scholarly journals The impact of metakaolin, silica fume and fly ash on the temperature resistance of high strength cement paste

2021 ◽  
Author(s):  
Nabil Abdelmelek ◽  
Eva Lubloy
Keyword(s):  
Fly Ash ◽  
Silica Fume ◽  
Cement Paste ◽  
Elevated Temperatures ◽  
High Strength ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Temperature Resistance ◽  
Maximum Temperatures ◽  
The Impact

AbstractThe effects of elevated temperatures on the properties of high-strength cement paste (HSCP) based on metakaolin (MK), silica fume (SF), and fly ash (FA) were studied in the current experimental research. The resistance of HSCP against elevated temperatures was evaluated as well. The new method is expressed by the total area under each curve of strength, known as “temperature resistance”, is adopted. Results of the HSCP mixtures containing MK, SF, and FA with replacements ratios of 9%, 6% and 15% have shown excellent temperature resistance at all levels of maximum temperatures, respectively. Properties added to HSCP by these supplementary cementitious materials (SCM) such as decreasing the amount of CaO and increasing the amounts of SiO2 and Al2O3 have minimized the harmful effects of the use of pure ordinary Portland cement (OPC) at elevated temperatures. The results have shown also that the grinding fineness of OPC influences the amount of optimum replacement of the used SCM on HSCP at elevated temperatures. Hence, the amount of optimum replacement of MK blended with CEM I 42.5 N was 9% whereas, the amount of optimum replacement of MK blended with CEM I 52.5 N shifted to 3%. Finally, the fineness of cement of 4500 cm2 g−1 has shown a better-elevated temperature resistance compared to the cement with a fineness of 4000 cm2 g−1 in case of using pure OPC.

scholarly journals Physical and Mechanical Properties of High-Strength Concrete Modified with Supplementary Cementitious Materials after Exposure to Elevated Temperature up to 1000 °C

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 532 ◽  
Author(s):  
Jianwei Zhou ◽  
Dong Lu ◽  
Yuxuan Yang ◽  
Yue Gong ◽  
Xudong Ma ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Physical Properties ◽  
Water Absorption ◽  
High Strength Concrete ◽  
Elevated Temperatures ◽  
High Strength ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Strength Concrete

This paper presents the experimental findings of a study on the influence of combining usage of supplementary cementitious materials (SCMs) on the performance of high-strength concrete (HSC) subjected to elevated temperatures. In this study, four types of HSC formulations were prepared: HSC made from cement and fly ash (FA), HSC made from cement and ultra-fine fly ash (UFFA), HSC made from cement and UFFA-metakaolin (MK), and HSC made from cement and FA-UFFA-MK. Mechanical and physical properties of HSC subjected to high temperatures (400, 600, 800, and 1000 °C) were studied. Furthermore, the relation between residual compressive strength and physical properties (loss mass, water absorption, and porosity) of HSC was developed. Results showed that the combined usage of SCMs had limited influence on the early-age strength of HSC, while the 28-d strength had been significantly affected. At 1000 °C, the residual compressive strength retained 18.7 MPa and 23.9 MPa for concretes containing 30% UFFA-5% MK and 10% FA-20% UFFA-5% MK, respectively. The specimen containing FA-UFFA-MK showed the best physical properties when the temperature raised above 600 °C. Combined usage of SCMs (10% FA-20% UFFA-5% MK) showed the lowest mass loss (9.2%), water absorption (10.9%) and porosity (28.6%) at 1000 °C. There was a strongly correlated relation between residual strength and physical properties of HSC exposed to elevated temperatures.

scholarly journals Experimental study on Strength Attainment of concrete containing silica fume and fly ash

2021 ◽  
Vol 1197 (1) ◽  
pp. 012003
Author(s):  
G.V.V. Raj Kishore
Keyword(s):  
Fly Ash ◽  
Silica Fume ◽  
High Strength Concrete ◽  
High Strength ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Strength Concrete ◽  
Construction Techniques ◽  
Class F Fly Ash ◽  
Strength And Durability

