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Abrasivity

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Jamal Rostami – 1st expert on this subject based on the ideXlab platform

  • introduction to rock and soil Abrasivity index rsai
    Wear, 2019
    Co-Authors: Mohsen Mosleh, Wei Hu, Jamal Rostami

    Abstract:

    Abstract Characterizing the abrasiveness of rock and soil and developing predictive models for wear of various tools that interact with such geo-materials is critical in selection of best tool materials for applications in earthmoving, drilling, mining, construction, tunneling, and agricultural industries. This paper introduces a Rock and Soil Abrasivity Index (RSAI), utilizes the abrasive wear theory for defining the parameters and examines a testing method for quantitative assessment of the index. The test method measures the wear mass of a target tool material (i.e. steel or hard facing) while it is pressed against the crushed rock or soil medium in a relative motion under high contact stresses based on a defined test protocol for reliability and repeatability. The RSAI is defined as the product of wear volume and hardness of tool divided by the work or energy deployed to overcome frictional forces, as measured by the torque in the device. The RSAI is expected to vary in the 0–100 range for the softest to the hardest possible rock and soil samples and conditions. The RSAI for various soil and crushed rock samples were experimentally determined and presented. Also, the correlation between the RSAI, Cerchar Abrasion Index (CAI) and Soil Abrasion Test (SAT) value, as the most common forms of abrasion testing of soil and rock is discussed.

  • effects of rock water content on cerchar Abrasivity index
    Wear, 2016
    Co-Authors: M Abu Z Bakar, Y. Majeed, Jamal Rostami

    Abstract:

    Cerchar Abrasivity Index (CAI) has been commonly used to represent rock abrasion for estimation of tool wear in rock excavation applications. This test is a simple and effective measure of rock abrasion but operating parameters can impact its results. This paper focuses on the influence of water saturation on CAI values based on laboratory testing of 33 sedimentary rock units collected from different regions of Pakistan. The tests include CAI measurements as well as engineering rock properties on both dry and saturated rocks. It was found that overall 79% of CERCHAR Abrasivity index values measured on saturated rock surfaces “CAIsat” were less than the CERCHAR Abrasivity index values measured on dry rock surfaces “CAIdry”. Meanwhile, 52% of CAIsat values showed significant reduction from CAIdry values in the statistical analysis of CAI results with significance level of 15% (α=0.15). Regression analysis was used to correlate CAIsat values with CAIdry, normally measured in CERCHAR testing. The proposed formula can be used to estimate CAIsat from result of laboratory testing where CAI reported is often CAIdry. This could lead into more accurate estimation of tool wear and related adjustments when CAI is used for estimation of tool wear when excavation is done under wet conditions. Multiple regression was also used to establish a predictive model of CAIsat with petrographical, wear indices and geotechnical rock properties of saturated rock samples. In addition, the validity of correlations of CAI with rock properties that are already published was evaluated.

  • study of dominant factors affecting cerchar Abrasivity index
    Rock Mechanics and Rock Engineering, 2014
    Co-Authors: Jamal Rostami, Amireza Ghasemi, Ehsan Alavi Gharahbagh, Cihan Dogruoz, Filip Dahl

    Abstract:

    The Cerchar abrasion index is commonly used to represent rock abrasion for estimation of bit life and wear in various mining and tunneling applications. Although the test is simple and fast, there are some discrepancies in the test results related to the equipment used, condition of the rock surface, operator skills, and procedures used in conducting and measuring the wear surface. This paper focuses on the background of the test and examines the influence of various parameters on Cerchar testing including pin hardness, surface condition of specimens, petrographical and geomechanical properties, test speed, applied load, and method of measuring wear surface. Results of Cerchar tests on a set of rock specimens performed at different laboratories are presented to examine repeatability of the tests. In addition, the preliminary results of testing with a new device as a potential alternative testing system for rock Abrasivity measurement are discussed.

