scholarly journals A Study on the Thermal Properties of High-Strength Concrete Containing CBA Fine Aggregates

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1493 ◽  
Author(s):  
In-Hwan Yang ◽  
Jihun Park
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Thermal Properties ◽  
Ultrasonic Velocity ◽  
High Strength Concrete ◽  
High Strength ◽  
Unit Weight ◽  
Test Results ◽  
Strength Concrete ◽  
Fine Aggregates

The thermal conductivity of concrete is a key factor for efficient energy consumption in concrete buildings because thermal conductivity plays a significant role in heat transfer through concrete walls. This study investigated the effects of replacing fine aggregates with coal bottom ash (CBA) and the influence of curing age on the thermal properties of high-strength concrete with a compressive strength exceeding 60 MPa. The different CBA aggregate contents included 25%, 50%, 75%, and 100%, and different curing ages included 28 and 56 days. For concrete containing CBA fine aggregate, the thermal and mechanical properties, including the unit weight, thermal conductivity, compressive strength, and ultrasonic velocity, were measured. The experimental results reveal that the unit weight and thermal conductivity of the CBA concrete were highly dependent on the CBA content. The unit weight, thermal conductivity, and compressive strength of the concrete decreased as the CBA content increased. Relationships between the thermal conductivity and the unit weight, thermal conductivity and compressive strength of the CBA concrete were proposed in the form of exponential functions. The equations proposed in this study provided predictions that were in good agreement with the test results. In addition, the test results show that there was an approximately linear relationship between the thermal conductivity and ultrasonic velocity of the CBA concrete.

Effects of Nano-CaCO3 on the Compressive Strength and Microstructure of High Strength Concrete in Different Curing Temperature

2011 ◽  
Vol 121-126 ◽  
pp. 126-131 ◽  
Author(s):  
Qing Lei Xu ◽  
Tao Meng ◽  
Miao Zhou Huang
Keyword(s):  
Compressive Strength ◽  
Low Temperature ◽  
High Strength Concrete ◽  
High Strength ◽  
Curing Temperature ◽  
Test Results ◽  
Strength Concrete ◽  
Calcium Nitrite ◽  
Orientation Index ◽  
Early Strength

In this paper, effects of nano-CaCO3 on compressive strength and Microstructure of high strength concrete in standard curing temperature(21±1°C) and low curing temperature(6.5±1°C) was studied. In order to improve the early strength of the concrete in low temperature, the early strength agent calcium nitrite was added into. Test results indicated that 0.5% dosage of nano-CaCO3 could inhibit the effect of calcium nitrite as early strength agent, but 1% and 2% dosage of nano-CaCO3 could improve the strength of the concrete by 13% and 18% in standard curing temperature and by 17% and 14% in low curing temperature at the age of 3days. According to the XRD spectrum, with the dosage up to 1% to 2%, nano-CaCO3 can change the orientation index significantly, leading to the improvement of strength of concrete both in standard curing temperature and low curing temperature.

Effect of Chopped Basalt Fiber on the Fresh and Hardened Properties of Fly Ash High Strength Concrete

2014 ◽  
Vol 567 ◽  
pp. 381-386 ◽  
Author(s):  
Nasir Shafiq ◽  
Muhd Fadhil Nuruddin ◽  
Ali Elheber Ahmed Elshekh ◽  
Ahmed Fathi Mohamed Salih
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
High Strength Concrete ◽  
Basalt Fiber ◽  
High Strength ◽  
Progressive Increase ◽  
Test Results ◽  
Strength Concrete ◽  
Hardened Properties ◽  
Chopped Basalt Fiber

In order to improve the mechanical properties of high strength concrete, HSC, several studies have been conducted using fly ash, FA. Researchers have made it possible to achieve 100-150MPa high strength concrete. Despite the popularity of this FAHSC, there is a major shortcoming in that it becomes more brittle, resulting in less than 0.1% tensile strain. The main objective of this work was to evaluate the fresh and hardened properties of FAHSC utilizing chopped basalt fiber stands, CBFS, as an internal strengthening addition material. This was achieved through a series of experimental works using a 20% replacement of cement by FA together with various contents of CBFS. Test results of concrete mixes in the fresh state showed no segregation, homogeneousness during the mixing period and workability ranging from 60 to 110 mm. Early and long terms of compressive strength did not show any improvement by using CBFS; in fact, it decreased. This was partially substituted by the effect of FA. Whereas, the split and flexural strengths of FASHC were significantly improved with increasing the content of CBFS as well as the percentage of the split and flexural tensile strength to the compressive strength. Also, test results showed a progressive increase in the areas under the stress-strain curves of the FAHSC strains after the CBFS addition. Therefore, the brittleness and toughness of the FAHSC were enhanced and the pattern of failure moved from brittle failure to ductile collapse using CBFS. It can be considered that the CBFS is a suitable strengthening material to produce ductile FAHSC.

scholarly journals Multigene Genetic Programming for Estimation of Elastic Modulus of Concrete

