Additives to cement pastes: Simultaneous effects on pore structure and corrosion of steel reinforcement

Gouda, V.K.; Mourad, W.E.; Mikhail, R. Sh.

doi:10.1016/0021-9797(73)90377-9

Cited by 13 publications

(3 citation statements)

References 8 publications

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“…Some authors reported that addition of CaCl 2 resulted in the coarsening of the pore structure or decrease in total porosity, [23][24][25][26] while others observed an increase in the pore volume, specifically in the range of nitrogen-accessible porosity. 27,28 Gouda et al 27 showed an increase in the volume of pores with radii of 1-6 nm (which was the extent of reported data) with 2% CaCl 2 addition, while Juenger and Jennings 28 observed that the addition of 1% CaCl 2 increases the volume of pores with radii of 1-40 nm. The disagreement regarding the effect of CaCl 2 on total porosity can be reconciled by the work of Ramachandran and Feldman 22 who showed that this effect is dosage dependent.…”

Section: Introductionmentioning

confidence: 84%

“…22 As for porosity, there are conflicting reports in the literature regarding the effect of CaCl 2 on porosity. 27,28 Gouda et al 27 showed an increase in the volume of pores with radii of 1-6 nm (which was the extent of reported data) with 2% CaCl 2 addition, while Juenger and Jennings 28 observed that the addition of 1% CaCl 2 increases the volume of pores with radii of 1-40 nm. 27,28 Gouda et al 27 showed an increase in the volume of pores with radii of 1-6 nm (which was the extent of reported data) with 2% CaCl 2 addition, while Juenger and Jennings 28 observed that the addition of 1% CaCl 2 increases the volume of pores with radii of 1-40 nm.…”

Section: Introductionmentioning

confidence: 85%

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Effect of Chloride‐Based Accelerator in the Presence of Water‐Reducing and Retarding Admixture on Autogenous Shrinkage

et al. 2016

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Rapid repair concrete mixtures commonly used for full‐depth concrete pavement repair sections can use large dosages of accelerating admixtures to increase strength gain rates and decrease the time to traffic opening. Most often, these mixtures also contain water‐reducing and retarding admixtures (WRRAs) to allow for the use of a low water–cementitious material ratio in order to meet strength requirements. The use of large dosages of accelerating admixtures in combination with retarding admixtures could have significant side effects on concrete. Autogenous shrinkage of low water–cementitious concrete can contribute to high tensile stresses and cracking problems. The effect of calcium chloride‐based accelerating admixture dosage, when used with WRRAs, on autogenous shrinkage was measured. It was found that the inclusion of calcium chloride‐containing accelerating admixtures has a nonlinear effect on the pore size distribution and consequently a nonlinear increase on the autogenous shrinkage.

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Section: Introductionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 85%

Effect of Chloride‐Based Accelerator in the Presence of Water‐Reducing and Retarding Admixture on Autogenous Shrinkage

et al. 2016

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“…Traditional accelerators of cement hydration include various inorganic salts, among which CaCl 2 is believed to be the most efficient and economical (Nelson et al 2006). However, usage of a CaCl 2 accelerator might increase the permeability of the set cement at later ages (compared to the same cement with no CaCl 2 ) and could possibly compromise its durability (Gouda et al 1973). The application of chloride accelerators also raises concerns about casing corrosion.…”

Section: Introductionmentioning

confidence: 99%

Nanosilicas as Accelerators in Oilwell Cementing at Low Temperatures

2014

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Accelerators are important cementing additives in deepwater wells where low temperatures can lengthen the wait-on-cement (WOC) time, potentially increasing the cost of operations. The cement set accelerators traditionally used for shortening WOC times are inorganic salts, such as CaCl 2 . These accelerators are known to have the potentially negative side effect of increasing the set cement permeability. Nanosilicas, on the other hand, can be advantageous compared to conventional cement set accelerators because they reduce the permeability while increasing the mechanical strength of cement-based materials. For this reason, nanosilicas are known to be particularly good candidates as replacement materials for traditional salt accelerators.This study investigates the feasibility of using different sizes and aspect ratios of nanosilicas as cement hydration accelerators under low-temperature conditions 59°F (15°). The nanosilica activities are herein defined through their comparative advantages with traditional accelerators as well as through the advantages and disadvantages of the different nanosilicas resulting from their various sizes and shapes. While hydration of oilwell cement is known to be accelerated by the addition of nanosilica, the effects of nanosilica particle shape on cement hydration kinetics has not been previously investigated. The isothermal calorimetry experiments conducted in this study reveal that just as smaller nanosilica particle sizes increase the cement set acceleration so do higher nanosilica aspect ratios.The effects of slurry density on the relative merits of CaCl 2 and nanosilica are also investigated. In regular-weight slurries, the effectiveness of nanosilica acceleration appears to be weaker than that of CaCl 2 , especially during early ages (≤ 3 days). In lightweight slurries, the effectiveness of nanosilica acceleration can be much stronger than that of CaCl 2 , especially when mid-to long-term properties (≥ 2 days) are considered. Smaller particle sizes and higher aspect ratios enhance the acceleration effect of nanosilica. The compressive strength development of lightweight oilwell cements with and without accelerators was also investigated. Lightweight cements accelerated with nanosilica displayed 7-day compressive strengths up to 136% higher than those accelerated with CaCl 2 .

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Effects of slag content, fineness and additive to cement pastes on the corrosion behaviour of embedded reinforcing steel

El-Sayed¹,

Shater²

1985

J. Chem. Tech. Biotechnol.

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Previous studies proved that the slag content of the blast furnace slag-Portland cement mix could be increased, while retaining the engineering properties of the produced slag cement pastes within the normal range and increasing the fineness of the mix. The corrosion behaviour of reinforcing steel embedded in the cement pastes giving the optimum mechanical properties was studied using the galvanostatic polarisation technique. The most corrosion-resistant mix has been determined. The effect of adding CaClz to a paste of this mix on the corrosion behaviour of embedded reinforcing steel has been investigated. For the purpose of comparison, anodic polarisation tests were carried out using pastes having the composition of the most corrosion-resistant mix but at the Blaine area of the ordinary slag cement. Portland and normal slag cements were also tested. The threshold concentration of CaCI2, below which breakdown of steel passivity did not occur, has been determined. The results of this study might have practical implications in the field.

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Additives to cement pastes: Simultaneous effects on pore structure and corrosion of steel reinforcement

Cited by 13 publications

References 8 publications

Effect of Chloride‐Based Accelerator in the Presence of Water‐Reducing and Retarding Admixture on Autogenous Shrinkage

Effect of Chloride‐Based Accelerator in the Presence of Water‐Reducing and Retarding Admixture on Autogenous Shrinkage

Nanosilicas as Accelerators in Oilwell Cementing at Low Temperatures

Effects of slag content, fineness and additive to cement pastes on the corrosion behaviour of embedded reinforcing steel

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