Effects of water-to-cement ratio and curing age on microscopic creep and creep recovery of hardened cement pastes by microindentation

AbstractEffects of NH4NO3, CH3COOH and HCOOH solutions on the pore structure and other properties of hardened cement pastes made out of portland, slag, and fly ash cements at different water-to-cement ratios are discussed.Total porosity and the volume of pores detectable by mercury intrusion porosimetry (MIP) increased with increasing water-to-cement ratio, concentration of aggressive solution, and time of immersion. The weight, bulk density, and compressive strenath of the samples decreased at the same time. Use of blended cements did not result in improvement of the long-term durability of the samples. The degradation of the cement pastes increased from NH4NO3 to CH3COOH to HCOOH.

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Rehydration Performance of Binary Binders Made with Dehydrated Cement Paste and Phosphogypsum

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.474-476.1238 ◽

2011 ◽

Vol 474-476 ◽

pp. 1238-1242 ◽

Cited By ~ 1

Author(s):

Tao Sun ◽

Zhong He Shui ◽

Tao Huo

Keyword(s):

Cement Paste ◽

Structural Characteristics ◽

Setting Time ◽

Physical And Mechanical Properties ◽

Hardened Cement ◽

Initial Water ◽

Cement Pastes ◽

Hydrated Calcium Silicate ◽

Water To Cement Ratio ◽

Hardened Cement Pastes

This paper presents the rehydration performance of binary binders made with dehydrated cement paste (DCP) and phosphogypsum (GP). DCP was obtained by thermal treatment of hardened cement pastes in which the initial water to cement ratio was 0.5. DCP we mixed with phosphogypsum (PG) to prepare the binary binders . The effect of PG on the physical and mechanical properties of the binary binders was investigated. Scanning electron microscope (SEM) was used to indentify the structural characteristics of the rehydration products. The results showed that the setting time was prolonged and the compressive strength increased slightly by mixing DCP with PG. Microstructural observations indicated that an remarkable amount of ettringite intergrows with the hydrated calcium silicate to form a network structure. Thus, the addition of phosphogypsum can not only utilize the industrial by-product, but enhances the hydraulic properties of the DCP.

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Effect of Some Acrylate—Poly(Ethylene Glycol) Copolymers as Superplasticizers on the Mechanical and Surface Properties of Portland Cement Pastes

Adsorption Science & Technology ◽

10.1260/0263617054353645 ◽

2005 ◽

Vol 23 (3) ◽

pp. 245-254 ◽

Cited By ~ 18

Author(s):

S.A. Abo-El-Enein ◽

S. Hanafi ◽

F.I. El-Hosiny ◽

El-Said H.M. El-Mosallamy ◽

M.S. Amin

Keyword(s):

Ethylene Glycol ◽

Portland Cement ◽

Ordinary Portland Cement ◽

Mechanical Characteristics ◽

Hardened Cement ◽

Poly Ethylene Glycol ◽

Cement Pastes ◽

Surface Areas ◽

Poly Ethylene ◽

Hardened Cement Pastes

Ordinary Portland cement (OPC) pastes with added superplasticizer were made using water/cement weight ratios of standard consistency. Three types of superplasticizer based on acrylate—poly(ethylene glycol) copolymers were used. The pastes were hydrated for various time lengths and the mechanical characteristics of the hardened cement pastes were studied and related to their pore structures. It was found that the addition of the superplasticizers to OPC improved the mechanical properties of the hardened pastes for all hydration lengths. The addition of such superplasticizers to OPC resulted in a decrease in the specific surface areas and total pore volumes of the hardened superplasticized cement pastes relative to the corresponding hardened neat cement pastes.

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Assessment of Anhydrous Ethanol Extraction to Determine the Ionic Concentration of Hardened Cement Pastes

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.177.506 ◽

2010 ◽

Vol 177 ◽

pp. 506-509 ◽

Cited By ~ 1

Author(s):

Man Jian Wu ◽

Wu Yao ◽

Wei Wang ◽

Yong Qi Wei

Keyword(s):

Pore Solution ◽

Ph Value ◽

Ionic Concentration ◽

Anhydrous Ethanol ◽

Hardened Cement ◽

Cement Pastes ◽

Ethanol Extraction ◽

Alkali Ions ◽

Ph Values ◽

Hardened Cement Pastes

A new method involving the extraction of various ions from hardened cement pastes by anhydrous ethanol is presented to determine the pH value and ionic concentration during the first 28 days. The volume content of pore solution extracted by ethanol in the leachate reached 12% or above and the pH values calculated by alkali ions are more than 12, even up to 12.73. The results were compared with those from parallel, conventional pore water expression experiments. All of these comparisons verified the feasibility of the proposed method. However, the application of this method to pore solution analysis needs further improvement.

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