Gram Of Cement Research Articles

An Integrated Hydration and Property Evaluation Model for Coral Powder–Cement Binary Blends

With the rise in the marine industry and marine tourism, coral powder is increasingly used to make concrete for marine islands. This study proposes a three-parameter hydration model and a hydration kinetic model to predict the performance of coral powder concrete based on previous experimental data. The process of the proposed prediction model is as follows: 1. The input parameters of the three-parameter hydration model are calibrated for the first 7 days using the cumulative hydration heat per gram of cement. The maximum cumulative hydration heat (455.87 J/g cement) and the shape coefficient (−0.87) remain constant. In this study, the hydration rate coefficients for 0%, 10%, and 20% coral powder were 6.91, 6.19, and 5.55, respectively, showing decreases of 10.41% and 19.68% compared with the specimens without coral powder. 2. At 28 days, the cumulative heat release values per gram of cement for 0%, 10%, and 20% coral powder were 389.77, 395.69, and 401.62 J/g, showing increases of 1.52% and 3.04% for the specimens containing 10% and 20% coral powder, respectively. Meanwhile, the hydration degrees for 0%, 10%, and 20% coral powder were 0.855, 0.868, and 0.881, respectively, showing increases of 1.52% and 3.04%. Furthermore, the cumulative heat release values per gram of binder were 389.77, 356.12, and 321.29 J/g, showing decreases of 8.63% and 17.56% for specimens containing 10% and 20% coral powder, respectively. 3. Properties such as compressive strength, ultrasonic pulse velocity (UPV), and surface electrical resistivity were evaluated using the power function and the cumulative hydration heat per gram of binder. 4. At 28 days, the chemically bound water contents for samples with 0%, 10%, and 20% coral powder were 0.2402, 0.2197, and 0.1981 g/g binder, respectively. Moreover, the calcium hydroxide contents were 0.1848, 0.1690, and 0.1524 g/g binder, showing reductions of 8.53% and 17.52% in bound water and 8.54% and 17.53% in calcium hydroxide. 5. A hydration kinetic model is proposed, which can distinguish between the dilution effect and the nucleation effect of coral powder, unlike the three-parameter model, which cannot distinguish between the two effects. Furthermore, the input parameters of the hydration kinetic model remain unchanged for different mixtures, while the input parameters of the three-parameter model must be varied among mixtures. Parameter analysis of the hydration kinetic model indicated that a low water–binder ratio and a high coral powder substitution rate significantly improve the relative reaction level of cement.

A Numerical Hydration Model to Predict the Macro and Micro Properties of Cement–Eggshell Powder Binary Blends

This study aims to propose a hydration kinetic model for the cement–eggshell powder binary system and predict the performance development of composite concrete through this model. The specific content and results of the model are as follows. First, based on the cumulative hydration heat of the cement and eggshell powder binary system in the first seven days, the parameters of the cement hydration model and the eggshell powder nucleation parameter are calibrated. These parameters remain constant regardless of the mix ratio. Secondly, the hydration heat of the cement–eggshell powder binary system over 28 days is calculated using the hydration model. The results show that at 28 days, for specimens with 0%, 7.5%, and 15% eggshell powder substitution, the cement hydration degrees are 0.832, 0.882, and 0.923, respectively. The hydration heat per gram of cement is 402.69, 426.88, and 446.73 J/g cement, respectively, while the hydration heat per gram of binder is 402.69, 394.86, and 379.72 J/g binder, respectively. Additionally, the hydration model is used to calculate the chemically bound water and calcium hydroxide content of the cement–eggshell powder binary system. At 28 days, for samples with 0%, 7.5%, and 15% eggshell powder, the chemically bound water content is 0.191, 0.188, and 0.180 g/g binder, respectively, and the calcium hydroxide content is 0.183, 0.179, and 0.173 g/g binder, respectively. Finally, a power function is used to regress the calculated hydration heat with experimentally measured compressive strength and surface electrical resistivity. The correlation coefficients for compressive strength and surface electrical resistivity are 0.8474 and 0.9714, respectively. This is because the strength weak point effect of eggshell powder has minimal impact on hydration heat and surface electrical resistivity experiments but significantly affects the strength experiment.