Abstract Increased utilization of cement in recent construction techniques leads to the global gas emission and involves high cost. Many researchers investigated the incorporation of pozzolanic materials in the cement in order to reduce its notorious effects on the environment which directed this research in order to develop high strength concrete by partially replacing supplementary cementitious materials with the cement. This study represents the experimental investigation on concrete which is blended with class F fly ash and silica fume in order to obtain high strength concrete. For this purpose, silica fume is used in 6%, 9% fly ash is replaced with 30%,40% and 50% by weight of cement. The specimens were subjected to curing up to 90 days and conducted tests in order to determine the mechanical properties like compressive strength, flexural strength and durability properties like RCPT and UPV. Based on the experimental results, addition of 6% silica fume and fly ash at 30% replacement is high strength attainment as well as durability in the concrete.

scholarly journals Effects of Elevated Temperatures on the Properties of High Strength Cement Paste Containing Silica Fume

2021 ◽  
Author(s):  
Nabil Abdelmelek ◽  
Éva Lublóy
Keyword(s):  
Compressive Strength ◽  
Ambient Temperature ◽  
Silica Fume ◽  
Cement Paste ◽  
Elevated Temperatures ◽  
High Strength ◽  
Supplementary Cementitious Materials ◽  
Cement Matrix ◽  
Strength Concrete ◽  
Residual Compressive Strength

High strength concrete (HSC) production is worldwide increased and gradually replacing the normal strength concrete (NSC). The cement matrix of concrete is the essential part that governs the behavior and strength of concrete. Several researchers have focused on the performance of hardened cement paste (HCP) at ambient temperature such as using different types of supplementary cementitious materials (SCM). However, the performance of HCP after exposure to elevated temperatures requires further evaluation. The present study investigates the influence of different replacements of silica fume (SF) to cement and different water/binder ratios (w/b) on the compressive strength of HCP before and after exposure to elevated temperatures. Eighteen mixes have been prepared and tested. Results of compressive strength tests at ambient temperature were ranged from 58 to 102 MPa depending on the difference of w/b. Furthermore, a new method has been adopted for comparing the responses of HCP at elevated temperatures "heat endurance". Results showed that using SF enhances the residual compressive strength of HCP after exposure to elevated temperatures due to the pozzolanic reaction and the filler contribution. Mixes containing 6%, 12%, and 15% of SF have shown the highest relative residual compressive strength values for 0.30, 0.35, and 0.40 w/b, respectively. Consequently, the results were significantly affected by changing the w/b ratio. Finally, different measurement techniques were provided to support the work, including Thermo-Gravimetric (TG), Computed Tomography (CT), and Scanning Electron Microscope (SEM) analysis to characterize the loss of mass, porosity, and micro-structure alteration of HCP.

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

2005 ◽  
Vol 32 (1) ◽  
pp. 129-143 ◽  
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.

scholarly journals Production of Ultra-High-Performance Concrete with Low Energy Consumption and Carbon Footprint Using Supplementary Cementitious Materials Instead of Silica Fume: A Review

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8291
Author(s):  
Mays A. Hamad ◽  
Mohammed Nasr ◽  
Ali Shubbar ◽  
Zainab Al-Khafaji ◽  
Zainab Al Masoodi ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Silica Fume ◽  
High Performance ◽  
High Performance Concrete ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Ultra High Performance Concrete ◽  
Cement Production ◽  
Granulated Blast Furnace Slag ◽  
The Impact

The increase in cement production as a result of growing demand in the construction sector means an increase in energy consumption and CO2 emissions. These emissions are estimated at 7% of the global production of CO2. Ultra-high-performance concrete (UHPC) has excellent mechanical and durability characteristics. Nevertheless, it is costly and affects the environment due to its high amount of cement, which may reach 800–1000 kg/m3. In order to reduce the cement content, silica fume (SF) was utilized as a partial alternative to cement in the production of UHPC. Nevertheless, SF is very expensive. Therefore, the researchers investigated the use of supplementary cementitious materials cheaper than SF. Very limited review investigates addressed the impact of such materials on different properties of UHPC in comparison to that of SF. Thus, this study aims to summarize the effectiveness of using some common supplementary cementitious materials, including fly ashes (FA), ground granulated blast furnace slag (GGBS), metakaolin (MK) and rice husk ashes (RHA) in the manufacturing of UHPC, and comparing the performance of each material with that of SF. The comparison among these substances was also discussed. It has been found that RHA is considered a successful alternative to SF to produce UHPC with similar or even higher properties than SF. Moreover, FA, GGBS and MK can be utilized in combination with SF (as a partial substitute of SF) as a result of having less pozzolanic activity than SF.

