Setting Time Of Cement Research Articles

Hydration Mechanism of the Hydrogen-Rich Water Based Cement Paste

With the aim to speed up the construction process, utilization of the hydrogen-rich water as a cement set accelerator would be a unique approach. The investigation deals with the effectiveness of the hydrogen-rich water in controlling the setting and the hydration behavior of cement. Analyzing the setting time using Vicat apparatus, the initial and final setting time of the control cement is measured to be 197 ± 6 and 257 ± 3 min, respectively, while the same is measured to be 8 ± 3 and 14 ± 3 min, respectively, for the 0.5 ppm hydrogen-rich water-based cement sample. The change in surface potential of the hydrogen-rich water based cement paste may lead to agglomerate the cement particle immediately. Additionally, the hydration test reveals that the hydrogen-rich water accelerates the cement hydration reaction. This phenomenon is primarily governed by the rapid dissolution of the cement component, followed by the early nucleation and flocculation of the hydrated products, which is confirmed monitoring the...

Effects of carbamide on sulfoaluminate cement paste for growing plants

To better understand the effects of carbamide on the properties of sulfoaluminate cement as potential matrix for eco-concrete suitable for growing plants, the fluidity, hydration heat evolution, setting time, compressive strength development, hydration products, pore characteristics and releasing characteristics of nitrogen nutrients of sulfoaluminate cement with carbamide were investigated. It was found that carbamide can reduce the water demand of sulfoaluminate cement. The fluidity increased from 80 to 149mm with carbamide content increasing from 0.2 to 4.0wt.%. Carbamide had noticeable retarding effect on the hydration of sulfoaluminate cement, especially on C3S phase. The cumulated hydration heat of sulfoaluminate cement pastes without and with 4.0wt.% carbamide was 329.5J/g and 296.3J/g, respectively. Carbamide retarded initial setting time of sulfoaluminate cement enabling it being able to meet the setting time requirement of GB20472-2006 (Chinese national standard for Sulfoaluminate cement). The early compressive strength of sulfoaluminate cement was low due to the retarding effect caused by carbamide and the production of NH3 increased the total porosity, but carbamide had limited effects on late age compressive strength of sulfoaluminate cement. Hardened sulfoaluminate cement pastes with carbamide can release nitrogen nutrients which is essential for growing plants. The amount of nitrogen nutrients released from sulfoaluminate cement paste with 2.0wt.% carbamide cured for 56days was 0.92mg/cm3, and the cumulative release rate was 75.0%. The presence of carbamide enables hardened cement paste being able to release nitrogen nutrients, suggesting that carbamide can mix with sulfoaluminate cement to produce eco-concrete and release nitrogen nutrients for growing plants.

Influence of Thermal Treatment Conditions on the Properties of Dental Silicate Cements

In this study the sol-gel process was used to synthesize a precursor mixture for the preparation of silicate cement, also called mineral trioxide aggregate (MTA) cement. This mixture was thermally treated under two different conditions (1400 °C/2 h and 1450 °C/3 h) followed by rapid cooling in air. The resulted material (clinker) was ground for one hour in a laboratory planetary mill (v = 150 rot/min), in order to obtain the MTA cements. The setting time and mechanical properties, in vitro induction of apatite formation by soaking in simulated body fluid (SBF) and cytocompatibility of the MTA cements were assessed in this study. The hardening processes, nature of the reaction products and the microstructural characteristics were also investigated. The anhydrous and hydrated cements were characterized by different techniques e.g., X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (FT-IR) and thermal analysis (DTA-DTG-TG). The setting time of the MTA cement obtained by thermal treatment at 1400 °C/2 h (MTA1) was 55 min and 15 min for the MTA cement obtained at 1450 °C/3 h (MTA2). The compressive strength values were 18.5 MPa (MTA1) and 22.9 MPa (MTA2). Both MTA cements showed good bioactivity (assessed by an in vitro test), good cytocompatibility and stimulatory effect on the proliferation of cells.