A Hydration Model to Evaluate the Properties of Cement-Quartz Powder Hybrid Concrete.

Although quartz powder is a common concrete filling material, the importance and originality of this study lies in the development of a hydration model for quartz powder-cement binary mixtures and the adoption of this model to predict the development of concrete material properties. The purpose of this study is to use this model to promote the material design of environmentally friendly concrete and to elucidate the relationships in the development of the various properties of quartz powder concrete. The method used in this study was as follows: The parameters of the hydration model were obtained through seven days of hydration heat experiments. The hydration heat up to 28 days was also calculated, and the various properties of the concrete were predicted from the heat of hydration. The main findings of this study were as follows: (1) The ultimate hydration heat released per gram of cement for the different quartz powder substitution rates and quartz powder particle fineness was the same, at 390.145 J/g cement, as was the shape index of the hydration model at -1.003. (2) Moreover, through the model calculations, we found that, at the twenty-eighth day of the curing period for the quartz powder specimens with different quartz powder substitution amounts and different fineness, the reaction level of the cement was similar, at 0.963, as were the values of the cumulative heat of hydration, with both at 375.5 J/g cement. (3) The model showed that, in the late stage (28 days) of hydration for quartz powders of different fineness and when the substitution amount was the same, the cumulative heat of hydration over 28 days was similar. (4) The properties of concrete were evaluated using the calculated hydration heat. Overall, the predictive performance of the power and linear functions was similar, with no significant differences being found.

Influence of Eggshell Powder on the Properties of Cement-Based Materials.

Replacing cement with industrial by-products is an important way to achieve carbon neutrality in the cement industry. The purpose of this study is to evaluate the effect of eggshell powder on cement hydration properties, and to evaluate its feasibility as a substitute for cement. The substitution rates of eggshell powder are 0%, 7.5%, and 15%. Studying the heat of hydration and macroscopic properties can yield the following results. First: The cumulative heat of hydration based on each gram of cementitious material falls as the eggshell powder content rises. This is a result of the eggshell powder's diluting action. However, the cumulative heat of hydration per gram of cement rises due to the nucleation effect of the eggshell powder. Second: The compressive strengths of ES0, ES7.5, and ES15 samples at 28 days of age are 54.8, 43.4, and 35.5 MPa, respectively. Eggshell powder has a greater negative impact on the compressive strength. The effect of eggshell powder on the speed and intensity of ultrasonic waves has a similar trend. Third: As the eggshell powder content increases, the resistivity gradually decreases. In addition, we also characterize the microscopic properties of the slurry with added eggshell powder. X-ray Diffraction (XRD) shows that, as the age increases from 1 day to 28 days, hemicaboaluminate transforms into monocaboaluminate. As the content of the eggshell powder increases, FTIR analysis finds a slight decrease in the content of CSH. Similarly, thermogravimetric (TG) results also show a decrease in the production of calcium hydroxide. Although the additional nucleation effect of eggshell powder promotes cement hydration and generates more portlandite, it cannot offset the loss of portlandite caused by the decrease in cement. Last: A numerical hydration model is presented for cement-eggshell powder binary blends. The parameters of the hydration model are determined based on hydration heat normalized by cement mass. Moreover, the hydration heat until 28 days is calculated using the proposed model. The strength development of all specimens and all test ages can be expressed as an exponential function of hydration heat.

Effect of nano-metakaolin on establishment of internal structure of fly ash cement paste

