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.

Composites of Portland Cement and Natural Polymers

2005 ◽  
Vol 498-499 ◽  
pp. 407-412 ◽  
Author(s):  
Ulisses Targino Bezerra ◽  
Antonio Eduardo Martinelli ◽  
D.M.A. Melo ◽  
D.M. Henrique ◽  
E.M. Rodrigues ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Portland Cement ◽  
Environmentally Friendly ◽  
Hardened Cement ◽  
Oil Well ◽  
Natural Polymer ◽  
Natural Polymers ◽  
Cement Pastes ◽  
Preliminary Results ◽  
Hardened Cement Pastes

The tensile strength of Portland cement may be increased by additional reinforcement. This is usually accomplished by means of steel rods, fibers or particles, which are mixed to the slurry. In an attempt of increasing toughness and tensile strength of hardened cement pastes, the present work describes the behavior of composites consisting of Portland reinforced by natural polymer particles for oil well cementing. The main purpose of the study was to select plastic and environmentally friendly powdered materials capable of filling the typical porosity developed on hardened Portland cement. Preliminary results suggested that the tensile strength of plain Portland hardened slurries could be increased by as much as 40% by adding 10% of reinforcement.

OPTIMAL CRITERIA OF ALGERIAN BLENDED CEMENT USING LIMESTONE FINES/ALŽYRIETIŠKAS MIŠRUSIS CEMENTAS SU MALTU KALKAKMENIU

2008 ◽  
Vol 14 (4) ◽  
pp. 269-275 ◽  
Author(s):  
Z’hor Guemmadi ◽  
Musa Resheidat ◽  
Hacéne Houari ◽  
Belkacem Toumi
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Blended Cement ◽  
Total Porosity ◽  
Hardened Cement ◽  
Compact Structure ◽  
Limestone Filler ◽  
Cement Pastes ◽  
Limestone Fines ◽  
Hardened Cement Pastes

The effect of substitution of Portland cement by limestone up to 40% as well as its fineness on the physico‐mechanical properties of fresh and hardened cement pastes is studied. The binder was prepared by substitution of cement by limestone filler. Fillers were chosen of various particle sizes and with percentages from 5 to 40. Test results revealed that the replacement of Portland cement by the finest filler of limestone slightly decreases the consistency and the setting times (initial and final). The total porosity decreases and accordingly the compressive strength is improved with the content and fines of limestone. Although limestone has a little accelerating effect on the hydration process of Portland cement, but acts only as a filler reducing the porosity due to its compact structure, in which the compressive strength of the hardened cement paste is enhanced. The XRD and DTA analyses of samples cured up to 28 days showed that this amelioration is due to formation of new hydrated compounds. It is concluded that an addition of finely ground limestone filler only up to 15% gives a better strength. Santrauka Tirtos šviežios ir sukietėjusios cementinės tešlos, kurioje iki 40 % cemento pakeista įvairaus smulkumo maltu kalkakmeniu, savybės. Rišiklis buvo paruoštas dalį cemento pakeitus maltu kalkakmenio užpildu. Užpildo dalelės buvo įvairaus dydžio, o jų kiekis buvo keičiamas nuo 5 % iki 40 %. Tyrimai parodė, kad priedas leidžia sumažinti vandens kiekį, reikalingą tos pačios konsistencijos mišiniui gauti, taip pat cemento rišimosi pradžiai ir pabaigai paankstinti. Sumažėja cementinio akmens suminis poringumas ir atitinkamai padidėja stipris gniuždant cementinio akmens, kuriame yra kalkakmenio priedų. Nors kalkakmenio priedas nedaug pagreitina portlandcemenčio hidratacijos procesą, tačiau veikia kaip užpildas, sutankinantis struktūrą, dėl to labai padidėja sukietėjusio cementinio akmens stipris gniuždant. Bandinių, išlaikytų 28 dienas, rentgenostruktūrinė ir diferencinė terminė analizė parodė, kad pagerėjimas yra dėl susidariusių naujadarų. Apibendrinant galima teigti, kad 15 % malto kalkakmenio priedas turi didžiausią įtaką stiprumo rezultatams.

scholarly journals Studies of Surface Area and Pore Structure on Portland Cement Produced in Bajil and Amran, Yemen

2008 ◽  
Vol 13 ◽  
pp. 13
Author(s):  
A.M. Saad ◽  
Abdul-Basit A. Saleh ◽  
Fatima A. Al-Kadri ◽  
Abdulla S. Babaqi ◽  
Abdulla A. Basissa ◽  
...  
Keyword(s):  
Portland Cement ◽  
Pore Structure ◽  
Hysteresis Loops ◽  
Hardened Cement ◽  
Pore System ◽  
Nitrogen Gas ◽  
Time Intervals ◽  
Cement Pastes ◽  
Adsorption Desorption ◽  
Hardened Cement Pastes

