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.

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.

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.

Shrinkage of Blended Cement Pastes with Mineral Additions

2013 ◽  
Vol 539 ◽  
pp. 55-59
Author(s):  
Yi Chen ◽  
Wu Yao ◽  
Dan Jin
Keyword(s):  
Fly Ash ◽  
Silica Fume ◽  
Cement Paste ◽  
Mercury Intrusion Porosimetry ◽  
Construction Materials ◽  
Blended Cement ◽  
Cement Pastes ◽  
Mercury Intrusion ◽  
Mineral Additions ◽  
By Products

Mineral additions such as fly ash and silica fume are industrial by products, and play an important role in properties improvement for construction materials. In this work, the shrinkage of cement paste blended with fly ash and silica fume by different substitute ratio was studied. Pore structures of specimens at different ages were determined by mercury intrusion porosimetry (MIP) and shrinkage deformation was measured by standard shrinkage tests. The effects of mineral addtions on shrinkage were discussed. The results show that the fly ash was significantly effective on shrinkage at early ages. Based on the research, several suitable advices were offered to optimize the performances of materials and reduce the shrinkage.

Bound Water in Cement Pastes and its Significance for Pore Solution Compositions

1986 ◽  
Vol 85 ◽  
Author(s):  
H. F. W. Taylor
Keyword(s):  
Fly Ash ◽  
Pore Solution ◽  
Bound Water ◽  
Free Water ◽  
Adsorbed Water ◽  
Interlayer Water ◽  
Structural Water ◽  
Cement Pastes ◽  
Evaporable Water ◽  
Definition Of

ABSTRACTThe problem of defining bound water in a cement paste is discussed; a reasonable definition is one that includes interlayer water in C-S-H and AFm phases, structural water in ettringite, and adsorbed water, but not water in micropores or in larger pores. On this basis, structural considerations indicate a value of around 32% on the ignited weight for a fully hydrated paste. ‘Non-evaporable’ water, typically around 22% on the ignited weight at full hydration, cannot be identified with bound water, because dehydration to the state in which only non-evaporable water remains causes major loss of interlayer water and destruction of ettringite. In the interpretation of pore solution data, the definition of bound water, and the value assumed for this quantity, are important, because the ionic concentrations in the pore solution are greatly affected by the volume of free water available to dissolve them. If cement is partially replaced by low calcium fly ash, the quantity of bound water at any given age is substantially reduced. This effect contributes to the relatively low concentrations of alkali metal and hydroxyl ions that are observed in the pore solutions of many portland-fly ash cement pastes.

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.

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.

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.

The Cement Paste Creep with Addition of Fly Ash in Time and Ratio of Parts 60/40

2013 ◽  
Vol 486 ◽  
pp. 341-346
Author(s):  
Pavel Padevět ◽  
Petr Bittnar
Keyword(s):  
Mathematical Model ◽  
Fly Ash ◽  
Cement Paste ◽  
Input Data ◽  
Basic Creep ◽  
Creep Coefficient ◽  
Measurement Results ◽  
The One ◽  
Water Saturated ◽  
The Mathematical Model

The article solves the comparing of the resize of cement paste creep with addition of fly ash in time. Creep was observed in the one monthly measurement for 4 and 10 months. The cement paste was prepared with fly ash in the ratio of the components 60/40 in favor of the cement components. Development of basic creep and creep was observed in water-saturated material. The measurement results are used as input data for the simulation of creep by the mathematical model and determine the values of the creep coefficient of cement paste. Results and comparison of q coefficients are presented.

Evolution of Various States of Water in Blended Cementitious Materials

2012 ◽  
Vol 193-194 ◽  
pp. 389-392
Author(s):  
An Ming She ◽  
Wu Yao ◽  
Wan Cheng Yuan
Keyword(s):  
Fly Ash ◽  
Cement Paste ◽  
Bound Water ◽  
Transverse Relaxation Time ◽  
Quantitative Relationship ◽  
Cementitious Materials ◽  
Relative Content ◽  
Cement Matrix ◽  
Transverse Relaxation ◽  
In Series

Low field NMR, as a nondestructure and noninvasive method was employed to study the evolution of various states of water in blended cementious materials added with fly ash during hydration from 1 day to 100 days. The relative content of water held in series of pores in cement matrix, e.g. capillary pore, mesopore and gel pore, was determined based on the quantitative relationship between transverse relaxation time, T2, and pore dimension. The results indicated that the relative content of chemically bound water was higher at long-term cure of 100 days compared with the neat cement paste. The water distributed in various pores was also influenced by the pozzolanic reactions between fly ash and calcium hydroxide. The gel water and mesopore water increased dramatically during the short-term age of 1 to 7 days in blended matrix, but then decreased gradually after 28 days, unlike that in pure cement paste. Due to the lower hydration degree in blended matrix, there was still amount of capillary water residual in paste to supply for the further hydration of fly ash.

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