The study aims to enhance the viscosity and establishment of internal structure of fly ash (FA) cement paste through the addition of nano-metakaolin (NMK). Various tests, including apparent viscosity test, small amplitude oscillatory shear test, and calorimetric test, were conducted to investigate the effects of FA content, NMK content, superplasticizer content, and test temperature. The results showed that NMK increased the apparent viscosity of FA cement paste while weakening its shear thinning behavior. Specifically, incorporating 5 wt% NMK increased the apparent viscosity of cement paste containing 30 wt% FA by 60%. Furthermore, NMK accelerated the growth of storage modulus (G') and facilitated the rapid establishment of internal structure in FA cement paste, the optimal amount of NMK admixture in a 30 wt% FA cement paste is determined to be 5 wt%. However, the presence of superplasticizer hindered the increase in G' and delayed the establishment of internal structure in NMK/FA cement pastes. For cement paste containing 5 wt% NMK and 30 wt% FA, the growth rate of G' within 60 min decreased to 26% when 0.12 wt% superplasticizer was added compared to the cement paste without superplasticizer. Temperature had a significant impact on the establishment process of internal structure in NMK/FA cement pastes within 90 min but had minimal effect on the final state at 90min. For N5FA30 cement paste hydrated for 30 min and 90 min respectively, G' at 10 °C was approximately 7.3% and 66.7% compared to that at 40 °C. Moreover, a power function correlation was observed between G' and cumulative hydration heat per gram of cement (Hc) in NMK/FA cement pastes. The inclusion of superplasticizer decreased both G' and Hc in the cement paste. Notably, the influence of superplasticizer on G' was more pronounced than its impact on Hc during the hydration process.

A review on structural performance of geopolymer beam and geopolymer for strengthening the beam

Geopolymer composites are emerging sustainable technology in the construction industry. Agro and industrial wastes can convert into useful construction material using geopolymer technology. Without using single gram of cement, geopolymer concrete can achieve superior characters as compared to normal concrete. A number of studies has been conducted on mix proportion, workability, durability, strength parameters of geopolymer concrete. But very few research studies are conducted on the geopolymer material as strengthening material. A critical review on geopolymer beam structural performance and geopolymer as a strengthening material is presented in this article. First part of the article cover the structural performance of geopolymer concrete beam. Another half cover the geopolymer material performance as a strengthening material.Structural performance of geopolymer beam has same manner as ordinary portland cement concrete beams. Failure patterns, bond strength, flexural strength, shear strength studies of the geopolymer beams by different researchers shows the geopolymer beam behavior. Compare to ordinary portland cement concrete beam, geopolymer beam shows good load resistance characters. While using geopolymer as a strengthening material of beam, the beam capacity can be increased efficiently. Textile reinforced geopolymer concrete, fiber reinforced geopolymer concrete, steel reinforced geopolymer concrete etc. are used as strengthening material for geopolymer and Ordinary Portland cement beam. From the previous studies it is clear that geopolymer material shows a promising character as a strengthening material for beams. Geopolymer material can be used as a structural beam as well as strengthening material for beam using the provisions of standard codes. More research studies in the area of geopolymer as a strength enhancement material required.

The effect of Polynaphthalene Sulfonates on the mixture composed of Air-entraining cement and fine sand with a maximum size of 600 micron

This study provides a new mixture using Poly Naphthalene Sulfonates (PNS) to improve the compressive strength, density, and flowability. An experimental study was conducted to study the effect of PNS on mixtures composed of air-entraining cement, fine sand with a maximum size of 600 µm, and low water content, the water to cement ratio was 0.3. The effect of PNS was evaluated based on three characteristics, namely the compressive strength, the density, and the flowability. Four different dosages of PNS (0.0%, 2.5%, 3.5%, and 4.5%) (g/g) of cement weight were used. The results showed that the more PNS dosages were added, the higher compressive strength, density, and flow became. The first mixture without PNS dosages (control mixture) showed no sign of flow resulting in the lowest density and strength among other mixtures. By adding (2.5%, 3.5%, 4.5%) of PNS dose, described as a gram of the superplasticizer to gram of cement, to the control mixture, the compressive strength increased by (58%, 69%, and 70%) compared to the control mixture, and the density increased by (7%, 12%, and 16%) and the flow diameter increased by (17%, 41%, and 52%), respectively. Adding PNS with air-entraining cement can significantly increase the workability, density, and compressive strength altogether. Increasing the compressive strength to above 20 MPa and reaching to 24 MPa may refer to the consent of this combination, PNS and air-entraining cement. To overcome the high-water demand of highly fine sand mixtures made with low water content, water surface tension can be diminished but with no ability to air-entraining or with no ability to retain air-bubbles that may be entrained.

