Methods for Determination of Residual Mortar Content Adhered to Recycled Aggregate

2014 ◽  
Vol 578-579 ◽  
pp. 568-571
Author(s):  
Chen Jia ◽  
Jia Chuan Yan ◽  
Qiong Hu ◽  
Chao Ying Zou ◽  
Fa Xin Chen
Keyword(s):  
Research Methods ◽  
Apparent Density ◽  
Sulfate Solution ◽  
External Factors ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Basic Principles ◽  
Theoretical Evidence ◽  
Better Than

To study the methods for determination of residual mortar content adhered to recycled aggregate, this paper aims at three methods which are apparent density method, quench hot method and sulfate solution freezing-thawing method. These methods were compared by experiments and their basic principles were also respectively stated. The principles of the latter two methods are similar, which are to separate the residual mortar and aggregate by external factors. But the effects of the sulfate solution freezing-thawing method is better than that of quench hot method. Finally, the best method is chosen to provide some theoretical evidence and research methods in studies and uses of recycled concrete.

Study on the Mechanical Properties and Frost Resistance of Recycled Concrete Prepared by Village Construction Wastes

2011 ◽  
Vol 418-420 ◽  
pp. 406-410
Author(s):  
Jun Liu ◽  
Yao Li ◽  
Dan Dan Hong ◽  
Yu Liu
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Frost Resistance ◽  
Cement Mortar ◽  
Strength Loss ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Replacement Rate ◽  
Concrete Mechanical Properties ◽  
Better Than

Abstract. Recycled aggregate—rural building material wastes pretreated by cement mortar—are applied into concrete with different replacement rates: 0, 25%, 50%, 75%, and 100%. Results from measurements of compressive strength, cleavage tensile strength, mass loss after fast freeze-thaw cycles, and compressive strength loss indicate that a different recycled aggregate replacement rate certainly influences concrete mechanical properties and frost resistance. Recycled aggregate replacement rates less than 75% performs better than common concrete. Data from the 100% replacement rate is worse than that of rates less than 75% but still satisfy the general demands of GB standard on C30 concrete.

scholarly journals Improved Serviceability and Environmental Performance of One-Way Slabs through the Use of Layered Natural and Recycled Aggregate Concrete

2020 ◽  
Vol 12 (24) ◽  
pp. 10278
Author(s):  
Nikola Tošić ◽  
Snežana Marinković ◽  
Yahya Kurama
Keyword(s):  
Environmental Performance ◽  
Concrete Strength ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Aggregate Concrete ◽  
Reinforced Concrete Slabs ◽  
Service Load ◽  
Better Than

Recycled aggregate concrete (RAC), i.e., concrete produced with recycled concrete aggregate (RCA) has been heavily investigated recently, and the structural design of RAC is entering into design codes. Nonetheless, the service load deflection behavior of RAC remains a challenge due to its larger shrinkage and creep, and lower modulus of elasticity. A novel solution to this challenge is the use of layered concrete, i.e., casting of horizontal layers of different concretes. To investigate the potential benefits and limits of layered concrete, this study contains a numerical parametric assessment of the time-dependent sustained service load deflections and environmental impacts of homogeneous and layered NAC and RAC one-way slabs. Four types of reinforced concrete slabs were considered: homogeneous slabs with 0%, 50% and 100% of coarse RCA (NAC, RAC50 and RAC100, respectively) and layered L-RAC100 slabs with the bottom and top halves consisting of RAC100 and NAC, respectively. In the deflection study, different statical systems, concrete strength classes and relative humidity conditions were investigated. The results showed that the layered L-RAC100 slabs performed as well as, or even better than, the NAC slabs due to the differential shrinkage between the layers. In terms of environmental performance, evaluated using a “cradle-to-gate” Life Cycle Assessment approach, the L-RAC100 slabs also performed as well as, or slightly better than, the NAC slabs. Therefore, layered NAC and RAC slabs can be a potentially advantageous solution from both structural and environmental perspectives.

Long-term sulfate attack on recycled aggregate concrete immersed in sodium sulfate solution for 10 years

2020 ◽  
Vol 70 (337) ◽  
pp. 212
Author(s):  
L. R. Santillán ◽  
F. Locati ◽  
Y. A. Villagrán-Zaccardi ◽  
C. J. Zega
Keyword(s):  
Sodium Sulfate ◽  
Fluorescent Microscopy ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Sodium Sulfate Solution ◽  
Microscopy Image

The effect of recycled concrete aggregate (RCA) on concrete performance against external sulfate attack (ESA) is not yet fully known. In this paper, recycled aggregate concretes (RAC) with 0, 50, 75 and 100% of RCA contents were evaluated after 10 years of exposure immersed in 50g/l sodium sulfate solution. Sulfate ingress profiles were obtained by wet chemical analyses and FRX. Also, the mineralogy of the ingress profile was evaluated by thermogravimetric analyses. Finally, microcracking development in samples was evaluated by optical fluorescent microscopy image analysis. Although RAC showed a slight increase in sulfate ingress, due to its higher porosity (about 30% higher SO3 content near the surface for 50% or higher replacement ratio than control concrete), a dense new matrix still allows a good performance of RAC to external sulfate attack with even 100% RCA content.

scholarly journals Validation of Rock Testing Methods in Determination of Apparent Density

2018 ◽  
Vol 66 ◽  
pp. 02003
Author(s):  
Joanna Hydzik-Wiśniewska ◽  
Sebastian Olesiak
Keyword(s):  
Research Methods ◽  
Apparent Density ◽  
Test Method ◽  
Systematic Evaluation ◽  
Test Results ◽  
Factors Affecting ◽  
Testing Procedures ◽  
Precision Evaluation ◽  
Mathematical Formulas