Viability of Eggshells Ash Affecting the Setting Time of Cement

Viability of Eggshells Ash Affecting the Setting Time of Cement

Methodologies for measuring the setting times of mineral trioxide aggregate and Portland cement products used in dentistry

Objective The current standard used to measure setting time for Mineral Trioxide Aggregate (MTA) involves indentation testing with arbitrary weights. This study compared indentation testing against rheological measurements and assessed the influences of particle size and the inclusion of bismuth oxide on the setting time of experimental MTA and Portland cement (PC).Material and methods Two PCs (P1 and P2) of different particle sizes were produced using the same clinker. From these two PCs, two experimental MTAs (M1 and M2) were created with the addition of bismuth oxide. Particle size distributions were assessed using laser diffraction analysis. Indentation setting time tests were performed in accordance to the Gillmore needle test. Elastic modulus was assessed using a strain-controlled rheometer at 1 rad s−1 and an applied strain of 0.01%.Results P1, P2, M1 and M2 cements had median particle sizes of 6.1, 12.5, 6.5 and 13.0 μm, respectively. Using indentation testing, final setting times were ranked P1 < M1 < P2 < M2. The ranking of the final setting time corresponded with the rheological assessment of time required to reach 95% of the elastic modulus plateau.Conclusions The time to reach 95% elastic modulus plateau of 9.3 min corresponds to a time close to the point where the material can be overlaid with another restorative material to give a final restoration. The 95% plateau value for elastic modulus may be a more useful parameter for determining how the setting reaction of PC and MTA cements progress over time.

Effect of M-Sand on Setting Time of High Performance Concrete

The setting time of concrete has more practical significance to Engineers and Contractors, than the setting time of cement. The present study seeks to gauge The efficacy manufactured sand or M-sand a fine aggregate in the place of natural river sand. The effect of M-sand on the setting time of high performance concrete is studied on an experimental basis under laboratory conditions. It is proved using three series of HPC with different compositions, through penetration resistance tests on the parameters of workability, setting time and compressive strength. On grounds of sustainable development and environment preservation, M-sand is seen as a viable substitute for river sand.

A novel injecable composite cement for vertebroplasty

Event Abstract Back to Event A novel injecable composite cement for vertebroplasty Mehran Dadkhah1, Lucia Pontiroli1, 2, Sonia Fiorilli1, Ion Tcacencu3 and Chiara Vitale-Brovarone1 1 Politecnico di Torino, Department of Applied Science and Technology, Italy 2 University of Leeds, Oral Biology, School of Dentistry, United Kingdom 3 Karolinska Institutet, Department of Dental Medicine, Sweden Introduction: In the past two decades, vertebroplasty has been considered as a safe, efficient and common surgical procedure that plays a main role in the treatment of vertebral compression fractures. This technique has been applied in pain reduction and for preventing further loss of vertebral body height in osteoporosis[1]. Calcium sulphate cements (CSC) are nontoxic, osteoconductive, bioresorbable and have been applied in clinical practice for over 100 years. However, their degradation rate is faster than the formation of new bone, which has limited their application[2],[3]. This study aimed to overcome the drawbacks of calcium sulphate by developing an injectable material containing three phases. Materials and Methods: The injectable cement formulation included: calcium sulphate hemihydrate (CSH-type III), a radiopaque glass ceramic and mesoporous bioactive glass particles. The glass-ceramic particles (mol. composition: SiO2 =57%, CaO=30%, Na2O=6% and ZrO2=7%) were prepared by melting, casting and ceramisation treatment. Mesoporous glass particles were synthesized by spray-drying technique using a water-based synthesis. In order to obtain a cement, the three phases were combined with an optimized liquid to powder ratio, which ensured that the paste remained injectable and completely set in proper time. The new cement was studied in vitro both in simulated body fluid (SBF) and by culturing rat bone marrow stromal cells (BMSC). The behaviour of the calcium sulphate-based composite cement (setting time, injectability, compressive strength) was evaluated with respect to type III calcium sulphate and Cerament® (as a commercial reference). Results: It was found that the new composite cement possessed slightly higher initial (48 min) and final (56 min) setting times, respectively (table 1). Moreover, the injectable cement showed a better compressive strength in both wet (13.8MPa) and dry (18.6MPa) conditions with respect to the commercial reference (table 1). The new cement samples were biodegradable and significantly improved bioactivity during the first week in vitro and this may enhance new bone formation in vivo (figure 1). The in vitro cell culture results proved that the new cement are cytocompatible, and might enhance osteogenic differentiations of the BMSC by increasing alkaline phosphatase activity. The new formulation of the injectable cement for vertebroplasty showed good setting times and compressive strength, and in vitro osteogenic properties which are comparable or better than Cerament®. This composite cement might has significant clinical advantages compared to the traditional CSH. Fig. 1. FESEM micrograph of the composite cement after 24 hr of SBF soaking showing with hydroxyapatite crystals. The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n°[280575]-Restoration

Dataset of producing and curing concrete using domestic treated wastewater.

