The Effect of Surface Properties of Steel Sections on Bond Strength in Soil-Cement Mix

Qualitative construction materials in highway pavement prompted addition of cement at different proportion of 2 - 10% to lateritic soils for enhanced performance. Engineering geological tests were performed on the soil-cement mixture to determine their highway pavement suitability for durable road construction. Furthermore, modelling of the strength characteristics of the mixture presents the correlation between the structural properties and cement mix. Thus, increase in soil-cement California bearing ratio (CBR) and unconfined compressive strength (UCS) values with higher cement mix of 8%, revealed enhanced soil improvement. The soil strength is also affected by the curing period. Better quality strength characteristics obtained decreases pavement thickness with reduced cost in road construction. Relationship between the soil strength properties and cement mix content are represented by polynomial model. This reveals stronger bearing capacity of soil cement mix cured in 14 days with R2 ≥ 0.8. The lateritic soil cement mix at 8% cement content could serve as highway subbase and base construction materials. Cement mix having positive effects on soil geotechnical properties are indication of its effectiveness in enhancing volume stability of different soils. Prolong curing time is essential for compacted soil cement mix for enhanced geotechnical engineering properties and to improve the quality of lateritic soil used as road construction materials. Thus, cement-stabilized lateritic soil reduces cost of road construction, its persistent failure, human and environmental losses.

Effect of surface treatment on roughness and bond strength of a heat-pressed ceramic

Effect of finishing protocols on dentin surface characteristics and bond strength after tooth preparation for indirect restorations.

This study aimed to evaluate the effects of different surface modification methods on the surface roughness, contact angle, and bond strength of composite-veneer materials of polyether-ether-ketone (PEEK). Fifty-five specimens (n = 11) with a size of 7 × 7 × 2mm were cut out from PEEK discs. The specimens were divided into five groups with different surface treatments: no treatment (NO) (control group), sulfuric acid (SA), plasma (P), femtosecond laser (FS), and Nd-YAG laser (NY). After the surface treatments, the specimens were checked for roughness, contact angle, and bond strength of the composite-veneer material. Data were analyzed with the Welch test for roughness, contact angle, and bond strength parameters. Individual Pearson correlation tests were executed for all surface treatment groups to determine any significant correlations among roughness, contact angle, and bond strength parameters (P < .001). Roughness, contact angle, and bond strength values were affected by surface modification methods (P < .001). In comparison to the control group, NY and FS treatments increased the surface roughness and bond strength; they also provided bond strength values comparable to the SA group. When the relationship between the variables was examined, no correlation was seen between roughness, contact angle, and bond strength values for the NY, SA, and control groups (P > .05); however, significant correlations were determined between the contact angle and surface roughness values for the P and FS groups (P < .05). Femtosecond and Nd-YAG laser treatments are viable surface modification alternatives to the sulfuric acid treatment for the PEEK material.

Unconfined compressive strength (UCS) and uniformity of soilcrete are strongly influenced by deep mixing equipment and its operating parameters. Soil cement mixing was applied to reinforce the two sections of earth levees (1) 60 m long in An Giang and (2) 30 m long in Dong Thap using a mini light-weight soil-cement wet mixing system, named as a NSV system. Core boring was employed to take field soilcrete samples and UCS tests were conducted to investigate soilcrete characteristics. The operating parameters were save in the built-in memory of the NSV system during construction. This paper instigated the proper operating parameters such as mixing energy, penetrating/lifting speeds, rotation speed, and mixing duration to optimize the NSV system for the Mekong Delta conditions. The results indicate that the field soilcrete achieved high UCS and uniformity along soilcrete columns with the mixing time of 800 times/m, mixing duration of 2.5–3.5 min/m, rod rotations of 40–50 times/m (penetration) and 70–80 times/m (lift), penetrating speed of 0.5 m/min and lifting speed of 1.2 m/min.

Surface Roughness and Bond Strength of Resin Composite to Additively Manufactured Zirconia with Different Porosities.

