scholarly journals Characterization, Antimicrobial Effects, and Cytocompatibility of a Root Canal Sealer Produced by Pozzolan Reaction between Calcium Hydroxide and Silica

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2863
Author(s):  
Mi-Ah Kim ◽  
Vinicius Rosa ◽  
Prasanna Neelakantan ◽  
Yun-Chan Hwang ◽  
Kyung-San Min
Keyword(s):  
Calcium Hydroxide ◽  
Root Canal ◽  
Calcium Silicate ◽  
Antibacterial Effect ◽  
Setting Time ◽  
X Ray Diffraction ◽  
Initial Setting Time ◽  
Colony Forming Units ◽  
Scratch Wound ◽  
Initial Setting

This study aimed to evaluate a newly developed pozzolan-based bioceramic sealer (PZBS) regarding setting time, radiopacity, antibacterial effect, and cytocompatibility. The PZBS was manufactured by mixing calcium hydroxide and silica. The pozzolan reaction was verified by identification of calcium silicate hydrate (C-S-H) using X-ray diffraction analysis. The initial setting time and radiopacity were measured using the ISO 6876/2012 protocol in comparison with other commercially available calcium silicate (CS) sealers. The antibacterial effect of PZBS on biofilms cultured in the bovine root canal was evaluated by measurement of colony-forming units and volume of biofilms in comparison with other calcium hydroxide pastes. The morphological features of the biofilms were observed by scanning electron microscopy (SEM). The cytocompatibility of PZBS was assessed by the viability of bone marrow–derived mesenchymal stem cells and scratch wound healing rate in comparison with other CS sealers. The morphology of the cells cultured on the tested sealers was observed by SEM. The detection of the CS peak confirmed the formation of C-S-H. The initial setting time of PZBS was around 11 h, which was twice as long as the other tested sealers. The radiopacity of PZBS was 4.3 mm/Al, which satisfied the ISO criteria. The antibacterial effect and cytocompatibility of PZBS were comparable to those of the commercially available intracanal medicaments and CS endodontic sealers, respectively. The PZBS has the potential to be used for root canal obturation, and is expected to exert a favorable antibacterial effect.

Modification Effects of Nano-CaCO3 on Engineering Performance of Cement Grouts

2020 ◽  
Vol 20 (8) ◽  
pp. 5043-5048
Author(s):  
Xiang Qiu ◽  
Huangbin Jiang ◽  
Guijin Zhang
Keyword(s):  
Yield Stress ◽  
Cement Hydration ◽  
Setting Time ◽  
X Ray Diffraction ◽  
Bleeding Rate ◽  
X Ray ◽  
Initial Setting Time ◽  
Study Results ◽  
Initial Setting ◽  
Cement Grouts

Efficacy of added nano-CaCO3 (NC) on engineering performances, including fluidity, initial setting time, bleeding rate and yield stress of cement grouts was investigated in this study. Results showed that the fluidity and bleeding rate for NC-cement (NCC) composite grout first decreased with increased NC content (i.e., ratio of NC mass to cement mass) and then slightly recovered as the NC content exceeded 2%. The initial setting time was always reduced while the yield stress increased with increased NC content. The microstructure of NCC was analyzed by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was found that the NC can promote the cement hydration, but an excess amount of NC will inhibit the cement hydration and affect the engineering performances of cement grouts. The optimum NC content for modification of cement grouts was thus 2%.

scholarly journals Effect of Naphthalene-Based Superplasticizer and Polycarboxylic Acid Superplasticizer on the Properties of Sulfoaluminate Cement

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 662
Author(s):  
Yonghua Wu ◽  
Qiqi Li ◽  
Guoxin Li ◽  
Shiying Tang ◽  
Mengdie Niu ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Setting Time ◽  
Hydration Products ◽  
Polycarboxylic Acid ◽  
X Ray Diffraction ◽  
Calcium Sulfoaluminate Cement ◽  
X Ray ◽  
Initial Setting Time ◽  
Calcium Sulfoaluminate ◽  
Initial Setting