We tested the setting time of cement, slump and compressive and tensile strength of 54 triplicate cubic samples and 9 cylindrical samples of concrete with and without a Super plasticizer admixture. We produced concrete samples made with drinking water and treated domestic wastewater containing 300, 400 kg/m3 of cement before chlorination and then cured concrete samples made with drinking water and treated wastewater. Second, concrete samples made with 350 kg/m3 of cement with a Superplasticizer admixture made with drinking water and treated wastewater and then cured with treated wastewater. The compressive strength of all the concrete samples made with treated wastewater had a high coefficient of determination with the control concrete samples. A 28-day tensile strength of all the samples was 96–100% of the tensile strength of the control samples and the setting time was reduced by 30 min which was consistent with a ASTMC191 standard. All samples produced and cured with treated waste water did not have a significant effect on water absorption, slump and surface electrical resistivity tests. However, compressive strength at 21 days of concrete samples using 300 kg/m3 of cement in rapid freezing and thawing conditions was about 11% lower than concrete samples made with drinking water.

Influence of ZrO2 oxide on the properties and crystallization of calcium fluoro-alumino-silicate glasses

The impact of ZrO2 content of the glass on the formation, properties and crystallization of glass ionomer cements (GICs) was investigated. Glass series based on SiO2–Al2O3–ZrO2–P2O5–CaO–CaF2 system was synthesized and studied. The cements were characterized using a setting time, flexural strength, fracture toughness and in vitro biocompatibility test. The setting time of the ionomer cement increased with increasing the ZrO2 content of the glass. The cements showed a slight decrease of cell biocompatibility with increase the ZrO2 oxide content in the glasses. The results also showed that the flexural strength and the fracture toughness of the cements increased with immersion time and ZrO2 oxide content. The crystallization characteristics of the glasses were investigated by differential scanning calorimeter (DSC) and X-ray diffraction analysis (XRD). The addition of ZrO2 oxide in the glasses led to increase both the glass transition and crystallization temperatures. Fluorapatite [Ca5(PO4)3F], mullite [Al6Si2O13], cristobalite [SiO2] and zircon [ZrSiO4] phases were crystallized from the investigated glasses. The role played by the glass oxide constituents in determining the setting time, mechanical properties and crystallization characteristics of the prepared glass ionomer was discussed.

Addition of a Fluoride-containing Radiopacifier Improves Micromechanical and Biological Characteristics of Modified Calcium Silicate Cements

IntroductionCalcium silicate cements (CSCs) with the addition of nanohydroxyapatite and calcium carbonate play a critical role in dental applications. To further improve their properties, particularly radiopacity and biointeractivity, the fluoride-containing radiopacifier ytterbium trifluoride (YbF3) was added to their composition, and biological and mechanical characteristics were evaluated. MethodsYbF3 was added to 3 different CSCs: cement I (CSC + calcium carbonate), cement II (CSC + nanohydroxyapatite), and Portland cement. Material characterization encompassed measurements of pH, calcium, ytterbium, and fluoride ion release; radiopacity; setting time; porosity; microindentation properties; wettability; and Fourier transform infrared spectroscopic, x-ray diffraction, and scanning electron microscopic analyses. Osteoblast- and osteoclast-like cells were grown on the materials' surface to evaluate their adherence. ResultsThe addition of calcium carbonate, nanohydroxyapatite, and 30 wt% of YbF3 improved radiopacity and the setting time of experimental cements. The pH values did not differ among the groups. The greatest ytterbium and fluoride releases occurred in the Portland cement + YbF3 group. Combined x-ray diffraction and Fourier transform infrared spectroscopic analysis showed the presence of calcium hydroxide and calcium silicate hydrates. In addition, the presence of calcium ytterbium fluoride and ytterbium oxide proved that YbF3 reacted with cement compounds. Wettability of cement I + YbF3 was superior to other formulations, but its porosity and microindentation properties were weaker than in the Portland cement + YbF3 mixture. Cement II + YbF3 presented micromechanical indentation and porosity characteristics similar to the Portland-based cement formulation. Osteoclast- and osteoblast-like cells adhered to the cements' surfaces without alteration of the cell structural integrity. ConclusionsYbF3-containing CSCs with nanostructured hydroxyapatite and calcium carbonate are well suited for dental application.

