scholarly journals Bonding Strength Characteristics of FA-Based Geopolymer Paste as a Repair Material When Applied on OPC Substrate

2020 ◽  
Vol 10 (9) ◽  
pp. 3321 ◽  
Author(s):  
Warid Wazien Ahmad Zailani ◽  
Aissa Bouaissi ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Rafiza Abd Razak ◽  
Sorachon Yoriya ◽  
...  
Keyword(s):  
Bond Strength ◽  
Bonding Strength ◽  
Shear Test ◽  
Substrate Surface ◽  
Setting Time ◽  
Morphological Properties ◽  
Repair Material ◽  
Optimal Mix ◽  
Slant Shear ◽  
Geopolymer Paste

This investigative study aims to study the mechanical and morphological properties of fly ash (FA)-based geopolymer paste as a repair material when applied on ordinary Portland cement (OPC) overlay concrete. The first part of this study investigates the optimal mix design of FA-based geopolymer paste with various NaOH concentrations of 8, 10, 12, and 14 M, which were used later as a repair material. The second part studies the bonding strength using a slant shear test between the geopolymer repair material and OPC substrate concrete. The results showed that a shorter setting time corresponds to the higher NaOH molarity, within the range of 53 and 30 min at 8 and 14 M, respectively. The compressive strength of FA-based geopolymer paste was found to reach 92.5 MPa at 60 days. Also, from the slant shear test results, prism specimens with 125 mm length and 50 mm wide have a large bond strength of 11 MPa at 12 M. The scanning electron microscopy/energy-dispersive X-ray (SEM/EDX) analysis showed that the OPC substrate has a significant effect on slant shear bond strength, where the presence of free cations of Ca2+ on the OPC substrate surface contributed to the formation of calcium alumina-silicate hydrate gel (C-A-S-H) by building various cross-links of Ca-O-Si.

scholarly journals Potential of Carbon Nanotube Reinforced Cement Composites as Concrete Repair Material

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Tanvir Manzur ◽  
Nur Yazdani ◽  
Md. Abul Bashar Emon
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Setting Time ◽  
Cement Composites ◽  
Repair Material ◽  
Concrete Repair ◽  
Multiwalled Carbon ◽  
Aspect Ratios ◽  
Reinforced Cement ◽  
Slant Shear

Carbon nanotubes (CNTs) are a virtually ideal reinforcing agent due to extremely high aspect ratios and ultra high strengths. It is evident from contemporary research that utilization of CNT in producing new cement-based composite materials has a great potential. Consequently, possible practical application of CNT reinforced cementitious composites has immense prospect in the field of applied nanotechnology within construction industry. Several repair, retrofit, and strengthening techniques are currently available to enhance the integrity and durability of concrete structures with cracks and spalling, but applicability and/or reliability is/are often limited. Therefore, there is always a need for innovative high performing concrete repair materials with good mechanical, rheological, and durability properties. Considering the mechanical properties of carbon nanotubes (CNTs) and the test results of CNT reinforced cement composites, it is apparent that such composites could be used conveniently as concrete repair material. With this end in view, the applicability of multiwalled carbon nanotube (MWNT) reinforced cement composites as concrete repair material has been evaluated in this study in terms of setting time, bleeding, and bonding strength (slant shear) tests. It has been found that MWNT reinforced cement mortar has good prospective as concrete repair material since such composites exhibited desirable behavior in setting time, bleeding, and slant shear.

scholarly journals Bonding Behavior of Repair Material Using Fly-Ash/Ground Granulated Blast Furnace Slag-Based Geopolymer

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1697 ◽  
Author(s):  
Wen-Ten Kuo ◽  
Ming-Yao Liu ◽  
Chuen-Ul Juang
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Tensile Test ◽  
Blast Furnace Slag ◽  
Shear Test ◽  
Repair Material ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag ◽  
Split Tensile Test ◽  
Slant Shear

