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.

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.

Creep of Cement Pastes with Content of Fly Ash one Year Old

2015 ◽  
Vol 732 ◽  
pp. 385-388
Author(s):  
Pavel Padevět ◽  
Petr Bittnar
Keyword(s):  
Fly Ash ◽  
Cement Paste ◽  
Material Properties ◽  
Bound Water ◽  
Basic Creep ◽  
Cement Pastes ◽  
One Year ◽  
Creep Measurement ◽  
Ratio Of Components

The paper discusses the creep cement pastes with addition of fly ash. The evolution of the creep was observed in age of one year, for length one month. The size of the creep is influenced by the amount the creep physically bound water. The material properties depend on the ratio of components from which the cement paste is composed. The paper presents the results of creep measurement for the ratio of cement and fly ash 70:30, 60:40 and 50:50. The basic creep and creep of the saturated cement paste were calculated from measurements.

Mechanical and Rheological Properties of Aluminous Cement under High Temperatures

2014 ◽  
Vol 982 ◽  
pp. 141-144 ◽  
Author(s):  
Ondřej Holčapek ◽  
Pavel Reiterman ◽  
Petr Konvalinka
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
High Temperature ◽  
Rheological Properties ◽  
Cement Paste ◽  
Rheological Behavior ◽  
Experimental Program ◽  
Before And After ◽  
Aluminous Cement ◽  
Strength In Bending

The following article deals with the relations between rheological behavior and strength characteristics of high aluminous cement paste. There were investigated the values of flow of fresh mixture (tested with Högermann ́s table), tensile strength in bending and compressive strength at the age of 28 days on specimens 40 x 40 x 160 mm. The influence of high temperature was examined by exposure to 600 °C and 1000 °C. The results of provided experimental program confirm the fact that with increasing water-cement ration decreases compressive and tensile strength before and after temperature loading. Also was shown the effect of high temperature on refractory aluminous cement paste properites.

High Volume Slag and Slag-Fly Ash Blended Cement Pastes Containing Nano Silica

2019 ◽  
Vol 967 ◽  
pp. 205-213
Author(s):  
Faiz U.A. Shaikh ◽  
Anwar Hosan
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Cement Paste ◽  
Ordinary Portland Cement ◽  
Blended Cement ◽  
High Volume ◽  
Ash Content ◽  
Partial Replacement ◽  
Nano Silica ◽  
Cement Pastes

This paper presents the effect of nanosilica (NS) on compressive strength and microstructure of cement paste containing high volume slag and high volume slag-fly ash blend as partial replacement of ordinary Portland cement (OPC). Results show that high volume slag (HVS) cement paste containing 60% slag exhibited about 4% higher compressive strength than control cement paste, while the HVS cement paste containing 70% slag maintained the similar compressive strength to control cement paste. However, about 9% and 37% reduction in compressive strength in HVS cement pastes is observed due to use of 80% and 90% slag, respectively. The high volume slag-fly ash (HVSFA) cement pastes containing total slag and fly ash content of 60% exhibited about 5%-16% higher compressive strength than control cement paste. However, significant reduction in compressive strength is observed in higher slag-fly ash blends with increasing in fly ash contents. Results also show that the addition of 1-4% NS improves the compressive strength of HVS cement paste containing 70% slag by about 9-24%. However, at higher slag contents of 80% and 90% this improvement is even higher e.g. 11-29% and 17-41%, respectively. The NS addition also improves the compressive strength by about 1-59% and 5-21% in high volume slag-fly ash cement pastes containing 21% fly ash+49%slag and 24% fly ash+56%slag, respectively. The thermogravimetric analysis (TGA) results confirm the reduction of calcium hydroxide (CH) in HVS/HVSFA pastes containing NS indicating the formation of additional calcium silicate hydrate (CSH) gels in the system. By combining slag, fly ash and NS in high volumes e.g. 70-80%, the carbon footprint of cement paste is reduced by 66-76% while maintains the similar compressive strength of control cement paste. Keywords: high volume slag, nanosilica, compressive strength, TGA, high volume slag-fly ash blend, CO2 emission.

Dry Shrinkage and Compressive Strength of Blended Cement Pastes with Fly Ash and Silica Fume

2012 ◽  
Vol 535-537 ◽  
pp. 1735-1738 ◽  
Author(s):  
Yan Li ◽  
Dao Sheng Sun ◽  
Xiu Sheng Wu ◽  
Ai Guo Wang ◽  
Wei Xu ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Silica Fume ◽  
Cement Paste ◽  
Blended Cement ◽  
Drying Shrinkage ◽  
Cementitious Material ◽  
Strength Increase ◽  
Cement Pastes ◽  
Dry Shrinkage

This paper reports the drying shrinkage and compressive strength results of cement pastes with fly ash and silica fume. In this study, Portland cement (PC) was used as the basic cementitious material. Fly ash (FA) and silica fume (SF) were used as cement replacement materials at levels of 0%, 5%, 10%, and 15% , 40%, 35%, 25%, and 15% by weight of the total cementitious material, respectively. The water/cement (PC + FA + SF) ratios (w/c) was 0.28 by weight. The samples produced from fresh pastes were demoulded after a day; then they were cured at 20 ±1°C with 50 ± 3% relative humidity (RH) until the samples were used for drying shrinkage and compressive strength measurement at various ages. The results show that drying shrinkage and compressive strength increase with increasing SF content, and the optimum composition of blended cement pastes is the cement paste with 30% fly ash and 10% silica fume, which possesses lower drying shrinkage values than that of plain cement paste and higher early age strength than that of blended cement pastes with fly ash. Furthermore, a linear relationship is established between compressive strength and drying shrinkage. By comparing the development of compressive strength and the drying shrinkage deformations, it appears possible to predict the drying shrinkage according to the acquired compressive strength.

