scholarly journals Ultrasonic NDT determination of initial and final setting time of cement paste

2020 ◽  
Vol 310 ◽  
pp. 00027
Author(s):  
Petr Misák ◽  
Barbara Kucharczyková ◽  
Dalibor Kocáb ◽  
Tomáš Vymazal
Keyword(s):  
Cement Paste ◽  
Setting Time ◽  
High Variability ◽  
Final Setting Time ◽  
Setting Times ◽  
Innovative Method ◽  
Major Disadvantage ◽  
Measurement Results ◽  
Ultrasonic Ndt

There are several methods for determination of the setting and early hardening in the cementitious composites. The most common method is using the Vicat apparatus. The major disadvantage of this method is that it is invasive and therefore the measurement results exhibit high variability. The paper deals with the continual monitoring of the process of setting and early hardening of a cement paste using the ultrasonic measurement. The innovative method of using the ultrasonic NDT method for determination of the setting times of cement paste is presented in the paper.

Behaviour of Calcium Alkali Orthophosphate Cements under Simulated Implantation Conditions

2008 ◽  
Vol 396-398 ◽  
pp. 213-216 ◽  
Author(s):  
Daniela Jörn ◽  
Renate Gildenhaar ◽  
Georg Berger ◽  
Michael Stiller ◽  
Christine Knabe
Keyword(s):  
Compressive Strength ◽  
Simulated Body Fluid ◽  
Clinical Application ◽  
Body Fluid ◽  
Setting Time ◽  
Great Decrease ◽  
Final Setting Time ◽  
Laboratory Conditions ◽  
Setting Times

The setting behaviour, the compressive strength and the porosity of four calcium alkali orthophosphate cements were examined under laboratory conditions (dry) and under conditions similar to those during clinical application (37°C, contact with body fluid). The results showed an increase of the setting times when specimens were covered with simulated body fluid. Especially, the final setting time (FHZ) was significantly higher for three of the four cements. Furthermore, when specimens were stored in SBF for 16h, an extensive decrease of the compressive strength was noted. The porosity was more than twice as high after 16h in SBF and this may be the cause for the great decrease of the compressive strength.

scholarly journals Comparison of Effects of Sodium Bicarbonate and Sodium Carbonate on the Hydration and Properties of Portland Cement Paste

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1033 ◽  
Author(s):  
Yuli Wang ◽  
Fengxia He ◽  
Junjie Wang ◽  
Qianku Hu
Keyword(s):  
Compressive Strength ◽  
Sodium Bicarbonate ◽  
Portland Cement ◽  
Cement Paste ◽  
Sodium Carbonate ◽  
Ordinary Portland Cement ◽  
Setting Time ◽  
Sprayed Concrete ◽  
Final Setting Time ◽  
Portland Cement Paste

Carbonates and bicarbonates are two groups of accelerators which can be used in sprayed concrete. In this study, the effects of the two accelerators sodium carbonate (Na2CO3) and sodium bicarbonate (NaHCO3) (0%, 1%, 2%, 3%, and 4% by weight of ordinary Portland cement OPC) on the properties of OPC paste were compared. The results show that both of them could accelerate the initial and final setting time of OPC paste, but the effect of the two accelerators on the compressive strength were different. After 1 day, sodium bicarbonate at 3% had the highest strength while sodium carbonate at 1% had the highest strength. After 7 days, both of the two accelerators at 1% had the highest compressive strength. After 28 days, the compressive strength decreased with the increase of the two. The improved strength at 1 and 7 days was caused by the accelerated formation of ettringite and the formation of CaCO3 through the reactions between the two with portlandite. The decrease of strength was caused by the Na+ could reduce the adhesion between C-S-H gel by replacing the Ca2+. NaHCO3 was found be a better accelerator than Na2CO3.

