Influence of Hydration Time Prior to Carbonation in Portland Cement Admixed with CaO Expansive Additive

The mechanical strength change trend of Portland cement at different temperatures (+5°C, 0°C,-5°C,-10°C) was researched, and hydration performance and slurry structure of Portland cement was studied. Results showed that hydration process of Portland cement didn't vary with the lowering of curing temperature, but each stage of hydration time extended. The temperature decrease prolonged formation time of hydration products, making the early microstructure to loose, produces more pores, and causes the early mechanical strength of Portland cement to decrease.

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Effect of Curing Humidity on Stiffness of Cement Based Mortars with Recycled Fillers

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.825.19 ◽

2016 ◽

Vol 825 ◽

pp. 19-22

Author(s):

Mirek Jarolím ◽

Andrej Osvald ◽

Václav Nežerka ◽

Jaroslav Topič ◽

Richard Ťoupek ◽

...

Keyword(s):

Portland Cement ◽

Elastic Stiffness ◽

Cementitious Material ◽

Recycled Concrete ◽

Impulse Excitation ◽

The Relationship ◽

Non Destructive ◽

Influence Of Hydration ◽

Common Laboratory ◽

Secondary Hydration

Values of the dynamic Young’s modulus were monitored on cement-based samples containing recycled concrete. In particular, the study was focused on investigation of the relationship between the elastic stiffness and amount of recycled microfiller to replace Portland cement. The amount of the microfiller was ranging between 30 and 70 % per weight of the samples. The samples were cured in common laboratory conditions for 50 days, followed by their placement into a water bath for 2 days and consequent natural drying period for 6 days. The development of elastic stiffness was monitored using non-destructive impulse excitation method in order to demonstrate the influence of hydration when the specimens are stored in high humidity. The increase of elastic stiffness proves a secondary hydration of both – Portland cement and cement grains from the recycled cementitious material.

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Solubility behavior of Ca-, S-, Al-, and Si-bearing solid phases in Portland cement pore solutions as a function of hydration time

Cement and Concrete Research ◽

10.1016/s0008-8846(02)00855-4 ◽

2002 ◽

Vol 32 (10) ◽

pp. 1663-1671 ◽

Cited By ~ 113

Author(s):

David Rothstein ◽

Jeffrey J Thomas ◽

Bruce J Christensen ◽

Hamlin M Jennings

Keyword(s):

Portland Cement ◽

Hydration Time ◽

Solubility Behavior ◽

Solid Phases

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Evaluation of shrinkage and cracking in concrete of ring test by acoustic emission method

Modern Physics Letters B ◽

10.1142/s0217984915400333 ◽

2015 ◽

Vol 29 (06n07) ◽

pp. 1540033

Author(s):

Takeshi Watanabe ◽

Chikanori Hashimoto

Keyword(s):

Acoustic Emission ◽

Portland Cement ◽

Drying Shrinkage ◽

Length Change ◽

Ring Test ◽

Emission Method ◽

Expansive Additive ◽

Free Body ◽

Lime Stone ◽

Methods Of Measurement

Drying shrinkage of concrete is one of the typical problems related to reduce durability and defilation of concrete structures. Lime stone, expansive additive and low-heat Portland cement are used to reduce drying shrinkage in Japan. Drying shrinkage is commonly evaluated by methods of measurement for length change of mortar and concrete. In these methods, there is detected strain due to drying shrinkage of free body, although visible cracking does not occur. In this study, the ring test was employed to detect strain and age cracking of concrete. The acoustic emission (AE) method was adopted to detect micro cracking due to shrinkage. It was recognized that in concrete using lime stone, expansive additive and low-heat Portland cement are effective to decrease drying shrinkage and visible cracking. Micro cracking due to shrinkage of this concrete was detected and evaluated by the AE method.

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