scholarly journals Experimental Studies on the Structural Strength of Pumping Concrete in Winter

2021 ◽  
Vol 261 ◽  
pp. 02005
Author(s):  
Sheng Chang ◽  
Zhou Qunmei ◽  
Ling Shangzhuan
Keyword(s):  
Compressive Strength ◽  
Structural Strength ◽  
Concrete Strength ◽  
Experimental Studies ◽  
Curing Temperature ◽  
Hydration Reaction ◽  
Hydration Rate ◽  
Temperature And Humidity ◽  
The Relationship

The strength growth of concrete depends on the hydration reaction of cement. Curing temperature and humidity are important conditions to determine the hydration rate of cement. In this paper, rebound method is used to detect the structural strength of pumping commercial concrete in winter construction in Jinhua. The relationship between temperature, rebound value and compressive strength value is analyzed based on the concrete strength detection data. At the same time, some effective measures are put forward to solve the problems in winter construction.

The Relationship of NaOH Molarity, Na2SiO3/NaOH Ratio, Fly Ash/Alkaline Activator Ratio, and Curing Temperature to the Strength of Fly Ash-Based Geopolymer

2011 ◽  
Vol 328-330 ◽  
pp. 1475-1482 ◽  
Author(s):  
M. M. A. Abdullah ◽  
H. Kamarudin ◽  
M. Bnhussain ◽  
I. Khairul Nizar ◽  
A.R. Rafiza ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Construction Industry ◽  
Curing Temperature ◽  
Test Results ◽  
Compression Tests ◽  
Naoh Solution ◽  
Alkaline Activator ◽  
Relationship Of ◽  
The Relationship

Geopolymer, produced by the reaction of fly ash with an alkaline activator (mixture of Na2SiO3 and NaOH solutions), is an alternative to the use of ordinary Portland cement (OPC) in the construction industry. However, there are salient parameters that affecting the compressive strength of geopolymer. In this research, the effects of various NaOH molarities, Na2SiO3/NaOH ratios, fly ash/alkaline activator, and curing temperature to the strength of geopolymer paste fly ash were studied. Tests were carried out on 50 x 50 x 50 mm cube geopolymer specimens. Compression tests were conducted on the seventh day of testing for all samples. The test results revealed that a 12 M NaOH solution produced the highest compressive strength for the geopolymer. The combination mass ratios of fly ash/alkaline activator and Na2SiO3/NaOH of 2.0 and 2.5, respectively, produced the highest compressive strength after seven days. Geopolymer samples cured at 60 °C produced compressive strength as high as 70 MPa.

scholarly journals The estimation of compressive strength of normal and recycled aggregate concrete

2011 ◽  
Vol 9 (3) ◽  
pp. 419-431 ◽  
Author(s):  
Ksenija Jankovic ◽  
Dragan Nikolic ◽  
Dragan Bojovic ◽  
Ljiljana Loncar ◽  
Zoran Romakov
Keyword(s):  
Experimental Data ◽  
Compressive Strength ◽  
Concrete Strength ◽  
Recycled Aggregate Concrete ◽  
Curing Temperature ◽  
Recycled Aggregate ◽  
Coefficient Of Determination ◽  
Aggregate Concrete ◽  
Ready Mixed Concrete

Estimation of concrete strength is an important issue in ready-mixed concrete industry, especially, in proportioning new mixtures and for the quality assurance of the concrete produced. In this article, on the basis of the existing experimental data of compressive strength of normal and recycled aggregate concrete and equation for compressive strength calculating given in Technical regulation are compared. The accuracies of prediction by experimental data obtained in laboratory as well as by EN 1992-1-1, ACI 209 and SRPS U.M1.048 are compared on the basis of the coefficient of determination. The determination of the compressive strengths by the equation described here relies on determination of type of cement and age of concrete with the constant curing temperature.

scholarly journals Microstructure Characteristics of Self Compacting Concrete using Sea Water

