Short Setting Time Research Articles

Formulation and performance of slow-setting cement-based grouting paste (SCGP) for capsule grouting technology using orthogonal test

Capsule grouting technology (CGT) is a newly proposed technology to control the deformation of soil and underground structure. However, the conventional cement-based grouting slurry, with short setting time and poor fluidity, would not meet requirements for multiple capsule grouting. This study developed a slow-setting cement-based grouting paste (SCGP) based on ordinary Portland cement, bentonite, fly ash, and Etidronic acid as a retarder. The orthogonal test design and multiple linear regression analysis were used to optimize the material composition of SCGP, with the flowability, bleeding rate, initial setting time, and compressive strength as indexes. Moreover, the microstructure properties of the optimal SCGP were investigated. The results show that the influence of water-cement ratio and bentonite content on the fluidity and bleeding rate is more significant than that of other factors. The initial setting time of the paste would be greatly extended to nearly 60 h by adjusting the mixing ratio of retarder and raw materials. Although the retarder inhibits the early hydration reaction of the slurry, resulting in lower 7d strength, it does not affect the 28d compressive strength. Therefore, the optimal formulation of SCGP is recommended to be 1.1 for water-cement ratio, 30% for bentonite, 30% for fly ash, and 0.45% for retarder, which presents excellent performance for CGT.

A novel degradable tricalcium silicate/calcium polyphosphate/polyvinyl alcohol organic-inorganic composite cement for bone filling.

In this study, tricalcium silicate (C3S) calcium/polyphosphate/polyvinyl alcohol organic-inorganic self-setting composites were successfully designed. A variety of tests were conducted to characterize their self-setting properties, mechanical properties, degradation properties, and related biological properties. The composite bone cements showed a short setting time (5.5-37.5 min) with a 5:5-6:4 ratio of C3S/CPP to maintain a stable compressive strength (28 MPa). In addition, PVA effectively reduced the brittleness of the inorganic phase. Degradation experiments confirmed the sustainable surface degradation of bone cement. A maximum degradation rate of 49% was reached within 56 days, and the structure remained intact without collapse. Culturing MC3T3 cells with bone cement extracts revealed that the composite bone cements had excellent biological properties in vitro. The original extract showed a proliferation promotion effect on cells, whereas most of the other original extracts of degradable bone cements were toxic to the cells. Meanwhile, extracellular matrix mineralization and alkaline phosphatase expression showed remarkable effects on cell differentiation. In addition, a good level of adhesion of cells to the surfaces of materials was observed. Taken together, these results indicate that C3S/CPP/PVA composite bone cements have great potential in bone defect filling for fast curing.

Tensile response of Ultra High Performance PE Fiber Reinforced Concretes (PE-UHPFRC) under imposed shrinkage deformations

PE-UHPFRC is a new Ultra High-Performance Fiber Reinforced Concrete (UHPFRC), which is developed to reduce the environmental impact of conventional UHPFRC by replacing the steel fibers with synthetic ones and reducing the clinker content in the mix. The development of the dynamic elastic modulus, the evolution of free autogenous deformations and the eigenstresses development with age, under full and partial restraint conditions, were investigated for PE-UHPFRC and the results were put into perspective with that for conventional UHPFRC with steel fibers. Furthermore, the tensile responses of different mixes under imposed shrinkage were compared and discussed. The results showed a shorter setting time and consequently an earlier initiation of elastic modulus development for PE-UHPFRC compared with that of conventional UHPFRC. Furthermore, the developed eigenstresses under full restraint conditions in a PE-UHPFRC layer compared with that for conventional UHPFRC were reduced by more than 70%, which is highly beneficial especially for cast-in-place rehabilitation applications.

Design of self-heating test platform for sulfide corrosion and oxidation based on Fuzzy PID temperature control system

In this paper, the changes of oxidation temperature of sulfide corrosion and the deficiency of distributed optical fiber application were analyzed. The test platform of oxidation temperature of sulfide corrosion was established, and the performance test of optical fiber and the simulation of oxidation temperature of sulfide corrosion were realized. The hardware part of the control system used STM32 as the controller, the software part was based on the process characteristics of the controlled object, using MATLAB to carry out the simulation of PID, fuzzy, fuzzy PD plus I, fuzzy PID algorithms, and their performance are evaluated using both single indexes and comprehensive indexes. The experimental results also showed that the proposed fuzzy PID can achieve better control performance with less overshoot and shorter setting time. Therefore, the fuzzy PID was chosen as the temperature control algorithm to build the optical fiber sensor test platform, and an alarm method for testing the oxidation temperature of large area sulfide corrosion based on the optical fiber performance was obtained. Then, considering the influence of spatial resolution on optical fiber sensor, this paper used piecewise PID to simulate the temperature rise process of three stages of sulfurization corrosion and oxidation. The results showed that the alarm method of oxidation temperature of sulfurization corrosion has limitations for small-scale oxidation of sulfurization corrosion, and it needed to be combined with machine learning to identify temperature anomaly.

