Reduction In Setting Time Research Articles

Development of an ettringite-based low carbon binder by promoting the nucleation and Ostwald ripening process

A low-carbon binder with ettringite as the main binding phase is prepared at ambient temperature using waste gypsum and metallurgical slag as raw materials. The technical limits of slow setting and low early strength are caused by the insufficient ettringite formation. This is tackled by fine tuning the thermodynamic route of ettringite formation process using polyaluminium compound via promoting the nucleation and Ostwald ripening process of ettringite formation. The high positive charge polymeric Al species and numerous Al(OH)4- generated by the hydrolysis of polyaluminium compounds increase the oversaturation degree and enhance the driving force of the Ostwald ripening process of ettringite. The volume ratio of ettringite/C-(A)-S-H in hydration products is further increased remarkably, resulting in the reduction of setting time and the enhancement of compressive strength. The carbon emission of the non-calcined ettringite-based binders developed in this study is 71–87 kg CO2-e/t. The research provides theoretical support for the development and application of a novel ettringite-based low carbon binders.

Comprehensive evaluation of early-age hydration and compressive strength development in seawater-mixed binary and ternary cementitious systems

Seawater-mixed concrete (SWC) is a proposed solution for catering to the needs of developing nations facing extremely severe water stress. Recent research works advocate the feasibility of producing SWC by adding supplementary cementitious materials (SCMs) and alternative reinforcements without reducing the engineering properties of the same. However, limited information is available for optimising the type and amount of SCMs in binary and ternary blended SW-mixed cementitious systems for achieving desirable strength development and early-age hydration. A comprehensive study to understand the evolution of heat of hydration and strength up to 28 days was conducted on 31 binder compositions mixed with both fresh water (FW) and seawater (SW). Fly ash, slag, metakaolin, and limestone are the supplementary cementitious materials used with CEM I as a primary binder at a replacement level between 10 and 70%. Isothermal calorimetry results revealed an increase in total heat of hydration and a reduction in setting time with SW-mixed cement pastes compared to their FW-mixed counterparts. Similarly, a significant increase in strength between 0 and 50% was observed in SW-mixed cement pastes. Suitable binder combinations showing an increase in compressive strength and not a significant reduction in strength compared to the CEM I reference mix were identified using the strength improvement factor approach. Binary and ternary blended cementitious, consisting of fly ash, slag, and metakaolin at different replacement levels, are amongst the chosen binder combinations.

The Physical Properties of Vanillin-Incorporated Irreversible Hydrocolloid Impression Material

Irreversible hydrocolloid impression material is extensively used in dentistry to record and duplicate the details of tooth structure, surrounding tissue, and other intraoral structures. The materials allow dentists to work more easily and perform better diagnosis and treatment planning. When used, the material is exposed to oral microorganisms, some are pathogens, from the patient’s teeth, mucosa, blood, and saliva. These pathogens can be absorbed into the material and transmitted to dentists and other dental workers. Hydrocolloid impression material incorporated with vanillin has been shown to exhibit antimicrobial potential, however, its physical properties have not been performed. Therefore, this study aims to investigate the physical properties of a vanillin-incorporated irreversible hydrocolloid impression material on four different physical properties: working time, setting time, elastic recovery, and strain-in compression. The impression powder was mixed with varying concentrations of vanillin (0.1%, 0.5%, and 1.0% w/w) using the electric vacuum mixer. The impression material without vanillin was used as a control. All the tests were done following the ISO specification 21563: 2021 for dental materials with 15 specimens for each test. The result showed that at concentrations of 0%, 0.1%, and 0.5% w/w vanillin, no significant change in the four physical properties has been observed. However, the working time and setting time values of impression material with 1% vanillin were reduced significantly and did not meet the ISO standard. In conclusion, the incorporation of 0.1%, 0.5%, and 1% w/w vanillin into irreversible hydrocolloid impression material showed a significant reduction in setting time and working time. However, when considering the ISO standard specifications, the 0.1% and 0.5% w/w vanillin-added materials can still be used due to their acceptable values of all physical properties (setting time, working time, elastic recovery, and strain-in compression). These impression materials will be valuable for use in clinical settings to reduce the disinfection procedure and the risk of cross-contamination.