The Effect of Varying Water to Powder Ratios on the Microhardness and Microstructure of Mineral Trioxide Aggregate

The composition of water and powder in a mixture is one of the common problems in application as clinicians typically estimate the ratio chairside. The purpose of this study was to investigate the effect of varying water-to-powder ratios on the microhardness and microstructure of mineral trioxide aggregate (MTA). ROOTDENT MTA was investigated. One gram of cement was mixed with 0.28, 0.33, and 0.40 grams of distilled water and was stored for 1, 7, and 28 days in the water. Samples were subjected to x-ray diffraction (XRD), scanning electron microscopy (SEM), and microhardness tests. Tricalcium silicate, dicalcium silicate, zirconium dioxide, calcium carbonate, and calcium hydroxide were detected by XRD. SEM showed the presence of amorphous, porous capillary channel and capillary structure on the surface of the specimens. The SEM image for each water-to-powder ratio of the surface of the material was indistinguishable from the other. The highest microhardness was exhibited by the MTA specimen with the 0.33 water-to-powder ratio submerged in the water for 28 days.

Bioactive, Ion‐Releasing PMMA Bone Cement Filled with Functional Graphenic Materials

Graphene oxide and functionalized graphenic materials (FGMs) have promise as platforms for imparting programmable bioactivity to poly(methyl methacrylate) (PMMA)-based bone cement. To date, however, graphenic fillers have only been feasible in PMMA cements at extremely low loadings, limiting the bioactive effects. At higher loadings, graphenic fillers decrease cement strength by aggregating and interfering with curing process. Here, these challenges are addressed by combining bioactive FGM fillers with a custom cement formulation. These cements contain an order of magnitude more graphenic filler than previous reports. Even at 1 wt% FGM, these cements have compressive strengths of 78- 88 MPa, flexural strengths of 74-81 MPa, and flexural stiffnesses of 1.8-1.9 GPa, surpassing the ASTM requirements for bone cement and competing with traditional PMMA cement. Further, by utilizing designer FGMs with programmed bioactivity, these cements demonstrate controlled release of osteogenic calcium ions (releasing a total of 5 ± 2 µmol of Ca2+ per gram of cement over 28 d) and stimulate a 290% increase in expression of alkaline phosphatase in human mesenchymal stem cells in vitro. Also, design criteria are described to guide creation of future generations of bone cements that utilize FGMs as platforms to achieve dynamic biological activity.

Performance of mortar incorporating calcined marine clays with varying kaolinite content

This study is an attempt in exploring the feasibility of low-grade kaolinite clays, generated as waste from excavation works, as supplementary cementitious materials and potential candidate for cement replacement. Clays from five sources were investigated for composition, pozzolanic reactivity and effect on mortar strength and durability. Clays were grinded and calcined at 700 °C to convert kaolinite into metakaolin. Thereafter, 30% by wt. of cement was replaced with a combination of calcined clay and limestone in a 2:1 wt ratio. The pozzolanic nature of the clays was studied through thermo-gravimetric analysis (TGA), isothermal calorimetry (ITC) and X-ray diffraction (XRD). The effect on corrosion resistance was examined using electrical resistivity and rapid chloride penetration tests (RCPT). Results show that marine clays in Singapore in general have low to moderate kaolinite content (20–40%). In the ITC tests, blended mixes displayed accelerated hydration and 20–30% higher heat of hydration per gram of cement at 7th day compared to the reference mix without any substitution. The bound water per gram of cement calculated from the TGA results showed a noticeable increase in blended mixes, indicating additional hydration products in those samples. Though a 10–20% decrease in strength was observed in blended mortars compared to reference samples at 28-days, their corrosion resistance showed remarkable improvement. The charge passed during RCPT reduced by 20–60% while the electrical resistivity increased by 50–200% depending on the clay and its properties. Overall, the results were encouraging to suggest the use of low-grade marine clays as viable alternative to replace cement thereby producing a sustainable and low carbon concrete.