scholarly journals The Relationship between Cementitious Composition and Properties of Ultrahigh Strength Concrete

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Dehui Wang ◽  
Zhiwen Zhang
Keyword(s):  
Fly Ash ◽  
Calcium Hydroxide ◽  
Silica Fume ◽  
Design Method ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Strength Concrete ◽  
Ultrahigh Strength ◽  
Acceleration Period ◽  
The Relationship

It is well known that supplementary cementitious materials (SCMs) have obvious effects on the properties of concrete. In order to understand the relationship between cementitious materials and properties of ultrahigh strength concrete (UHSC), the cementitious compositions of UHSC were designed by the simple-centroid design method. The effects of cementitious compositions on the properties of UHSC were investigated. It was found that the incorporation of silica fume (SF) improved the flowability and strength of UHSC, but it decreased the time of acceleration period, calcium hydroxide (CH) content, and porosity of UHSC at a certain content. The incorporation of fly ash (FA) increased the flowability, time of acceleration period, and porosity of UHSC, but it decreased the strength and CH content of UHSC. The relationships between cement, silica fume, and fly ash and the properties of UHSC were calculated based on the simple-centroid design method.

scholarly journals Efficiency Concepts and Models that Evaluates the Strength of Concretes Containing Different Supplementary Cementitious Materials

2019 ◽  
Vol 5 (1) ◽  
pp. 18 ◽  
Author(s):  
Rahul Biswas ◽  
Baboo Rai
Keyword(s):  
Fly Ash ◽  
Silica Fume ◽  
Research Work ◽  
Cementitious Materials ◽  
Mineral Admixture ◽  
Supplementary Cementitious Materials ◽  
Hardened Concrete ◽  
Effective Utilization ◽  
Natural Pozzolans ◽  
Quantitative Understanding

The usage of Supplementary Cementitious Materials (SCM) is very much acknowledged due to the several improvements possible in the concrete composites, and because of the general economy. Research work till date suggests that utilization of SCMs enhance a significant number of the performance characteristics of the hardened concrete. The idea of efficiency can be utilized for comparing the relative performance of different pozzolans when incorporated into concrete. The efficiency concept, which was initially developed for fly ash, can be effortlessly connected to other advantageous s as well, such as silica fume, slag and natural pozzolans. A quantitative understanding of the efficiency of SCMs as a mineral admixture in concrete is essential for its effective utilization. The paper reviews the literature pertaining to the different efficiency concepts and models present to date that evaluates the strength of concretes containing different SCMs. This short survey demonstrates that there is a need for a superior comprehension of the SCMs in concrete for its powerful usage. Also, it is an effort directed towards a specific understanding of the efficiency of SCMs in concrete.

Triple Blending with Superfine Natural Zeolite and Condensed Silica Fume to Improve Performance of Cement Paste

2017 ◽  
Author(s):  
P.L. Ng ◽  
J.J. Chen ◽  
A.K.H. Kwan
Keyword(s):  
Silica Fume ◽  
Cement Paste ◽  
Packing Density ◽  
Natural Zeolite ◽  
Water Film ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Concrete Production ◽  
Fine Size ◽  
Condensed Silica Fume

