Nanoindentation as a tool to measure and map mechanical properties of hardened cement pastes

2015 ◽  
Vol 5 (1) ◽  
pp. 83-87 ◽  
Author(s):  
Chuanlin Hu
Keyword(s):  
Mechanical Properties ◽  
Hardened Cement ◽  
Cement Pastes ◽  
Image Position ◽  
Hardened Cement Pastes

Abstract

Cement in the context of new materials for an energy-expensive future

1983 ◽  
Vol 310 (1511) ◽  
pp. 31-42 ◽  
Keyword(s):  
Mechanical Properties ◽  
Large Scale ◽  
High Strength ◽  
Hardened Cement ◽  
New Materials ◽  
Biological Origin ◽  
Cement Pastes ◽  
Inorganic Solids ◽  
Mild Conditions ◽  
Hardened Cement Pastes

Hydraulic cements are energy-cheap relative to other common materials, are manufactured on a large scale and, when mixed with water, form readily mouldable pastes that harden at low temperature. In a technological sense, such pastes can be regarded as inorganic ‘plastics’, but the types of article that can usually be fabricated from the cements has been restricted by the low tensile strength and fracture toughness of hardened cement pastes. Poor mechanical properties are not inherent in inorganic solids formed under mild conditions; mineral structures of biological origin can display relatively high strength and useful toughness as a result of microstructural features determined by biopolymers. Recent studies have shown that the low tensile properties of cement paste result from the presence of macroscopic pores. The elimination of such defects by the use of polymeric rheology modifiers gives unreinforced cement pastes a flexural strength of 150 MPa or more. Such novel materials should considerably extend the range of uses for hydraulic cements.

scholarly journals Studying physico-mechanical properties of cement pastes in presences of blend polymer as chemical admixtures

2015 ◽  
Vol 4 (3) ◽  
pp. 297 ◽  
Author(s):  
Elsayed Negim ◽  
G. Yeligbayeva ◽  
Rimma Niyazbekova ◽  
R. Rakhmetullayeva ◽  
A.A Mamutova ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Setting Time ◽  
Hardened Cement ◽  
Sem Images ◽  
Cement Pastes ◽  
Setting Times ◽  
Blend Ratios ◽  
Hardened Cement Pastes ◽  
Blend Polymer

<p>Physico-mechanical properties of cement pastes were studied by setting time, combined water, compressive strength, SEM as well as porosity in presence of blend polymers. Blend polymers were used based on polyvinyl alcohol and carbamide with blend ratios 20/80, 40/60 and 80/20 respectively. The addition of blend polymers to cement pastes affected the physico-mechanical properties of cement pastes. As the content of carbamide in the polymer blends decreased, the water of consistency decreased, whereas the setting times (initial &amp; final) were elongated. The combined water content and compressive strength of the hardened cement pastes were increased at all ages of hydration. The SEM images showed that the addition of these polymers to cement material improves the dispensability and workability of cement pastes.</p>

scholarly journals Multiscale Modeling of Elastic Properties of Sustainable Concretes by Microstructural-Based Micromechanics

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
V. Zanjani Zadeh ◽  
C. P. Bobko
Keyword(s):  
Mechanical Properties ◽  
Elastic Properties ◽  
Multiscale Modeling ◽  
Analytical Methods ◽  
Hardened Cement ◽  
Cement Pastes ◽  
Sustainable Concrete ◽  
Concrete Mixtures ◽  
Self Consistent ◽  
Hardened Cement Pastes

This paper addresses multiscale stiffness homogenization methodology to extract macroscale elastic mechanical properties of four types of sustainable concretes from their nanoscale mechanical properties. Nine different sustainable concrete mixtures were studied. A model based on micromechanics was used to homogenize the elastic properties. The hardened cement pastes were homogenized by three analytical methods based on Self-Consistent and Mori-Tanaka schemes. The proposed multiscale method combines advanced experimental and analytical methods in a systematic way so that the inputs are nanoscale phases properties extracted from statistical nanoindentation technique and mechanical properties of mixture ingredient. Predicted elastic properties were consistent with traditional experimental results. Linking homogenized mechanical properties of sustainable concrete to volume proportions through an analytical approach provides a critical first step towards rational optimization of these materials.

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

2005 ◽  
Vol 23 (3) ◽  
pp. 245-254 ◽  
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.

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

2010 ◽  
Vol 177 ◽  
pp. 506-509 ◽  
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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