Portland cement pastes of various porosities were prepared using water/cement ratios of 0.30, 0.35, 0.40, 0.45, 0.50 and 0.55; and were hydrated for various time intervals ranging from 0.021 to 28 days.  Pore structure and VL–t plots (plots of volume vs. thickness) of the hardened cement pastes were measured using nitrogen gas as the adsorbate. The results were found to be related to the mechanism of hydration as controlled by the pore system of the hardened pastes. Type ІІ adsorption isotherms of nitrogen were obtained for all hardened cement pastes. The adsorption-desorption isotherms indicated the existence of closed hysteresis loops for most of the investigated samples and in some other cases, these isotherms were fully reversible.  

scholarly journals Effect of Mineral Composition and w/c Ratios to the Growth of AFt during Cement Hydration by In-Situ Powder X-ray Diffraction Analysis

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4963
Author(s):  
Bo Chen ◽  
Yongming Zhang ◽  
Qing Chen ◽  
Fei Yang ◽  
Xianping Liu ◽  
...  
Keyword(s):  
Portland Cement ◽  
Cement Hydration ◽  
Hardened Cement ◽  
X Ray Diffraction ◽  
Cement Pastes ◽  
X Ray ◽  
Hardened Cement Pastes ◽  
Maximum Content ◽  
Very High

AFt is one of the major products at the early stage of cement hydration. It is an important product that influences the performance of the fresh and hardened cement pastes such as the setting time. However, there is a lack of detailed investigation on the growth of AFt in the cement pastes with a long-time scale. In this work, we reported a detailed analysis by using in-situ powder X-ray diffraction (XRD) on the growth of AFt in the cement pastes during hydration. Samples of the hydrated ordinary Portland cement (OPC) and another locally produced Portland cement with very high tricalcium silicate (C3S) content with different water–cement (w/c) ratios were investigated continually till they were hydrated for about 270 days by powder XRD. The work shows that during Portland cement hydration, the AFt reaches its maximum content with very high speed within about 24 h, which is influenced by the content of C3S in the raw cement samples and the w/c ratios of the cement pastes. Once the maximum content of AFt was reached, it decreases very fast within the following couple of days, and then decreases slowly and finally reaches a stable level at the late stage of hydration. The results also present that a lower w/c ratio is beneficial to the formation of AFt and the conversion of AFt to AFm as well. While higher w/c ratios are favorable for the AFt to remain stable in the hardened cement pastes.

scholarly journals The Influence of Zeolitic By-Product Containing Ammonium Ions on Properties of Hardened Cement Paste

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 123
Author(s):  
Danutė Vaičiukynienė ◽  
Agnė Mikelionienė ◽  
Aras Kantautas ◽  
Algirdas Radzevičius ◽  
Diana Bajare
Keyword(s):  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Petroleum Industry ◽  
Pozzolanic Reaction ◽  
Strength Development ◽  
Hardened Cement ◽  
Reaction Products ◽  
Ammonium Ions ◽  
Cement Pastes ◽  
By Products

Fluid catalytic cracking (FCC) catalysts, used in the petroleum industry, are sources of zeolitic by-products. These by-products are often used as sorbents for the removal of ammonium ions from wastewater. After a period of use, the zeolitic by-product loses its sorption properties and is no longer effective. The problem is the use of zeolitic by-product with ammonium ions. In this study, a zeolitic by-product containing ammonium ions and high contents of active SiO2 and Al2O3 was used as a supplementary cementitious material (SCM). Cement pastes containing 0.5%, 1%, 3%, 5%, and 10% of the by-product were prepared, and the compressive strength and density of the pastes were evaluated. Incorporation of the zeolitic by-product increased the cement strength by 17% and 32% after 7 and 28 days of hydration, respectively. Thus, incorporation of the zeolitic by-product with ammonium ions as an SCM has a complex effect on an ordinary Portland cement (OPC) system. Ammonium chloride accelerated cement setting after 7 days of hydration, and the pozzolanic reaction positively affected strength development after 28 days of hydration. The reaction products caused the cement to have a compact microstructure. The zeolitic by-product containing absorbed ammonium ions can be successfully reused to replace ordinary Portland cement in cement pastes.

PIEZOELECTRIC PROPERTIES OF POLY(3-HYDROXYBUTYRATE-CO-3-HEDROXYBUTYRATE)-CO-POLY(ETHYLENE GLYCOL) PRODUCED BY CONTROLLED MICROBIOLOGICAL BIOSYNTHESIS

2019 ◽  
Vol 10 (10) ◽  
Author(s):  
Anton Bonartsev ◽  
Vera Voinova ◽  
Elizaveta Akoulina ◽  
Andrey Dudun ◽  
Irina Zharkova ◽  
...  
Keyword(s):  
Ethylene Glycol ◽  
Piezoelectric Properties ◽  
Poly Ethylene Glycol ◽  
Poly Ethylene

Thermosensitives hydrogels based on poly (ethylene glycol): I. Synthesis, characterization and release

2007 ◽  
Vol 32 (5) ◽  
pp. 431-446 ◽  
Author(s):  
Tahar Bartil ◽  
Mahmoud Bounekhel ◽  
Cedric Calberg ◽  
Robert Jerome
Keyword(s):  
Ethylene Glycol ◽  
Poly Ethylene Glycol ◽  
Poly Ethylene
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