Micro-structural development of gap-graded blended cement pastes containing a high amount of supplementary cementitious materials

AbstractThis contribution is the second part of an in-depth study on the hydration and strength evolution of blended cement pastes at a water to binder (W/B) ratio of 0.3, cured by two different methods. The blended cement pastes showed significant hydration up to 7 days, when almost all of the hydration products had already formed; thereafter, carbonation played an important role up to, and possibly beyond, 91 days. Likewise, the hydration of alite (tricalcium silicate, Ca3SiO5, C3S) proceeded up to 14 days and then started to slow down. However, the hydration of belite (dicalcium silicate, Ca2SiO4, C2S) was affected most strongly, as it nearly ceased, under the air-curing conditions. During hydration, some of the blended cement pastes had a larger calcium hydroxide (CH) content than the unblended (plain) ones. The accelerating effects of the addition of supplementary cementitious materials (SCMs), the air-curing conditions and the low W/B ratio may explain these unusual results. Under these experimental conditions, the water incorporated into hydrates was about 50% of the total amount of water used during full hydration of the cement pastes. The pozzolanic reaction predominated during the early ages, but disappeared as time passed. In contrast, the carbonation reaction increased by consuming ∼45% of the total amount of CH produced after aging for 91 days. Only one blended cement paste reached the compressive strength of the plain cements. The blended cement pastes containing 5% of the zeolitic tuffs, Zeo1 or Zeo2, or 10% of the calcareous siltstone, Limo, developed the greatest compressive strength under the experimental conditions used in this study.

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The Combined Effect of the Initial Cure and the Type of Cement on the Natural Carbonation, the Portlandite Content, and Nonevaporable Water in Blended Cement

Advances in Materials Science and Engineering ◽

10.1155/2017/5634713 ◽

2017 ◽

Vol 2017 ◽

pp. 1-17 ◽

Cited By ~ 7

Author(s):

Saida Boualleg ◽

Mohamed Bencheikh ◽

Larbi Belagraa ◽

Aziz Daoudi ◽

Mohamed Aziz Chikouche

Keyword(s):

Blended Cement ◽

Cementitious Materials ◽

Pozzolanic Reaction ◽

Supplementary Cementitious Materials ◽

Cement Pastes ◽

Slowing Down ◽

Carbonation Process ◽

Two Parameters ◽

Physical And Chemical ◽

Natural Carbonation

The aim of this work is to better understand the physical and chemical phenomena involved in hydrated mix (clinker + addition) during the natural carbonation process, to characterize cement with supplementary cementitious materials (SCMs) under various curing environment. The prepared cement pastes were characterized by thermogravimetric analysis. The results showed a considerable influence of the environment on the properties of mortars and cement and a perfect correlation between compressive strength, natural carbonation, nonevaporable water, and portlandite content. It was observed that the reduction of the curing period makes the mortars more sensitive. The kinetics of process was evaluated from Ca(OH)2 content and nonevaporable water contained in mortars. These two parameters reflect the hydration progress of the water/cement ratio studied. The weight loss due to Ca(OH)2 decomposition, calculated by DTA/TG analysis, shows the effect of the pozzolanic reaction and the natural carbonation. The supplementary cementitious materials (SCMs) play a considerable role in the slowing down of the aggression environment.

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New Approach for the Determination of Radiological Parameters on Hardened Cement Pastes with Coal Fly Ash

Materials ◽

10.3390/ma14030475 ◽

2021 ◽

Vol 14 (3) ◽

pp. 475

Author(s):

Ana María Moreno de los Reyes ◽

José Antonio Suárez-Navarro ◽

Maria del Mar Alonso ◽

Catalina Gascó ◽

Isabel Sobrados ◽

...

Keyword(s):

Fly Ash ◽

Activity Concentration ◽

Gamma Ray ◽

Coal Fly Ash ◽

Cementitious Materials ◽

New Method ◽

Supplementary Cementitious Materials ◽

Hardened Cement ◽

Cement Pastes ◽

Activity Concentrations

Supplementary cementitious materials (SCMs) in industrial waste and by-products are routinely used to mitigate the adverse environmental effects of, and lower the energy consumption associated with, ordinary Portland cement (OPC) manufacture. Many such SCMs, such as type F coal fly ash (FA), are naturally occurring radioactive materials (NORMs). 226Ra, 232Th and 40K radionuclide activity concentration, information needed to determine what is known as the gamma-ray activity concentration index (ACI), is normally collected from ground cement samples. The present study aims to validate a new method for calculating the ACI from measurements made on unground 5 cm cubic specimens. Mechanical, mineralogical and radiological characterisation of 28-day OPC + FA pastes (bearing up to 30 wt % FA) were characterised to determine their mechanical, mineralogical and radiological properties. The activity concentrations found for 226Ra, 212Pb, 232Th and 40K in hardened, intact 5 cm cubic specimens were also statistically equal to the theoretically calculated values and to the same materials when ground to a powder. These findings consequently validated the new method. The possibility of determining the activity concentrations needed to establish the ACI for cement-based materials on unground samples introduces a new field of radiological research on actual cement, mortar and concrete materials.