In order to study what the effect of superplasticizers on the setting time, fluidity and compressive strength of calcium sulfoaluminate cement (CSA) a naphthalene-based superplasticizer (BNS) and a polycarboxylic acid superplasticizer (PC) were selected to interact with CSA pastes and ye’elimite, respectively. X-ray diffraction (XRD), thermogravimetric (TG) analysis and scanning electron microscopy (SEM) analytical methods were used to investigate the class, amount and microstructure of the CSA pastes and ye’elimite pastes hydration products under the effect of the superplasticizers. The results showed that the addition of BNS can promote ettringite generation and thus improve the early compressive strength. As the addition of BNS increased from 0.8 wt% to 2.0 wt%, the initial setting time was prolonged 10 min, the final setting time was prolonged 7 min, the 5 min fluidity was improved from no fluidity to 220 mm. However, as the addition of PC increased from 0.08 wt% to 0.20 wt%, the setting time of the PC just changed within 3 min; the 5 min fluidity increased from 110 mm to 195 mm and no 15 min fluidity at all was observed. AS seen by SEM, it can be stated that generated ettringite under the addition of PC was layered and lacking bonding, and its morphology changed from rod-like to flake-like, leading to a decrease in early compressive strength.

scholarly journals Durability and Microstructure Properties of Concrete with Arabic Gum Biopolymer Admixture

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Abdeliazim Mustafa Mohamed ◽  
Mohd Hanim Osman ◽  
Hichem Smaoui ◽  
Mohd Azreen Mohd Ariffin
Keyword(s):  
Setting Time ◽  
Hardened Concrete ◽  
X Ray Diffraction ◽  
Arabic Gum ◽  
X Ray ◽  
Initial Setting Time ◽  
Objective Evidence ◽  
Flow Table ◽  
Mechanical And Physical Properties ◽  
Initial Setting

Arabic gum biopolymer (AGB) has recently been demonstrated to improve mechanical and physical properties of fresh and hardened concrete which makes it a promising sustainable and environmentally friendly water-reducing admixture. The present work focuses on the effect of added AGB on the workability, setting time, and durability of concrete. Furthermore, a microstructure analysis is conducted to provide objective evidence and support for previous findings and hypothetic interpretations. Flow table experiments are conducted on Portland cement mortar mixed with different percentages of AGB to evaluate the workability. The initial setting time of cement paste is measured for different AGB contents. X-ray fluorescence tests are performed on cement-AGB mix powder to determine its chemical composition. Carbonation depth in AGB concrete samples is estimated to assess durability. AGB-added cement powder was subjected to X-ray diffraction and SEM tests to determine the rate of hydration and to expose the microstructure properties of AGB cement mix and help explain its macroscopic behavior, respectively.

scholarly journals Influence of Ultrafine Natural Steatite Powder on Setting Time and Strength Development of Cement

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
K. Sudalaimani ◽  
M. Shanmugasundaram
Keyword(s):  
Compressive Strength ◽  
Setting Time ◽  
Element Distribution ◽  
Strength Development ◽  
X Ray Diffraction ◽  
Dormant Period ◽  
Initial Setting Time ◽  
Final Setting Time ◽  
Initial Setting ◽  
Cement Binder

This paper deals with the setting time and pozzolanic activity of cement when ultra fine natural steatite powder (UFNSP) is used as replacement for cement. Initial setting time, final setting time, and mortar cube strength were studied, due to the replacement of ultra fine natural steatite powder with cement at 5%, 10%, 15%, 20%, and 25% by mass of cement. The setting time of fresh cement-binder paste and compressive strength of mortar cubes are observed. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were applied to investigate the microstructural behaviour and chemical element distribution inside cement-binder matrix. Results indicate that the length of dormant period is shortened. The replacement of ultra fine natural steatite powder with cement reduces initial setting time, and final setting time and increases mortar cube compressive strength.

The Influence of Steel Slag on Phosphorous Slag Cement

2012 ◽  
Vol 509 ◽  
pp. 106-112 ◽  
Author(s):  
Qian Zhao ◽  
You Wu
Keyword(s):  
Setting Time ◽  
Steel Slag ◽  
X Ray Diffraction ◽  
Slag Cement ◽  
Early Hydration ◽  
Initial Setting Time ◽  
Initial Setting ◽  
Cement Strength ◽  
Grinding Power ◽  
Phosphorous Slag

In this paper, the influence of steel slag and its pretreatment method on properties of phosphorus slag cement has been studied. The hydration process and microstructure were studied by X-ray diffraction (XRD) and scanning electronic microscopy (SEM). Results show that, the problem of long setting time of high content phosphorous slag cement can be effectively solved by adding steel slag and pretreated steel slag. About 6% content of steel slag could promote the early hydration of phosphorus slag cement and reduced the initial setting time 2 hours. Grinding phosphorous slag and steel slag with different water content, the initial set time of phosphorus slag cement for 6 hours has reduced to 2.5 hours without changing the strength. Ageing the mixed grinding power of phosphorous slag and steel slag and keeping 2.5 hours of the initial set time, the early cement strength can increase 3 MPa.

