scholarly journals Effect of re-vibration on the compressive strength and surface hardness of concrete

2017 ◽  
Vol 271 ◽  
pp. 012057
Author(s):  
H B Koh ◽  
D Yeoh ◽  
S Shahidan
Keyword(s):  
Compressive Strength ◽  
Surface Hardness

scholarly journals Evaluation of Self-Compacting Concrete Strength with Non-Destructive Tests for Concrete Structures

2019 ◽  
Vol 9 (23) ◽  
pp. 5109 ◽  
Author(s):  
Miguel C. S. Nepomuceno ◽  
Luís F. A. Bernardo
Keyword(s):  
Compressive Strength ◽  
Concrete Strength ◽  
Surface Hardness ◽  
Pulse Velocity ◽  
Concrete Compressive Strength ◽  
Self Compacting Concrete ◽  
Coarse Aggregates ◽  
Pull Out ◽  
Concrete Maturity ◽  
Non Destructive

Self-compacting concrete (SCC) shows to have some specificities when compared to normal vibrated concrete (NVC), namely higher cement paste dosage and smaller volume of coarse aggregates. In addition, the maximum size of coarse aggregates is also reduced in SCC to prevent blocking effect. Such specificities are likely to affect the results of non-destructive tests when compared to those obtained in NVC with similar compressive strength and materials. This study evaluates the applicability of some non-destructive tests to estimate the compressive strength of SCC. Selected tests included the ultrasonic pulse velocity test (PUNDIT), the surface hardness test (Schmidt rebound hammer type N), the pull-out test (Lok-test), and the concrete maturity test (COMA-meter). Seven sets of SCC specimens were produced in the laboratory from a single mixture and subjected to standard curing. The tests were applied at different ages, namely: 1, 2, 3, 7, 14, 28, and 94 days. The concrete compressive strength ranged from 45 MPa (at 24 h) to 97 MPa (at 94 days). Correlations were established between the non-destructive test results and the concrete compressive strength. A test variability analysis was performed and the 95% confidence limits for the obtained correlations were computed. The obtained results for SCC showed good correlations between the concrete compressive strength and the non-destructive tests results, although some differences exist when compared to the correlations obtained for NVC.

scholarly journals The Assessment of Strength of Cementitious Materials Impregnated Using Hydrophobic Agents Based on Near-Surface Hardness Measurements

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4583
Author(s):  
Martyna Nieświec ◽  
Łukasz Sadowski
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Concrete Structures ◽  
Surface Hardness ◽  
Cementitious Materials ◽  
Schmidt Hammer ◽  
Near Surface ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
The Impact

Recently, the surfaces of concrete structures are impregnated to protect them against the environment in order to increase their durability. It is still not known how the use of these agents affects the near-surface hardness of concrete. This is especially important for experts who use the near-surface hardness of concrete for estimating its compressive strength. The impregnation agents are colorless and, thus, without knowledge of their use, mistakes can be made when testing the surface hardness of concrete. This paper presents the results of investigations concerning the impact of impregnation on the subsurface hardness concrete measured using a Schmidt hammer. For this research, samples of cement paste with a water–cement ratio of 0.4 and 0.5 were used. The samples were impregnated with one, two, and three layers of two different agents. The first agent has been made based on silanes and siloxanes and the second agent has been made based on based on polymers. The obtained research results allow for the conclusion that impregnation affects the near-surface hardness of concrete. This research highlights the fact that a lack of knowledge about the applied impregnation of concrete when testing its near-surface hardness, which is then translated into its compressive strength, can lead to serious mistakes.

Mechanical Gypsum Wall System Performance

2020 ◽  
Vol 400 ◽  
pp. 117-122
Author(s):  
João M.P.Q. Delgado
Keyword(s):  
Compressive Strength ◽  
System Performance ◽  
Mechanical Performance ◽  
Surface Hardness ◽  
Water Repellent ◽  
Experimental Characterization ◽  
Strength Tests ◽  
Tensile Adhesion ◽  
Wall System

This paper has the aim to evaluate the mechanical performance of gypsum walls. It was carried out a laboratory experimental characterization of the gypsum materials properties and different waterproofing contents, which determine their mechanical behaviour, by flexural and compressive strength tests, tensile adhesion and surface hardness. The wall system performance was also evaluated in terms of its water-tightness.The results showed that the samples with lower water repellent additive content present higher compressive strength values and the gypsum walls tested achieved the minimum level of performance (Level M).