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Investigation of C-S-H in ternary cement pastes containing nanosilica and highly-reactive supplementary cementitious materials (SCMs): Microstructure and strength

Construction and Building Materials ◽

10.1016/j.conbuildmat.2018.10.235 ◽

2019 ◽

Vol 198 ◽

pp. 445-455 ◽

Cited By ~ 11

Author(s):

Daniel da Silva Andrade ◽

João Henrique da Silva Rêgo ◽

Paulo Cesar Morais ◽

Anne Neiry de Mendonça Lopes ◽

Moisés Frías Rojas

Keyword(s):

Cementitious Materials ◽

Supplementary Cementitious Materials ◽

Cement Pastes

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Mechanically activated mine tailings for use as supplementary cementitious materials

RILEM Technical Letters ◽

10.21809/rilemtechlett.2021.143 ◽

2021 ◽

Vol 6 ◽

pp. 61-69

Author(s):

Sivakumar Ramanathan ◽

Priyadarshini Perumal ◽

Mirja Illikainen ◽

Prannoy Suraneni

Keyword(s):

Mine Tailings ◽

Isothermal Calorimetry ◽

Cementitious Materials ◽

Supplementary Cementitious Materials ◽

Strong Correlations ◽

Negative Effects ◽

Cement Pastes ◽

Amorphous Content ◽

Milling Duration ◽

Median Particle

Two mine tailings are evaluated for their potential as supplementary cementitious materials. The mine tailings were milled using two different methods – ball milling for 30 minutes and disc milling for durations ranging from 1 to 15 minutes. The modified R3 test was carried out on the mine tailings to quantify their reactivity. The reactivity of the disc milled tailings is greater than those of the ball milled tailings. Strong correlations are obtained between milling duration, median particle size, amorphous content, dissolved aluminum and silicon, and reactivity of the mine tailings. The milling energy results in an increase in the fineness and the amorphous content, which do not appreciably increase beyond a disc milling duration of 8 minutes. The reactivity increases significantly beyond a certain threshold fineness and amorphous content. Cementitious pastes were prepared at 30% supplementary cementitious materials replacement level at a water-to-cementitious materials ratio of 0.40. No negative effects of the mine tailings were observed at early ages in cement pastes based on isothermal calorimetry and thermogravimetric analysis, demonstrating the potential for these materials to be used as supplementary cementitious materials.

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A Study on Porous Sealing Efficacy of hydrophilic Admixture on Blended Cement Concrete

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i2.12.11514 ◽

2018 ◽

Vol 7 (2.12) ◽

pp. 446

Author(s):

L Krishnaraj ◽

P T. Ravichandran ◽

M V.A.Karthik ◽

N Satheeshram Avudaiyappan ◽

. .

Keyword(s):

Blended Cement ◽

Cementitious Materials ◽

Supplementary Cementitious Materials ◽

Partial Replacement ◽

Chloride Permeability ◽

Split Tensile Strength ◽

Micro Cracks ◽

Significant Strength ◽

Strength And Durability ◽

Durability Of Concrete

The life of the concrete is strongly influenced by durability parameters. The permeability is one of the main characteristics influencing the durability of concrete. The concrete is more permeable due to the ingress of water, oxygen, chloride, sulphate, and other potential deleterious substances. The durability of concrete is mainly affected by pore structure system of concrete and addingthe supplementary cementitious materials (SCM), such as fly ash, slag cement, and silica fume can be decrease permeability. Crystalline technology enhances the strength of concrete by filling the poresand micro-cracks with non-dissolvable substances. To study the efficiency of crystalline formation in concrete in terms of more permeable should be guaranteed through a specific technique.The effectiveness of crystalline waterproofing system with partial replacement cement by GGBS is studiedin terms of strength and durability. The performance of the two different types of crystalline waterproofing integral admixtures has been studied for compressive strength, Split tensile strength, workability, water permeability, Rapid chloride permeability test and porosity in this paper.The early strength increased in GGBS with crystalline admixture concretes compare to the control concrete. No significant strength reduction is observed in GGBS concretes with crystalline admixture when replaced with 20% and 40% of cement than control concrete.