Green synthesis and bioactivity of vaterite-doped beta-dicalcium silicate bone cement

.Vaterite-doped beta-dicalcium silicate bone cement has been successfully synthesized by green synthetic method. The purpose is to reduce the adverse effect caused by the hydration products Ca(OH)2 in the β-Ca2SiO4 bone cement, and improve the bioactivity of the β-Ca2SiO4 bone cement. The in vitro bioactivity of vaterite-doped β-Ca2SiO4 bone cements was evaluated compared with β-Ca2SiO4 bone cement without vaterite by soaking in simulated body fluid (SBF) for the same time (3 days). The formation abilities of hydroxyapatite (HAp) on their surfaces were analyzed by XRD, SEM, EDS and FT-IR. In addition, the setting time of vaterite-doped cement was measured. Experimental results demonstrated that vaterite-doped β-Ca2SiO4 bone cements could easily induce the formation of HAp on their surfaces after immersion in SBF. And vaterite-doped β-Ca2SiO4 bone cement has much better HAp forming ability and appropriate setting time (12±2min) than the other one, which can not only eliminate the alkali-silica reaction (ASR) for bone cements but also be expected to be a satisfactory substrate for the bone repairing.

Evaluation of Strength Characteristics of Laterized Concrete with Corn Cob Ash (CCA) Blended Cement

Agricultural wastes are dumped in landfills or left on land in which they constitute nuisance. This study presents the results of investigation of strength characteristics of reinforced laterized concrete beams with cement partially replaced with corn cob (agricultural wastes) ash (CCA). Laterized concrete specimen of 25% laterite and 75% sharp sand were made by blending cement with corn cob ash at 0 to 40% in steps of 10%. A concrete mix ratio of 1:2:4 was used to cast 54 cubes of 150×150×150mm size and 54 beams of dimension 750×150×150mm.The results show that the consistency and setting time of cement increased as the percentage replacement of cement with CCA increased while the workability and density of concrete decreased as the percentage of CCA increased. There was a decrease in compressive strength when laterite was introduced to the concrete from 25.04 to 22.96N/mm2 after 28 days and a continual reduction in strength when CCA was further added from 10% to 40% at steps of 10%. Generally, the beam specimens exhibited majorly shear failure with visible diagonal cracks extending from support points to the load points. The corresponding central deflection in beams, due to two points loading, increased as the laterite was added to the concrete mix but reduced and almost approaching that of the control as 10% CCA was added. The deflection then increased as the CCA content further increased to 20%, 30% and 40% in the mix. It was also noted that the deflection of all percentage replacement including 40% CCA is less than the standard recommended maximum deflection of the beam. The optimal flexural strength occurred with 10% CCA content.

A new method to determine initial setting time of cement and concrete using plate test

The present study developed a new method for determination of cement and concrete setting times. The disadvantage of current methods is that most only determine setting time of either cement or concrete and cannot determine the setting time of all types of concrete and cement, especially those containing mineral admixtures. In the proposed method, a plate with a rough surface is rigidly attached to the bottom of a precision balance in a PVC cylinder and immersed in fresh mixture poured into the side of the cylinder opposite the balance. The shear force exerted on the plate increases over time and the value recorded by the balance increases moment-by-moment. The difference between the sequential weights recorded at specific intervals was maximized at the setting time moment. Three types of cement paste and three types of self-compacting concrete were evaluated using the new method. The initial setting time obtained by this method was confirmed using the results of existing test methods. The results show the feasibility and accuracy of the proposed plate test method to determine initial setting times of cement and concrete.

