scholarly journals The Application of a New Oxidation Mortar Bar Test to Mixtures containing Different Cementing Systems

2021 ◽  
Author(s):  
Bassili Guirguis ◽  
Medhat Shehata ◽  
Josée Duchesne ◽  
Benoît Fournier ◽  
Benoît Durand ◽  
...  
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Pore Structure ◽  
Heat Of Hydration ◽  
Iron Sulphide ◽  
Oxidizing Agent ◽  
Field Exposure ◽  
Bar Test ◽  
Reactive Alumina ◽  
Mortar Bar

The effects of different cementing systems on the expansion of mortars containing iron sulphide-bearing aggregate was studied. Using a recently developed oxidation mortar bar test, the results showed that cementing systems containing low-calcium fly ash, metakaolin, slag, high-sulphate resisting Portland cement, or low heat of hydration Portland cement could reduce the expansion by 50–85%. The main suggested mechanisms behind the reduced expansion is the more refined pore structure of samples with SCMs, and the reduced C3A of low heat of hydration Portland cement. The refined pore structure reduces the permeation of the oxidizing solution into the samples. The similarity of this to penetration of oxygen into concrete under field exposure needs to be determined. Soaking the samples for >3 h in the oxidizing agent can produce excessive expansion – not related to oxidation of iron sulphide phases – in samples with cementing blends containing reactive alumina such as metakaolin.

scholarly journals The Application of a New Oxidation Mortar Bar Test to Mixtures containing Different Cementing Systems

2021 ◽  
Author(s):  
Bassili Guirguis ◽  
Medhat Shehata ◽  
Josée Duchesne ◽  
Benoît Fournier ◽  
Benoît Durand ◽  
...  
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Pore Structure ◽  
Heat Of Hydration ◽  
Iron Sulphide ◽  
Oxidizing Agent ◽  
Field Exposure ◽  
Bar Test ◽  
Reactive Alumina ◽  
Mortar Bar

The effects of different cementing systems on the expansion of mortars containing iron sulphide-bearing aggregate was studied. Using a recently developed oxidation mortar bar test, the results showed that cementing systems containing low-calcium fly ash, metakaolin, slag, high-sulphate resisting Portland cement, or low heat of hydration Portland cement could reduce the expansion by 50–85%. The main suggested mechanisms behind the reduced expansion is the more refined pore structure of samples with SCMs, and the reduced C3A of low heat of hydration Portland cement. The refined pore structure reduces the permeation of the oxidizing solution into the samples. The similarity of this to penetration of oxygen into concrete under field exposure needs to be determined. Soaking the samples for >3 h in the oxidizing agent can produce excessive expansion – not related to oxidation of iron sulphide phases – in samples with cementing blends containing reactive alumina such as metakaolin.

scholarly journals The Application of a New Oxidation Mortar Bar Test to Mixtures containing Different Cementing Systems

2021 ◽  
Author(s):  
Bassili Guirguis ◽  
Medhat Shehata ◽  
Josée Duchesne ◽  
Benoît Fournier ◽  
Benoît Durand ◽  
...  
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Pore Structure ◽  
Heat Of Hydration ◽  
Iron Sulphide ◽  
Oxidizing Agent ◽  
Field Exposure ◽  
Bar Test ◽  
Reactive Alumina ◽  
Mortar Bar

The effects of different cementing systems on the expansion of mortars containing iron sulphide-bearing aggregate was studied. Using a recently developed oxidation mortar bar test, the results showed that cementing systems containing low-calcium fly ash, metakaolin, slag, high-sulphate resisting Portland cement, or low heat of hydration Portland cement could reduce the expansion by 50–85%. The main suggested mechanisms behind the reduced expansion is the more refined pore structure of samples with SCMs, and the reduced C3A of low heat of hydration Portland cement. The refined pore structure reduces the permeation of the oxidizing solution into the samples. The similarity of this to penetration of oxygen into concrete under field exposure needs to be determined. Soaking the samples for >3 h in the oxidizing agent can produce excessive expansion – not related to oxidation of iron sulphide phases – in samples with cementing blends containing reactive alumina such as metakaolin.