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Suitability of Cordia millenii Ash Blended Cement in Concrete Production

International Journal of Engineering Research in Africa ◽

10.4028/www.scientific.net/jera.22.59 ◽

2016 ◽

Vol 22 ◽

pp. 59-67 ◽

Cited By ~ 11

Author(s):

Olusola Emmanuel Babalola ◽

Paul O. Awoyera

Keyword(s):

Compressive Strength ◽

Setting Time ◽

Blended Cement ◽

Cementitious Materials ◽

Strength Properties ◽

Supplementary Cementitious Materials ◽

Sieve Analysis ◽

Concrete Production ◽

Alternative Materials ◽

Concrete Control

Supplementary cementitious materials are most needed to enhance a sustainable development in poor communities. It is pertinent to investigate the suitability of such alternative materials for construction. The present study evaluates the strength characteristics of concrete made with varied proportion of Cordia millenii ash blended with Portland cement. Chemical composition of Cordia millenii and the setting time when blended with cement was determined. Other laboratory tests performed on Cordia millenii blended cement include: sieve analysis and specific gravity. Five replacement percentages of Cordia millenii (5%, 10%, 15%, and 20%) were blended with cement in concrete. Control specimens were also produced with only cement. Tests to determine the workability, air entrained, bulk density and compressive strength properties of the concrete were also conducted. Results obtained revealed that optimum Cordia millenii mix is 10%, which yielded the highest density and compressive strength in the concrete.

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Current situation with the production and use of supplementary cementitious materials (SCMs) in concrete construction in Canada

Canadian Journal of Civil Engineering ◽

10.1139/l04-109 ◽

2005 ◽

Vol 32 (1) ◽

pp. 129-143 ◽

Cited By ~ 10

Author(s):

Nabil Bouzoubaâ ◽

Benoît Fournier

Keyword(s):

Fly Ash ◽

Silica Fume ◽

Blended Cement ◽

Cementitious Materials ◽

Current Situation ◽

Supplementary Cementitious Materials ◽

Market Demand ◽

Granulated Blast Furnace Slag ◽

The Us ◽

Economic Barriers

The data gathered on the current situation of supplementary cementing materials (SCMs) in Canada have shown that around 524 000, 347 000, and 37 000 t of fly ash, ground granulated blast furnace slag (GGBFS), and silica fume were used in cement and concrete applications in 2001, respectively, which represents 11%, 90%, and 185% of the quantity produced. The remaining 10% of GGBFS produced was used in the US, and 17 000 t of silica fume were imported from the US and Norway to meet market demand. Fly ash appears to be the only material that is underused and that represents a potential for increased use of SCMs in Canada. For the GGBFS, the quantity produced can be increased if the demand increases. This investigation has shown, however, that there are policy, technical, and economic barriers to the increased use of SCMs in Canada. Some solutions were proposed to overcome these barriers and are summarized in the conclusions of the paper.Key words: fly ash, slag, silica fume, concrete, blended cement.

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Synthesis of a New Polycarboxylate at Room Temperature and Its Influence on the Properties of Cement Pastes with Different Supplementary Cementitious Materials

Advances in Civil Engineering ◽

10.1155/2020/8854422 ◽

2020 ◽

Vol 2020 ◽

pp. 1-10

Author(s):

Shuncheng Xiang ◽

Yingli Gao ◽

Caijun Shi

Keyword(s):

Room Temperature ◽

Autogenous Shrinkage ◽

Drying Shrinkage ◽

Cementitious Materials ◽

Heat Evolution ◽

Hydration Heat ◽

Supplementary Cementitious Materials ◽

Cement Pastes ◽

Binder Ratio ◽

Water Binder Ratio

Three polycarboxylates with different comb structures (i.e., the same degree of polymerization in side chains but different main chains) were synthesized via radical polymerization reaction at room temperature. The effect of polycarboxylates on the surface tension and the flowability in cement pastes was determined. The best product was selected to study its effects on the hydration heat evolution, compressive strength, autogenous shrinkage, and drying shrinkage of cement pastes with different kinds and contents of supplementary cementitious materials. The results showed that with the increase of molar ratio between AA and TPEG to 6 : 1, we could synthesis the best product. When the water-binder ratio was 0.4, with the increase of polycarboxylates, the cement hydration heat evolution had been slowed down, and the more the dosage was, the more obvious the effect was. Adding supplementary cementitious materials to cement under the same experimental conditions also played a mitigation role in slowing down the hydration heat. When the water-binder ratio was 0.3, supplementary cementitious materials could increase the strength of cement by 24.5% in maximum; its autogenous shrinkage and drying shrinkage could be decreased, respectively, by 60.1% and 21.9% in the lowest.

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