Internal curing by superabsorbent polymers in ultra-high performance concrete

“…However, the initial moisture of the LWA also influences the properties of concrete at both the fresh state and the hardened state [4,6,7]. Recently, the use of SAP in concrete has been studied to limit the internal relative humidity decrease and the autogenous shrinkage [8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

“…Expansive agents are used to provide early-age expansion to compensate drying shrinkage [14,15]. Internal curing materials are also used to supply internal water for hydration and reduce the autogenous shrinkage in concrete in some studies [4,5,[8][9][10][11]. However, the external curing of concrete is still not preferred because good practices are usually ignored by the workers at many construction sites.…”

Section: Introductionmentioning

confidence: 99%

Influence of Bottom Ashes with Different Water Retainabilities on Properties of Expansive Mortars and Expansive Concretes

Nguyen¹,

Saengsoy²,

Tangtermsirikul³

2019

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This study investigates the influence of bottom ashes with different water retainabilities as an internal curing material on the performances of mixtures containing an expansive additive and fly ash. Two series of experiments were conducted: mortar containing expansive agent (expansive mortar) with a controlled w/b ratio and concrete containing expansive agent (expansive concrete) with a controlled initial slump. Test results indicate that workability of expansive mortar is improved due to retained water of bottom ash. Compressive strength of expansive mortar with bottom ash decreases. Total shrinkage of the expansive mortars, with a constant w/b, increases with the use of bottom ashes that have high water retainability in the condition of 7 days of water curing and then air curing. However, by using bottom ashes, compressive strength increases when the slump of the expansive concrete is controlled due to decrease of w/b ratio. The internal curing ability of bottom ashes leads to enhanced expansion of expansive mortars with sealed curing and expansive concretes with moist curing, reducing total shrinkage of expansive mortars with air curing. It was found by DTG analysis that expansive concretes with higher expansion containing bottom ash with higher water retainability had a higher amount of ettringite.

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“…Due to the brittleness of cement, many well operations could lead to integrity failure [3]. Superabsorbent polymers (SAP) have been used in cement for many functions [5][6][7][8][9]. Superabsorbent polymers (SAP) have been used in cement for many functions [5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Self-Plugging Technology of Microcrack with Water in Cement Sheath

Liu

2016

Day 4 Fri, March 25, 2016

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Cement is the main material used to seal wells which are drilled for the production of oil and gas. However, many well operations could induce cement sheath to crack and hence, lose zonal isolation. The research objectives in this paper are designed to realize the application of superabsorbent polymer (SAP) in well cement to plug the microcrack.Since SAP is highly reactive with water, if SAP is used directly, the cement slurry will have a too high viscosity for pumping in favorable conditions. Therefore, SAP microspheres which were coated were applied. The method of manufacturing quantitative microcrack was established by using the chisel and transparent plastic tube, and the self-designed instrument was taken to test the self-plugging performance of microcrack. Based on the percolation theory, the percolation analysis of microcrack plane flow was carried out. The distribution model of coated SAP microspheres in cement paste was established, which could ensure SAP microspheres exist in any microcrack plane.Finally, the gypsum-chitosan-gypsum coated SAP is proposed. Microscopic analysis and percolation theory are combined to research the plugging microcrack mechanism. And according to the exact analytical solution of plane percolation threshold, the dosage threshold of coated SAP microspheres which can realize the self-plugging performance of microcrack is 28.40%. The cement slurry whose basic performance met the demand of cementing engineering was developed to test the self-plugging performance of microcrack with water, and the results show that when the dosage of coated SAP microspheres is higher than the threshold, microcrack could be plugged.In this paper, the percolation theory was first used to design the cement slurry. The application of coated SAP can effectively seal the microcrack in cement sheath, which is of great significance to guarantee the long-term sealing performance of cement sheath.

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Internal curing by superabsorbent polymers in ultra-high performance concrete

Cited by 431 publications

References 35 publications

Internal curing of alkali-activated fly ash-slag pastes using superabsorbent polymer

Internal curing of alkali-activated fly ash-slag pastes using superabsorbent polymer

Influence of Bottom Ashes with Different Water Retainabilities on Properties of Expansive Mortars and Expansive Concretes

Self-Plugging Technology of Microcrack with Water in Cement Sheath

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