Objective:The purpose of the study is the evaluation and comparison of surface roughness and bond strength of glass fiber post (GFP) after different types of surface treatment and the application of a universal bonding agent.Materials and Methods:Forty GFPs were divided into four groups based on surface treatment: Group I, silane coupling agent application for 60 s; Group II, air abrasion with 30 μm silicon dioxide powder particles in 2.5 bar pressure from 2 cm distance for 10 s, followed by silane coupling agent application; Group III, 9% hydrofluoric acid application for 10 s, rinsed and air-dried, followed by silane coupling agent application; and Group IV, silane coupling agent application, followed by universal bonding agent application. Surface roughness evaluation is done by a profilometer. All posts were cemented in the root of the maxillary central incisor with resin cement. After that, root was placed in an acrylic mold, and the external end part of the post was mounted on another acrylic mold. Pull-out bond strength was measured by a universal testing machine.Results:Highest surface roughness and bond strength values were found in Group II.Conclusion:Pretreatment of GFP increases the surface roughness of post as well as bond strength of post to root dentin. There is a correlation between surface roughness and bond strength. However, the use of only universal bonding agent also showed comparable pull-out bond strength of GFP, which means only use of universal bonding agent also a new alternative as pretreatment of GFP and helps in increase in bond strength.

Statement of the Problem: Polyetheretherketone material shows good physical and mechanical properties but research is lacking optimum air blasting parameters for good bond strength to resin cement. Aim: To evaluate the effect of different air blasting pressure of PEEK on surface roughness and shear bond strength to adhesive resin cement. Materials and Methods: 24 discs of BioHPP PEEK (bredent, UK) were manufactured. Samples were air blasted with 110 μm Al2O3 particles for 10 seconds at distance of 10 mm and divided into 3 groups according to pressure. Group A: 3 bar, Group B: 2.5 bar and Group C: 3.5 bar. Surface roughness was measured by SEM, Visio Link primer (Bredent, Germany) was applied and cured then G-CEM resin cement (GC, Japan) was applied and cured. Shear bond strength was measured using universal testing machine. EDX analysis was done, and failure mode was detected by stereo-microscope. Results: Statistical analysis showed that roughness average (Ra) increased by increasing pressure, Group B was significantly the lowest (p < 0.05), while there was insignificant difference between other groups (P > 0.05). Regarding shear bond strength, Group A recorded (12.6864 ± 2.486 MPa), Group B (11.2842 ± 1.555 MPa) and Group C (10.1024 ± 2.317 MPa), there was significantly statistical difference between Groups A & C (p < 0.05). The failure mode was mainly adhesive in group C and mixed in groups A & B. EDX analysis showed an increase in Carbon and Silica and a decrease in Oxygen and Aluminum weight percentages after the bond strength test. Conclusion: Increasing the air blasting pressure up to 3 bar increases the surface roughness and bond strength to resin cement, but more than 3 bar showed unfavorable surface roughness and decreased bond strength.

ObjectivesThis study investigated the effects of different surface modifications on surface roughness, phase transformation, and bond strength of polyetheretherketone (PEEK) to composite resin.Materials and MethodsA total of 140 specimens measuring 10 mm × 10 mm × 2 mm were fabricated from PEEK blocks (BioHPP; Bredent GmbH & Co KG, Germany). Seven groups were randomly formed from the specimens: C) untreated control group, (SE) sulfuric acid application (Merck KGa, Darmstadt, Germany), (PE) piranha solution application (Albar Chemistry, Kocaeli, Turkey), (S) sandblasting with Al2O3 particle (Zhermack, Rovigo, Italy), (T) tribochemical silica coating (3 M ESPE, Seefeld, Germany), (L) Er-YAG laser treatment (LightWalker AT, Fotona, Slovenia), and (P) plasma treatment (Kinpen, Neoplas, Germany) (n = 20). Surface topography was examined using a profilometer device (Taylor Hobson, Leicester, England). Surface images of the specimens were captured using Scanning Electron Microscopy (SEM) (JSM- 6610, Jeol, USA). Phase change analysis was conducted on each group using an X-Ray Diffractometer device (Rigaku SmartLab Diffraktometer, Tokyo, Japan). After thermal aging, shear bond strength was tested using a Universal Test Machine (Model 3340, Instron Corp., Wycombe, UK). Data were analyzed with One-way analysis of variance (ANOVA) test; comparisons were made with Tukey's multiple comparison test, with a significance level of 0.05.ResultsGroup S (3.09 ± 0.40 μm) exhibited significantly higher surface roughness values compared to the other groups (p < 0.05). Group SE (13.28 ± 1.69 MPa) exhibited significantly higher shear bond strength values than the other groups (p < 0.05). No statistically significant correlation was found between surface roughness and bond strength data (p > 0.05). According to XRD results, Group S and Group L differ from the other groups in having a slightly higher intensity and broader peaks.ConclusionsAll surface modification methods enhanced the bond strength between PEEK to composite resin. However, Group L and Group S revealed different XRD patterns from the control group. Tribochemical silica coating can be a reliable alternative method for acid applications due to its stable phase structure and high bond strength.