Fly ash/ground-granulated blast-furnace slag geopolymer (FGG) contains reaction products with a high volume of Ca, hydrated CaSiO3, and hydrated AlCaSiO3. These compounds enable the filling of large air voids in a structure, thus increasing compactness. Therefore, FGG is a more effective repair material to stabilize structures and can function as a sealing and insulating layer. This study used FGG as the repair material for concrete with ground-granulated blast-furnace slag (GGBFS) as the main cement material. The bond strength of the repair was discussed from different aspects, including for fly-ash substitution rates of 0%, 10%, 20%, and 30% and for liquid–solid ratios of 0.4 and 0.5. The slant shear test, and the split tensile test were employed in this analysis. Moreover, acoustic emission (AE) and scanning electron microscopy were used to confirm the damage modes and microstructural characteristics of these repairs. The results revealed that when the liquid–solid ratio increased from 0.4 to 0.5, the slant shear strength of the repaired material decreased from 36.9 MPa to 33.8 MPa, and the split tensile strength decreased from 1.97 MPa to 1.87 MPa. The slant shear test and split tensile test demonstrated that the repair material exhibited the highest effectiveness when the fly-ash substitution was 10%, and revealed that the repair angle directly affected the damage modes. The AE technique revealed that the damage behavior pattern of the FGG repair material was similar to that of Portland concrete. The microstructural analysis revealed that the FGG–concrete interphase contained mostly hydration products, and based on energy-dispersive X-ray spectroscopy (EDX), the compactness in the interphase and bond strength increased after the polymerization between the geopolymer and concrete. This indicated that the geopolymer damage mode was highly related to the level of polymerization.

scholarly journals Interfacial Bond Properties between Normal Strength Concrete and Epoxy Resin Concrete

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Nannan Sun ◽  
Yifan Song ◽  
Wei Hou ◽  
Hanhao Zhang ◽  
Datong Wu ◽  
...  
Keyword(s):  
Bond Strength ◽  
Epoxy Resin ◽  
Shear Test ◽  
Bond Properties ◽  
Interfacial Bond ◽  
Normal Strength Concrete ◽  
Normal Strength ◽  
Direct Tensile ◽  
Push Out ◽  
Slant Shear

It is necessary to pay attention to the bonding strength of the interface between precast normal strength concrete (NSC) and cast-in-place epoxy resin concrete (EMR) when using EMR as a repair or filling material or an overlay in bridges’ rehabilitation. However, the performances of epoxy concrete are different due to differential mix ratios; thus, the bonding properties between various epoxy resin concrete and cement concrete are not completely the same. This article investigated the interfacial bond properties between NSC and ERC by direct tensile, push-out, and slant shear test with specimens of special size and structure and observed the interfacial bond strength and corresponding failure modes. The minimum bond strength under direct tension was 0.72 MPa, while the minimum bond strength was 1.71 MPa and 3.19 MPa for the push-out test and slant shear test, respectively. Results indicated that the slant shear test specimens with an inclination angle of 45° are not suitable for the slant shear test due to higher compressive stress. Furthermore, the cohesion and friction coefficient of interface bond strength were calculated inversely in accordance with the results obtained from the corresponding direct tensile and slant shear tests. The minimum cohesion value was 1.71 MPa, and the minimum friction coefficient value was 0.46.

Bond Strength between Old and New Concretes with Focus on the Strengthening of Reinforced Concrete Columns - Slant Shear Test versus Double Sleeve Test

2017 ◽  
Vol 864 ◽  
pp. 324-329 ◽  
Author(s):  
E.M. Piancastelli ◽  
Aldo G. Magalhães ◽  
Fernando José Silva ◽  
M.A.P. Rezende ◽  
White J. Santos ◽  
...  
Keyword(s):  
Experimental Study ◽  
Linear Regression ◽  
Bond Strength ◽  
Shear Test ◽  
Concrete Columns ◽  
Transverse Reinforcement ◽  
Test Results ◽  
Strength Tests ◽  
Existing Structure ◽  
Slant Shear

The purpose of this paper is to present the main aspects and results of an experimental study to determine the bond strength between the concrete of a column of an existing structure (old concrete) and the concrete that will be used in its strengthening project (new concrete). For the bond strength tests, a specimen was conceived, called Double Sleeve specimen. The bond strength results obtained from the tests using Double Sleeve specimens, called Double Sleeve Tests, were compared to the results obtained from using the Slant Shear Test. The values for the bond strength between the two concretes, obtained from the Double Sleeve Tests, were either below or above the values obtained from linear regression of the Slant Shear Test results, depending on the sleeve diameter and the ratio of transverse reinforcement used. This fact, enabled concludes that the Double Sleeve Test is the most appropriate test to evaluate the bond strength between concretes of columns strengthened.