Particle Engineering of Gypsum Through Templating with Starch

The conversion of CaSO₄·0.5H₂O to CaSO₄·2H₂O (gypsum) is of great importance industrially, being the reaction behind plasterboard production and the setting of medical plasters. This hydration process is inherently slow, and to ensure that it occurs on a practical timescale, “seeds” of gypsum are typically added to accelerate the reaction. The seeds used in industry are mostly produced by milling quarried gypsum, resulting in huge variations in their accelerant properties between batches. Here, we develop a bottom-up process to prepare gypsum seeds with a tightly defined morphology, using starch as a templating agent during precipitation from water/ethanol mixtures. When the seeds thereby generated are dried, they tend to aggregate, which results in diminished accelerant properties. The hydration (or setting) time can be markedly reduced if these aggregates are broken up and suspended in a liquid medium. This indicates that directly adding the suspension reaction product to an industrial production line could be a powerful way to accelerate the setting reaction. However, the use of ethanol in the seed synthesis precludes this (because the ethanol would halt the setting reaction). Therefore, a direct one-step process involving evaporation of ethanol was developed to produce gypsum seeds in a water suspension with no ethanol present. The resultant “liquid seeds” are highly potent in accelerating the hydration process of CaSO₄·0.5H₂O to CaSO₄·2H₂O, resulting in shorter setting times than a commercial standard gypsum accelerant.

Design of polymeric binders to improve the properties of magnesium phosphate cement

In the context of reducing the environmental impact of cement manufacturing, magnesium phosphate cements raise interest as alternative binders in construction, for immobilization of wastes, and recycling purposes. Their use in applications is somehow limited by short setting time, brittleness and low water resistance; this calls for the use of additives. Two polymer additives were designed adopting emulsion polymerization, an environmentally friendly solution to make available polymers as water-based latex dispersions. The composites containing 5 wt% of polymer, exhibited better elastic behaviour, with up to twice the toughness of the reference sample and of a sample produced with commercial styrene-butadiene rubber latex. Moreover, the additives reduced the apparent porosity, promoted phosphate crystallization, modified the size and shape of crystals, and effectively retarded the reaction, extending working time. The acrylic emulsion developing keto-hydrazide self-crosslinking reaction imparted better properties to the composite, thanks to the synergistic effect with the MPC setting reaction.

Influence of water repellent on the property of solid waste based sulfoaluminate cement paste and its application in lightweight porous concrete

• It is feasible to use water repellents reduce the water absorption of LPC based on SW-CSA cement. • The effect of water repellents on the properties of SW-CSA cement paste was presented. • Using calcium stearate as the water repellent doesn’t affect the hydration of SW-CSA cement. Solid waste-based calcium sulfoaluminate (SW-CSA) cement is a type of low carbon cement that uses solid waste as raw material. It is usually used to prepare lightweight porous concrete (LPC) due to its short setting time. However, high water absorption of LPC based on SW-CSA cement limits its extensive application. Water repellent can be mixed into binder material to reduce the water absorption of LPC, but it may affect the hydration properties of SW-CSA cement paste, which influences the performance of LPC correspondingly. Calcium stearate (CS), sodium oleate (SO) and sodium methyl siliconate (SMS) are three familiar commercial water repellents. To find the suitable internal mixing water repellent for LPC based on SW-CSA cement, the effects of three CS, SO and SMS on the water absorption, hydration, compressive strength, fluidity, and setting time of SW-CSA cement paste were explored. Besides, the properties of LPC with CS and SO added were also studied. The results indicated that using CS as the water repellent could reduce the 1 day water absorption of SW-CSA cement paste by 45.9% and the water absorption of LPC by 33.0%. It also reduced the setting time of SW-CSA cement paste and increased the final compressive strength of LPC, which was conducive to the preferred rapid setting and high compressive strength of LPC. The hydrophobicity of SW-CSA cement paste with SO was better than that of SW-CSA cement paste with CS. But using SO and SMS as the water repellent retarded the early hydration of SW-CSA cement and prolonged the setting time of SW-CSA cement and reduced the final compressive strength of SW-CSA cement paste. Therefore, SO and SMS can’t be used as the internal mixing water repellent of LPC based on SW-CSA cement, while CS is a promising internal mixing water repellent of SW-CSA cement to prepare LPC.