Characterisation and evaluation of physical properties of AH-Plus sealer with and without the incorporation of petasin, pachymic acid, curcumin and shilajit-an invitro study

BackgroundAH Plus, an epoxy resin-based sealer, is widely used in endodontic practice, owing to its good physical properties that confers longstanding dimensional stability and good adhesion to dentin. Nevertheless, its propensity to trigger inflammation, especially in its freshly mixed state, has been extensively documented. Phytochemicals such as Petasin, Pachymic acid, Curcumin, and Shilajit are known for their anti-inflammatory and analgesic effects. This study aimed to analyze and determine the effect of these natural products on the physical properties of AH Plus sealer when incorporated with the sealer.MethodsAH Plus (AHR) sealer was mixed with 10% petasin, 0.75% pachymic, 0.5% and 6%shilajit to obtain AHP, AHA, AHC and AHS in the ratio of 10:1 and 5:1 respectively. Five samples of each material were assessed for setting time, solubility, flow, and dimensional stability in accordance with the ISO 6876:2012 standardization. Sealers were characterized through scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy, X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. Statistical evaluation involved the Kolmogorov-Smirnov and Shapiro-Wilks tests for normality and the one-way ANOVA test for analysis.ResultsIn this investigation, the characterisation analysis revealed a relatively similar microstructure in all the experimental root canal sealers. All experimental groups, excluding the control group, exhibited an increase in flow ranging from 11.9 to 31.4% at a 10:1 ratio. Similarly, for the 5:1 ratio, the increase ranged from 12.02 to 31.83%. In terms of dimensional stability, all groups at the 10:1 ratio showed a decrease compared to the control group. The addition of natural agents to AHR in 10:1 ratio led to a reduction in setting time by 8.9–31.6%, and at a 5:1 ratio, the reduction ranged from 8.1 to 31.5%. However, regarding solubility, the addition of natural agents did not induce any significant alterations.ConclusionBased on the results of this study, it can be concluded that all tested root canal sealers exhibited properties that met the acceptable criteria outlined in the ISO 6876:2012 standardization.

The Impact of Nano- and Micro-Silica on the Setting Time and Microhardness of Conventional Glass-Ionomer Cements.

The objective of this study was to investigate the effect of the incorporation of 2, 4 or 6 wt% of amorphous nano- or micro-silica (Aerosil® OX 50 or Aeroperl® 300 Pharma (Evonik Operations GmbH, Essen, Germany), respectively) on the net setting time and microhardness of Ketac™ Molar (3M ESPE, St. Paul, MN, USA) and Fuji IX GP® (GC Corporation, Tokyo, Japan) glass-ionomer cements (GICs) (viz. KM and FIX, respectively). Both silica particles were found to cause a non-linear, dose-dependent reduction in setting time that was within the clinically acceptable limits specified in the relevant international standard (ISO 9917-1:2007). The microhardness of KM was statistically unaffected by blending with 2 or 4 wt% nano-silica at all times, whereas 6 wt% addition decreased and increased the surface hardness at 1 and 21 days, respectively. The incorporation of 4 or 6 wt% nano-silica significantly improved the microhardness of FIX at 1, 14 and 21 days, with no change in this property noted for 2 wt% addition. Micro-silica also tended to enhance the microhardness of FIX, at all concentrations and times, to an extent that became statistically significant for all dosages at 21 days. Conversely, 4 and 6 wt% additions of micro-silica markedly decreased the initial 1-day microhardness of KM, and the 21-day sample blended at 4 wt% was the only specimen that demonstrated a significant increase in this property. Scanning electron microscopy indicated that the nano- and micro-silica particles were well distributed throughout the composite structures of both GICs with no evidence of aggregation or zoning. The specific mechanisms of the interaction of inorganic nanoparticles with the constituents of GICs require further understanding, and a lack of international standardization of the determination of microhardness is problematic in this respect.

Impact of Particle Size on the Setting Behavior of Tricalcium Silicate: A Comparative Study Using ISO 6876 Indentation Testing and Isothermal Induction Calorimetry.