Objectives: Comparative evaluation of surface changes and bond strength of Microabrasion Bleached enamel before and after Remineralization with Nano-hydroxyapatite paste, an In vitro study. Methods: Enamel samples were divided into - Group I - Conventional bleaching (HB), Group II - Conventional bleaching with remineralization (HB+N-Hp), Group III - Microabrasion-assisted bleaching (M+HB), and Group IV - Microabrasion-assisted bleaching with remineralization (M+HB+N Hp). Surface roughness was measured using a profilometer. Samples were stored in artificial saliva for two weeks, then bonded with nanofilled composite resin and subjected to shear bond strength (SBS) analysis. Results: Group IV (M+HB+N-Hp) showed higher surface roughness than Groups I (HB) and II (HB+N-Hp), while Group II had significantly lower surface roughness compared to Groups III (M+HB) and IV. In terms of shear bond strength (SBS), Group III exhibited significantly higher SBS than Group I, whereas Group II showed significantly reduced SBS compared to Group I. All values were statistically significant. Conclusions: Remineralization with N-Hp reduces the surface roughness caused by bleaching and microabrasion, potentially decreasing bacterial biofilm adherence. Despite increased surface roughness correlating with better bond strength, microabrasion-assisted bleaching followed by remineralization and direct composite veneering after two weeks is a promising minimally invasive treatment for severe tooth discolorations. Further studies should explore varying frequencies and concentrations of N-Hp application.

Long-term retention of the restoration depends on strength and durability of the bond of the luting composite resin to the tooth and the porcelain substrates. This in vitro study was conducted to compare and evaluate the influence of hydrofluoric acid (HF) and acidulate phosphate fluoride (APF) gel-etched treatments on surface roughness and bond strength to dentin of a commercially available lithium disilicate ceramic (E-Max). Sixty lithium disilicate ceramic disks measuring 5 mm in diameter and 2 mm thick were fabricated and divided into three groups: Group A (n = 24), Group B (n = 24), and Group C (n = 12) and were subdivided to Group A1, A2, and A3which were surface treated with 1.23% APF gel (pH = 3-4) at different time intervals 4, 7, and 10 min, respectively. Group B1, B2, and B3 were surface treated with 1% APF gel (pH = 1-2) at different time intervals 4, 7, and 10 min, respectively. Group C were surface treated with 9.6% HF (pH = 1-2) for 1 min. Morphological changes obtained with the surface treatments were analyzed using a surface profilometer. All specimens were subjected to a tensile bond strength test using a tensometer, and the obtained data were statistically analyzed using Kruskal-Wallis test. The surface roughness (μm) and bond strength (MPa) of lithium disilicate discs (samples) etched with 1.23% APF gel and 1% APF gel for 10 min and etched with 9.6% HF for 1 min showed no statistical significant difference among them. In this study, the lithium disilicate discs etched with 1.23% APF gel and 1% APF gel for 10 min showed similar surface roughness and bond strength to those etched with 9.6% HF for a minute.

Effect of different resin cements and surface treatments on the shear bond strength of ceramic-glass polymer materials

In geotechnical projects involving soft soils, cement-mixed soils are an excellent way to improve the mechanical behaviour and engineering performance of soils. The water-to-cement ratio, cement content, and porosity are the most critical parameters impacting the strength of cement-mixed soils, but their effects are less well understood. The proportional influence of cement amount, porosity, and moisture content on cement-mixed soil strength is investigated in this research. The results showed that as the water-to-cement ratio increases, the influence of cementation and porosity on unconfined compressive strength decreases. The blended volume ratio is proposed as a new and adequate index for evaluating cement-mixed soil strength based on the experimental results. The blended volume ratio is the product of the void/cement volume ratio and the water/cement volume ratio. While the current index has not fully addressed the important effects of the water-to-cement ratio and porosity, the blended volume ratio allows describing the concurrent influences of porosity, cement amount, and water amount on the strength development. The experimental results showed that the cement-mixed soil strength is a function of the blended volume ratio. An empirical equation based on the blended volume ratio was then proposed for predicting the strength of cement-mixed soils. The validation of the proposed equation is verified by strength analysis for several different test data sets. A good agreement between measured and predicted results indicated that the proposed model is applicable to predict well the strength of cement-mixed soils.

Influence of Acidic Environment on Properties of Biodentine and White Mineral Trioxide Aggregate: A Comparative Study

Effect of two-step and one-step surface conditioning of glass ceramic on adhesion strength of orthodontic bracket and effect of thermo-cycling on adhesion strength.