Magnesium oxychloride cement reinforced via D-gluconic acid sodium salt for slow-curing, with enhanced compressive strength and water resistance

Magnesium oxychloride cement (MOC) has the advantages of low-carbon emission, reducing the magnesium chloride waste, and lack of humid curing. However, the MOC has not been widely utilized yet due to the poor water resistance and the short setting time at high ambient temperatures. Herein, a simple and low-cost approach was developed through incorporating D-gluconic acid sodium salt into the MOC. After adding 1.4 wt% D-gluconic acid sodium salt, the initial and final setting time were extended to 257 min and 421 min, respectively, compared to that of unmodified MOC (92 min and 192 min). Based on the X-ray photoelectron spectroscopy (XPS) analysis, the rod-like phase 5 (5 Mg(OH)2·MgCl2·8H2O) in the MOC was converted into the gel-like phase 5 through the chelation between D-gluconic acid sodium salt and phase 5. The gel-like structures were evidently observed in the MOC pores (especially after immersing in water), and they efficiently hinder the moisture penetrating into internal structure of the MOC. Subsequently, the softening coefficient was enhanced from 0.38 to 0.91 when the D-gluconic acid sodium salt content was increased from 0% to 1.4%. In comparison to the unmodified MOC, 0.6 wt% of D-gluconic acid sodium salt could enhance the compressive strength by 24.6% after curing for 7 days. When the D-gluconic acid sodium salt content increased to over 0.6%, the compressive strength decreased. Meanwhile, the analysis of phase components proved that the phase 5 content of the modified MOC specimens remained unchanged or even increased after immersing into the water, establishing protection of the gel-like structure on the phase 5.

Nanoscale insight on the initial hydration mechanism of magnesium phosphate cement

The hydration rate, microstructure, mechanical properties and durability of Magnesium phosphate cement (MPC) prepared by different kinds of phosphates are quite different. These differences in macroscopic properties are essentially determined by microscopic chemical reactions. Therefore, in this paper, the adsorption mechanism of MgO interface to water and ions in the initial hydration process of MPC and the hydration structure of different ions were discussed at the molecular level. Herein, the structure and dynamics properties of water, NH4+, Na+, K+ and Cl− ions at MgO interface were analyzed by molecular dynamics method. The results show that the water molecules near the MgO interface can be connected to the matrix oxygen through hydrogen bonding and have a Coulomb interaction with the Mg on the interface. Therefore, the water molecules accumulate and stratify at the interface and the density distribution curve of water molecules forms a peak near the interface. This explains the stage of MgO adsorption of water molecules during the initial hydration of MPC. Besides, a large amount of ammonium ion, sodium ion and potassium ion are adsorbed on the MgO surface, and the cation density distribution curve also forms a peak near the interface. In addition, the radius of sodium ion is smaller and the Na-Os bond is stronger than that of NH4+ and K+ (Os represents the oxygen atom in MgO). Hence, the number of sodium ions adsorbed to the interface is the largest, the radial distribution function (RDF) of Na-Os forms a high-strength and sharp peak, The Os coordination number of Na+ is more than that of NH4+ and K+. This also explains the experimental phenomenon that sodium magnesium phosphate cement has a faster hydration rate and shorter setting time than ammonium magnesium phosphate cement and potassium magnesium phosphate cement. Due to the adsorption of the interface, the mean square displacement of cations has decreased to some extent compared with that in the corresponding pure solution models. This study provides a basic understanding of the initial hydration mechanism of MPC at the molecular level.

