scholarly journals Rebound Hammer Test: An Investigation into Its Reliability in Applications on Concrete Structures

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Antonio Brencich ◽  
Rossella Bovolenta ◽  
Valeria Ghiggi ◽  
Davide Pera ◽  
Paolo Redaelli
Keyword(s):  
Building Materials ◽  
Concrete Strength ◽  
Research Work ◽  
Third Party ◽  
Test Reliability ◽  
Surface Finishing ◽  
Engineering Practice ◽  
Rebound Hammer ◽  
Existing Structures ◽  
Concrete Maturity

The issue of concrete strength often arises in civil engineering practice, either due to quality control of new constructions or due to the assessment of existing structures. To this aim, one of the most widely spread techniques is the rebound hammer (Schmidt hammer) test, for which calibration is still related to the original Schmidt curve dating back to the early 50’s. In spite of the large amount of research work performed in the last decades, the uncertainties of the rebound test are still not clearly quantified and open to further insight. This paper presents and discusses a wide research campaign on laboratory specimens and on third-party specimens delivered to the Laboratory for Building Materials of the University of Genoa, Italy, for standard quality controls. While it is well known that moisture content, surface finishing, and concrete maturity strongly affect the test result, the effect of the stress state has not yet been studied and is found in this research to be a further parameter affecting the test reliability. The final outcome of all the uncertainties is variability in estimated concrete strength as large as ±70%; additionally, some issues are discussed on the intrinsic uncertainty of this test. As already demonstrated by many authors, the results of this research also show that a universal calibration curve to be used for any concrete, in any condition, conceptually does not exist.

scholarly journals Cotton Wastes Functionalized Biomaterials from Micro to Nano: A Cleaner Approach for a Sustainable Environmental Application

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1006
Author(s):  
Samsul Rizal ◽  
Abdul Khalil H. P. H. P. S. ◽  
A. A. Oyekanmi ◽  
Niyi G. Olaiya ◽  
C. K. Abdullah ◽  
...  
Keyword(s):  
Building Materials ◽  
Expansive Soils ◽  
Research Work ◽  
Functional Materials ◽  
Extraction Process ◽  
Process Conditions ◽  
Environmental Application ◽  
Isolation Technique ◽  
Metals Removal ◽  
Combined Pretreatment

The exponential increase in textile cotton wastes generation and the ineffective processing mechanism to mitigate its environmental impact by developing functional materials with unique properties for geotechnical applications, wastewater, packaging, and biomedical engineering have become emerging global concerns among researchers. A comprehensive study of a processed cotton fibres isolation technique and their applications are highlighted in this review. Surface modification of cotton wastes fibre increases the adsorption of dyes and heavy metals removal from wastewater. Cotton wastes fibres have demonstrated high adsorption capacity for the removal of recalcitrant pollutants in wastewater. Cotton wastes fibres have found remarkable application in slope amendments, reinforcement of expansive soils and building materials, and a proven source for isolation of cellulose nanocrystals (CNCs). Several research work on the use of cotton waste for functional application rather than disposal has been done. However, no review study has discussed the potentials of cotton wastes from source (Micro-Nano) to application. This review critically analyses novel isolation techniques of CNC from cotton wastes with an in-depth study of a parameter variation effect on their yield. Different pretreatment techniques and efficiency were discussed. From the analysis, chemical pretreatment is considered the most efficient extraction of CNCs from cotton wastes. The pretreatment strategies can suffer variation in process conditions, resulting in distortion in the extracted cellulose’s crystallinity. Acid hydrolysis using sulfuric acid is the most used extraction process for cotton wastes-based CNC. A combined pretreatment process, such as sonication and hydrolysis, increases the crystallinity of cotton-based CNCs. The improvement of the reinforced matrix interface of textile fibres is required for improved packaging and biomedical applications for the sustainability of cotton-based CNCs.

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 LiNbO3Coating on Concrete Surface: A New and Environmentally Friendly Route for Artificial Photosynthesis

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Ranjit K. Nath ◽  
M. F. M. Zain ◽  
Abdul Amir H. Kadhum
Keyword(s):  
Building Materials ◽  
Artificial Photosynthesis ◽  
Reaction Pathway ◽  
Research Work ◽  
Pollution Prevention ◽  
Environmentally Friendly ◽  
Concrete Surface ◽  
Concrete Material ◽  
Gas Phases ◽  
Work Done

The addition of a photocatalyst to ordinary building materials such as concrete creates environmentally friendly materials by which air pollution or pollution of the surface can be diminished. The use of LiNbO3photocatalyst in concrete material would be more beneficial since it can produce artificial photosynthesis in concrete. In these research photoassisted solid-gas phases reduction of carbon dioxide (artificial photosynthesis) was performed using a photocatalyst, LiNbO3, coated on concrete surface under illumination of UV-visible or sunlight and showed that LiNbO3achieved high conversion of CO2into products despite the low levels of band-gap light available. The high reaction efficiency of LiNbO3is explained by its strong remnant polarization (70 µC/cm2), allowing a longer lifetime of photoinduced carriers as well as an alternative reaction pathway. Due to the ease of usage and good photocatalytic efficiency, the research work done showed its potential application in pollution prevention.