2018 ◽  
Author(s):  
erniati ◽  
muhammad wihardi tjaronge ◽  
Rudy Djamaluddin ◽  
Victor Sampebulu
Keyword(s):  
Compressive Strength ◽  
Sea Water ◽  
Concrete Strength ◽  
Infrastructure Development ◽  
Self Compacting Concrete ◽  
Microstructure Characteristics ◽  
Dense Microstructure ◽  
Water Curing ◽  
The Relationship ◽  
Mixing Water

In the cycle of life, the needs of freshwater more and more. Infrastructure development is increasing. On the concrete industry, several billion tones of water used in earth as mixing water, treatment water (curing) and cleaner water every year, where using of sea water is obstructed. For that, the using of sea water which consists of 97% of the total water on earth is absolutelynecessary. Self-compacting concrete (SCC) has dense microstructure. Knowledge about the microstructure and properties of each component a concrete and their relationship is useful to control the behavior. This research aims to know the relationship between compressive strength and microstructure characteristics of Self Compacting Concrete which using seawater up to the age of 90 days. The results of this study were the compressive strength of SCC using sea water is higher than the SCC using fresh water. Seawater does not reduce the strength of SCC concrete until the age of 90 days, but instead of Seawater is accelerating the development of SCC concrete strength at an early age. The compressive strength of concrete SCC is influenced by the phase microstructure (especially with tobermorite and portlandite) formed in the concrete.

Effect of high temperature on SCC containing fly ash

2021 ◽  
Vol 12 (1) ◽  
pp. 1
Author(s):  
Mehmet Canbaz ◽  
Erman Acay
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Fly Ash ◽  
Concrete Strength ◽  
Experimental Studies ◽  
Strength Loss ◽  
Ultrasonic Pulse Velocity ◽  
Pulse Velocity ◽  
Unit Weight ◽  
Self Compacting Concrete

The effect of high temperature on self-compacting concrete, which contains different amounts of fly ash, has been investigated. By considering the effect of concrete age and increased temperatures, the optimum fly ash-cement ratio for the optimum concrete strength is determined using experimental studies. Self-compacting concrete specimens are produced, with fly ash/cement ratios of 0%, 20% and 40%. Specimens were cured for 28, 56 and 90 days. After curing was completed, the specimens were subjected to temperatures of 20°C, 100°C, 400°C, 700°C and 900°C for three hours. After the cooling process, tests were performed to determine the unit weight, ultrasonic pulse velocity and compressive strength of the specimens. According to the experiment results, an increase in fly ash ratio causes a decrease in the compressive strength of self-compacting concrete. However, it positively contributes to self-compaction and strength loss at high temperatures. The utilization of fly ash in concrete significantly contributes to the environment and the economy. For this reason, the addition of 20% fly ash to concrete is considered to be effective.

The Study of Mechanical Properties of Structural Lightweight Concrete

2010 ◽  
Vol 97-101 ◽  
pp. 1620-1623 ◽  
Author(s):  
Hong Zhi Cui ◽  
Feng Xing
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Bond Strength ◽  
Modulus Of Elasticity ◽  
Lightweight Concrete ◽  
Experimental Studies ◽  
Lightweight Aggregate ◽  
Experimental Results ◽  
The Relationship

Many investigations have been conducted on compressive strength of lightweight aggregate concretes (LWAC), but there are few experimental studies on the relationship between compressive strength, bond strength and elastic modulus of LWAC. In this paper, the specimens of twenty kinds of LWACs with different mix proportions were made. Properties of compressive strength, bond strength and modulus of elasticity of the LWACs were tested. Based on the testing resulting, equations for relationship between bond strength and compressive strength of the LWAC were established. For LWAC modulus of elasticity, the experimental results of this study can fit well with predicted equation of ACI 318

Effect of Freezing Temperature on the Microstructure of Negative Temperature Concrete