Experimental Research on Bond Strength between Rebar and Concrete after High Temperature

2011 ◽  
Vol 71-78 ◽  
pp. 1057-1061 ◽  
Author(s):  
Ke Fang Yin ◽  
Yang Han ◽  
Yi Liu
Keyword(s):  
Reinforced Concrete ◽  
High Temperature ◽  
Bond Strength ◽  
Experimental Research ◽  
Bonding Strength ◽  
Different Temperatures ◽  
Ultimate Bond Strength

With the centrally pulling-out test, the bond strength of reinforced concrete is measured with different temperatures and different cooling ways after high temperature; and the ultimate bond strength and slip of reinforced and concrete under different conditions are analyzed. The results show that the bonding strength declines gradually with the increase of temperature, and the ultimate slippage also decreases gradually.

scholarly journals Evaluation of cementitious repair mortars modified with polymers

2017 ◽  
Vol 9 (1) ◽  
pp. 168781401668858 ◽  
Author(s):  
Tsai-Lung Weng
Keyword(s):  
Thermal Expansion ◽  
Bond Strength ◽  
Vinyl Acetate ◽  
Polyvinyl Acetate ◽  
Setting Time ◽  
Drying Shrinkage ◽  
Ethylene Vinyl Acetate ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Repair Mortars

The aim of this study was to evaluate the effects of added polymers on the properties of repair mortars. Two types of polymers, ethylene vinyl acetate and polyvinyl acetate–vinyl carboxylate, were used as a replacement for 3%, 5%, and 8% of the cement (by weight). All tests were conducted using two water–cement ratios of 0.5 and 0.6. The effectiveness of the repair materials was evaluated according to setting time, drying shrinkage, thermal expansion, compressive strength, and bond strength. Specimens containing polyvinyl acetate–vinyl carboxylate at a water–cement ratio of 0.5 presented the highest compressive and bond strength. Specimens containing ethylene vinyl acetate presented strength characteristics exceeding those of the control at 28 days. The drying shrinkage of polyvinyl acetate–vinyl carboxylate specimens was similar to that of the control. At a water–cement ratio of 0.5, the thermal expansion of polyvinyl acetate–vinyl carboxylate specimens was lower than that of ethylene vinyl acetate specimens; however, at a water–cement ratio of 0.6, the thermal expansion was independent of the type of polymer.

Setting Behaviour of Phosphate Cement

2011 ◽  
Vol 194-196 ◽  
pp. 853-857
Author(s):  
Zhong Hua Li ◽  
He Fei Gao ◽  
Shu Rong Feng ◽  
Chao Su
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Influencing Factors ◽  
Setting Time ◽  
Repair Material ◽  
Rapid Repair ◽  
Binder Ratio

For the situation that concrete engineering required rapid and timely repair after nature disaster, setting time and influencing factors of phosphate rapid repair material were studied in this paper. The results showed that setting time of phosphate rapid repair material increased a little with increase of water and binder ratio but the setting time was short. When water and binder ratio was less than 0.20 setting time was less than 3min. Setting time was shorted with reducing of P/M. Setting time was from 2min30s to 5min when P/M was reduced from 1:0.6 to 1:4. Setting time of phosphate cement increase a little mixed with fly ash, slag or portland cement but effect of their content on setting time was little. Setting time of phosphate rapid repair material increased with increase of B/M. When content was greated than 12% the setting time was longer than 20min. Fly ash, slag and portland cement can reduce setting time of phosphate cement with borax obviously.

scholarly journals Micromorphological analysis and bond strength comparison of two adhesives for different degrees of dental fluorosis

