Anti-washout Performance Research Articles

Konjac glucomannan: A promising environmental friendly anti-washout agent for ordinary Portland cement mortar

Adding polymer-based anti-washout admixture (AWA) is considered one of the most effective methods to improve the anti-washout performance of underwater-cement. However, the addition of polymer-based anti-washout admixture suffers from the unclear anti-washout mechanism and the potential micro-plastic pollution. This study reported an eco-friendly, high-performance AWA based on konjac glucomannan (KGM) extracted from biomass-based Konjac. The results from the interaction between the KGM and the pore solution indicate that KGM can effectively increase the viscosity of underwater cement mortar by chelation ions. The increase of viscosity made by introducing a small amount of KGM solution (0.2 wt%) can effectively enhance the anti-washout performance of underwater cement mortar. Simultaneously, introducing KGM will not adversely affect other working properties of cement mortar. This study not only proves the mechanism of KGM-based AWA to adjust the anti-washout performance of cement materials but also provides a new strategy for developing green, high-performance AWAs.

Improving the Anti-washout Property of Acrylate Grouting Material by Bentonite: Its Characterization, Improving Mechanism, and Practical Application.

Acrylate is a popular polymer grouting material that has been widely used to control groundwater seepage. However, the vulnerability of acrylate slurry to dynamic water washout restricts its application in groundwater environments characterized by high flow velocity and water pressures. In this paper, lithium bentonite (Li-B) was used to modify the traditional magnesium acrylate (AC) grouting material. The influence of Li-B to AC ratios on the modified materials' washout resistance was explored, and the modification mechanism was analyzed using X-ray diffraction (XRD), infrared spectroscopy (IR), and scanning electron microscopy (SEM). Finally, the anti-washout ability of the modified slurry was verified through engineering applications. Results revealed that LiB-AC grout had adjustable setting times (10.5 to 395.6 s), minimal bleeding (0.1%), higher viscosity (65 mPa·s) and expansibility (350%), stronger anti-water dispersibility (24 times that of pure AC slurry), higher mechanical strength (compressive strength is 0.386 MPa, tensile strength is 0.088 MPa), and better impermeability (2.23 × 10-8 m/s). The lithium bentonite was beneficial to the setting time, bleeding, viscosity, slurry retention rate, impermeability, and mechanical strength of the acrylate grout. However, it diminished the expansibility of the acrylate grout. At the optimal acrylate content (20%), the mechanical strength and impermeability of the LiB-AC grout were the highest. The better performance of LiB-AC grout was attributed to the formation of a more stable and dense interlaced spatial network structure after the modification by Li-B. The LiB-AC grout was used in the dynamic water grouting project of a metro shield tunnel segment and achieved better anti-washout performance than cement-water glass and pure AC slurry.

Physicochemical properties and cytocompatibility of radiation-resistant and anti-washout calcium phosphate cement by introducing artemisia sphaerocephala krasch gum

The anti-washout ability of calcium phosphate cement (CPC) determines the effectiveness of CPC in clinical application. The γ-ray irradiation method often used in the sterilization process of CPC products is easy to degrade some commonly polymer anti-washout agent, which greatly reduces its anti-washout performance. Artemisia sphaerocephala Krasch gum (ASKG) has the potential of radiation resistance and anti-washout, but no one has considered its performance as anti-washout agent of CPC and mechanism of radiation resistance and anti-washout so far. In this study, we report the effect of γ-ray on ASKG and the effectiveness of ASKG for enhancing of radiation resistance and anti-washout ability of CPC, the physical, chemical properties and in vitro cell behaviors of ASKG-CPCs were also investigated. The results showed that addition of ASKG before and after irradiation could significantly enhanced the anti-washout performance of CPC, which is differ from conventional anti-washout agents. Meanwhile, ASKG-CPCs had an excellent injectable property and biocompatibility, and low content of irradiated ASKG could promote bone differentiation well. We anticipate that the radiation-resistant and anti-washout ASKG-CPCs have potential application prospect in orthopaedic surgery.