Treatment of date palm fibres mesh: Influence on the rheological and mechanical properties of fibre-cement composites

An experimental study was conducted on the influence of different treatments of date palm fibres on the properties of mortars in both fresh and hardened states. Three types of treatment were discussed: boiling water treatment, sodium hydroxide treatment and a polymer surface treatment based on linseed oil. As a first step, tests of water absorption, setting times and direct tensile strength were performed on single fibres to assess the relevance of the predominant parameter for each treatment. Thereafter, unreinforced mortar and mortars reinforced with raw and treated date palm fibres were made and tested using a flow table test, as well as for porosity accessible to water, three-point bending strength, compressive strength and capillary water absorption. The results for individual fibres show that treatments with a 3-hour boiling of the fibres, a 3% NaOH concentration, and a 1.5% linseed oil/fibre ratio yield the lowest absorption kinetics, the shortest setting times, and the most interesting tensile properties. However, the results for fibrous composites indicate that the workability of mortars reinforced with linseed oil treated fibres was improved compared with raw fibres. In the hardened state, boiling and sodium hydroxide treatments improve the flexural strength of the composites. The same trend was observed for compressive strength. Therefore, the mortar reinforced by fibre treated with linseed oil does not improve the strength and is the most porous. The incorporation of date palm fibres decreases the kinetics of the capillary absorption of mortars compared to unreinforced mortar. The lowest absorption coefficients are obtained after the treatment with linseed oil.

Constituents, properties and clinical applications of OrthoMTA & RetroMTA: A systematic review.

OrthoMTA and RetroMTA are newly developed mineral trioxide aggregates that were developed to achieve maximum benefits and clinical performance. This systematic review aimed at assessing and describing the constituents, properties and uses of OrthoMTA and RetroMTA. Literature search was performed using the keywords, "OrthoMTA", "RetroMTA", "BioMTA", "constituents" and "properties" in the databases, PubMed, Cochrane, Semantic scholar and Europe PubMed Central. Original articles in English describing the properties, constituents, uses/indications, history and recent advances on OrthoMTA and RetroMTA were considered for the study. A total of 35 articles were selected for the systematic review based on keywords selected. Among the 35 articles, 5 articles described the composition and properties of OrthoMTA and RetroMTA, 7 articles depicted the usage of OrthoMTA and RetroMTA and the remaining articles discussed on the various properties of both OrthoMTA and RetroMTA. The present review confirmed that RetroMTA exhibits an excellent property, namely, short setting time, less tooth discoloration, high compressive strength, higher shear bond strength with time, higher push-out bond strength, low solubility, low cytotoxicity, biocompatibility, antibacterial property, and can be used in reparative processes in case of blood contamination. However, even OrthoMTA showed less microleakage, is biocompatible and possesses antibacterial properties.

The chemical reagents influence on the regulation of the powder composite materials setting time for construction purposes

Additives were selected, and a method for modifying the structure of gypsum-containing materials for construction purposes and a method for their dispersion were developed. Based on the selected modifiers, effective compositions of composite gypsum-containing materials based on local and secondary raw materials were developed. An increase in their strength and resistance to water was established. The use of gypsum plaster mixes shows their high efficiency and advantages compared to traditional finishing works methods. They provide a high and stable level of finishing quality, reduced transportation costs, and easy recycling of materials. However, despite the high consumer properties, the modern use of compositions based on the most affordable gypsum raw materials in the Republic and the production of gypsum binder beta calcium sulfate semi hydrate is limited to plasters and putties for rooms with normal operation. This is mainly because the compositions have a short setting time, low water resistance, and low strength characteristics. As a rule, the softening factor for such compositions does not exceed 0.5, and the compressive strength is 4-6 MPa

Identification of the Factors for the Selection of Cement Brands by Construction Companies and Selection of Optimal Cement Brand using TOPSIS for Kathmandu Valley along with the Physical Strength Comparison of Various Cement Brands

Cement comprises major proportion in any construction materials and the right selection of cement is equally important for construction companies. The objective of this research is to find the criteria used by the construction companies in cement selection and using the required criteria adopt TOPSIS (Technique of Order Preference by Similarity to Ideal Solution) as Multi Criteria Decision Making method for the selection of optimal cement brand among various cement brands for the construction projects in Kathmandu. Another objective is to find the physical characteristics of the selected cement brands in laboratory. For the methodology, non-random sampling was adopted. Data were collected by questionnaire, semi-structured interviews, KII and Lab test. For physical characteristics comparison of cement brands, samples were collected from hardware shop and lab test were conducted in private lab. For the factors in cement selection quality, ex-factory rate, credit-terms, delivery-time, relationship, self-clinker production, production-capacity, technology and financial-conditions were identified and ranked in relevant order. Six factors were chosen for TOPSIS for the six cement brands for Kathmandu valley. From TOPSIS, it was foundSarbottam cement is best suited for projects in Kathmandu valley in terms of physical strength Hongshi had the highest 3 and 7 days of compressive strength where as Sarbottam had highest 28 days strength. Maruti cement had longest setting time whereas United cement had shortest setting time. 28 days strength of all the cement were as per the NS 49whereas except for Maruti and Shivam, all the brands had strength as per IS 8112 criteria.

