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Sisal fibers (SF) and polycarboxylate superplasticizers (PCE) contribute to the sustainable development of cementitious materials by improving and optimizing their hardening properties. In this study, the impact of SF and PCE on the workability of cement pastes was investigated. The workability was evaluated through spreading diameter, yield stress, and plastic viscosity measurements, and the adsorption behavior of PCE was analyzed. The results showed that the introduction of SF had a negative effect on the workability of PCE plasticized cement pastes, reducing flowability and increasing yield stress and plastic viscosity, regardless of aspect ratio or dosage. A contact angle tester and a scanning electron microscope (SEM) were employed to examine the surface properties of SF. The mechanism behind this interaction of cement-PCE-SF was explored and found to be due to the rough surface of SF, which increased the consumption of PCE, and the formation of hydrogen bonds between PCE and SF. Additionally, PCE modified the interfacial structure between SF and the cement matrix, strengthening the relationship between the different phases. These findings provide new insights into the modification of fiber-reinforced cementitious materials. This paper presents a comprehensive study on the workability and rheology behavior of cementitious material that coupled PCE superplasticizer and SF. The interaction between PCE and SF was experimentally studied by suitable tests, and the results and mechanism behind were well explained. The fresh properties were evaluated through a mini slump test, rheological properties, and the adsorption behavior of PCE on the surface of cement and SF was analyzed. The results showed that the introduction of SF decreases the spread diameter and increases the yield stress and plastic viscosity, regardless of aspect ratio and dosage, which indicate that a negative effect on the workability of PCE plasticized cement pastes. The mechanism behind the cement-PCE-SF interaction was explored in depth by the surface properties of SF, which revealed that the rough surface of SF increased the consumption of PCE. In addition, the formation of hydrogen bonds between PCE and SF provides an additional explanation. The significance of this study provides valuable guidance in using fibers and PCE together in cementitious materials. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess adaptation and bonding to root canal dentin of discontinuous (short) glass fiber-reinforced composite to intra-radicular dentin (DSGFRC). Methods: Seventy virgin human teeth were extracted and then endodontically treated; then samples were randomly divided into 7 groups (n = 10), based on the materials' combinations as follows: Group 1, a two-bottle universal adhesive + DSGFRC; Group 2, a single-component universal adhesive + DSGFRC; Groups 3 and 4, the same materials of Goups 1 and 2 were used but after cleaning of the canal walls with 17% EDTA and final irrigation with 5.25% NaOCl Ultrasound Activated (UA); Group 5, traditional prefabricated fiber posts were luted after being silanized with G-Multi Primer; Groups 6 and 7, like Group 5 but after ultrasonic irrigation (UA). All sample roots were cut 1 mm thick (n = 10) to be evaluated regarding root canal adaptation using a light microscope and scanning electron microscope (SEM) and push-out bond strength. These results were statistically analyzed by Kruskal–Wallis analysis of variance by ranks. The level of significance was set at p < 0.05. Results: Bond strength forces varied between 6.66 and 8.37 MPa and no statistically significant differences were recorded among the groups. By microscopic examination, it was noted that ultrasonic irrigation increased the adaptation of the materials to the dentin surface. Conclusions: Within the limitations of this in vitro study, it may be concluded that when DSGFRC was used for intracanal anchorage in the post-endodontic reconstruction, similar push-out retentive force and strength to those of traditional fiber posts cemented with particulate filler resin composite cements were achieved. [ABSTRACT FROM AUTHOR]

Successful implementation of microbial self-healing cementitious materials requires the provision of a suitable incubation environment, which activates the bacteria to produce calcium carbonate sealing the cracks. Affecting microbial mineralization, incubation temperature determines the self-healing efficiency of microbial cement which limits its widespread application. To investigate the effect of incubation temperature on the self-healing abilities, laboratory experiments were conducted on polyvinyl alcohol (PVA) fiber reinforced cement mortar impregnated with Sporosarcina pasteurii. The mortar specimens were initially cracked by three point bending to generate 0.4 mm width cracks at the bottom and then sprayed the calcium chloride and urea solution periodically for 2 days and immersed in the water for 28 days at ambient temperatures of 20 ∘ C, 25 ∘ C, 30 ∘ C, and 35 ∘ C. The cracks were inspected regularly which were further analyzed via deep learning to evaluate the crack healing ratio and sealing rate. The cracks failed to completely repair at 20 ∘ C, while cracks at 30 ∘ C requires only 4 days to seal. The crack healing rate accelerated with increasing temperature from 20 ∘ C to 30 ∘ C, exhibiting a trend of initial increase followed by decrease across all temperatures. The bacterial-repaired mortar specimens exhibited a recovery in flexural strength, with a regained strength ratio of approximately 7.184 % at 30 ∘ C. Supported by Scanning Electron Microscope (SEM) and X-ray diffractometer (XRD), the results revealed that the higher temperature actives larger particle CaCO 3 with mainly vaterite and some calcite morphology. The interaction mechanism of temperature effect on bacterial self-healing capabilities was revealed by the comprehensive assessment between the microbial activity, crack width evolution and mechanical performance. This paper may shed some light on the engineering application of microbial cementitious material resilient infrastructures with desirable healing efficiency under real ambient temperatures during service. • The optimal incubation temperature is 30 °C taking 3 days for complete healing. • Crack width sealing rates displayed an initial increase followed by a decrease. • Wider cracks exhibited faster sealing rates due to more friendly ecological niches. [ABSTRACT FROM AUTHOR]