Fabrication and characterization of novel rapid-setting and anti-washout bioactive glass cements for direct pulp capping

Although Mineral trioxide aggregate (MTA) has been widely used for pulp capping procedures and obtains outstanding clinical outcomes, too long setting time and poor anti-washout property of MTA still constrain its widespread applications. This study was aimed to develop a novel rapid-setting and washout resistance bioactive glass cements (BGC) via combining appropriate bioactive glass (BG) and brushite (DCPD) powders. Various ratios of BG and DCPD cement from 10B (10% BG in cement) to 70B (seven groups) had been prepared. The setting mechanism, setting time, compressive strength, degradability, pH, anti-washout and apatite-formation ability of the BGC were evaluated. The results showed that shorter setting time about 5 min and least degradability were achieved for 40–50B cements, and 30–40B cements held superior anti-washout performance. Moreover, the compressive strength varied form 1.48 ± 0.18 MPa (60B) to 12.04 ± 1.32 MPa (20B). Furthermore, all 10–70B BGC exhibited excellent apatite-formation ability and the surface of 30–50B preserved dense structure after immersion in simulated body fluids (SBF). What's more, the 40B cement also possessed good formability, and the extracts of 40B could effectively stimulate the proliferation and odontogenic differentiation of human dental pulp stem cells (DPSC). Overall, the properties of novel BGC could be adjusted effectively by the component and 40B bioactive glass cements possessed comprehensively superb performance, especially for rapid-setting and anti-washout properties, which had great potential as a new class pulp capping material.

A novel anti-washout curing solution of calcium phosphate cement prepared via irradiation polymerization.

The anti-washout ability of calcium phosphate cement (CPC) determines its effectiveness in clinical application. In the current research, the common method for improving the anti-washout ability of CPC is to add anti-washout polymer agents. Sodium polyacrylate powder is an excellent anti-washout agent but when bonded with CPC it basically degrades the anti-washout performance of CPC after γ-ray irradiation, and is widely used in the sterilization process of CPC products. Therefore, we propose a method for the preparation of a sodium polyacrylate solution through irradiation polymerization as curing solution for CPC. This method first uses γ-ray irradiation sterilization to improve the anti-washout ability of CPC directly. It not only avoids the adverse effects of γ-rays on anti-washout agents, but also the CPC blended using this sodium polyacrylate solution had good biological properties and injectability. It provides a new method for promoting the anti-washout properties of calcium phosphate cement, which is of great significance for expanding the clinical application of CPC.

Preparation and characterization of injectable gelatin/alginate/chondroitin sulfate/α-calcium sulfate hemihydrate composite paste for bone repair application.

In this study, a group of injectable composite pastes with a novel formulation consisting of two inorganic components: α-calcium sulfate hemihydrate (α-CSH, P/L = 1.8-2.1g/ml) and calcium-deficient hydroxyapatite (CDHA, P/L = 0.1g/ml) nanoparticles; and three biopolymers: gelatin (2, 4wt. %), alginate (1, 1.5wt. %), and chondroitin sulfate (0.5wt. %) were carefully prepared and thoroughly characterized with commensurate characterizations. The composite sample composed of gelatin (2wt. %), alginate (1.5wt. %), chondroitin sulfate (0.5wt. %), and also CDHA nanoparticles and α-CSH with P/L ratios of 0.1 and 2.1g/ml, respectively, exhibited optimal properties in terms of injectability, anti-washout performance, and rheological characteristics. After 14days of immersion of the chosen sample in the simulated body fluid medium, a dense layer of apatite was formed on the surface of the composite paste. The cellular in vitro tests, such as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (MTT), alkaline phosphatase assay, 4',6-diamidino-2-phenylindole staining, and cellular attachment, revealed the desirable response of MG-63 cells to the composite paste. The chondroitin sulfate significantly improved the injectability, anti-washout performance, and cellular response of the samples. Considering the promising features of the composite paste prepared in this research work, it could be considered as an alternative injectable bioactive material for bone repair applications.[Formula: see text].

Ultra-stable anti-washout cement grout achieved by super water absorbing villus-like nanocomposite hydrogel

In this paper, super absorbent polymer (SAP) is used as anti-washout admixtures (AWA) to investigate the influence of the swelling property, salt resistance swelling property and chemical interaction of SAP on the washout of underwater cement grout. Herein, a new villus-like nanocomposite hydrogel (V-NC gel), one self-synthesized new SAP, were used to fabricate underwater cement grout with ultra-stable anti-washout performance. Incorporating V-NC gel can significantly reduce underwater cement grout washout loss from 91.05% to 62.22%, which was much better than those of adding commercial water absorbent polyacrylate sodium (PAAS). The villus-like structure of V-NC gel ensured super water absorbing performance in the cement environment, leading to strengthening the anti-washout performance. Further, the –COO− group (from V-NC gel) could chelate with Ca2+ (released from cement hydration) to form a cross-linking network, being conducive to gluing the cement particles, thereby enhancing the anti-washout performance of the cement grout.

