elasticity ◽  
Volume Weight ◽  
Strength In Bending

Paper describes properties of cement paste included addition various kinds of the fly ash. Firstly is described the preparation of the cement paste. Next part is focused on the testing of the properties. Results of the testing are summarized in properties like a compression strength, Modulus of elasticity and tensile strength in bending. Finally the relation between material properties and volume weight is discussed. An article is described paste made from the same amount of cement and fly ash and water coefficient of 0.4.

Numerical analysis and investigation of short- and long-term behavior of unidirectional composites

2017 ◽  
Vol 52 (5) ◽  
pp. 659-678
Author(s):  
Elias Dib ◽  
Jean François Caron ◽  
Wassim Raphael ◽  
Ioannis Stefanou ◽  
Fouad Kaddah
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Fiber Strength ◽  
Fiber Type ◽  
Glass Fibers ◽  
Shear Lag ◽  
Unidirectional Composites ◽  
Long Term Behavior ◽  
Shear Lag Theory

This study gives a detailed analysis on estimating the ultimate tensile strength of unidirectional fiber reinforced composites and its creep behavior under sustained tension load. We develop two different micromechanical models that allow us to estimate the longitudinal tensile strength and the evolution with time of fiber and matrix stresses around arbitrary array of fiber breaks. The first model is based on the shear-lag theory while the second one is developed using the software Abaqus. The comparison of the above models allowed to validate the fundamental assumptions of the shear-lag theory (first model) as well as several numerical issues related to time integration and spatial discretization. The Monte–Carlo method was used in order to account for the stochastic fiber strength and its impact on the ultimate tensile strength (short-term) and creep (long-term behavior) of unidirectional composites. Finally, a parametric investigation on the fiber type and the load level on the long-term behavior of unidirectional composites was performed showing an accelerating creep effect for fibers of inferior quality such as glass fibers compared to carbon fibers.

Changes of the Properties of Cement Paste with Fly Ash Exposed to the High Temperature

2016 ◽  
Vol 677 ◽  
pp. 138-143
Author(s):  
Romana Lovichová ◽  
Pavel Padevět ◽  
Jindřich Fornůsek
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
High Temperature ◽  
Fly Ash ◽  
Cement Paste ◽  
Material Properties ◽  
Bound Water ◽  
Material Structure ◽  
Cement Pastes ◽  
Strength In Bending

This paper describes influence of exposure to high temperatures on material properties of cement paste with addition of fly ash. The properties of cement pastes are significant to the assumption behaviour of concrete and concrete structures. In the cement paste containing fly ash, the effect of high temperature up to 600 ° C causes the changes of content in physically bound water and the change in the material structure. The results of research indicate changes that are reflected in the material properties of the cement paste as compressive strength, tensile strength in bending.

Long-Term Performance of Blended Cement Paste Containing Fly Ash against Sodium Sulfate Attack

2018 ◽  
Vol 30 (12) ◽  
pp. 04018309 ◽  
Author(s):  
Kaiwei Liu ◽  
Daosheng Sun ◽  
Aiguo Wang ◽  
Gaozhan Zhang ◽  
Jinhui Tang
Keyword(s):  
Fly Ash ◽  
Cement Paste ◽  
Sodium Sulfate ◽  
Blended Cement ◽  
Sulfate Attack ◽  
Long Term Performance ◽  
Term Performance ◽  
Blended Cement Paste

Experimental Analysis of Mechanical Properties on Concrete with Nano Silica Additive

2019 ◽  
Vol 57 ◽  
pp. 93-104 ◽  
Author(s):  
Usha Sivasankaran ◽  
Seetha Raman ◽  
S. Nallusamy
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Fly Ash ◽  
Compression Strength ◽  
Experimental Analysis ◽  
Strength Properties ◽  
Concrete Mixture ◽  
Partial Replacement ◽  
Cement Particle ◽  
Nano Silica

In the current scenario nanotechnology and nanomaterials are emerging as key role in engineering and medical industries. The objective of this research is to increase the usage of fly ash in concrete to enhance the strength properties of concrete mixed with nano silica and to reduce the emission control caused by CO2discharged from cement manufacturing industries. The strength properties of concrete mixture is enhanced with nano size particles filled the voids amoung micron size cement particle, and hence a denser concrete mixture was being attained. Fly ash is used for partial replacement of cement to enhance the environmental sustainability and to reduce the cost. This research work focussed on preparation of nano silica mixed concrete with replacement of fly ash in concrete mixture. Nano silica was added in addition to the above by 1% and 2% to improve the overall strength properties. Different experimental analysis were carried out to obtained the results such as compression strength, ultimate divide tensile strength and elastic modulus of the enriched concrete mixture. From the observed results it was found that, compression strength was increased by adding 1% nano silica and 25% of fly ash and also increased the ultimate tensile strength by 28%. Scanning Electrom Microscope (SEM) results reveal that, the incorporation of the nano silica in concrete increases the mechanical properties and porosity was successfully minimized with enhancement of pore size distribution.

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