Prototyping of a concrete maturity sensor with a hermetically sealed housing made of two-component plastic

2021 ◽  
Vol 103 (3) ◽  
pp. 60-70
Author(s):  
Ye. Utepov ◽  
◽  
A. Tulebekova ◽  
S. Akhazhanov ◽  
Sh. Zharassov ◽  
...  
Keyword(s):  
Electronic Device ◽  
Concrete Strength ◽  
Marked Change ◽  
Construction Costs ◽  
Monitoring Method ◽  
Wireless Monitoring ◽  
Advantages And Disadvantages ◽  
Working Together ◽  
Concrete Maturity ◽  
Server Application

The construction industry, traditionally considered quite conservative, is now going through a marked change. With competition intensifying, companies have begun to gradually adopt various digital technologies to reduce construction costs, such as the wireless concrete monitoring sensors, which implement a temperature-strength monitoring method for concrete. Each device has its technological features, which are considered in the development of the concepts. Enclosure design is the most important stage of product development. An enclosure made in-house has many advantages and disadvantages. The most important part of the design of an electronic device enclosure is the preliminary research stage. This article presents features of wireless monitoring sensor enclosure design. A data acquisition station (DAS), also referred to in the network topology as a “gateway”, will be used to collect data from the wireless monitoring sensor over the selected protocol. The server application was created based on HTML, PHP, CSS, JavaScript. Testing of the wireless monitoring sensor, SDS, and the server application working together showed full functionality. A study is also given on the determination of concrete strength using the developed sensor according to the ASTM method and using the IPS MG 4.0 by GOST.

scholarly journals Multilevel Privacy Assurance Evaluation of Healthcare Metadata

2021 ◽  
Vol 11 (22) ◽  
pp. 10686
Author(s):  
Syeda Amna Sohail ◽  
Faiza Allah Bukhsh ◽  
Maurice van Keulen
Keyword(s):  
Privacy Preservation ◽  
Process Mining ◽  
Research Work ◽  
Healthcare Providers ◽  
Conceptual Modeling ◽  
Empirical Evaluation ◽  
Healthcare Services ◽  
Privacy Preserving ◽  
Third Party ◽  
Conformance Checking

Healthcare providers are legally bound to ensure the privacy preservation of healthcare metadata. Usually, privacy concerning research focuses on providing technical and inter-/intra-organizational solutions in a fragmented manner. In this wake, an overarching evaluation of the fundamental (technical, organizational, and third-party) privacy-preserving measures in healthcare metadata handling is missing. Thus, this research work provides a multilevel privacy assurance evaluation of privacy-preserving measures of the Dutch healthcare metadata landscape. The normative and empirical evaluation comprises the content analysis and process mining discovery and conformance checking techniques using real-world healthcare datasets. For clarity, we illustrate our evaluation findings using conceptual modeling frameworks, namely e3-value modeling and REA ontology. The conceptual modeling frameworks highlight the financial aspect of metadata share with a clear description of vital stakeholders, their mutual interactions, and respective exchange of information resources. The frameworks are further verified using experts’ opinions. Based on our empirical and normative evaluations, we provide the multilevel privacy assurance evaluation with a level of privacy increase and decrease. Furthermore, we verify that the privacy utility trade-off is crucial in shaping privacy increase/decrease because data utility in healthcare is vital for efficient, effective healthcare services and the financial facilitation of healthcare enterprises.

scholarly journals THE MICROSTRUCTURAL PROPERTIES OF PLASTER COMPOSITE PRODUCED DURING PRE-REPUBLIC AND EARLY REPUBLIC PERIODS IN DEMIRCI

2020 ◽  
Vol 4 (12) ◽  
pp. 8-12
Author(s):  
SadıkAlper Yıldızel
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Early Republic ◽  
Building Materials ◽  
Optical Microscope ◽  
Microstructural Properties ◽  
Micro Structure ◽  
Existing Structures ◽  
Composite Production ◽  
Scanning Electron

Structural plaster properties of the residence type buildings that were constructed during prerepublic and early republic periods in Demirci were investigated within the scope of this study. Samples taken from the existing structures were dried in laboratory conditions and made ready for micro-structure examination. Proper samples were examined with scanning electron microscopy (SEM) with the sensitivity of 5 nm and a magnification of 20.000 times, and the optical microscope (magnification: 250 x). In the light of obtained results, it has been determined that the microstructure of the composite used in the Demirci county in the preRepublican period and early republic period is similar to the resultant of mixes produced with the modern fiber added composite production technology. It is thought that this study will contribute to the study of the production of the related building materials to be improved in the future within the limits of the district.