Heat of hydration of Portland Cement–Metakaolin–Fly ash (PC–MK–PFA) blends

2008 ◽  
Vol 38 (6) ◽  
pp. 832-840 ◽  
Author(s):  
David G. Snelson ◽  
Stan Wild ◽  
Martin O'Farrell
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Heat Of Hydration

How does fly ash mitigate alkali–silica reaction (ASR) in accelerated mortar bar test (ASTM C1567)?

2013 ◽  
Vol 37 ◽  
pp. 143-153 ◽  
Author(s):  
Seyed M.H. Shafaatian ◽  
Alireza Akhavan ◽  
Hamed Maraghechi ◽  
Farshad Rajabipour
Keyword(s):  
Fly Ash ◽  
Alkali Silica Reaction ◽  
Accelerated Mortar Bar Test ◽  
Bar Test ◽  
Mortar Bar

scholarly journals Influence of Amount of Calcareous Fly Ash on Heat of Hydration of Portland Cement

2019 ◽  
Vol 603 ◽  
pp. 042081
Author(s):  
Patrycja Miera ◽  
Jacek Golaszewski ◽  
Zbigniew Giergiczny
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Heat Of Hydration

Effect of the Composite of Fly Ash and Slag on Alkali-Silica Reaction

2014 ◽  
Vol 936 ◽  
pp. 1428-1432
Author(s):  
Tong Chao Liu ◽  
Bo Xiao ◽  
Gu Hua Li ◽  
Nian Hong Luo ◽  
Long Sheng Zhang
Keyword(s):  
Fly Ash ◽  
Inhibitory Effect ◽  
Alkali Silica Reaction ◽  
Alkali Aggregate Reaction ◽  
Accelerated Mortar Bar Test ◽  
Bar Test ◽  
Mortar Bar ◽  
Better Than

The study used the method of accelerated mortar bar test to study alkali aggregate reaction (ASR) with sandstone aggregate. Both fly ash and slag can inhibit the expansion of mortar bar. Results show that 50% slag can inhibit ASR reluctantly, but 10% fly ash and 20% slag can inhibit ASR very well, and the inhibitory effect of fly ash is far better than slag. Because of the high content of CaO in slag, it has inhibit and promote aspects, when the ASR is fierce, slag can inhibit ASR, otherwise slag can promote ASR.

scholarly journals Investigation into the Heat of Hydration and Alkali Silica Reactivity of Sustainable Ultrahigh Strength Concrete with Foundry Sand

2017 ◽  
Vol 2017 ◽  
pp. 1-11
Author(s):  
Federico Aguayo ◽  
Anthony Torres ◽  
Tate Talamini ◽  
Kevin Whaley
Keyword(s):  
High Strength ◽  
Heat Of Hydration ◽  
Foundry Sand ◽  
Supplementary Cementitious Material ◽  
Strength Concrete ◽  
Ultrahigh Strength ◽  
Accelerated Mortar Bar Test ◽  
Bar Test ◽  
Mortar Bar ◽  
The Impact

This study presents the hydration reactivity and alkali silica reaction (ASR) of ultrahigh strength concrete (UHSC) that has been made more sustainable by using spent foundry sand. Spent foundry sand not only is sustainable but has supplementary cementitious material (SCM) characteristics. Two series of UHSC mixtures were prepared using a nonreactive and reactive sand (in terms of ASR) to investigate both the impact of a more reactive aggregate and the use of spent foundry sand. Conduction calorimetry was used to monitor the heat of hydration maintained under isothermal conditions, while ASR was investigated using the accelerated mortar bar test (AMBT). Additionally, the compressive strengths were measured for both series of mixtures at 7, 14, and 28 days to confirm high strength requirements. The compressive strengths ranged from 85 MPa (12,345 psi) to 181.78 MPa (26,365 psi). This result demonstrates that a UHSC mixture was produced. The calorimetry results revealed a slight acceleration in the heat of hydration flow curve compared to the control from both aggregates indicating increased hydration reactivity from the addition of foundry waste. The combination of foundry sand and reactive sand was found to increase ASR reactivity with increasing additions of foundry sand up to 30% replacement.