Copyright of Fly Ash Comprehensive Utilization is the property of Hebei Fly Ash Comprehensive Utilization Magazine Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Odontologica Latinoamericana: AOL is the property of Acta Odontologica Latinoamericana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Architecture & Civil Engineering is the property of Chang'an Daxue Zazhishe and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To investigate the effects of basalt fiber content on the mechanical properties and microstructure characteristic of metakaolin-based cement clay, the static and dynamic uniaxial compressive and splitting tensile, nuclear magnetic resonance (NMR), and scanning electron microscope (SEM) tests were performed to study the stress-strain curves, static and dynamic peak stress, pore distribution characteristic, and reinforcement mechanism. In this research, the basalt fiber with the length of 12 mm were selected and the ratios between fiber and dry soil were 0%, 0.5%, 1.0%, 1.5%, and 2.0%, respectively. The obtained results showed a noticeable difference of stress-strain curve characteristics in the static and dynamic compressive tests. A positive correlation between deformation modulus and compressive strength was found for both static and dynamic tests. The addition of basalt fiber could efficiently increase the static and dynamic strengths of metakaolin-based cement clay, and the increment 66.15% and 74.63% was observed at 1.0% basalt fiber content for static and dynamic compressive strengths, respectively, while the corresponding increment values were 93.75% and 97.62% for its splitting tensile strengths, respectively. The basalt fiber could decrease the porosity of cement clay; moreover, the reinforcement mechanism of metakaolin and basalt fiber to cement clay was analyzed based on the SEM test results. [ABSTRACT FROM AUTHOR]

Abstract Dynamic and quasi-static in-plane compression failure process of a 2D-SiC/SiC composite were explored in this paper. Specular Reflection Method (SRM) was introduced to capture the real-time high-resolution images of the SiC/SiC composite in tests. The fracture surfaces of the subject composite under dynamic and quasi-static loading show different angles with loading direction. Dynamic fracture surface results showed a larger angle with the loading direction, with fiber breakage without debonding. However, in the quasi-static tests fracture surface showed a small angle with the loading direction, with fiber debonding and fiber bundle buckling. Scanning electron microscope (SEM) characterization of fragments obtained after experiments were used to characterize the deformation mechanisms of the 2D-SiC/SiC composite. Although both shear deformation and delamination were found under quasi-static and dynamic loading, shear deformation dominated the failure process of specimens during dynamic compression. Two microscopic fracture modes were concluded from the failure process of quasi-static and dynamic loadings. The strength of the fiber-matrix interface significantly influenced the fracture modes. Finally, an effort was made to simulate the dynamic failure process of SiC/SiC composite using the topological structure of a full-size specimen. [ABSTRACT FROM AUTHOR]

This study represents an extension work to investigate the role of ultra fine sand (UFS) in enhancing the mechanical properties of fiber reinforced cementitious compounds. The micro-structural origins were identified by scanning electron microscope (SEM). About 50% of UFS had a diameter of less than 20 µm. Ordinary Portland Cement (OPC) was partially substituted by UFS at 3, 5, 7 and 10% by weight of binder. It was found that as UFS loadings increase, the flexural, compressive, and tensile strengths increased up to about 5% UFS loading by 12.9, 15.7 and 30.1%, respectively, thereafter, a decrease in these properties was observed. This can be attributed to the pozzolanic effect besides the filling effect of UFS resulting in enhancing the interfacial bonds between the sand grains and hydration products that makes the paste more homogeneous and dense. The effect of both short natural and artificial fiber loadings on the structural performance of compounds was also studied. Loadings of 2%, by weight, of short natural date palm leaves' midribs fibers (DP) and artificial polypropylene fibers (PP) were added to the 5% UFS blended mix. An increase in both flexural and tensile strength was achieved, while a decrease in the compressive strength was observed. [ABSTRACT FROM AUTHOR]