Research on the physical properties of rock materials and aggregates used for construction should be based on standardized methods. Whereas scientific research is focused more on the development of new methods, testing and evaluation of new properties, etc. In case of own testing procedures and standardized but modified methods, they should be validated before being put into use. Validation is the confirmation of the ability to designate that method and tests its usefulness. In order to investigate the method's possibilities, the following assessment methods can be used: calibration or precision evaluation using reference standards or reference materials, systematic evaluation of factors affecting the result, resistance of the test method to variability of controlled parameters, comparison of test results obtained by various methods, inter-laboratory comparisons, and uncertainty of measurement. The paper presents mathematical formulas allowing to evaluate the precision of research methods and the consistency of results, which are the basis for validation of research methods. In the practical part of the article, own method of apparent density testing, was validated based on the analysis of repeatability, internal laboratory reproducibility and between laboratory reproducibility.

scholarly journals Determination of Two-Liquid Mixture Composition by Assessing Dielectric Parameters 1. Precise Measuring System / Divu Šķidrumu Maisījuma Sastāva Noteikšana, Izvērtējot to Dielektriskos Parametrus 1. Precīza Mērīšanas Sistēma

2013 ◽  
Vol 50 (4) ◽  
pp. 62-73
Author(s):  
O. Vilitis ◽  
P. Shipkovs ◽  
D. Merkulovs
Keyword(s):  
Structural Design ◽  
Measuring System ◽  
Water Mixture ◽  
Dielectric Parameters ◽  
Basic Principles ◽  
Dielectric Liquids ◽  
Operational Frequency ◽  
Microbiological Analyses ◽  
Better Than

Abstract Concentration measurements are important in bioethanol industries, in the R&D areas, for chemical, medical and microbiological analyses and processing as well as for diagnostics, manufacturing, etc. The overview shows development of the structural design of a system for measuring the concentration of solutions and mixtures consisting of two dielectric liquids. The basic principles of the system's design are given along with relevant equations. The concentration of dielectric liquids is measured using devices with capacitive sensors (1-300 pF). The operational frequency of the developed measuring system is 100.000 kHz. Configuration of the system excludes some errors usually arising at measurements, and broadens its applicability. For testing, the system was calibrated for measuring the concentration of anhydrous ethanol + de-ionized water mixture. Experimental results have shown a stable resolution of ±0.005 pF at measuring the sensor capacitance and a reproducible resolution better than ±0.01% at measuring the ethanol volume concentration

Collaborative Study of the Determination of Ethanol in Wine by Chemical Oxidation

1969 ◽  
Vol 52 (1) ◽  
pp. 85-88 ◽  
Author(s):  
Arthur Caputi ◽  
Dawson Wright
Keyword(s):  
Steam Distillation ◽  
Potassium Dichromate ◽  
Collaborative Study ◽  
Sulfate Solution ◽  
Chemical Oxidation ◽  
Ferrous Ammonium Sulfate ◽  
Alcohol Content ◽  
Ferrous Ammonium ◽  
Better Than

Abstract A collaborative study was conducted on a chemical or dichromate oxidation procedure for etlianol in wine. The method is based on the steam distillation of ethanol from a 1 ml wine sample into an acidified solution of potassium dichromate, followed by heating 20 min at 60°C to complete the oxidation of the ethanol to acetic acid. The unreacted dichromate is determined by titration with a standard ferrous ammonium sulfate solution, using o-phenanthroline as an indicator. Eleven collaborators participated in the study, of whom seven were familiar with the method and four were not. Eight samples with alcohol content ranging from 11.8 to 23.5% by volume were analyzed. The standard deviations of the reported answers on the identical samples varied from 0.024 to 0.063% in the range of 11.8–20% ethanol and rose to 0,161% in the sample which contained 23.3% ethanol by volume. This reproducibility is better than has been reported with other commonly used methods, and it is recommended that the method be adopted as official first action.

Time and Latitude in South Africa

1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers
Keyword(s):  
South Africa ◽  
Cape Town ◽  
Astronomical Observations ◽  
Royal Observatory ◽  
The Republic ◽  
Astronomical Determination ◽  
Limited Accuracy ◽  
Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

Mekanisme Dan Proteksi Jaminan Nasabah Pada Gadai Informal

Liquidity ◽  
2017 ◽  
Vol 6 (2) ◽  
pp. 103-109
Author(s):  
Yuri Nanda Larasati ◽  
Jafril Khalil
Keyword(s):  
Qualitative Research ◽  
Research Methods ◽  
Financial Services ◽  
Field Data ◽  
Qualitative Research Methods ◽  
Research Field ◽  
Consumer Society ◽  
Library Research ◽  
The Cost

Regulation of the financial services authority (OJK) No. 31/POJK.05/2016 on Venture had arranged that the financial services agency on the basis of the law of pledge is in coaching and supervision OJK. Yet the existence of laws – invitation to Governing Enterprise pawn shops causing business activities conducted by the above parties are not yet regulated. The condition is feared could cause harm to the consumer society. The purpose of this research is to know the procedures, mechanisms, protection of goods and guarantee the consumer on an informal pledge financing, methods of determination of the cost of maintenance of the goods and the goods of the execution mechanism of the pledge as well as protection for the collateral items are viewed from the side of the consumer by looking at laws-invitations and Sharia. To find out whether the pledge have gotten permission from OJK. This research uses qualitative research methods with the study of library research, field data and simulations. The approach used in this study is the empirical juridical approach. Elaboration upon the results is discussed further in this article.

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