scholarly journals Microstructural characterisation of a collection of Protohistoric bronzes

2013 ◽  
Vol 19 (S4) ◽  
pp. 109-110
Author(s):  
E. Figueiredo ◽  
R.J.C. Silva ◽  
M.F. Araújo ◽  
R. Vilaça
Keyword(s):  
Tin Oxide ◽  
Research Work ◽  
Dendritic Structure ◽  
Polarized Light ◽  
Metallic Matrix ◽  
Surface Finishing ◽  
Internal Corrosion ◽  
Small Areas ◽  
Microstructural Characterisation ◽  
Copper Sulphides

Microstructural characterisation of an archaeological collection of Protohistoric bronze artefacts attributed to around the VIII century B.C. and has been carried out using optical microscopy (OM) and scanning electron microscopy combined with energy dispersive spectroscopy (SEM-EDS). The collection was found in Medronhal cave (Condeixa-a-Nova, Portugal) and is composed by 1 fibula, 5 bracelets and 31 rings.Small areas on the surfaces of the artefacts were cleaned from corrosion and were metallographically prepared by a manual polishing with several diamond suspensions in a cotton swab until 1 micron diamond size. OM observations were performed in bright field (BF) illumination and under polarized light (Pol), in unetched and etched conditions. SEM-EDS was performed without a conductive coating for a minimum external elemental interference.OM observations allowed the study of the method and sequence of manufacture involved in the production of the various types of artefacts. Results show that the fibula and the bracelets have equiaxed (recrystallised) grain structures resulting from cyclic thermo-mechanical treatments performed to a pre-form cast bar until requested shape and surface finishing was attained. The rings, which are of diverse sizes, have various types of microstructures as a result of diverse manufacturing techniques. Some show a dendritic structure that resulted from the casting, and others show recrystallised structures that resulted from cycles of deformation and annealing procedures posterior to their casting (Figure 1).SEM-EDS analysis allowed the study of the presence of inclusions in the metallic matrix and the study of corrosion in some artefacts (Figure 2). Different types of inclusions were identified, namely copper sulphides, tin oxide, and lead rich inclusions. Both copper sulphides and lead inclusions are commonly found in archaeological bronzes, and can be a result of copper ores impurities. Tin oxide, on the other hand, is not so common, and its presence can be understood as a result of preferential oxidation of tin regarding copper during a melting or alloying operation. The study of the interface alloy/corrosion showed the presence of chlorides in internal corrosion layers, which can probably be related to an aggressiveness of the burial environment.This research work has been financed by the Portuguese Science Foundation (FCT) through the EarlyMetal project (PTDC/HIS-ARQ/110442/2008), the grant SFRH/BPD/73245/2010 (to EF) and the Strategic Project-LA25-2011-2012 (PEst-C/CTM/LA0025/2011) (to CENIMAT/I3N).

Effect of Flyash- Rice Husk Ash Blend in the Energy Efficient Geopolymer Tiles Using Industrial Wastes

2022 ◽  
Vol 1048 ◽  
pp. 403-411
Author(s):  
A. Chithambar Ganesh ◽  
K. Mukilan ◽  
B.P.V. Srikar ◽  
L.V.S. Teja ◽  
K.S.V. Prasad ◽  
...  
Keyword(s):  
Rice Husk ◽  
Energy Efficient ◽  
Building Materials ◽  
Rice Husk Ash ◽  
Research Work ◽  
Industrial Wastes ◽  
Modulus Of Rupture ◽  
Ceramic Tiles ◽  
Heat Curing ◽  
Intensive Approach

Infrastructural developments are inevitable for the developing countries and hence the production of sustainable building materials is promoted worldwide. Sustainable development in the vicinity of tiles is bewildered for more than a decade. Production of conventional tiles such as cement concrete tiles, clay tiles and ceramic tiles is energy intensive approach and levies lot of strain over the adjunct ecosystem. On the other hand there are serious problems related to the disposal of flyash, Rice Husk Ash throughout the world. An approach has been taken to synthesis tiles based on these industrial byproducts as the base materials through Geopolymer technology. In this work, Geopolymer mortar after heat curing is applied as tiles. In this work, Flyash is replaced by Rice Husk Ash in various proportions such as 20, 40, 60, 80 and 100 percent. Tests such as workability, flatness, straightness, perpendicularity, water absorption, modulus of rupture and abrasion are conducted and fair results are obtained. This research also portrays the effect of Rise Husk Ash addition over the flyash based Geopolymer binder in the utility as tiles. The findings of this research work encourages the development of energy efficient tiles using industrial wastes. Keywords: Geopolymer, Rice Husk Ash, Tiles

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