Abstract: Glass fiber reinforced cement (GRC) is a composite material produced by the union of a cement mortar matrix and chopped glass fibers. Its good mechanical properties deteriorate with time. This phenomenon has been studied performing a tensile test program on both young and aged samples of GRC produced by using different chemical additives. Once the tests were carried out, a microstructural analysis of fracture surfaces was performed using a scanning electronic microscope (SEM). Pictures taken showed that the addition of metakaolin enables more fibers to be pulled out from the matrix instead of being broken in aged GRC samples. However, the increase in the number of such fibers pulled out did not prevent the embrittlement of GRC. Also, all the other chemical additions used did not show any improvement in the mechanical properties of GRC. [Copyright &y& Elsevier]

Abstract: Polymer modified steel fiber-reinforced concretes were produced with addition of both steel fibers and a styrene butadiene rubber emulsion (SBR). Both flexural and compressive strength of the composites after 28days curing were tested. Microstructures of the composites were analyzed by using scanning electron microscope and mercury intrusion porosimetry. Results show that the addition of steel fibers increases both flexural and compressive strength of the composites. The flexural strength increases significantly when containing 3–10wt.% SBR. The optimal use of SBR is 5wt.%. However, the compressive strength may decrease with the addition of SBR. When the addition arrives 10wt.%, a 16% reduction is observed. The overall porosity and pore size distribution of the composites vary with SBR content. The addition of 3 or 5wt.% SBR can refine the pore size distribution. Interweaving polymer films were observed in the composites. [Copyright &y& Elsevier]

• Hemp fibers improved both flexibility and impact resistance of the composites. • Waxy substances on the surface of hemp fibers were washed out with NaOH reagent. • Alkalinity in geopolymer acted as a (self)pre-treatment reagent for hemp fibers. • Self-treatment process can shorten the preparation process of hemp fibers. • Self-treatment process could be applied to any natural fibers in geopolymers. The novelty and the aim of this research is to investigate the feasibility of the self-treatment process, which is governed by various levels of alkalinity, i.e., sodium hydroxide (NaOH) solution in the geopolymer system, for natural fibers, and the effect of such treatment on the properties of hemp-geopolymer composites. A digital microscope is used to examine the contact angle (CA). Fourier Transform Infrared (FT-IR) spectrometer, Scanning Electron Microscope (SEM), X-Ray diffractometer (XRD) are used to examine changes in surface functional groups, bonding, micrographs and structural formation of the resulted hemp-based geopolymer products. The results showed that the alkalinity in the geopolymer alternatively acted as an alkaline treatment reagent for the reinforced hemp fibers, which evidently provided effectively self-treatment, indicating by the FT-IR and contact angle analysis. The compressive strength of the composites was slightly dropped as the binder was replaced by the hemp fibers, while the flexural strength and impact resistance were improved by the additional adhesion between the natural fibers and cement matrix. The self-treatment approach could also shorten the preparation process of any natural fibers in geopolymers, allowing both cost-effectiveness in practical usages and in-field applications. [ABSTRACT FROM AUTHOR]

• Addition of graphene oxide increases compressive strength of cement mortar. • Denser microstructure is observed in graphene mortar as compared to normal mortar. • Graphene oxide improves pullout load, bond strength and energy absorption of fiber. • Pullout behavior of fiber embedded in GM mortar is sensitive to loading rate. The properties of fiber reinforced concrete (FRC) depends strongly on bond between fiber and cement matrix. Any change in matrix and fiber characteristics affects the bond behavior. In this study, the effect of graphene oxide on cement composite strength and bond behavior between fiber and cement matrix was investigated. The graphene oxide solution with concentration of 10 mg/ml was mixed with cement mortar at 0.05% by weight of cement. Four types of fibers viz., hooked end steel, double hooked end steel, polypropylene and glass fibers were tested by embedding in both plain cement mortar (M) and cement graphene mortar (GM). The single fiber pullout test was performed at the rates of 60 and 180 mm/min. Results were collected in form of failure mode, scanning electron microscope (SEM) images, bond-slip response, bond strength and energy absorption. SEM images showed that the failure modes depended on fiber type, matrix type and loading rate. The steel fibers showed almost no damage except for the change of hooked end shape at the fiber end. For polypropylene fiber, the fiber surface scraping was commonly observed while the debonding of coating material was observed for glass fiber. The bond strength was higher in GM mortar than that of M mortar and increased with the increase in loading rate. In the case of fiber type, steel fibers exhibited higher bond and energy absorption than both polypropylene and glass fibers. [ABSTRACT FROM AUTHOR]