2020 ◽  
Author(s):  
Shuangfeng Liu ◽  
Yanxia Zhu ◽  
Tana Gegen
Keyword(s):  
Shear Strength ◽  
Bond Strength ◽  
Bonding Strength ◽  
Laser Scanning ◽  
Dental Fluorosis ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Cohesive Failure ◽  
Bonding System ◽  
Significant Difference

Abstract The objective of this study was to analyze morphologically the all-etching bonding system and self-etching bonding system for enamel with different degrees of fluorosis and evaluate the bond strength of each system. Teeth that were indicated for extraction owing to orthodontic or periodontal problems were selected. According to Dean’s index and the Thylstrup-Fejerskov index, 180 extracted teeth were divided into three groups of mild, moderate, and severe dental fluorosis (DF), with 60 teeth in each group. The teeth in each group were randomly divided into two subgroups (n = 30), which were then subjected to the all-etching bonding system (Prime & Bond NT) and self-etching bonding system (SE-Bond). Each group of adhesives was used to bond Z350 universal resin (3M) to the etched dental enamel. Tensile and shear tests were conducted to determine the bond strength. Subsequently, the fractured specimens were investigated using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The Prime & Bond NT was statistically significant for the tensile and shear strength of enamel with mild fluorosis (P < 0.05) but did not exhibit a significant difference for moderate and severe DF (P > 0.05). The SE-Bond was not statistically significant for the tensile and shear strength of mild, moderate, or severe DF (P > 0.05). The SEM and CLSM results reveal that the mild fluorosis enamel crystals were relatively dense, and a small amount of resin remained. The moderate fluorosis enamel crystals were loosely arranged, and the gaps were widened. The severe fluorosis enamel crystals were irregularly arranged. The disorder was aggravated, and the dentinal orifice was exposed by partial enamel exfoliation. The bonding strength of mild fluorosis enamel with the Prime & Bond NT was better than that with the SE-Bond, and cohesive failure was the most common mode of failure. Because there was no difference in the bonding strength of the SE-Bond for different degrees of DF, we recommend the use of the all-etching adhesive system in the clinical treatment of teeth with mild fluorosis.

scholarly journals Influence of Powder-to-Gel Ratio on Physicochemical Properties of a Calcium Silicate Sealer

2020 ◽  
pp. 337-345
Author(s):  
Fernanda F. E. Torres ◽  
Patricia Perinoto ◽  
Roberta Bosso-Martelo ◽  
Gisselle M. Chávez-Andrade ◽  
Juliane M. Guerreiro-Tanomaru ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Calcium Silicate ◽  
Setting Time ◽  
Repair Material ◽  
Alkaline Ph ◽  
Root Canal Sealer ◽  
Work Time ◽  
Lower Solubility ◽  
Low Solubility ◽  
One Way Anova

Differences in liquid-to-powder ratio can affect the properties of calcium silicate-based materials. This study assessed the influence of powder-to-gel ratio on physicochemical properties of NeoMTA Plus. Setting time (minutes), flow (mm and mm²), pH (at different periods), radiopacity (mm Al) and solubility (% mass loss) were evaluated using the consistencies for root repair material (NMTAP-RP; 3 scoops of powder to 2 drops of gel) and root canal sealer (NMTAP-SE; 3 scoops of powder to 3 drops of gel), in comparison to Biodentine cement (BIO) and TotalFill BC sealer (TFBC). Statistical analysis was performed using one-way ANOVA and Tukey tests (α=0.05). BIO had the shortest setting time, followed by NMTAP-RP and NMTAP-SE. TFBC showed the highest setting time and radiopacity. BIO, NMTAP-RP, and NMTAP-SE had similar radiopacity. All materials promoted an alkaline pH. NMTAP-RP/SE presented lower solubility than BIO and TFBC. Regarding the flow, TFBC had the highest values, followed by NMTAP-SE, and NMTAP-RP. BIO had the lowest flow. In conclusion, NMTAP in both powder-to-gel ratios showed high pH and low solubility. The increase in the powder ratio decreased the setting time and flow. These findings are important regarding the proper consistency and work time to clinical application.

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