Nano-CSH modified high volume fly ash concrete: Early-age properties and environmental impact analysis

To reduce the carbon footprint in concrete industry, fly ash (FA) as the solid waste has been widely used to replace cement in concrete material. Nano-CSH crystals is used in this research to improve the early age properties of concrete with high volume fly ash (HVFA). The characteristic analysis of the HVFA concrete incorporating nano-CSH crystals was first conducted including early age strength development and setting time. The changes in hydration and microstructure due to the adding of nano-CSH crystals were explored by the isothermal calorimetry, X-ray diffraction (XRD) and scanning electron microscopy (SEM) testings. The environmental impact of concrete mixes was assessed using CMLCA software. The FA dosage in cement was up to 70% and the investigated nano-CSH crystals were 0.5%, 1% and 1.5%. The results showed that addition of 1% nano-CSH crystals in HVFA60% mixes and incorporation of 1.5% nano-CSH crystals in HVFA70% mixes achieved the highest strength and the shortest setting time. The adding of nano-CSH crystals accelerated the hydration of C3A and C3S to form more C–S–H and ettringite responsible for concrete strength and densified the overall microstructure. Ca(OH)2 content is reduced at the age of 28 days due to its reaction with FA. Adding 1.5% nano-CSH crystals in HVFA70% mix and incorporating 1% nano-CSH crystals in HVFA60% mix decreased the total environmental impact by 6.39% and 4.36% compared to pure HVFA70 and pure HVFA60 mixes respectively.

Developing a biodegradable tricalcium silicate/glucono-delta-lactone/calcium sulfate dihydrate composite cement with high preliminary mechanical property for bone filling

Bone cements with the feature of easily shaping could ideally match the defect site and prevent the ingrowth of fibrous tissue. In this manuscript, a biodegradable tricalcium silicate (C3S)/glucono-delta-lactone (GDL)/calcium sulfate dihydrate (CSD) organic-inorganic composite cement was fabricated with shorter setting time (less than 15 min) and high preliminary mechanical property (5.27 MPa in the first hour). Many methods were applied to study the physicochemical and biological properties of the cement in vitro. The weight loss in PBS can reach 58% after 12 weeks soaking indicating the better biodegradability. The excellent bioactivity in vitro was emerging after the cement was soaked in the simulated body fluid. The cell experiments showed that suitable concentration of the extract liquid of cement was conducive to the proliferation, differentiation and extracellular matrix calcification of the mouse bone marrow stromal cells. Briefly, the C3S/GDL/CSD composite cement would have the bright capacity for bone filling.

Biodentine as a Perforative Repair Material- A Review

Perforations are anomalous communications between the root canal system and the external dental surfacethat connects the pulp cavity to the periodontal tissue. Current advances in biomaterials has made the recoveryof tooth structure and function possible even in the most complicated cases. Ideally, perforations should beimmediately repaired with a biocompatible material to seal the communication between the perforation siteand the gingival sulcus in order to achieve a more favorable prognosis. This review article is focussed onBiodentine as perforative repair material, and has found to provide good biocompatibility, bioactivity, highcompressive strength and a short setting time.

Effect of Internal Curing by Super Absorbent Polymer on the Autogenous Shrinkage of Alkali-Activated Slag Mortars.