Experimental and statistical studies of using wash water from ready-mix concrete trucks and a batching plant in the production of fresh concrete

We studied experimentally and statistically the feasibility of using concrete wash water in the production of fresh concrete. The setting time of hydraulic cement and the compressive strength of the hydraulic cement mortars were acceptable. In the framework of 54 mix designs and using various mixes of tap water and concrete wash water, we produced concrete samples to assess the characteristics of the samples. The workability and penetration depth of all the samples were allowable. We used an analysis of variance (ANOVA) technique to analyze the tensile, flexural and compressive strengths which indicated the concrete wash water did not alter the strengths significantly.

Assessing the pozzolanic activity of cements with added sugar cane straw ash by synchrotron X-ray diffraction and Rietveld analysis

Sugar and alcohol industries generate large amount of wastes that could produce ashes of great reactivity with pozzolan properties. The objective of this paper is to evaluate the pozzolanicity of Sugar Cane Straw Ashes (SCSA), thermal treated, at different curing times. Employing Synchrotron X-ray radiation for XRD measurements, scans from 10° to 110° (θ-2θ setup) allowed the quantification of several phases of the cement pasts through Rietveld analysis. The SCSA substitution of 20% (weight) in Ordinary Portland Cement (OPC) has improved the AFt (Ettringite) formation up to 47% for 90days curing time. The Portlandite concentration analysis allowed concluding that this addition of SCSA in OPC has caused a delay in the cement setting time. Moreover, the behaviour of the C3S and Calcite contents in both OPC and OPC/SCSA samples were determined by refinement of the XRD pattern using the Rietveld method.

Characterization of Groundnut Husk Ash (GHA) Admixed with Rice Husk Ash (RHA) in Cement Paste and Concrete

This paper investigates the effect of Groundnut Husk Ash (GHA) blended with Rice Husk Ash (RHA) in cement paste and concrete with a view to improve its suitability as a supplementary cementing material. The GHA and RHA used were obtained by controlled burning of groundnut husk and rice husk, respectively in a kiln to a temperature of 600 °C, and after allowing cooling, sieved through sieve 75 μm and characterized. The effects of GHA admixed with 10 % RHA on cement paste and concrete were investigated at replacement levels of 0, 10, 20, 30 and 40 %, respectively by weight of cement. Fresh concrete grade 20 of mixes made with partial replacement with GHA admixed with 10 % RHA in the order as above were tested for workability and hardened concrete tested for compressive, splitting tensile and flexural strengths at curing ages of 3, 7, 28, 60 and 90 days in accordance with standard procedures. The result of the investigations showed that GHA was of low reactivity and RHA was more reactive, with combined SiO2, Al2O3 and Fe2O3 content of 26.06 % and 80.33 %, respectively. The use of GHA admixed with 10 % RHA increased consistency, initial and final setting times of cement, but decreased linear shrinkage. The workability, compressive strength, splitting tensile strength and flexural strength of concrete decreased with increase in GHA-RHA content. However, 15 % would be considered as the optimum for structural concrete.

Effects of Temperature and Aging on Working/Setting Time of Dual-cured Resin Cements.

To evaluate the effects of aging and temperature on working time (WT) and setting time (ST) of several dual-cured resin cements. WT and ST were determined with a thermo-controlled stage oscillating rheometer. New cement kits were used for the study. Cements were mixed according to instructions and dispensed on the oscillating stage that was preset at 22°C or 37°C. Rheologic charts were generated from the beginning of mixing until no further oscillation was detected. After initial measurements, cement kits were aged at 37°C for 12 weeks, and WT/ST was determined again at both temperatures. Five samples were read for each material and condition. Data were analyzed with repeated measures analysis of variance and a Tukey test at α=5% for each individual material. The WT and ST of all cements were significantly affected by temperature and aging (p<0.05). In general, higher temperature accelerated WT/ST, but aging effects were material dependent. Some materials presented reduced WT/ST, whereas others showed increased WT/ST, regardless of the temperature. The WT and ST were significantly affected by temperature variation and aging condition. Although temperature changes appeared to affect all materials similarly, aging effects were material dependent.