Fire is one of the most unfavorable conditions that cement-based composites can face during their service lives. The uniaxial tensile and flexural tensile properties of the steel-polyvinyl alcohol fiber-calcium carbonate whisker (CW) multi-scale fiber reinforced cement matrix composites (MSFRCs) under high temperatures are studied, including strength, deformation capacity, energy dissipation capacity, and its ability to be assessed through the empirical calculation method. The study showed that with the increase of the treatment temperature, the MSFRC residual bending strength, bending toughness, and tensile strength decreased overall, but the decline was slow at 600 °C. The peak flexural deflection and peak tensile strain of MSFRC first reduced and then increased with the increase of the temperature. As the temperature increased, the nominal stiffness of MSFRC bending and straight gradually reduced, and the rate of decline was faster than that of its strength. However, the uniaxial tensile properties were more sensitive to the temperature and degraded more rapidly. A quantitative relationship was established between MSFRC residual bending, tensile strength, and temperature. A comparison with existing research results shows that MSFRC has achieved an ideal effect of high temperature resistance. The multi-scale hybrid fiber system significantly alleviates the deterioration of cement-based composite's mechanical properties under high temperatures. With the help of an optical microscope and scanning electron microscope (SEM), the high temperature influence mechanism on the uniaxial tensile and flexural properties of MSFRC was revealed. [ABSTRACT FROM AUTHOR]

This study aims to prepare bamboo-fiber-reinforced cement composites and provide a solution to the issue of poor interfacial adhesion between bamboo fibers and cement matrix. The original bamboo fibers were modified by three moderately low-cost and easy-to-handle treatments including glycerol, aluminate ester, and silane treatments. The performance of the modified bamboo-fiber-reinforced cement composites was evaluated by a series of mechanical and durability tests, including flexural and compressive strength, water absorption, chloride ion penetration, drying shrinkage, freeze–thaw resistance, and carbonization. In addition, the microstructures of composites were characterized using a scanning electron microscope (SEM). The results showed that the composites reinforced with glycerol-modified bamboo fibers had 14% increased flexural strength and comparable compressive strength. From durability perspectives, all treatments showed similar performance in drying shrinkage, whereas aluminate ester treatment was the most effective in terms of impermeability, chloride resistance, freeze–thaw resistance, and carbonization. The results could provide insights to efficient and effective natural fiber treatment to enable better performance of natural-fiber-reinforced cement-based materials. [ABSTRACT FROM AUTHOR]

• Pull-out tests on basalt fiber reinforced cementitious composites were conducted. • Bonding properties of BFRCC specimens with different fiber sizing were analyzed. • Micromorphology of BFRCC specimens from the pull-out tests was analyzed by SEM. Bonding performance of basalt fiber reinforced cementitious composites (BFRCC) was studied through analyses on pull-out tests and scanning electron microscope (SEM) results. It is concluded that: (1) The rupture failure occurred for dispersed and flexible-type fibers, the pull-out failure controlled cluster-type fibers, and failure modes of alkali-resistant fibers are related to their embedded lengths (l e). (2) As l e increases, peak pull-out load (N pmax) increases and then becomes unchanged. Appropriate le is within 15–18 mm. (3) As specimen ages, N pmax first increases and starts to decrease at 7-day. (4) Comparisons of bonding strength among different fiber types: dispersed > flexible > alkali-resistant > cluster. (5) SEM analyses are consistent with the macro bonding performance of BFRCC. [ABSTRACT FROM AUTHOR]

This study investigated several approaches for silane-removal from the surface of short carbon fiber bundles, and short carbon fibers uniformly dispersed in cement to produce a novel compound of carbon-fiber-reinforced cement. In order to facilitate the uniform distribution of short carbon fibers in the carbon-fiber-reinforced cement, it is necessary to remove the silane from the carbon fiber's surface. Short carbon fiber bundles were submerged into a pure water, sodium hydroxide solution, and acetic acid solution, and placed in high-temperature furnace used to remove silane from the carbon fiber surface. The results were observed under a scanning electron microscope to determine the level of silane removal from the surface, and an effective method for removing the silane was developed from among the several approaches. This method employed a pneumatic dispersion device to disperse carbon fibers then mixed in a high-early-strength cement which led to an excellent compressive and impact-resistance performance of carbon-fiber-reinforced cement. Final testing showed that the compressive strength and impact energy increased by 14.1% and 145%, respectively. [ABSTRACT FROM AUTHOR]