This study examines the impact of particle size on the setting behavior of tricalcium silicate powders. The setting behavior was evaluated using ISO 6876 indentation testing and isothermal induction calorimetry techniques. The objective was to compare the outcomes obtained from these methods and establish a correlation between particle size and setting characteristics. The cement pastes were manually mixed with a water-to-solid ratio of 0.66 for conducting indentation tests according to ISO 6876, while calorimetry measurements were performed using isothermal (conduction) calorimetry at room temperature. The findings demonstrate a significant influence of smaller particle sizes on accelerating the hydration process of cement pastes, resulting in a reduction of setting time by up to 24%. Moreover, the final setting times obtained through the indentation method closely approximate the inflection points of the acceleration curves acquired by calorimetry, with time deviations of less than 12% regardless of particle size.

Effects of 1,2,3-Propanetricarboxylic acid on the hydration and microstructure of fluorogypsum

Aiming at the issues of poor hydration activity, long setting time, and low early strength in industrial by-product fluorogypsum (FG), 1,2,3-propenyltricarboxylic acid (PA) was utilized to enhance its reactivity. The mechanism was investigated using modern analytical techniques such as XRD, 1H low-field NMR, and FTIR spectroscopy. The results indicate that the incorporation of PA can significantly augment the rate of FG hydration and enhance its hydration activity. The optimal concentration of PA was determined to be 0.008%. The FG paste exhibited a reduction in setting time by approximately 500 min compared to the control sample. Furthermore, the flexural and compressive strengths increased by 29.6% (reaching 3.5 MPa) and 40.2% (reaching 40.1 MPa), respectively, after a curing period of 28 d. Through the process of physical adsorption, PA facilitates the transformation from anhydrite (CaSO4-II) to dihydrate gypsum (CaSO4·2H2O). Subsequently, PA promotes the growth of dihydrate gypsum crystals along each crystal axis, resulting in the formation of regular hexagonal prisms. The prismatic crystals of dihydrate gypsum are arranged in a closely packed, layered structure that results in reduced pore and porosity content, and enhanced mechanical strength.

Controlled low strength materials (CLSM) activated with alkaline solution: Flowability, setting time and microstructural characteristics

Conventional controlled low strength materials (CLSM) are used in rapid construction due to their self-leveling and self-consolidating properties. However, as these mixes contain low cement content, the setting time of CLSM mixes are slow, making it less desirable in most construction applications where fast setting mixes are required. In this paper, authors prepared twelve conventional CLSM mixes with different cement to cementitious material ratios to represent current practice of CLSM mixes typically used for construction. The control mixes were modified by reducing the cement content and substituting it with an equivalent quantity of fly ash activated with alkaline solution constituting of NaOH and Na2SiO3. Authors performed flowability, initial setting time and compressive strength tests on these mixes to quantify the improvements in mechanical properties of modified CLSM mixes compared to their control counterparts. Authors also performed microstructural characterization using Scanning Electron Microscopy (SEM) to identify morphological changes in modified CLSM mixes. The primary objective of this study was to observe improvement in flowability, setting time and compressive strength of conventional mixes after addition of alkaline solution. Significant improvements in flowability and over 70% reduction in setting time were observed for modified mixes compared to their conventional counterparts.

Effect of different mixture parameters on the setting time of fly ash/rice husk ash-based geopolymer mortar

The present study investigated the effects of different mixture parameters on the setting time of fly ash/rice husk ash – based geopolymer mortars. Mortar mixtures were prepared using fly ash and rice husk ash as the raw material, activated using a blended alkali activator solution consisting of sodium hydroxide (SH) and sodium silicate (SS). The concentration of SH was varied from 10M to 14M, while the SS/SH ratio was varied to 1.0, 1.5 or 2.0. The ratio of alkali activator solution to binder (A/B) was also varied from 0.45 to 0.55. Fresh mortar mixtures were subjected to setting time measurement at curing temperatures of 80 °C. Cubes of 50 mm size were also prepared and subjected to compressive strength testing at different ages. Results showed that increases in both parameters comprising SS/SH ratio and SH concentration resulted in reduction of setting time, while rise in A/B ratio led to increase in setting time of mortars.