2013 ◽  
Vol 663 ◽  
pp. 343-348 ◽  
Author(s):  
Shu Hui Dong ◽  
De Cheng Feng ◽  
Shou Heng Jiang ◽  
Wei Zhong Zhu
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Pore Size ◽  
Standard Condition ◽  
Negative Temperature ◽  
Freezing Temperature ◽  
Curing Temperature ◽  
Original Structure ◽  
Testing Methods ◽  
The Relationship

The pore size distribution and the microstructure of negative temperature concrete was studied with different temperature, combining with some testing methods, such as MIP and SEM. Moreover, the change of the compressive strength was also studied with different ages. In addition, the relationship between the microstructure and the macro-mechanical properties on negative temperature concrete was explored further with different freezing temperature. It indicated that the lower the early curing temperature, the looser the original structure of cement paste; the total volume of gel pore whose pore size was less than 20nm was decreasing apparently, and the compressive strength declined. When changing to standard curing, the pore size trended to be thinner, the compressive strength was increasing sharply. The concrete was cured from -5°C to standard curing, the volume of pore that was less than 200nm was equal to that of the concrete with the standard curing in the age of 28d, so was the compressive strength. However, the volume of the macro pore of the concrete curing under -10°C and -15°C was greater than the concrete curing the standard condition, the compressive strength was less.

scholarly journals Correlation between the Compressive, Tensile Strength of Old Concrete under Marine Environment and Prediction of Long-Term Strength

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Weilai Yao ◽  
Shiyong Jiang ◽  
Wei Fei ◽  
Tao Cai
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Marine Environment ◽  
Concrete Strength ◽  
Exponential Model ◽  
Experimental Result ◽  
Term Strength ◽  
Two Parameters ◽  
The Relationship

Compressive strength and tensile strength are important mechanical properties of concrete. The long-term strength of concrete under real service environment is an important parameter when evaluating existing buildings, which should also be properly considered in structural design. In this study, the relationship between compressive and splitting tensile strength of old concrete existing for long period under marine environment was investigated. At a deserted harbour, concrete cores samples were drilled by pairs in site. For each pair of samples, the two cores were drilled from the adjacent location and conducted to compressive, splitting tensile test, respectively. 48 compressive and splitting tensile strengths were finally obtained. From the test results, tensile strength presents general uptrend with compressive strength, and the two parameters are well positively correlated. Exponential model generally recommended by building codes or literatures is still capable of describing the relationship between compressive and tensile strength of old deteriorated concrete, when function parameters are properly determined. Based on statistical theory and the experimental result of this study, a method for predicting long-term tensile strength of concrete is developed and an example is given, which may provide a potential way to estimate long-term concrete strength under real marine environment.

scholarly journals Correlation between concrete strength properties and surface electrical resistivity

2022 ◽  
Vol 15 (1) ◽  
Author(s):  
Carla Cavalcante Araújo ◽  
Gibson Rocha Meira
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Electrical Resistivity ◽  
Concrete Strength ◽  
Strength Properties ◽  
Splitting Tensile Strength ◽  
Test Parameters ◽  
Periodic Inspections ◽  
The Relationship ◽  
Non Destructive

abstract: Periodic inspections in reinforced concrete structures are important to be carried out to assess their state of conservation. In this scenario, non-destructive tests can be a suitable option since destructive tests are invasive and may be difficult to be performed in some cases. Considering this option, correlations between non-destructive test parameters and the concrete properties to be analyzed are useful tools that make easier the structure inspection. In the present work, correlations between the compressive strength (fc) and splitting tensile strength (ft) and surface electrical resistivity (ρ) of concretes were studied. Brazilian concretes of six different mixtures were analyzed at five different ages and correlation curves between strength properties and surface electrical resistivity of concrete were obtained, which are represented by the general relationships fc= 14.18·ln(ρ) + 18.43 and ft = 0.69·ln(ρ) + 2.15 for compressive strength and splitting tensile strength, respectively. In addition, a general curve considering literature data and results from this work was proposed to represent the relationship between compressive strength and surface electrical resistivity - fc = 11.89·ln(ρ) + 18.90.