Effect of Fly Ash and nanoCaCO3 on the Setting Time of Cement Paste

2013 ◽  
Vol 405-408 ◽  
pp. 2885-2888
Author(s):  
Zhi Qin Zhao ◽  
Zhi Ge ◽  
Ren Juan Sun ◽  
Gong Feng Xin ◽  
Da Wei Huang
Keyword(s):  
Experimental Study ◽  
Fly Ash ◽  
Cement Paste ◽  
Setting Time ◽  
Test Group ◽  
Cementitious Materials ◽  
Ash Content ◽  
Setting Times

This paper presents an experimental study to evaluate the effects of fly ash and nanoCaCO3 on setting time of cement paste. The test group included the contents of fly ash was 30%, 40%, 50%, 60% and content of nanoCaCO3 was 2.5%, 5%, 10%, 20%. Results indicate that setting time was increased with the incorporation of fly ash, shortened with the incorporation of nanoCaCO3. The incorporation of 5% nanoCaCO3 by mass of cementitious materials reduced initial and final setting times by 60 and 70 min, respectively. In comparison to the referenced paste with 40% fly ash. The best fly ash content appear to be 40% when nanoCaCO3 was added.

scholarly journals IMPACT OF MULTI-WALLED CARBON NANOTUBES ON WOOD SAWDUST EXTRACT CEMENT MORTAR

2019 ◽  
Vol 11 (4) ◽  
pp. 119-124
Author(s):  
Ekaterina Karpova ◽  
Gintautas Skripkiūnas ◽  
Grigory Yakovlev ◽  
Asta Kičaitė
Keyword(s):  
Carbon Nanotubes ◽  
Cement Paste ◽  
Cement Mortar ◽  
Setting Time ◽  
Final Setting Time ◽  
Wood Sawdust ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Mineral Additives ◽  
Time Density

It is well known that organic waste materials deteriorate the performance of concrete. The impregnation of organic aggregates and their application in combination with other chemical admixtures and mineral additives are used in order to improve the concrete properties in case of their modification by organic components. The current research is focused on the evaluation of impact of multi-walled carbon nanotubes (MWCNT) on the properties of cement systems prepared based on wood sawdust extract (WSE). The setting time, density, consistency, flexural and compressive strength, water absorption tests were undertaken. The retardation effect of (WSE) on the initial and final setting time of cement paste was observed. The additional modification of cement paste with WSE by MWCNT in the dosage of 0.005% by weight of cement (bwoc) did not show the significant changes in initial and final setting time. The application of MWCNT in the dosage of 0.005% bwoc contributed to the increase of early strength of cement mortar prepared with WSE.

scholarly journals HYDRATION AND MICROSTRUCTURAL PROPERTIES OF CEMENT PASTE CONTAINING NANO AND MICROSILICA

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
P. L. Chow ◽  
Salim Barbhuiya
Keyword(s):  
Cement Paste ◽  
Ordinary Portland Cement ◽  
Setting Time ◽  
Xrd Analysis ◽  
Hardened Cement ◽  
Microstructural Properties ◽  
Hydration Products ◽  
Hardened Cement Paste ◽  
Final Setting Time ◽  
Binder Ratio

The influence of nano-and microsilica addition on ordinary Portland cement (OPC) pastes has been studied in terms of hydration and microstructural properties. Three different combinations of nano-and microsilica mixes were used. A constant water-binder ratio of 0.35 was maintained throughout the experiment. All samples were tested for initial and final setting time and compressive strengths were determined at the age of 3, 7, 28, and 90 days of hydration. The hydration products were examined by SDT and XRD analysis at various curing ages. The inclusion of nano-and microsilica reduced the initial and final setting time significantly, increased the compressive strength of hardened cement paste after 7 days of hydration, and reduced the amount of calcium hydroxide in the hardened paste compared to mixes without these nanoparticles.

scholarly journals Setting time of construction gypsum, dental plaster, and white orthodontic gypsum

2020 ◽  
Vol 14 (3) ◽  
pp. 167-170
Author(s):  
Imelda Darmawan ◽  
Octarina Willy ◽  
Johan Arief Budiman
Keyword(s):  
Setting Time ◽  
Essential Property ◽  
Initial Setting Time ◽  
Final Setting Time ◽  
Setting Times ◽  
Initial Setting ◽  
Experimental Laboratory ◽  
Dental Plaster ◽  
Post Hoc ◽  
One Way Anova