A facile approach for large-scale recovery of phosphogypsum: An insight from its performance

The calcination treatment for recycling phosphogypsum (PG) is very promising, which can transform PG into a binder material and remove harmful impurities. To effectively recycle and reutilize PG, the influence of calcination temperatures on the properties of calcined and hydrated PG with and without pretreatment should be investigated. This paper systematically studied the effect of calcination temperature on the properties of water-washed and untreated plaster. The calcined untreated (UPG) and water-washed PG (WPG) were characterized by an X-ray fluorescence spectrometer (XRF), X-ray diffraction analyzer (XRD), and isothermal calorimetry, as well as by determining water requirement for normal consistency, setting time, whereas hydrated PG products were characterized by XRD, differential scanning calorimetry (DSC), thermogravimetry (TG), derivative thermogravimetry (DTG), and scanning electron microscope (SEM), as well as by measuring the mechanical properties. The results show that the chemical and mineralogical composition of calcined untreated PG (CUG) is similar to that of calcined water-washed PG (CWG) at the same calcination temperatures, and higher temperatures resulted in lower F content but no change in P2O5 content. At low calcination temperatures (150 °C–400 °C), the cumulative heat of CUG was lower than that of CWG, and the hydration rate is similar; however, the cumulative heat and hydration rate of CUG at 700 °C or 800 °C were much higher than that of CWG, resulting in the significant reduction in setting time. Hydrated CUG (HUG) showed tiny crystals with lower interlocking at low calcination temperatures, but a more compact microstructure with defined crystals was observed in the HUG-800 due to the high formation of dihydrate gypsum; thus, HUG calcined at low temperature showed a lower strength but at 800 °C showed the maximum strength. This work indicates that calcination at 800 °C showed a potential application for the recovery and utilization of raw PG because of its excellent performance.

Development of geopolymer concrete mixes with ambient air curing

Mix design for geopolymer concrete is yet to evolve. Though geopolymer concrete has made the much required transition from laboratory to the field, due to inherent difficulties such as huge variation in the chemical composition of the raw material, the sensitivity of this composition and the chemicals involved in the fresh and hardened properties have led to most of the mix development through trials with the actual materials. The aim of the work reported in this paper was to design an optimum mix proportion for geopolymer concrete using fly ash and ground granulated blast furnace slag (GGBS) as an aluminosilicate source, which has good workability, slump retention, and compressive strength without special curing requirements. A total of 10 mixes were prepared with varying fly ash to GGBS ratios. Ambient curing for 28 days was adopted for all mixes; however, heat curing at 85°C for 24 hours, followed by ambient curing, was adopted for one mix alone. It was clear that with the increase in GGBS content, there was a reduction in setting time, and the mix set faster. However, with more GGBS, greater strength was achieved at a relatively milder alkali activator solution. When the GGBS content increased beyond a certain level, the slump retention time reduced to levels where the mixes were unfit for practical applications. However, it can be concluded that with a judicious choice of fly ash and GGBS proportions, a strength of as high as 60MPa can be achieved in geopolymer concrete without any special curing methods.

Perbaikan Stabilitas Dinamik Sistem Tenaga Terintegrasi Pembangkit Listrik Tenaga Mikro Hidro dan Diesel Menggunakan PSS Berbasis ANFIS

Power generating units should be built closed to load centers according to electric power company regulation. These units are generally small in capacity, so that makes power transfer among inter- and outer-areas is easier to be done. This study aims to improve dynamic stability of a Micro Hydro Power Plant (MHPP) on perspective of 5% load increased in Diesel Power Plant (DPP). The DPP is equipped by an ANFIS-based Power System Stabilizer (PSS) in this scheme. Two inputs with Gauss2mf membership function (MF) type and 5-number of the each MF are used to implement the ANFIS model. Simulation results show that overshoot of MHPP power angle deviation is reduced to the values of 0.023, 0.0138 and 0.0132°, for the DPP without PSS, conventional and ANFIS PSS, respectively. Also, reduction in setting time is achieved at times >6, 4.051 and 3.553 s. It is shown that the ANFIS PSS is more effective to enhance the dynamic stability compared to other PSS