scholarly journals Compressive strength and grade of concrete in structures

2020 ◽  
Vol 23 (1) ◽  
pp. 27-35
Author(s):  
L.O. Zharko ◽  
V.P. Ovchar ◽  
V.H. Tarasyuk ◽  
О.А. Fesenko
Keyword(s):  
Compressive Strength ◽  
Concrete Strength ◽  
Point Of View ◽  
Concrete Compressive Strength ◽  
Economic Interests ◽  
Core Samples ◽  
Strength Variation ◽  
The Difference ◽  
Grade Assessment ◽  
The Relationship

The paper summarizes the experience of the Department of Buildings and Facilities Structures Research in determining the compressive strength and grade of concrete in the structures, which characterize one of the main requirements for ensuring the structures mechanical strength and stability. Their unambiguous interpretation at the stages of concrete composition selection, products manufacture and structures operation leads to a conflict of interests and corruption risks between a concrete producer, a builder and an investor. Two approaches to the concrete strength and grade assessment are considered: the first one reasons from the economic interests of a concrete producer (the possibility of cement saving at a stable well-organized production facility), the second one takes into account the consumer's point of view (design indicators ensuring). The first approach is based on the coefficient of the tested control concrete cubes strength variation declared by the concrete mixture manufacturer. The calculation of the relationship between the average and characteristic compressive resistance of concrete at various coefficients of concrete compressive strength variation and grades showed that this coefficient can significantly change the assessment results. The second approach is based on the use of reference core samples cut directly from the structure, which are tested and interpreted according to established international experience. The difference in strength assessments is shown for the cases with the use of samples tests results selection compared to groups in which the smallest values are removed. Both approaches are analyzed based on the experience of determining the concrete compressive strength grade using the core samples from the entire floor slab in the existing structure and from some its areas; the results were far from straightforward and not consistent with the project. It is necessary to clearly define the areas of application of norms and standards that, firstly, serve the technology and the production market of concrete and concrete and reinforced concrete products, and secondly, ensure obtaining the actual characteristics of existing products, structures and facilities and their conformity to the project. It is advisable, especially for the structures of the higher levels of responsibility and in some controversial matters, to verify the results obtained with the first approach application to the concrete mix test specimens by testing core samples cut from the structures.

scholarly journals EN 206 Conformity Testing for Concrete Strength in Compression

2016 ◽  
Vol 77 (2) ◽  
Author(s):  
Daneti Saradhi Babu ◽  
Li Wei ◽  
Tam Chat Tim
Keyword(s):  
Compressive Strength ◽  
Concrete Strength ◽  
Concrete Structures ◽  
Strength Level ◽  
Test Results ◽  
Concrete Construction ◽  
The Mean ◽  
Compressive Strength Of Concrete ◽  
Strength In Compression ◽  
The Relationship

The design of concrete structures in accordance with EN 1992-1-1 adopts the characteristic cylinder compressive strength inits equations. EN 206 provides for conformity testing for concrete strength in compression using 150mm diameter by 300mm length cylinders or 150mm cubes only. The complementary standard to EN 206 in UK, BS 8500 (SS 544 in Singapore, MS 523 in Malaysia) has added provisions (clause 12.2) for the use of 100mm cubes for conformity testing. The conformity criteria for 100mm cube specimens are to be the same as those for 150mm cubes. A series of tests based on 3 selected levels of compressive strength has been conducted to examine the relationship between these 3 types of test specimens for compressive strength of concrete. For each strength level, 100 batches of concrete were produced over a period of several months. The test results are presented with analysis based on the mean of 3 numbers for each type of test specimens prepared from the same batch at each time of preparation. The results of this study for the 3 strength levels support the relationship between standard cylinder compressive strength and standard cube compressive strength in EN 206. In addition, results also support the recommendation that standard 100mm cube compressive strength is equivalent to that of standard 150mm cube compressive strength in BS 8500. The use of the small size cubes and certiication of designed concrete promote sustainability in concrete construction.

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