Yiming Li – 2nd expert on this subject based on the ideXlab platform

  • Stain removal and whitening by baking soda dentifrice: A review of literature.
    Journal of the American Dental Association (1939), 2020
    Co-Authors: Yiming Li

    Abstract:

    Tooth discoloration may be caused by intrinsic or extrinsic stains or a combination of both. There are 2 major approaches to removing the stains, including the chemical mechanism using peroxides for tooth bleaching and the mechanical mechanism using abrasives in prophylactic pastes and dentifrices to remove stains, resulting in a whitening effect. Attempts have also been made to add a low concentration of peroxides to dentifrices to enhance their abrasive cleaning to remove tooth stains.
    This article provides a review of both in vitro and clinical studies on stain removal and whitening effect of dentifrices containing sodium bicarbonate (baking soda). In recent years, whitening dentifrices have become popular because of little additional effort for use, ease of availability, low cost, and accumulated evidence of clinical efficacy and safety in the literature. Advances in research and technology have led to innovative formulations of dentifrices using baking soda as the sole abrasive or a component of an abrasive system. Baking soda is biologically compatible with acid-buffering capacities, antibacterial at high concentrations, and has a relatively lower Abrasivity.
    The evidence available in the literature indicates that baking soda-based dentifrices are effective and safe for tooth stain removal and consequently whitening. A number of clinical studies have also shown that baking soda-based dentifrices are more effective in stain removal and whitening than some non-baking soda-containing dentifrices with a higher Abrasivity. So far, research efforts have mainly focused on stain removal and tooth-whitening efficacy and clinical safety of baking soda dentifrices used with manual toothbrushes, with only a few studies investigating their effects using powered toothbrushes, for which further research is encouraged.
    As part of a daily oral hygiene practice, baking soda-based dentifrice is a desirable, alternative or additional measure for tooth stain removal and whitening.
    Copyright © 2017 American Dental Association. Published by Elsevier Inc. All rights reserved.

  • stain removal and whitening by baking soda dentifrice a review of literature
    Journal of the American Dental Association, 2017
    Co-Authors: Yiming Li

    Abstract:

    Abstract Background Tooth discoloration may be caused by intrinsic or extrinsic stains or a combination of both. There are 2 major approaches to removing the stains, including the chemical mechanism using peroxides for tooth bleaching and the mechanical mechanism using abrasives in prophylactic pastes and dentifrices to remove stains, resulting in a whitening effect. Attempts have also been made to add a low concentration of peroxides to dentifrices to enhance their abrasive cleaning to remove tooth stains. Types of Studies Reviewed This article provides a review of both in vitro and clinical studies on stain removal and whitening effect of dentifrices containing sodium bicarbonate (baking soda). In recent years, whitening dentifrices have become popular because of little additional effort for use, ease of availability, low cost, and accumulated evidence of clinical efficacy and safety in the literature. Advances in research and technology have led to innovative formulations of dentifrices using baking soda as the sole abrasive or a component of an abrasive system. Baking soda is biologically compatible with acid-buffering capacities, antibacterial at high concentrations, and has a relatively lower Abrasivity. Conclusions The evidence available in the literature indicates that baking soda–based dentifrices are effective and safe for tooth stain removal and consequently whitening. A number of clinical studies have also shown that baking soda–based dentifrices are more effective in stain removal and whitening than some non–baking soda—containing dentifrices with a higher Abrasivity. So far, research efforts have mainly focused on stain removal and tooth-whitening efficacy and clinical safety of baking soda dentifrices used with manual toothbrushes, with only a few studies investigating their effects using powered toothbrushes, for which further research is encouraged. Practical Implications As part of a daily oral hygiene practice, baking soda–based dentifrice is a desirable, alternative or additional measure for tooth stain removal and whitening.

Anderson T Hara – 3rd expert on this subject based on the ideXlab platform

  • baking soda as an abrasive in toothpastes mechanism of action and safety and effectiveness considerations
    Journal of the American Dental Association, 2017
    Co-Authors: Anderson T Hara, Cecilia Pedroso Turssi

    Abstract:

    Abstract Background Toothpastes can be formulated with different abrasive systems, depending on their intended clinical application. This formulation potentially affects their effectiveness and safety and, therefore, requires proper understanding. In this article, the authors focused on abrasive aspects of toothpastes containing sodium bicarbonate (baking soda), which have gained considerable attention because of their low Abrasivity and good compatibility, while providing clinical effectiveness (further detailed in the other articles of this special issue). The authors first appraised the role of toothpaste Abrasivity on tooth wear, exploring some underlying processes and the existing methods to determine toothpaste Abrasivity. Types of Studies Reviewed The authors reviewed the available data on the Abrasivity of toothpastes containing baking soda and reported a summary of findings highlighting the clinical implications. Conclusions On the basis of the collected evidence, baking soda has an intrinsic low-abrasive nature because of its comparatively lower hardness in relation to enamel and dentin. Baking soda toothpastes also may contain other ingredients, which can increase their stain removal effectiveness and, consequently, Abrasivity. Practical Implications Even those formulations have Abrasivity well within the safety limit regulatory agencies have established and, therefore, can be considered safe.

  • dentifrice fluoride and Abrasivity interplay on artificial caries lesions
    Caries Research, 2014
    Co-Authors: Hani M Nassar, Frank Lippert, George J Eckert, Anderson T Hara

    Abstract:

    Incipient caries lesions on smooth surfaces may be subjected to toothbrushing, potentially leading to remineralization and/or abrasive wear. The interplay of dentifrice Abrasivity and fluoride on this process is largely unknown and was investigated on three artificially created lesions with different mineral content/distribution. 120 bovine enamel specimens were randomly allocated to 12 groups (n = 10), resulting from the association of (1) lesion type [methylcellulose acid gel (MeC); carboxymethylcellulose solution (CMC); hydroxyethylcellulose gel (HEC)], (2) slurry abrasive level [low (REA 4/ RDA 69); high (REA 7/RDA 208)], and (3) fluoride concentration [0/275 ppm (14.5 mM) F as NaF]. After lesion creation, specimens were brushed in an automated brushing machine with the test slurries (50 strokes 2×/day). Specimens were kept in artificial saliva in between brushings and overnight. Enamel surface loss (SL) was determined by optical profilometry after lesion creation, 1, 3 and 5 days. Two enamel sections (from baseline and post-brushing areas) were obtained and analyzed microradiographically. Data were analyzed by analysis of variance and Tukey’s tests (α = 5%). Brushing with high-abrasive slurry caused more SL than brushing with low-abrasive slurry. For MeC and CMC lesions, fluoride had a protective effect on SL from day 3 on. Furthermore, for MeC and CMC, there was a significant mineral gain in the remaining lesions except when brushed with high-abrasive slurries and 0 ppm F. For HEC, a significant mineral gain took place when low-abrasive slurry was used with fluoride. The tested lesions responded differently to the toothbrushing procedures. Both slurry fluoride content and Abrasivity directly impacted SL and mineral gain of enamel caries lesions.

  • comparison between radiotracer and surface profile methods for the determination of dentifrice Abrasivity
    Wear, 2013
    Co-Authors: Alaa H A Sabrah, Frank Lippert, Adam B Kelly, Anderson T Hara

    Abstract:

    Abstract This study compared the traditional radiotracer method (Rt) for determination of dentifrice Abrasivity to the recently introduced surface profile (Sp) method (ISO 11609). Specimens from human root dentin were prepared for each method and randomly assigned to 8 dentifrice/abrasive groups (n=8), of wide Abrasivity range. Aqueous dentifrice slurries or abrasive suspensions were used to brush specimens in a toothbrushing machine. Two independent studies (Rt, Sp) were carried out. For Rt, the specimen preparation, study design, analysis and calculation of the dentifrice abrasive level (RDA) followed the ISO 11609/Annex-A guidelines. Similarly for Sp, the ISO 11609/Annex-B recommendations were followed, except by the number of brushing strokes, which was pre-determined to be 2000 strokes. RDA data were analyzed using ANOVA and Tukey tests (α=0.05). The correlation between methods was also investigated. Overall, higher variation and RDA values were observed for Sp compared to Rt. While good correlation was found between methods (R2=0.841), group ranking was dissimilar and better statistical differentiation among groups was observed in Rt. The Rt method showed to be a more standardized and robust method compared to Sp for the determination of RDA values of dentifrices/abrasives. Sp needs further development before being considered as an equivalent method to Rt.