Superfine natural zeolite (SNZ) is obtained by grinding natural zeolite to micro-fine size, whereas condensed silica fume (CSF) is by-product of ferrosilicon industry. Both SNZ and CSF are environmentally-friendly supplementary cementitious materials for mortar and concrete production. Owing to the high fineness and favourable grading of SNZ and CSF (the median particle sizes were 4 μm and 0.4 μm, respectively), the addition of SNZ and CSF could successively fill the voids between ordinary Portland cement (OPC) grains and increase the packing density of the binder, so as to reduce the volume of voids to be filled with water. Therefore, triple blending of OPC+SNZ+CSF can benefit the overall performance of cement paste by releasing more water for flowability improvement at the same water/binder (W/B) ratio, or adopting a lower W/B ratio for strength improvement at the same flowability requirement. This study evaluated the effects of adding SNZ and CSF on the packing density and water film thickness of binder. The experimental results proved that triple blending with SNZ and CSF could increase the packing density and improve the flowability and cohesiveness of cementitious paste.

Durability of Sustainable Self-Consolidating Concrete

2018 ◽  
Vol 765 ◽  
pp. 285-289
Author(s):  
Osama Ahmed Mohamed ◽  
Waddah Al Hawat ◽  
Omar Fawwaz Najm
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Silica Fume ◽  
Cementitious Materials ◽  
Chloride Penetration ◽  
Supplementary Cementitious Materials ◽  
Test Results ◽  
Self Consolidating Concrete ◽  
Human Footprint ◽  
Granulated Blast Furnace Slag

Supplementary cementitious materials such as fly ash, silica fume and ground granulated blast furnace slag (GGBS) have been used widely to partially replace cement in producing self-consolidating concrete (SCC). The production of cement is associated with emission of significant amounts of CO2 and increases the human footprint on the environment. Fly ash, silica fume, and GGBS are recycled industrial by-products that also impart favorable fresh and hardened properties on concrete. This study aims to assess the effect of the amounts of fly ash and silica fume on strength and chloride penetration resistance of concrete. Rapid Chloride Penetration Test (RCPT) was used to assess the ability of SCC to resist ingress of chlorides into concrete. SCC mixes with different dosages of fly ash and silica fume were developed and tested at different curing ages. Test results showed that replacing 20% of cement with fly ash produced the highest compressive strength of 67.96 MPa among all fly ash-cement binary mixes. Results also showed that replacing15% of cement with silica fume produced the highest compressive strength of 95.3 MPa among fly ash-cement binary mixes. Using fly ash and silica fume consistently increased the concrete resistance to chloride penetration at the early ages. Silica fume at all dosages results in low or very low levels of chloride penetration at all curing ages of concrete.

scholarly journals Flexural strength of silica fume, fly ash, and metakaolin of hardened cement paste after exposure to elevated temperatures

2021 ◽  
Author(s):  
Nabil Abdelmelek ◽  
Eva Lubloy
Keyword(s):  
Fly Ash ◽  
Silica Fume ◽  
Cement Paste ◽  
Elevated Temperatures ◽  
The Other ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Structural Element ◽  
Pozzolanic Material ◽  
Pozzolanic Materials

AbstractThe mechanical properties of concrete based mainly on flexural and compressive bearing capacity. Generally, researchers have an interest in the evaluation of compression property through the importance of the flexural performance of the material in the constructions, namely the significance of each mechanical property based upon the position of the structural element. The present experimentally work is directed toward improving the flexural strengths performance of ordinary hardened cement paste (HCP) at ambient and after elevated temperatures exposure. The used parameters were different pozzolanic materials with different replacements ratios to cement mass and different levels of temperature. Results proved the significant contribution of pozzolanic material to enhance the flexural properties of HCP after being exposed to elevated temperatures. The low content of CaO, the high grinding fineness, and the physical morphology of the used pozzolanic materials, made their adoption effective to HCP after exposure to elevated temperatures. Using 3%, 12%, and 15% of silica fume (SF), metakaolin (MK), and fly ash (FA), respectively, showed the highest heat endurance among the other replacements. However, the optimum replacement of MK has shown a better heat endurance than the optimum replacements of SF and FA. On the other hand, the spalling has occurred at high replacements of SF. Finally, the results are supported by means of thermo-gravimetric, SEM, and computed tomography investigations.

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