High Temperatures - Influence on the Material Properties of Cement Paste with Fly Ash

2013 ◽  
Vol 742 ◽  
pp. 187-191 ◽  
Author(s):  
Pavel Padevět ◽  
Romana Lovichová
Keyword(s):  
Fly Ash ◽  
High Temperatures ◽  
Cement Paste ◽  
Compression Strength ◽  
Material Properties ◽  
Modulus Of Elasticity ◽  
Volume Weight ◽  
Strength In Bending

Paper describes properties of cement paste included addition 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 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.

Influence of Ceramic Fibers on Mechanical Characteristics of Refractory Composites

2014 ◽  
Vol 1054 ◽  
pp. 22-26
Author(s):  
Ondřej Holčapek ◽  
Pavel Reiterman ◽  
Petr Konvalinka
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
High Temperature ◽  
Cement Composite ◽  
Ceramic Fibers ◽  
Explosive Spalling ◽  
Industrial Sectors ◽  
Temperature Load ◽  
Before And After ◽  
Strength In Bending

New and unexpected way of using cement composite in industrial sectors represents a current challenge for many research teams all over the world. Following contribution deals with the study of fiber-cement composite ́s mechanical properties after exposure to high temperature. This composite could be used for industry applications or for fire-resistance cladding production. Tensile strength in bending, compressive strength, bulk density and dynamic modulus of elasticity were examined on samples 40 x 40 x 160 mm. All parameters were measured before and after exposure to high temperature in electric furnace. One group contained three specimens was reference, without temperature load, the second group was exposure to 600 °C and the last one to 1000 °C. High aluminous cement Secar®71 works as refractory binder and nature crushed basalt aggregates two fractions works as filler. The composite ́s matrix was supplemented by various amounts of ceramic fibers. Especially the influence of amount of fibers on final properties was the main goal of this research. Measured mechanical parameters provide deep knowledge of their behavior after temperature on 1000 °C level. The compressive strength and tensile strength in bending achieved values 1.5 MPa. Behavior of the composite during and after temperature load was without any negative phenomena such as explosive spalling, cracks in aggregates or cement paste and macro disintegration of the composite ́s structure.

The Influence of High Temperatures and Time on the Material and Mechanical Properties of Cement Binder with Fly Ash

2018 ◽  
Vol 760 ◽  
pp. 119-126 ◽  
Author(s):  
Ondřej Zobal ◽  
Pavel Padevět
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Fly Ash ◽  
Dynamic Modulus ◽  
Cement Pastes ◽  
Temperature Load ◽  
Cement Binder ◽  
Pozzolanic Properties ◽  
Non Destructive

The paper deals with the use of fly ash in cement and concrete. Fly ash, primarily waste material, can be used as a binder because of pozzolanic properties. This fact positively influences the economic and ecological part of the construction. At present, also in the context of higher fire protection requirements fly ash, it is mentioned as a possible material for the protection of structures from fire. The article presents and discusses the results of destructive tests of tensile strength and compressive strength and non-destructive verification of dynamic modulus of elasticity of cement pastes with fly ash after high temperature load. The test samples were almost six years old.

scholarly journals Effect of Calcium Nitrate on the Properties of Portland–Limestone Cement-Based Concrete Cured at Low Temperature

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1611
Author(s):  
Gintautas Skripkiūnas ◽  
Asta Kičaitė ◽  
Harald Justnes ◽  
Ina Pundienė
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Setting Time ◽  
Calcium Nitrate ◽  
Curing Temperature ◽  
Hardened Concrete ◽  
Cement Pastes ◽  
Initial Setting Time ◽  
Initial Setting ◽  
Early Strength

The effect of calcium nitrate (CN) dosages from 0 to 3% (of cement mass) on the properties of fresh cement paste rheology and hardening processes and on the strength of hardened concrete with two types of limestone-blended composite cements (CEM II A-LL 42.5 R and 42.5 N) at different initial (two-day) curing temperatures (−10 °C to +20 °C) is presented. The rheology results showed that a CN dosage up to 1.5% works as a plasticizing admixture, while higher amounts demonstrate the effect of increasing viscosity. At higher CN content, the viscosity growth in normal early strength (N type) cement pastes is much slower than in high early strength (R type) cement pastes. For both cement-type pastes, shortening the initial and final setting times is more effective when using 3% at +5 °C and 0 °C. At these temperatures, the use of 3% CN reduces the initial setting time for high early strength paste by 7.4 and 5.4 times and for normal early strength cement paste by 3.5 and 3.4 times when compared to a CN-free cement paste. The most efficient use of CN is achieved at −5 °C for compressive strength enlargement; a 1% CN dosage ensures the compressive strength of samples at a −5 °C initial curing temperature, with high early strength cement exceeding 3.5 MPa but being less than the required 3.5 MPa in samples with normal early strength cement.

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