Background. Dental plaster, white orthodontic gypsum, and construction gypsum have β-hemihydrate particles. Setting time is an essential property of dental gypsum, which can affect the strength of the material. This research aimed to compare construction gypsum, dental plaster, and white orthodontic gypsum’s initial and final setting times. Methods. Three groups were included in this experimental laboratory study: construction gypsum (A), dental plaster (B), and white orthodontic gypsum (C). Each group consisted of 10 samples. Gypsum manipulation consisted of using 120 gr of powder and 60 mL of water. Gypsum powder and water were mixed using a gypsum mixer at 120 rpm. A homogeneous mixture was poured into a mold, and the setting time was measured using a Gillmore needle, according to ASTM C266-03. The initial setting time test was measured using 113.4 grams and a 2.12-mm needle. The final setting time was measured using 453.6 grams and a 1.06-mm needle. This test was repeated until the needle failed to penetrate the gypsum’s surface. All the data were analyzed with one-way ANOVA and post hoc Tukey tests using SPSS 23. Results. The average initial setting time for groups A, B, and C were 10.39±1.19, 16.17±1.40, and 24.46±1.51, respectively. The average final setting time for groups A, B, and C were 15.97±0.79, 24.31±0.88) and 33.37±0.66, respectively. One-way ANOVA and post hoc Tukey tests showed significant differences in the initial and final setting times between the three groups (P<0.05). Conclusion. There were differences in setting time between dental plaster, white orthodontic gypsum, and construction gypsum. The construction gypsum’s setting time is suitable as a type II dental gypsum, according to ADA No.25.

The Influence of Alcohol Amine Admixtures on the Macroscopic Properties of Portland Cement Paste

2014 ◽  
Vol 525 ◽  
pp. 573-579
Author(s):  
Tian Yong Huang ◽  
Dong Min Wang ◽  
Ze Liu
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Portland Cement ◽  
Cement Paste ◽  
Setting Time ◽  
Initial Setting Time ◽  
Final Setting Time ◽  
Cement Mortars ◽  
Macroscopic Properties ◽  
Initial Setting

It is studied the influence of triethanolamine (TEA), diethylenetriamine (DEA), Triisopropanolamine (TIPA), aminoethyl ethanolamine (AE), and polyvinyl alcohol ammonium phosphate (PAAP) at different dosages on the properties of fresh and hardened cement pastes and mortars prepared by Portland cement, including standard consistency water, setting time, the cement paste fluidity, and compressive and flexural strength. It is showed that the high polarity alcohol amine molecules exhibit strong chemical interactions with cement matrix, which are reflected in modified macroscopic properties of the cement system. All alcohol amine admixtures increased the standard consistency water and decreased cement paste fluidity of Portland cement. TEA significantly shortened the initial setting time and final setting time of Portland cement. On the other hand, TIPA, DEA, AE and PAAP extended the initial setting time of cement but shortened the cement final setting time. All alcohol amine admixtures except TIPA at 0.2 and 0.5 dosage increased the compressive and flexural strength of the Portland cement mortars at 3 days. Especially when the dosage of PAAP is 1, the compressive strength of the Portland cement mortars at 3 days is increased 10.5MPa. All alcohol amine admixtures except AE at 0.2 and 0.5 dosage increase the compressive and flexural strength of the Portland cement mortars at 28 days, Especially when the dosage of TIPA is 1, the compressive strength of the Portland cement mortars at 28 days is increased 8.8MPa.

Influences of Mixing Procedure on Properties of Fresh Latex Modified Cement Paste(I)

2015 ◽  
Vol 1129 ◽  
pp. 530-537
Author(s):  
Dong Dong Han ◽  
Wei Deng Chen ◽  
Shi Yun Zhong
Keyword(s):  
Adsorption Isotherm ◽  
Cement Paste ◽  
Setting Time ◽  
Adsorption Behavior ◽  
Setting Times

In this study, influences of mixing procedure on the latex adsorption behavior, slurry fluidity and setting time of latex modified cement paste (LMCP) mixed with polycarboxylate (PC) as superplasticizer were analyzed. There were three kinds of mixing procedure: LMCP added latex later than PC (LMCP-L), LMCP added latex before PC (LMCP-B), LMCP added latex and PC simultaneously (LMCP-S). The results show that, the adsorption isotherm of SAE latex by cement grains fits the Langmiur type, and the presence of PC can affect the adsorption behavior. Regardless of the mlatex/mcement (4% or10%), LMCP-B had the highest amount of adsorbed latex and slurry fluidity while LMCP-L had the lowest. And, the LMCP-B also had the longest initial and final setting times, while the setting times of LMCP-L and LMCP-S were comparable.

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