Behavior of Cement Pastes and Mortar Containing Phosphogypsum

2015 ◽  
Vol 668 ◽  
pp. 181-188 ◽  
Author(s):  
Hanan El Nouhy ◽  
Enas Khattab ◽  
Sayieda Zeedan
Keyword(s):  
Compressive Strength ◽  
Setting Time ◽  
Blended Cement ◽  
X Ray Diffraction ◽  
Cement Pastes ◽  
Initial Setting Time ◽  
Second Stage ◽  
Setting Times ◽  
Initial Setting ◽  
Two Stages

The aim of this study is to investigate the effects of phosphogypsum on the properties of both cement pastes and mortars. Normal Portland cement CEM Ι 32,5N, Limestone Blended cement CEM ΙΙ B-L32,5N, and Slag cement CEM ΙΙ A-S32,5N were used. These cements were partially substituted by 0,2,4,6,8,10,and 15% of phosphogypsum. The test program was divided to two stages. In the first stage, tests were conducted according to BSEN 196, namely setting times (initial and final), soundness, and compressive strength (at ages 7 and 28 days). In the second stage, X-ray diffraction (XRD), and scanning electron microscope (SEM) were conducted on selected mixes from first stage. The results show that the three types of cements with the various replacement percentages of phosphogypsum met the limit of initial setting time, as well as, provided soundness of 2 mm. Also, in terms of compressive strength, it was proven, that it is possible to partially replace the three tested types of cements by phosphogypsum by up to 8%and 15% with regard to cement/sand ratio of (1:3) and (1:2) respectively.

Performance of High-Efficiency Liquid Cement Setting Accelerator with Alkali-Free and its Acceleration Mechanism

2013 ◽  
Vol 377 ◽  
pp. 69-73
Author(s):  
Yan Wang ◽  
Jun Wang ◽  
Shu Heng Qiu ◽  
Fei Gao ◽  
Rui Gu
Keyword(s):  
Compressive Strength ◽  
High Efficiency ◽  
Bending Strength ◽  
Setting Time ◽  
X Ray Diffraction ◽  
Initial Setting Time ◽  
Acceleration Mechanism ◽  
Initial Setting ◽  
Strength Retention ◽  
Cement Setting

A kind of non-alkali high efficiency liquid cement setting accelerator named ZJ-NSA was developed by regulating the chemical composition of polymerized aluminum sulfate in this paper. The results show that the initial setting time and the final setting time are sharply shortened to 2 minutes 48 seconds and 4 minutes 37 seconds respectively, and the 1 d-aged compressive strength reach to 8.6MPa when it is mixed into P.O42.5 Portland cement with 5% addition; meanwhile, its compressive strength and bending strength retention at the age of 1d and 28d reach to 79.63%, 81.89% and 78.13%, 97.89% respectively. Phase characteristics on the hydrated cement specimens by means of x-ray diffraction (XRD) and differential scanning calorimeter (DSC) were analyzed and the acceleration mechanism was discussed.

Development of Injectable Calcium Phosphate Cement Adding with ZrO2

2007 ◽  
Vol 361-363 ◽  
pp. 347-350
Author(s):  
J.Y. Gong ◽  
Shu Xin Qu ◽  
Q. Cui ◽  
Jie Weng
Keyword(s):  
Compressive Strength ◽  
Calcium Phosphate ◽  
Setting Time ◽  
X Ray Diffraction ◽  
Liquid Component ◽  
X Ray ◽  
Initial Setting Time ◽  
Mass Fractions ◽  
Initial Setting ◽  
Diffraction Peaks

In the present study, ZrO2 was added into the injectable calcium phosphate cements (CPCs) to improve their mechanical strength. Different mass fractions of ZrO2 (5 %, 10 %, 15 %, 20%) were mixed with the powder components consisted of tricalcium phosphate (α-TCP) and hydroxyapatite (HA). Then formed the paste via adding the liquid component consisted of citric acid. The compressive strength, the injectability, the initial setting time and finial time of CPC were measured, respectively. X-ray diffraction (XRD) was employed to analyse the phase of as-prepared CPC. Scanning Electron Microscope (SEM) and Energy dispersive spertrum (EDS) were used to observe the morphology and indicate the element components of CPC. The compressive strength of ZrO2-CPC was higher than that of CPC without added ZrO2. The compressive strength got the maximal when the mass fraction of ZrO2 was 15%. It had no effect on the injectability with adding ZrO2, which were 89 % to 92 %. It had a slight down-regulation of the initial and final setting time with adding ZrO2. SEM showed that there was amounts needle-like substance in CPC, which might be related to the improvement of compressive strength of CPC. XRD showed that there were HA, a few of α-TCP and ZrO2 diffraction peaks in CPCs. The present results indicate that it is feasible to improve the compressive strength of injectable CPC via adding ZrO2.