Effect of Varying Water-to-Powder Ratios on Compressive Strength and Porosity of Mineral Trioxide Aggregate

The proportion of MTA powder and water is a common factor impacted on the properties of the material in clinical application. The purpose of this research was to determine the compressive strength and porosity of Mineral Trioxide Aggregate (MTA) mixed with varying water-to-powder (WP) ratios. ROOTDENT MTA was investigated. One gram of cement was mixed with 0.28, 0.33 or 0.40 grams of distilled water and was submerged either for 1, 7, or 28 days in the water. The chemical composition of un-hydrated MTA was characterized by X-ray fluorescence. Samples were carried out for compression and porosity test. ROOTDENT MTA was composed primarily of calcium, oxygen, and zirconium. Minor quantities of sodium, aluminum, and silicon were presented in the cement and lack of bismuth was found. The highest mean compressive strength value was MTA with 0.33 WP ratio submerged in the water for 28 days. The percentage of porosity increased as the WP ratio increased. The percentage of porosity submerged in the water for 7 and 28 days showed no significant differences while the lowest porosity was MTA with 1 day in the water.

Cement Waste During Primary Total Knee Arthroplasty and its Effect on Cost Savings: An Institutional Analysis.

PurposeHealthcare costs are increasingly garnering more media attention and there is increasing focus on improving efficiencies in daily practice. Orthopedic surgery is also subject to these fiscal pressures, particularly in arthroplasty surgeries, secondary to high volumes with costly equipment. Total knee arthroplasties (TKA) are one of the most common surgical procedures, with over 64,000 annual cases in Canada. Even marginal cost reductions per procedure can be compounded over the large volume to result in considerable savings. This study’s purpose is to investigate and quantify the cost of wasted intraoperative cement used in primary TKA.MethodsResidual amounts of wasted bone cement were collected and measured following uncomplicated primary TKAs performed by the senior authors in a high-volume arthroplasty centre between January and June 2017. Stryker Simplex® with Tobramycin Bone Cement was the specific institutional cement used.ResultsOne hundred and two primary total knee arthroplasties were investigated. The results revealed that an average 91.2 g of surgical cement was wasted per case, with less than 30 g retained in the bone-implant interface (26.8 g). Institutional costs per package of cement is $120.62, amounting to $2.04 per gram of cement. This represents a value of $186.25 CAD per case.ConclusionOn average, each primary TKA procedure wastes 91.2 g of bone cement per case. The value of this wasted cement is $186.25 CAD per TKA. When extrapolated to the most recent recorded numbers of TKAs done in Canada, that figure nears $12 million. The results of this study are important, as they reveal a potential source to target for both waste reduction and cost control.

Influence of Thermomechanical Pulp Fiber Compositions on Internal Curing of Cementitious Materials

AbstractThis research examines the efficiency of thermomechanical pulp (TMP) fibers, both untreated and after chemical treatment to produce holocellulose and α-cellulose, for internal curing. In addition, the effect of TMP fibers on early hydration behavior was investigated. The results show that TMP and α-cellulose fibers had a negligible effect on cement hydration. Holocellulose, conversely, significantly reduced the rate of hydration, noticeably delaying setting time. The addition of the fibers in dosages to provide an additional amount of entrained water of 0.05 g per gram of cement resulted in a decrease of early autogenous shrinkage of cement paste. Holocellulose, reducing autogenous shrinkage of cement paste by 93%, was shown to be the most effective for internal curing; however, its adverse effect on cement hydration may require acceleratory admixtures when used in concrete. Thermomechanical pulp and α-cellulose showed a similar efficiency in mitigating autogenous shrinkage; these fibers reduced s...

Isothermal and solution calorimetry to assess the effect of superplasticizers and mineral admixtures on cement hydration

The heat of hydration evolution of eight paste mixtures of various water to binder ratio and containing various pozzolanic (silica fume, fly ash) and latent hydraulic (granulated blast furnace slag) admixtures have been studied by means of isothermal calorimetry during the first 7 days of the hydration process and by means of solution calorimetry for up to 120 days. The results of early heat of hydration values obtained by both methods are comparable in case of the samples without mineral admixtures; the values obtained for samples containing fly ash and granulated blast furnace slag differ though. The results from isothermal calorimetry show an acceleration of the hydration process by the presence of the fine particles of silica fume and retarding action of other mineral admixtures and superplasticizer. The influence of the presence of mineral admixtures on higher heat development (expressed as joules per gram of cement in mixture) becomes apparent after 20 h in case of fly ash without superplasticizer and after 48 h for sample containing fly ash and superplasticizer. In case of samples containing slag and superplasticizer the delay observed was 40 h. The results obtained by solution calorimetry provide a good complement to the ones of isothermal calorimetry, as the solution calorimetry enables to study the contribution of the mineral admixtures to the hydration heat development at later ages of the hydration process, which is otherwise hard to obtain by different methods