UHB RIGOR A2

Alloy Digest ◽  
1977 ◽  
Vol 26 (3) ◽  
Keyword(s):  
Wear Resistance ◽  
Compressive Strength ◽  
High Surface ◽  
Surface Hardness ◽  
Heat Treating ◽  
High Dimensional ◽  
Metal Working ◽  
Good Resistance ◽  
High Hardenability ◽  
Compression Resistance

Abstract UHB RIGOR AR is a chromium-molybdenum-vanadium tool steel characterized by high surface hardness, high hardenability, high dimensional stability after hardening and tempering, high compression resistance, good machinability, good resistance to tempering and good wear resistance. Its many uses include metal-working tools, dies for porcelain and gages. This datasheet provides information on composition, physical properties, hardness, elasticity, and compressive strength. It also includes information on forming, heat treating, machining, and joining. Filing Code: TS-315. Producer or source: Uddeholm Aktiebolag.

scholarly journals Microstructure and Mechanical Properties of Composite Resins Subjected to Accelerated Artificial Aging

2013 ◽  
Vol 24 (6) ◽  
pp. 599-604 ◽  
Author(s):  
Andrea Candido dos Reis ◽  
Denise Tornavoi de Castro ◽  
Marco Antonio Schiavon ◽  
Leandro Jardel da Silva ◽  
Jose Augusto Marcondes Agnelli
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Artificial Aging ◽  
Thermal Analyses ◽  
Surface Hardness ◽  
Composite Resins ◽  
Scanning Calorimetry ◽  
Good Thermal Stability ◽  
Microstructure And Mechanical Properties ◽  
Before And After

The aim of this study was to investigate the influence of accelerated artificial aging (AAA) on the microstructure and mechanical properties of the Filtek Z250, Filtek Supreme, 4 Seasons, Herculite, P60, Tetric Ceram, Charisma and Filtek Z100. composite resins. The composites were characterized by Fourier-transform Infrared spectroscopy (FTIR) and thermal analyses (Differential Scanning Calorimetry - DSC and Thermogravimetry - TG). The microstructure of the materials was examined by scanning electron microscopy. Surface hardness and compressive strength data of the resins were recorded and the mean values were analyzed statistically by ANOVA and Tukey's test (α=0.05). The results showed significant differences among the commercial brands for surface hardness (F=86.74, p<0.0001) and compressive strength (F=40.31, p<0.0001), but AAA did not affect the properties (surface hardness: F=0.39, p=0.53; compressive strength: F=2.82, p=0.09) of any of the composite resins. FTIR, DSC and TG analyses showed that resin polymerization was complete, and there were no differences between the spectra and thermal curve profiles of the materials obtained before and after AAA. TG confirmed the absence of volatile compounds and evidenced good thermal stability up to 200 °C, and similar amounts of residues were found in all resins evaluated before and after AAA. The AAA treatment did not significantly affect resin surface. Therefore, regardless of the resin brand, AAA did not influence the microstructure or the mechanical properties.

scholarly journals Analysis of Additives in Gypsum Coatings Based on Melamine, Polycarbonate Salts, Polycarboxylate, and Polycarboxylic Acids

Coatings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1204
Author(s):  
José Antonio Flores Yepes ◽  
Luis Miguel Serna Jara ◽  
Antonio Martínez Gabarrón ◽  
Ana María Codes Alcaraz ◽  
Joaquín Julián Pastor Pérez
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Citric Acid ◽  
Calcium Sulfate ◽  
Surface Hardness ◽  
Mechanical Tests ◽  
Polycarboxylic Acid ◽  
Polycarboxylic Acids ◽  
Compression Resistance ◽  
Hydrated Calcium

In this paper, we evaluate different gypsum coating additives that are available on the market, which are categorized by their chemical bases. The results will serve as a reference for future investigations of new additive bases in order to improve the properties of gypsum. As such, the objective of the this study is to assess the workability, mechanical behavior, and crystalline structure of calcium sulfate combined with different retarding and fluidifying bases, including melamine bases, which have a compressive strength of 19.32 N/mm2 and handling times with polycarbonate salts of up to 117.58 min. The following study presents the results of standard mechanical tests, analyzing semi-hydrated calcium sulfate (without additives) as a reference, along with the addition of melamines, synthetic melanin polymers, polycarbonate salts, polycarboxylates, and a polycarboxylic acid (citric acid). We already know that the addition of these additives will modify the mechanical properties of calcium sulfate, such as the Shore C surface hardness, flexural strength, modulus of elasticity, and compression resistance, which is the object of this study.

scholarly journals Study the Effects of Reactive Materials Replacement on Some Properties of Cement Mortar

2018 ◽  
Vol 6 (4) ◽  
pp. 183-190
Author(s):  
Mohammed J. Kadhim ◽  
Raeid K. Mohammed Jawad ◽  
Hamza M. Kamal
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Cement Mortar ◽  
Surface Hardness ◽  
Type I ◽  
Fine Aggregate ◽  
Curing Time ◽  
Natural Materials ◽  
Water To Cement Ratio ◽  
Water Absorption Test

This study involves natural--materials replacement and its reaction with cement mortar behavior for many mortar samples under variable curing time with constant water to cement ratio (W/C = 0.5).In this researchsomeproperties such as (compressive strength the surface hardness and water absorption test), were affected by adding small ratios ofpowder (from (RHA) and (BRP) particles)as replacements to the Ordinary Portland Cement (OPC) / type (I). The percentages of natural materials additives replacement on the mixture of mortar include (0, 5, 10, 15 and 20%) with constant (W/C) ratio. Also the amount of the fine aggregate used was three times the amount of cement. The results showed that, the compressive strength and splitting tensile strength and water absorption of the mortars for (replacement) gives better properties than mortar without replacement in all tests. Best enhancements in properties for mortars with pozzalanic replacements were achieved at (15%) for (RHA) and 10% for (RBP) replacement from weight of cement.

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