Evaluation of the Hydration Characteristics and Anti-Washout Resistance of Non-Dispersible Underwater Concrete with Nano-SiO2 and MgO

In this paper, the effect of nano-SiO2 (NS) and MgO on the hydration characteristics and anti-washout resistance of non-dispersible underwater concrete (UWC) was evaluated. A slump flow test, a viscosity test, and setting time measurement were conducted to identify the impacts of NS and MgO on the rheological properties of UWC. The pH and turbidity were measured to investigate the anti-washout performance of UWC mixes. To analyze the hydration characteristics and mechanical properties, hydration heat analysis, a compressive strength test, and thermogravimetric analyses were conducted. The experimental results showed that the fine particles of NS and MgO reduced slump flow, increased viscosity, and enhanced the anti-washout resistance of UWC. In addition, both NS and MgO shortened the initial and final setting times, and the replacement of MgO specimens slightly prolonged the setting time. NS accelerated the peak time and increased the peak temperature, and MgO delayed the hydration process and reduced the temperature due to the formation of brucite. The compressive results showed that NS improved the compressive strength of the UWC, and MgO slightly decreased the strength. The addition of NS also resulted in the formation of extra C–S–H, and the replacement of MgO caused the generation of a hydrotalcite phase.

Premixed tricalcium silicate/sodium phosphate dibasic cements for root canal filling

Mineral Trioxide Aggregate (MTA) showed good clinical outcomes for many endodontic diseases. However, poor handling characteristics and anti-washout ability of MTA largely limit its widespread applications. In this study, a premixed tricalcium silicate (TCS)/sodium phosphate dibasic (SPD) cement was developed to overcome the aforementioned disadvantages of MTA. The hardening mechanism of TCS/SPD premixed pastes was studied. The influences of SPD on washout resistance, injectability, flowablity, setting time and compressive strength of the premixed TCS pastes were investigated. Considering required radiopacity, ZrO2 was incorporated, and radiopacity, anti-washout characteristics, bioactivity and sealability of radiopaque cements were studied. The results revealed that addition of SPD changed the phase compositions and morphologies of hydration products of cements. The anti-washout performance of TCS/SPD premixed cements was greatly enhanced due to improved cohesion of pastes. Additionally, TCS/SPD premixed pastes had good injectability and flowability. The setting time and compressive strength displayed a decreasing trend after adding SPD. The radiopacity of cements significantly increased from 1.54 to 3.64 mm Al with increasing ZrO2 content from 0 to 30 wt%, and the radiopaque premixed pastes showed good apatite formation-ability and sealing property. These results indicated that radiopaque TCS/SPD premixed cements could be a novel promising dental cement.

In vitro and in vivo osteogenesis of gelatin-modified calcium silicate cement with washout resistance.

The purpose of this study was to evaluate the physicochemical properties and the in vitro and in vivo osteogenesis of the newly developed calcium silicate containing 5wt% gelatin (CSG) cement compared with calcium silicate (CS) and calcium sulfate hemihydrate (CSH) cements. In addition to the phase composition and microstructure, washout resistance, setting time, and diametral tensile strength of the bone cements were also performed. In vitro examination of cell growth, differentiation, and mineralization were performed with macrophage cell line (RAW 264.7), MG63 human osteoblast-like cells, and human mesenchymal stem cells (hMSCs). The mini-pig model with mandibular alveolar bone defect was used to assess the in vivo function of cement. Histological and histomorphometric assessments were performed at 6 and 12weeks after implantation. The results indicated that the CS and CSG powders were mainly composed of poorly crystalline β-dicalcium silicate, and the irregular CSH powders had a highly crystalline phase. After setting, the product of CS and CSG was calcium-silicate-hydrate gel and CSH exhibited a plate-like gypsum crystal structure. The setting time of CS, CSG, and CSH was 19, 35, and 10min, respectively. Gelatin effectively improved the washout resistance and diametral tensile strength of CS from 2.4MPa to 3.4MPa, while CSH had no washout resistance and its strength was 7.6MPa. The osteogenic activity of MG63 and hMSC cells on the CSG cement surface was consistently shown to be significantly higher than that on the CSH cement surface. Interestingly, CS and CSG cements exhibited lower macrophage expression compared to CSH cements. Twelve week after implantation, the amount of new bone in the defect area of the CS group was slightly higher than that of the CSG and CSH groups. It is concluded that CSG cement had improved anti-washout performance, favorable osteogenesis in vitro and in vivo, which was beneficial for clinical application.