Stimuli responsive workability retention of cement paste containing polycarboxylate superplasticiser

Polycarboxylate superplasticisers (PCE) were synthesised and their structure was characterised by Fourier-transformed infrared spectroscopy. The simulated physiological environmental effects on the workability retention of cement paste containing PCE were studied; that is, stimuli response to sulfates by measuring the fluidity, water-reducing ratio, compressive strength and setting time. The fluidity and water-reducing ratio of cement paste containing PCE with a long chain weakly depended on the salt dosage, but properties of compressive strength and setting time were strongly influenced by the salt dosage. However, the fluidity, water-reducing ratio, compressive strength and setting time of cement containing PCE with both long and short chains were strongly influenced by alkaline sulfate. PCE with a long side chain has a good compatibility with cement paste. The ionic responsive properties are attributed to the change of the PCE adsorption ratio, which results directly in a variation of the dispersing force of superplasticiser.

Rebamipide delivered by brushite cement enhances osteoblast and macrophage proliferation.

Many of the bioactive agents capable of stimulating osseous regeneration, such as bone morphogenetic protein-2 (BMP-2) or prostaglandin E2 (PGE2), are limited by rapid degradation, a short bioactive half-life at the target site in vivo, or are prohibitively expensive to obtain in large quantities. Rebamipide, an amino acid modified hydroxylquinoline, can alter the expression of key mediators of bone anabolism, cyclo-oxygenase 2 (COX-2), BMP-2 and vascular endothelial growth factor (VEGF), in diverse cell types such as mucosal and endothelial cells or chondrocytes. The present study investigates whether Rebamipide enhances proliferation and differentiation of osteoblasts when delivered from brushite cement. The reactive oxygen species (ROS) quenching ability of Rebampide was tested in macrophages as a measure of bioactivity following drug release incubation times, up to 14 days. Rebamipide release from brushite occurrs via non-fickian diffusion, with a rapid linear release of 9.70% ±0.37% of drug per day for the first 5 days, and an average of 0.5%-1% per day thereafter for 30 days. Rebamipide slows the initial and final cement setting time by up to 3 and 1 minute, respectively, but does not significantly reduce the mechanical strength below 4% (weight percentage). Pre-osteoblast proliferation increases by 24% upon exposure to 0.4uM Rebamipide, and by up to 73% when Rebamipide is delivered via brushite cement. Low doses of Rebamipide do not adversely affect peak alkaline phosphatase activity in differentiating pre-osteoblasts. Rebamipide weakly stimulates proliferation in macrophages at low concentrations (118 ±7.4% at 1uM), and quenches ROS by 40-60%. This is the first investigation of Rebamipide in osteoblasts.

D90: The Strongest Contributor to Setting Time in Mineral Trioxide Aggregate and Portland Cement

IntroductionThe setting times of commercial mineral trioxide aggregate (MTA) and Portland cements vary. It was hypothesized that much of this variation was caused by differences in particle size distribution. MethodsTwo gram samples from 11 MTA-type cements were analyzed by laser diffraction to determine their particle size distributions characterized by their percentile equivalent diameters (the 10th percentile, the median, and the 90th percentile [d90], respectively). Setting time data were received from manufacturers who performed indentation setting time tests as specified by the standards relevant to dentistry, ISO 6786 (9 respondents) or ISO 9917.1 (1 respondent), or not divulged to the authors (1 respondent). In a parallel experiment, 6 samples of different size graded Portland cements were produced using the same cement clinker. The measurement of setting time for Portland cement pastes was performed using American Society for Testing and Materials C 191. Cumulative heat release was measured using isothermal calorimetry to assess the reactions occurring during the setting of these pastes. In all experiments, linear correlations were assessed between setting times, heat release, and the 3 particle size parameters. ResultsParticle size varied considerably among MTA cements. For MTA cements, d90 was the particle size characteristic showing the highest positive linear correlation with setting time (r = 0.538). For Portland cement, d90 gave an even higher linear correlation for the initial setting time (r = 0.804) and the final setting time (r = 0.873) and exhibited a strong negative linear correlation for cumulative heat release (r = 0.901). ConclusionsSmaller particle sizes result in faster setting times, with d90 (the largest particles) being most closely correlated with the setting times of the samples.