Mineral Trioxide Aggregate (MTA) Solubility and Porosity with Different Water-to-Powder Ratios

This study tested mineral trioxide aggregate (MTA) solubility and porosity with different water-to-powder proportions. The study also determined the chemical composition of the salts dissolved by MTA. Four sets of specimens using the following water-to-powder proportions were prepared: 0.26, 0.28, 0.30, and 0.33 grams of water per gram of cement. The latter is the ratio recommended by the manufacturer. It was determined that the degree of solubility and porosity increased as the water-to-powder ratio increased. Significant differences were found among the sets of specimens. The chemical analyses of the salts dissolved by MTA in the water identified the presence of calcium as the main chemical compound. The pH level of the solution was highly alkaline, ranging between 11.94 and 11.99. It can be stated that the calcium found in the solution should be in its hydroxide state at this high pH level. This ability to release calcium hydroxide could be of clinical significance because it could be related to the proven capacity of MTA to induce mineralization.

In vitro investigation of aluminum and fluoride release from compomers, conventional and resin-modified glass-ionomer cements: A standardized approach

The amount of fluoride release from dental cements necessary for an anticariogenic effect is not established; moreover, the possible toxic effects due to high fluoride and aluminum release are not well known and the results are still controversial. The aim of our study was to evaluate fluoride (F) and aluminum (Al) release from dental cements using a 'standardized approach' according to the end-use of the materials, i.e. biocompatibility testing. Two polyacid-modified resin composites of recent application, commonly called compomers (Dyract® and Dyract Cem®), were compared with two conventional acid-based (Fuji I™, Ketac-Cem®) and two resin-modified (Vitremer™, Vitrebond™) glass-ionomer cements (GICs). All types of cement are used in dentistry and are commercially available. Extracts of the cements into minimum essential medium, after setting over a 1-h (group A) and 1-week (group B) period, were performed. The extraction conditions were rigorously standardized. Mean values +/- standard deviation of F- and Al-levels in such extracts were measured and were expressed as μg g-1 (micrograms of ions per gram of cement). A great difference in the amount of ion release, both F and Al, was shown among the tested materials. The GICs, as well as Ketac-Cem®, released more F and Al than the compomers. All of the materials released the greatest proportion of ions when the extraction was performed in the first hour after mixing (group A). Al- and F-values showed a highly significant positive correlation, independently from the curing time. We conclude that the biological assessment of dental cements can be performed only if a preevaluation of the leachables is obtained by applying a standardized protocol which allows a useful comparison between the different materials.

The depot administration of penicillin G and gentamicin in acrylic bone cement.

The in vitro elution of penicillin and gentamicin from polymethylmethacrylate was studied qualitatively and quantitatively. Penicillin eluted poorly from Simplex P. Higher levels of penicillin eluted in sustained fashion from Palacos; concentrations of one microgram or more per gram of cement were recorded during the thirteen weeks of observation. Although the in vitro leaching of gentamicin from Palacos cement was similar to that of penicillin, there were two important differences: (1) most of the gentamicin leaching from the Palacos did so within the first twenty-four hours, and (2) the concentrations decreased to less than one microgram per gram of cement after the sixth week of observation. The in vivo elutions of penicillin and gentamicin from Palacos were studied in canine femora. The concentrations of penicillin and gentamicin in the endosteal bone at the bone-cement interface exceeded the concentrations found after intravenous administration of either agent. Bactericidal concentrations of gentamicin in osseous tissue persisted for seven months after implantation. Peak concentrations in serum following the depot administration of either penicillin or gentamicin occurred within thirty minutes of implantation. Concentrations of gentamicin in serum did not approach toxic levels. These data suggest that a high concentration of either penicillin or gentamicin can be obtained at the bone-cement interface--one of the vulnerable sites in total joint arthroplasty--for a prolonged period with the depot administration of these agents in acrylic bone cement. These osseous concentrations can be achieved without exposing the patient to elevated levels in serum and their potential toxic side effects.