Enhanced antibacterial activity of calcium silicate-based hybrid cements for bone repair.

Calcium silicate cement has attracted much attention for bone defect repair and regeneration due to its osteogenic properties. Biomaterial-associated infections and washout have become a common clinical problem. In order to enhance the antibacterial and washout performance of calcium silicate cement to meet clinical needs, different types of chitosan, including chitosan polysaccharide (CTS), quaternary ammonium chitosan (QTS), and chitosan oligosaccharide (COS), as a liquid phase were added to the calcium silicate powder. The physicochemical properties, in vitro bioactivity, antibacterial efficacy, and osteogenic effects (MG63 cells) of the cement were evaluated. Antibacterial activity was conducted with Gram-negative Escherichia coli (E. coli) and a Gram-positive Staphylococcus aureus (S. aureus) bacteria. The amount of intracellular reactive oxygen species (ROS) produced in the bacteria cultured with the chitosan solution was also detected. The experimental results showed that the chitosan additive did not affect the crystalline phase of calcium silicate cement, but increased the setting time and strength of the cement in a concentration-dependent manner. Within the scope of this study, CTS and QTS solutions with a concentration of not <1wt% improved the washout resistance of the control cement, while the COS solutions failed to strengthen the cement. When soaked in simulated body fluid (SBF) for 1day, all cement samples formed apatite spherules. As the soaking time increased, the diametral tensile strength of all cements decreased and the porosity increased. The assays of MG63 cell function showed lower osteogenic activity of osteoblastic cells grown on the surfaces of the chitosan-incorporated cements in comparison with the control cement without chitosan. At the same 1% concentration, compared with QTS and COS cement, CTS cement had lower cell attachment, proliferation, differentiation, and mineralization. Conversely, the CTS cement resulted in the highest bacteriostasis ratio among the three hybrid cements against two bacteria. The ROS production followed the order of CTS>QTS>COS at the same 1% concentration. In conclusion, calcium silicate cement with 1% QTS may be a viable candidate for bone defect repair in view of anti-washout performance, setting time, antibacterial activity, and osteogenic activity shown in this study.

New Method to Evaluate Antiwashout Performance of Grout for Preventing Water-Inrush Disasters

AbstractGrouting is frequently used to prevent water-inrush disasters in tunnels and underground engineering. However, complex groundwater environment can significantly influence the grouting effec...

Fast-setting and anti-washout tricalcium silicate/disodium hydrogen phosphate composite cement for dental application

Although Mineral trioxide aggregate (MTA) has been widely used in endodontic treatments and gained great clinical success, development of fast-setting tricalcium silicate (TCS)-based cements with good anti-washout performance remains a huge challenge. Hence, this study was aimed at engineering a novel TCS-based endodontic material to meet abovementioned requirements via introduction of disodium hydrogen phosphate (Na2HPO4) as the hydration accelerator. The setting time, flowability, mechanical strength and anti-washout property of the composite cements were evaluated. Furthermore, bioinert ZrO2 was used as radiopacifier and the effects of ZrO2 content on the radiopacity, physicochemical properties, apatite-formation ability, pH, antibacterial activity, cement-dentin interface and cell cytocompatibility of radiopaque composite cements with an optimal component were also investigated. The results showed that the setting time of cement pastes notably shortened from 169 to 33 min with adjusting the amount of Na2HPO4 from 0 to 30 wt%, whereas flowability and compressive strength of cements exhibited a decreasing trend. Meanwhile, cement pastes displayed good anti-washout performance because of acceleratory effect of Na2HPO4 on hydration process of TCS and formation of additional binding phase. Furthermore, the radiopacity of hybrid cements obviously enhanced with the addition of ZrO2 while a little increase in setting time was observed, and washout resistance of composite pastes was slightly reduced with the increase in ZrO2 amount. The radiopaque composite pastes could induce apatite deposition on their surfaces and showed good marginal adaptation at cement-dentin interface. Additionally, the addition of ZrO2 content had no significant influences on alkaline formation ability, antibacterial activity, and cell cytocompatibility of cement pastes. Our results indicated that TCS/Na2HPO4/ZrO2 cement exhibited a great potential to be used as a novel dental material and might be a promising candidate for endodontic treatments.