scholarly journals Effects of Mixing and Curing Temperature on the Strength Development and Pore Structure of Fly Ash Blended Mass Concrete

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Ki-Bong Park ◽  
Takafumi Noguchi
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Pore Structure ◽  
Weather Conditions ◽  
Strength Loss ◽  
Curing Temperature ◽  
Strength Development ◽  
Mass Concrete ◽  
Term Strength

The aim of this work is to know clearly the effects of temperature in response to curing condition, hydration heat, and outside weather conditions on the strength development of high-performance concrete. The concrete walls were designed using three different sizes and three different types of concrete. The experiments were conducted under typical summer and winter weather conditions. Temperature histories at different locations in the walls were recorded and the strength developments of concrete at those locations were measured. The main factors investigated that influence the strength developments of the obtained samples were the bound water contents, the hydration products, and the pore structure. Testing results indicated that the elevated summer temperatures did not affect the early-age strength gain of concrete made using ordinary Portland cement. Strength development was significantly increased at early ages in concrete made using belite-rich Portland cement or with the addition of fly ash. The elevated temperatures resulted in a long-term strength loss in both belite-rich and fly ash containing concrete. The long-term strength loss was caused by a reduction in the degree of hydration and an increase in the total porosity and amount of smaller pores in the material.

Effect of Slate Powder on Mineral Admixtures in Suppressing Alkali-Silica Reaction of Slate Aggregate

2012 ◽  
Vol 204-208 ◽  
pp. 4201-4206
Author(s):  
Xian Xiao Peng ◽  
Gu Hua Li ◽  
Wu Huang ◽  
Yuan Fu Li ◽  
Xiao Chun He
Keyword(s):  
Fly Ash ◽  
Mineral Admixtures ◽  
Alkali Silica Reaction ◽  
Steam Curing ◽  
Durability Design ◽  
Accelerated Mortar Bar Test ◽  
Bar Test ◽  
Curing Method ◽  
Mortar Bar ◽  
Powder Content

In order to study the effects of slate powder on mineral admixtures in suppressing ASR of slate aggregate, refer to the following methods: accelerated mortar bar test in “Standard for Constructional Quality Acceptance of Railway Concrete Engineering” TB10424-2010 and “Durability Design of Railway Concrete Structures” TB10005-2010, as well as an improved steam curing method. The text has studied the expansion of the specimens that are made from slate aggregate with different powder contents and specimens using slate powder as admixtures. The results show : When powder content in aggregate is less than 20%, it dose not have adverse effects; ASR of high-activity slate aggregate can be suppressed by using 30% fly ash and 5% silica fume as mineral admixtures; when the mineral admixtures are effective, a certain amount of powder mixed with admixtures can contribute to suppression; the main mechanism that slate powder can suppress ASR is that alkali in concrete can be consumed and physically diluted by slate powder.

Retardation Effects in the Hydration of Cement-Fly Ash Pastes

1984 ◽  
Vol 43 ◽  
Author(s):  
Michael W. Grutzeck ◽  
Wei Fajun ◽  
Della M. Roy
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Solid Phase ◽  
Heat Of Hydration ◽  
Type I ◽  
Fly Ashes ◽  
Solution Composition ◽  
Early Hydration ◽  
High Calcium ◽  
Phase Characterization

AbstractThe hydration of high-calcium and low-calcium fly ash-cementmixtures was investigated to determine the effect of fly ash upon the hydration of a Type I portland cement, and to determine the associated mechanisms of hydration. When blended with portland cement, both fly ashes retarded the early hydration process, the high-Ca more so than the low-Ca. Analyses of solution compositions and calorimetric (heat of hydration) measurements were made. The retardation and hydration effects are discussed in terms of solution composition data and solid phase characterization. The hydration effects were interpreted and compared with the results of previous work.

Sign in / Sign up

Export Citation Format

Share Document