scholarly journals About frost resistance of the contact zone of dry adhesive mixes classes C1 and C2

2020 ◽  
Vol 157 ◽  
pp. 06027
Author(s):  
Grigory Nesvetaev ◽  
Anna Dolgova ◽  
Alexey Revyakin
Keyword(s):  
Contact Zone ◽  
Frost Resistance ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Freezing And Thawing ◽  
Concrete Base ◽  
Dry Adhesives ◽  
Low Modulus ◽  
Redispersible Polymer Powder

The purpose of the study: to identify the effect of the dose of redispersible polymer powders and the type of low-modulus inclusions on the frost resistance of dry adhesives mixes made using Portland cement with the concrete base. Methods of research: The research was carried out on the basis of 75 freezing-thawing cycles. The following parameters were determined: compressive and flexural strength on samples 40x40x160 mm in accordance with GOST 30744; bond strength to the concrete base after 28 days hardening and after 75 cycles of freezing and thawing in accordance with GOST 31356. The dynamic modulus of elasticity was determined by the value of the ultrasonic pulse velocity on samples of 40x40x160 mm. The influence of prescription factors on the ratio of these values after 75 freeze-thaw cycles relative to the values after 28 days hardening under normal conditions was studied. Main results: The coefficients of frost resistance of the contact zone of the adhesive mortar made using dry mixes after 75 cycles of freezing and thawing exceeds the values of the coefficients of frost resistance according to the criteria of strength or dynamic elastic modulus. Dry adhesives mixes of class C1 with a dosage of redispersible polymer powder from 1 to 3% and an air-entraining admixture after 75 freezing cycles may be corresponded to class C2. The coefficient of variation in the compressive strength of mortar inside a series of samples after 28 days of hardening under normal conditions is not appropriate to consider as an indicator of the homogeneity of the mortar structure, potentially having a high resistance to cyclic freezing-thawing.

scholarly journals Tensile Strength and Dynamic Modulus of Pervious Polymer Concrete with Freezing and Thawing Cycles

2021 ◽  
Vol 21 (6) ◽  
pp. 209-215
Author(s):  
Yunje Lee ◽  
Jaehun Ahn ◽  
Yungtak Oh ◽  
Jaegeon Lee
Keyword(s):  
Tensile Strength ◽  
Dynamic Modulus ◽  
Low Impact Development ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Polymer Concrete ◽  
Freezing And Thawing ◽  
Test Standards ◽  
Before And After

The expansion of impervious areas owing to urbanization has adverse effects on water circulation. The application of low-impact development techniques to solve these problems is gaining popularity. Among others, Permeable pavements are the most widely employed low-impact development techniques. In this study, the dynamic modulus and tensile strength of pervious polymer concrete pavement were evaluated before and after freezing-thawing cycles. A tensile strength test, performed to check the soundness of the pervious polymer concrete, yielded a tensile strength and tensile strength ratio of 0.66 to 0.96 MPa, and 72 to 83%, respectively. The ultrasonic pulse velocity was measured to determine the dynamic modulus according to the freezing-thawing cycles. When 300 freezing-thawing cycles were performed, the dynamic modulus was analyzed to drop to a level of 77~85% of the initial value. The standards for freezing and thawing tests of pervious concrete have not yet been established. It is necessary to develop test standards for freezing-thawing resistance of pervious concretes considering climate change.

scholarly journals Curing: The easiest and cheapest method to increase the durability and strength of concrete

2018 ◽  
Vol 16 (3) ◽  
pp. 475-487
Author(s):  
Badrinarayan Rath ◽  
Shirish Deo ◽  
Gangadhar Ramtekkar
Keyword(s):  
Reinforced Concrete ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Strength Test ◽  
Fiber Reinforced Concrete ◽  
Hardened Concrete ◽  
Fiber Reinforced ◽  
Freezing And Thawing ◽  
The Cost

Curing is a process which follows immediately after placing and finishing of concrete. It maintains a satisfactory moisture content and temperature in concrete for a period of time so that the desired properties may develop. Curing has a strong influence on the properties of hardened concrete. With proper curing concrete becomes stronger, more impermeable, and more resistant to stress, abrasion, and freezing and thawing. Using of fiber in concrete may improve these properties but it increases the cost of concrete. This paper reports the results of a study conducted to assess the effect of ages of curing on durability and strength of fiber and non fiber reinforced concrete. Also a comparative study of cost per unit strength and cost per unit service life period is done in between fiber reinforced concrete and non fiber reinforced concrete with proper curing. The concrete cubes were prepared by varying three water cement ratios and by curing them for a different number of curing days. Bulk electrical resistivity test, ultrasonic pulse velocity test, compressive strength test, flexural strength test and carbonation depth test of the cured cubes were performed. From the test results it is found that proper curing of traditional concrete is more economical than fiber reinforced concrete in achieving the same strength and durability.