Developing a Polypropylene Fabric, Silica Fume, and Redispersible Emulsion Powder Cementitious Composite for Dynamic Water Environment.

In the dynamic water environment, grouting requires a material with higher strength and anti-washout performance to prevent groundwater inrush. This study aims to develop a dynamic water slurry by mixing polypropylene fiber (PP fiber), silica fume (SF) and the polymer material of redispersible emulsion powder (REP) to the Portland cement. Towards this aim, a series of tests, including strength, gel time, bleeding rate, fluidity, and anti-washout, were conducted to evaluate the effects of SF, PP fiber, and REP on the slurry properties. The test results show that: (1) SF displays significant effects on strength, gel time, fluidity, and bleeding rate of cement slurry. Differently, PP fiber mainly affects the stress–strain behavior of the slurry and can improve the ductility significantly. (2) By mixing SF and fiber simultaneously, the slurry strength can increase by about 30%, and its strain can extend by more than 70%. Meanwhile, the composite slurry possesses great anti-washout properties at a low flow velocity (v ≤ 0.4 m/s), and the grouting retention rate (GRR) can reach up to 98.7%. However, the GRR decreases to a maximum value of 31.3% when v = 0.6 m/s. (3) By mixing the REP into the fiber-SF composite slurry, the GRR can further increase, reaching more than 60% even when v = 0.6 m/s. As a result, the developed fiber-SF cementitious composite slurry, which when mixed with REP, presents a favorable performance in the dynamic water environment.

Improvement of anti-washout property of calcium phosphate cement by addition of konjac glucomannan and guar gum.

The inferior anti-washout property of injectable calcium phosphate cement (CPC) limits its wider application in clinic. In this study, the improvement of anti-washout performance of CPC by addition of konjac glucomannan or guar gum, which was dissolved in the CPC liquid, was first studied. The influence of KGM/GG blend with different mass ratios on the anti-washout property, compressive strength and in vitro cytocompatibility of CPC was estimated. The results revealed that small amount of KGM or GG could obviously enhance the anti-washout property of CPC. Moreover, the washout resistance efficiency of KGM/GG blend was better than KGM or GG alone. The addition of KGM/GG blend slightly shortened the final setting time of CPC. Although the introduction of KGM/GG blend reduced the compressive strength of CPC, the compressive strength still reached or surpassed that of human cancellous bone. The best KGM/GG mass ratio was 5:5, which was most efficient at not only reducing CPC disintegration, but also increasing compressive strength. The addition of KGM/GG blend obviously promoted the cells proliferation on the CPC. In short, the CPC modified by KGM/GG blend exhibited excellent anti-washout property, appropriate setting time, adequate compressive strength, and good cytocompatibility, and has the potential to be used in bone defect repair. The addition of KGM/GG blend significantly improved the anti-washout property of CPC. The best KGM/GG mass ratio was 5:5, which was most efficient in reducing the CPC disintegration.

Setting behavior, mechanical property and biocompatibility of anti-washout wollastonite/calcium phosphate composite cement

In this study, a calcium phosphate-based composite cement was fabricated by incorporating wollastonite (WS) into calcium phosphate cement (CPC). The setting behavior, microstructure, injectability, porosity, compressive strength, anti-washout property, in vitro degradation, and cell behavior of the WS/CPC composite cement were systematically investigated. The results revealed that the addition of WS promoted the hydration reaction but without affecting the hydration product of CPC. The injectability of the WS/CPC composite cement declined with the incorporation of WS to a certain extent, especially when the content of WS was higher than 20wt%. By incorporating appropriate amount of WS into CPC, the composite cement obtained feasible setting time, enhanced compressive strength, improved anti-washout performance, and favorable biocompatibility. On the basis of its improved comprehensive application-relevant properties, the WS/CPC composite cement is prospective to be a promising biomaterial for bone defect repairing.