Effect of freshly produced electric arc-furnace dust and chloride-free chemical accelerators on concrete performance

This study investigates the use of chloride-free calcium-based chemical accelerators in ordinary concrete incorporating freshly homogenized electric arc-furnace dust (EAFD). The utilization of calcium nitrite (CN) and calcium formate (CF) counteracts the negative impact of elevated zinc oxide content in fresh EAFD. The presence of ZnO dramatically delays the setting time of cement in paste and concrete. In this study, EAFD was used in different replacement levels varied from 0 to 12% of cement. The incorporation of EAFD in concrete increased the setting time of concrete by up to 68 h. However, the presence of chemical accelerators enabled a significant reduction in setting time. The hydration reaction formed around cement grains due to the reaction between ZnO in EAFD and portlandite (Ca(OH)2) is responsible for the delay in setting time. This delay could be overcome under the influence of a concentration gradient due to the effective chemical accelerator dosage. The use of EAFD in concrete showed similar strength to silica fume (SF) mixes. The efficiencies of CN and CF rely on their dosage and EAFD content. It is concluded that the effective chemical accelerator-to-EAFD ratio plays a vital role in mitigating the extensive delay in setting time to practically feasible values. The mixture containing 4% CN and 4% EAFD was identified as the best concrete mixture.

The Comparison and Introduction of Plate Test and Electrical Resistance Methods of Determining the Setting Time and Thixotropy of Self-Consolidating Concrete

Abstract Setting time and rheology of mixtures are among the most important features in new generation concretes such as self-consolidating concrete (SCC) and can have a great impact on the behavior of fresh concrete. Therefore, introducing new methods for determining these parameters has always been one of the main concerns. In this research, we tried to determine a relationship between the measured setting time from the ASTM C403/C403M-08, Standard Test Method for Time of Setting of Concrete Mixtures by Penetration Resistance Method, and the electrical resistance (ER) method, as well as the rheological parameters, including dynamic and static yield stress. Also, a new method for determining the setting time and concrete thixotropy—called the plate test method—is introduced and validated. The results indicated that the ER method is an accurate one in determining the initial and final setting time of SCC mixtures. Concrete mixtures with higher yield stress (static and dynamic) have a shorter setting time. Investigating the results indicated that the higher the static yield stress mean of the mixture in the time period of thixotropic behavior, the shorter the initial setting time. Therefore, increasing static yield stress is associated with a reduction in the setting time. In the case of dynamic yield stress, similar events occurred with static yield stresses, and an increase in this stress and its growth rate was associated with a reduction in the initial setting time. Furthermore, the results obtained by the new method (plate method), along with the results of rheology parameters measured by the rheometer device, indicated that the difference between results was in the range of 4 to 11 %. Also, the difference in the setting time obtained from the plate method in comparison with the penetration resistance method was 9 % at maximum. These results indicated that the plate test method has an acceptable accuracy in measuring the setting time and thixotropy.

Die Design of Flexible Multi-Point Forming Process

Multi-point forming (MPF) is an advanced flexible manufacture technology, and the technology results from the idea that the whole die is separated into small punches that can be adjusted height. This idea is applied to the traditional rigid blank-holder, so flexible blank-holder (FBH) idea can be obtained. In this work, the performance of a multi-point die is investigated with pins in square matrix and suitable blank holder. Each pin in the punch holder can be a significant moved according to the die high and at different load that applied with spring with respect to spring stiffness. The results shows the reduction in setting time with respect to traditional single point incremental forming process that lead to (90%). and also show during the forming process, the deformation of the interpolator can induce a shape error in the formed work-piece and the blank holder can reduce/eliminate dimples that sometimes arise in the work-piece. The minimum force applied using multi-point die is 28.556KN, while the load when complete the forming process is 30.8KN that caused displacement of die to 32.8mm.