scholarly journals Effect of Calcium Nitrate on the Properties of Portland–Limestone Cement-Based Concrete Cured at Low Temperature

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1611
Author(s):  
Gintautas Skripkiūnas ◽  
Asta Kičaitė ◽  
Harald Justnes ◽  
Ina Pundienė
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Setting Time ◽  
Calcium Nitrate ◽  
Curing Temperature ◽  
Hardened Concrete ◽  
Cement Pastes ◽  
Initial Setting Time ◽  
Initial Setting ◽  
Early Strength

The effect of calcium nitrate (CN) dosages from 0 to 3% (of cement mass) on the properties of fresh cement paste rheology and hardening processes and on the strength of hardened concrete with two types of limestone-blended composite cements (CEM II A-LL 42.5 R and 42.5 N) at different initial (two-day) curing temperatures (−10 °C to +20 °C) is presented. The rheology results showed that a CN dosage up to 1.5% works as a plasticizing admixture, while higher amounts demonstrate the effect of increasing viscosity. At higher CN content, the viscosity growth in normal early strength (N type) cement pastes is much slower than in high early strength (R type) cement pastes. For both cement-type pastes, shortening the initial and final setting times is more effective when using 3% at +5 °C and 0 °C. At these temperatures, the use of 3% CN reduces the initial setting time for high early strength paste by 7.4 and 5.4 times and for normal early strength cement paste by 3.5 and 3.4 times when compared to a CN-free cement paste. The most efficient use of CN is achieved at −5 °C for compressive strength enlargement; a 1% CN dosage ensures the compressive strength of samples at a −5 °C initial curing temperature, with high early strength cement exceeding 3.5 MPa but being less than the required 3.5 MPa in samples with normal early strength cement.

scholarly journals Non-Dispersive Anti-Washout Grout Design Based on Geotechnical Experimentation for Application in Subsidence-Prone Underwater Karstic Formations

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1587
Author(s):  
Khaqan Baluch ◽  
Sher Q Baluch ◽  
Hyung-Sik Yang ◽  
Jung-Gyu Kim ◽  
Jong-Gwan Kim ◽  
...  
Keyword(s):  
Fractured Rock ◽  
Setting Time ◽  
Visual Assessment ◽  
Initial Setting Time ◽  
Permeable Sediments ◽  
Coarse Aggregates ◽  
Saturated Rock ◽  
Initial Setting ◽  
Level 3 ◽  
Grey Relational

A new non-dispersive, anti-washout grout consisting of ordinary Portland cement, slag, superplasticizer, and methylbenzyl cellulose is proposed herein for the treatment of open karst, jointed and fractured rock, open-work gravel, and permeable sediments. A series of laboratory experiments were performed to design an anti-wash out grout suitable for grout injection of coarse aggregates depicting partially and open-jointed saturated rock mass and grouting concrete aggregates for underwater construction. The Taguchi orthogonal array was used to obtain nine different grout mix ratios. A total of four variables were considered, each with three different levels of the water–cement ratio, slag, and dosage of additives such as the superplasticizer and methyl benzyl cellulose. The laboratory determination of grout characteristics recording of mini slump, temperature, pH, visual assessment of grout dispersion, bleeding, and initial setting time and as well as uniaxial compressive strengths and permeabilities of the hardened grout samples were tested. To evaluate the suitability of the grout mixes, an analysis of variance was used for factor analysis and Grey relational analysis (GRA) was used to determine the optimal grout mix design. Based on the GRA, the following levels of the factors afforded the best results: water level 1 (0.3%), SP level 3 (0.01%), methylbenzyl cellulose level 2 (0.002%), and slag level 3 (0.1%). This paper describes the research methodology, detailed research observations, and analyses involved in designing the appropriate concrete mix. Based on the conclusions, relevant commendations regarding the suitability of grout testing equipment and grout mix designs are presented.

Sign in / Sign up

Export Citation Format

Share Document