Experimental Research on Compatibility between Underwater Anti-Washout Admixture and Superplasticizer

The compatibility between underwater-washout admixture(AWA) and two different types of superplasticizers, polycarboxylate-type and naphthalene-based, was studied. The results showed that, there were different compatibilities between AWA and different superplasticizer, but the differences were not apparent. Compatibility of AWA with polycarboxylate superplasticizer was better than that of naphthalene superplasticizer. When the solid content is same, the difference of compatibility between AWA and different brand polycarboxylate-type superplasticizer was very slight. The underwater concrete with good anti-washout performance, good fluidity, self-compacting ability and corrosion resistance can be prepared easily through the reasonable compound. However it was difficult to solve the retarding problem and the contradiction between good fluidity and strength of the non-dispersible underwater concrete.

Improvement of Anti-Washout Performance of Calcium Phosphate Cement Using Modified Starch

Calcium phosphate cements (CPCs) are well-known orthopedic materials for filling bone. However, CPC pastes tend to disintegrate immediately when contacting with blood or other aqueous (body) fluids, which is a main limitation of its clinical applications in bone repairing, reconstruction and augmentation. To improve the anti-washout performance of CPC, modified starches such as pre-gelatinized starch, etherified starch, and esterified starch were added to the liquid phase of CPC in this work. CPC with good anti-washout performance was prepared and the effects of the modified starches on the properties of CPC were investigated. The results showed that the CPC with the modified starches were more stable in simulated body fluid than that without modified starch, especially the CPC with the etherified starch (II). X-ray diffraction analysis revealed that the modified starches did not inhibit CPC components from converting to hydroxyapatite. Furthermore, the anti-washout mechanism of the modified starches in CPC was discussed. It is concluded that the addition of the modified starches such as pre-gelatinized starch, etherified starch, and esterified starch to CPC can improve its anti-washout performance and should be of value in clinical surgery where the cement is exposed to blood.

Development of a New Injectable Calcium Phosphate Cement That Contains Modified Starch

In this study modified starch were used as anti-washout promoters of injectable calcium phosphate cement (CPC) and the effects of the modified starch on the injectability, anti-washout performance, setting time, compressive strength, phase evolution and microstructure of this cement were investigated. The injectability of the cement was improved by adding the modified starch (0.5-2.0%). After mixing with modified starch (0.5-2.0%), the cement showed better anti-washout performance than that without modified starch after immersed and shaken in SBF. Especially, when the content of the modified starch was 1.0%, the remaining percentage of the cement was reached to 92.6%, but only 5.9% of the CPC paste remained and set for the sample without modified starch after shaken for 2 hrs. The compressive strength of cements significantly increased from 44 MPa to 54 MPa when 0.5% of modified starch was added. And a slight increase on the mechanical strength can be observed for other concentrations. Powder X-ray diffraction analysis revealed no significant difference for the conversion of the cement to hydroxyapatite for any concentrations of modified starches. The influence of the modified starch on the microstructure of the set cement was also studied. The results showed the modified starch would reduce the acicular crystal size of hydroxyapatite accompanied with little flaky crystals generation and made a compact structure. It is concluded that modified starch, a suitable anti-washout promoter, improved the performance of CPC.

Influence of anti‐washout agents on the rheological properties and injectability of a calcium phosphate cement

Anti-washout-type calcium phosphate cement (aw-CPC) was prepared by introducing chitosan, sodium alginate, or modified starch into the powder phase of CPC, respectively. The results showed that these cements cannot be washed out and set within approximately 10-30 min even if the pastes were immersed in distilled water immediately and were shaken in a shaker after mixing and moulding. To our knowledge, it is the first report about the influence of the content of these anti-washout additives on the rheological properties and injectability of the cement. Moreover, novel approach of yield stress measurement was used to evaluate the injectability of the pastes. A modified starch was originally used as anti-washout agent for CPC. This study provided a convenient way to use the injectable CPC with good anti-washout performance when the paste was exposed to blood. The aw-CPC had potential prospects for the wider applications in surgery such as orthopaedics, oral, and maxillofacial surgery.