PENGKAJIAN KEKUATAN BETON STRUKTUR JEMBATAN PASCA KEBAKARAN

2013 ◽  
Vol 12 (3) ◽  
Author(s):  
Sudarmadi Sudarmadi
Keyword(s):  
Compressive Strength ◽  
Concrete Strength ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Test Results ◽  
Concrete Compressive Strength ◽  
Strength Assessment ◽  
Concrete Testing

In this paper a case study about concrete strength assessment of bridge structure experiencing fire is discussed. Assessment methods include activities of visual inspection, concrete testing by Hammer Test, Ultrasonic Pulse Velocity Test, and Core Test. Then, test results are compared with the requirement of RSNI T-12-2004. Test results show that surface concrete at the location of fire deteriorates so that its quality is decreased into the category of Very Poor with ultrasonic pulse velocity ranges between 1,14 – 1,74 km/s. From test results also it can be known that concrete compressive strength of inner part of bridge pier ranges about 267 – 274 kg/cm2 and concrete compressive strength of beam and plate experiencing fire directly is about 173 kg/cm2 and 159 kg/cm2. It can be concluded that surface concrete strength at the location of fire does not meet the requirement of RSNI T-12-2004. So, repair on surface concrete of pier, beam, and plate at the location of fire is required.

scholarly journals Correlation between Uniaxial Compression Test and Ultrasonic Pulse Rate in Cement with Different Pozzolanic Additions

2021 ◽  
Vol 11 (9) ◽  
pp. 3747
Author(s):  
Leticia Presa ◽  
Jorge L. Costafreda ◽  
Domingo Alfonso Martín
Keyword(s):  
Compression Test ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Uniaxial Compression Test ◽  
Unconfined Compression Test ◽  
Pozzolanic Cement ◽  
The Relationship ◽  
Compression Resistance

This work aims to study the relationship between the compression resistance and velocity from ultrasonic pulses in samples of mortars with 25% of pozzolanic content. Pozzolanic cement is a low-priced sustainable material that can reduce costs and CO2 emissions that are produced in the manufacturing of cement from the calcination of calcium carbonate. Using ultrasonic pulse velocity (UPV) to estimate the compressive resistance of mortars with pozzolanic content reduces costs when evaluating the quality of structures built with this material since it is not required to perform an unconfined compression test. The objective of this study is to establish a correlation in order to estimate the compression resistance of this material from its ultrasonic pulse velocity. For this purpose, we studied a total of 16 cement samples, including those with additions of pozzolanic content with different compositions and a sample without any additions. The results obtained show the mentioned correlation, which establishes a basis for research with a higher number of samples to ascertain if it holds true at greater curing ages.

scholarly journals Mechanical Characterisation and Shrinkage of Thermoactivated Recycled Cement Concrete

2021 ◽  
Vol 11 (6) ◽  
pp. 2454
Author(s):  
Sofia Real ◽  
José Alexandre Bogas ◽  
Ana Carriço ◽  
Susana Hu
Keyword(s):  
Mechanical Strength ◽  
Elasticity Modulus ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Cement Concrete ◽  
Supplementary Cementitious Material ◽  
Mechanical Characterisation ◽  
Shrinkage Behaviour ◽  
Binder Ratio

This paper investigates the mechanical and shrinkage behaviour of concrete with recycled cement (RC) thermoactivated from waste cement paste and waste concrete. Overall, compared to ordinary Portland cement (OPC), for the same water/binder ratio, the mechanical strength and ultrasonic pulse velocity were not significantly influenced by the incorporation of RC. The elasticity modulus decreased with the addition of RC and the shrinkage tended to increase at high RC content. The incorporation of up to 15% RC allowed the production of workable concrete with identical shrinkage and similar to higher mechanical strength than concrete with only OPC. RC proved to be a very promising more eco-efficient supplementary cementitious material.

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