Development of the electrolyzed water based set accelerated greener cement paste

The effect of electrolyzed water in controlling the setting behavior of cement paste was investigated in this study. The distilled, as well as the 30 min electrolyzed water, was used to prepare the cement paste. Analyzing the results, the final setting time of control cement (CC) paste, as well as the 30 min electrolyzed water based cement (EC) paste, was measured to be 172 ± 5 min and 108 ± 4 min, respectively. The reduction of setting time is due to the quick hydration of cement clinkers. Based on the Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analysis, the early setting and hydration performance of cement has been justified.

Fly ash based geopolymeric foams using silica fume as pore generation agent. Physical, mechanical and acoustic properties

The aim of this work is the development of a porous geopolymeric foam with sound absorbing properties using silica fume as the pore generation agent. The samples were manufactured using a coal combustion fly ash as source material for the geopolymerization reaction, an alkaline solution as activating solution and silica fume as pore forming agent. Three parameters were studied: silica fume proportion (0, 20 and 40 wt%), activating solution (potassium silicate and potassium hydroxide) and setting temperature (40 and 70 °C). Once the samples were prepared, the experimental study of the most important physical, mechanical and acoustic features were carried out. The increase in the proportion of silica fume in the mixture and setting temperature produced a reduction in setting time and a raise of open void porosity, reducing the compressive strength at 28 days up to a half but increasing the sound absorption. The influence of activating solution in open porosity and sound absorbing properties was not very important.

Computed Torque Control of a Caterpillar Robot Manipulator Using Neural Network

This paper presents a neural computed torque controller, which employs to a Caterpillar robot manipulator. A description to exert a control method application neural network for nonlinear PD computed torque controller to a two sub-mechanisms Caterpillar robot manipulator. A nonlinear PD computed torque controller is obtained via utilizing a popular computed torque controller and using neural networks. The proposed controller has some advantages such as low control effort, high trajectory tracking and learning ability. The joint angles of two sub-mechanisms have been obtained by using the numerical simulations. The discovered figures show that the performance of the neural computed torque controller is better than a conventional computed torque controller in trajectory tracking and reduction of setting time. Finally, snapshots of gain sequences are demonstrated.

The effect of adding nano-SiO2 and nano-Al2O3 on properties of high calcium fly ash geopolymer cured at ambient temperature

This article presents the effect of adding nano-SiO2 and nano-Al2O3 on the properties of high calcium fly ash geopolymer pastes. Nano-particles were added to fly ash at the dosages of 0%, 1%, 2%, and 3% by weight. The sodium hydroxide concentration of 10 molars, sodium silicate to sodium hydroxide weight ratio of 2.0, the alkaline liquid/binder ratio of 0.60 and curing at ambient temperature of 23°C were used in all mixtures. The results showed that the use of nano-SiO2 as additive to fly ash results in the decrease of the setting time, while the addition of nano-Al2O3 results in only a slight reduction in setting time. Adding 1–2% nano-particles could improve compressive strength, flexural strength, and elastic modulus of pastes due to the formation of additional calcium silicate hydrate (CSH) or calcium aluminosilicate hydrate (CASH) and sodium aluminosilicate hydrate (NASH) or geopolymer gel in geopolymer matrix. In addition, the additions of both nano-SiO2 and nano-Al2O3 enhances the shear bond strength between concrete substrate and geopolymer.

Effects of nano-SiO 2 and different ash particle sizes on sludge ash–cement mortar

The effects of nano-SiO 2 on three ash particle sizes in mortar were studied by replacing a portion of the cement with incinerated sewage sludge ash. Results indicate that the amount of water needed at standard consistency increased as more nano-SiO 2 was added. Moreover, a reduction in setting time became noticeable for smaller ash particle sizes. The compressive strength of the ash–cement mortar increased as more nano-SiO 2 was added. Additionally, with 2% nano-SiO 2 added and a cure length of 7 days, the compressive strength of the ash–cement mortar with 1 μm ash particle size was about 1.5 times better that of 75 μm particle size. Further, nano-SiO 2 functioned to fill pores for ash–cement mortar with different ash particle sizes. However, the effects of this pore-filling varied with ash particle size. Higher amounts of nano-SiO 2 better influenced the ash–cement mortar with larger ash particle sizes.