Alkali activated slag (AAS) mortar is becoming an increasingly popular green building material because of its excellent engineering properties and low CO2 emissions, promising to replace ordinary Portland cement (OPC) mortar. However, AAS’s high shrinkage and short setting time are the important reasons to limit its wide application in engineering. This paper was conducted to investigate the effect of internal curing(IC) by super absorbent polymer (SAP) on the autogenous shrinkage of AAS mortars. For this, an experimental study was carried out to evaluate the effect of SAP dosage on the setting time, autogenous shrinkage, compressive strength, microstructure, and pore structure. The SAP were incorporated at different dosage of 0, 0.05, 0.1, 0.2, 0.3, 0.4, and 0.5 percent by weight of slag. The workability, physical (porosity), mechanical, and shrinkage properties of the mortars were evaluated, and a complementary study on microstructure was made. The results indicated that the setting time increased with an increase of SAP dosage due to the additional activator released by SAP. Autogenous shrinkage decreased with an increase of SAP dosage, and was mitigated completely when the dosage of SAP ≥ 0.2% wt of slag. Although IC by means of SAP reduced the compressive strength, this reduction (23% at 56 days for 0.2% SAP) was acceptable given the important role that it played on mitigating autogenous shrinkage. In the research, the 0.2% SAP dosage was the optimal content. The results can provide data and basis for practical application of AAS mortar.

Osteogenic Potential of Fast Set Bioceramic Cements: Molecular and In Vitro Study

Recently, pre-mixed bioceramics in fast set formulations have been increasingly utilized in clinical practice as an alternative to mineral trioxide aggregate (MTA) for their shorter setting time and better handling properties. However, the impact on their osteogenic potential, due to modifications in chemical composition to promote a fast setting, is still unclear. This molecular and in vitro study compared the osteogenic potential of root repairing material putty fast set (FSP) with root-repairing material putty (RRMPU), root-repairing material paste (RRMPA), Biodentine™ and MTA. The null hypothesis tested was that there are no differences among the tricalcium silicate materials in terms of osteogenic potential. Standardized discs were cultured with MG-63 human osteoblastic-like cells to assess biocompatibility, the activity of alkaline phosphatase (ALP) and osteogenic potential. Biocompatibility was evaluated at baseline and after 24 and 48 h. Osteogenic differentiation was assessed after 15 days. Data were analyzed with one-way ANOVAs and Tukey’s post-hoc test (p < 0.05). All materials showed biocompatibility and bioactivity. ALP activity, which induces mineral nodule deposition, increased in all the cements tested, with a significant increase in RRMPU (p < 0.001) and FSP (p < 0.001) samples versus MTA. In vitro mineralization was significantly increased for RRMPU (p < 0.0001), FSP (p = 0.00012) and Biodentine™ (p < 0.0001) versus MTA. The bioceramics tested showed higher levels of biocompatibility and bioactivity than MTA; a higher capacity for mineralization was observed with RRMPU and FSP versus MTA.

Modeling and Analysis of the Fractional-Order Flyback Converter in Continuous Conduction Mode by Caputo Fractional Calculus

In order to obtain more realistic characteristics of the converter, a fractional-order inductor and capacitor are used in the modeling of power electronic converters. However, few researches focus on power electronic converters with a fractional-order mutual inductance. This paper introduces a fractional-order flyback converter with a fractional-order mutual inductance and a fractional-order capacitor. The equivalent circuit model of the fractional-order mutual inductance is derived. Then, the state-space average model of the fractional-order flyback converter in continuous conduction mode (CCM) are established. Moreover, direct current (DC) analysis and alternating current (AC) analysis are performed under the Caputo fractional definition. Theoretical analysis shows that the orders have an important influence on the ripple, the CCM operating condition and transfer functions. Finally, the results of circuit simulation and numerical calculation are compared to verify the correctness of the theoretical analysis and the validity of the model. The simulation results show that the fractional-order flyback converter exhibits smaller overshoot, shorter setting time and higher design freedom compared with the integer-order flyback converter.

Production of calcium silicate Nano-biocomposite and modeling of its flexural and compressive strength with statistics method

Nano Fast Cement (NFC) is a nanocomposite with a short setting time for repairing root teeth canals as an alternative to Mineral Trioxide Aggregate. The downside of this new tooth restorative material is the poor workability and low compressive strength. In this study, polyvinyl alcohol (PVA), colloidal nano-silica, and hydroxyapatite nanoparticles were added to NFC to improve its physical, mechanical, and biocompatibility properties of NFC. The effects of the three additives on strength were determined. Experiments were designed based on the Taguchi method. The optimum contents of the three additives for the highest compressive strength, flexural strength were also obtained. The results showed that the most effective factor on the mechanical (compressive & flexural strength) properties of NFC is polyvinyl alcohol. Based on the Taguchi method, the optimal (highest value) of the mechanical property is obtained for PVA, nano-silica, and nano-hydroxyapatite contents of 6, .0.5, 0 Wt.%.