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Alireza Mohammadi Bayazidi ◽  
Gai-Ge Wang ◽  
Hamed Bolandi ◽  
Amir H. Alavi ◽  
Amir H. Gandomi
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Genetic Programming ◽  
High Strength Concrete ◽  
Elastic Moduli ◽  
High Strength ◽  
Test Results ◽  
Strength Concrete ◽  
Multigene Genetic Programming ◽  
Compressive Strength Test

This paper presents a new multigene genetic programming (MGGP) approach for estimation of elastic modulus of concrete. The MGGP technique models the elastic modulus behavior by integrating the capabilities of standard genetic programming and classical regression. The main aim is to derive precise relationships between the tangent elastic moduli of normal and high strength concrete and the corresponding compressive strength values. Another important contribution of this study is to develop a generalized prediction model for the elastic moduli of both normal and high strength concrete. Numerous concrete compressive strength test results are obtained from the literature to develop the models. A comprehensive comparative study is conducted to verify the performance of the models. The proposed models perform superior to the existing traditional models, as well as those derived using other powerful soft computing tools.

Test Research on Strength of Concrete Shaft Lining under Salt Disaster Corrosion

2014 ◽  
Vol 926-930 ◽  
pp. 645-648 ◽  
Author(s):  
Xu Rong Li ◽  
Hong Guang Ji ◽  
Jun Wang ◽  
Cheng Lin Song
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
High Strength Concrete ◽  
High Strength ◽  
Solution Concentration ◽  
Test Results ◽  
Strength Concrete ◽  
Strength Change ◽  
Lining Structure ◽  
Shaft Lining

In order to study the strength change of high strength concrete shaft lining structure in underground complex environment resisting composite salt damage erosion, C70 high strength concrete test specimens were made and composite salt disaster solutions of different concentrations were compounded. The test results show that the coefficient of compressive strength and flexural strength of high strength concrete increase in early corrosion and then decline. The strength of specimen declines more quickly in higher corrosion solution concentration in latter time. The change law of the flexural strength is more complex than the compressive strength. Composite salt disaster solutions have little effect for no damage high strength concrete.

Performance of Rubberized High Strength Concrete after Fire

2010 ◽  
Vol 163-167 ◽  
pp. 1403-1408
Author(s):  
Feng Liu ◽  
Gui Xuan Chen ◽  
Li Juan Li
Keyword(s):  
Compressive Strength ◽  
High Strength Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Test Results ◽  
Rubber Powder ◽  
Strength Concrete ◽  
Spalling Failure ◽  
Powder Content ◽  
Small Content

The effects of recycled rubber powder on working abilities, density and compressive strength of high strength concrete (HSC) at room temperature were studied in this paper. The characteristics of rubberized high strength concrete (RHSC) after fire was investigated by surface observation, weight loss and retained strength testing. The sieve number of rubber powder used in test is No.40 (420μm), No.60 (250µm) and No.80 (178µm), and the content of rubber powder filled in RHSC is 1%, 2%, 3% and 4% with respect to cementation material respectively. Test results show that the increase in rubber powder content reduces the concrete strength, while the decrease in compressive strength of RHSC is less than 10% when the content of rubber powder is within 2%. RHSC with small content of rubber (1%) can restrain the spalling failure of concrete under high temperature.

Influence of Metakaolin on Strength and Microstructure of Steam-Cured High-Strength Concrete

2013 ◽  
Vol 838-841 ◽  
pp. 42-46 ◽  
Author(s):  
Jun Jie Zeng ◽  
Zhi Hong Fan ◽  
Long Chen
Keyword(s):  
Compressive Strength ◽  
High Strength Concrete ◽  
High Strength ◽  
Pozzolanic Reaction ◽  
Early Age ◽  
Test Results ◽  
Replacement Level ◽  
Strength Concrete ◽  
Pozzolanic Reactivity ◽  
Compressive Strength Test

The influence of metakaolin (MK) on strength and microstructure of steam-cured high-strength concrete has been investigated using compressive strength test, XRD, MIP and SEM. Three MK replacement levels were considered in the study: 5%, 10% and 15% by weight of cement. A mix double blended with 10% MK and 10% slag was prepared too. Test results have indicated that MK can increase the compressive strength of steam-cured concrete, especially at early age. Compressive strength up to 90MPa at 1 and 28 days is obtained with the incorporation of 10% MK and 10% slag. When the replacement level of MK is higher than 10%, the enhancement of strength becomes less significant. Content of Ca (OH)2 crystals is decreased while content of hydrates with Al is increased due to the pozzolanic reactivity of MK. Concrete pore structure is significantly refined and a denser hydrates structure is obtained due to the pozzolanic reaction and filler effect of MK. Meanwhile, combination of aggregate and paste is enhanced too. The improvements of strength and microstructure become more obvious when MK and slag are double incorporated.

Experimental Study on Compressive Bearing Capacity of High Strength Concrete-Filled Steel Tube Composite Columns

2011 ◽  
Vol 368-373 ◽  
pp. 410-414 ◽  
Author(s):  
Hong Zhen Kang ◽  
Lei Yao ◽  
Xi Min Song ◽  
Ying Hua Ye
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
High Strength Concrete ◽  
High Strength ◽  
Steel Tube ◽  
Test Results ◽  
Concrete Filled Steel Tube ◽  
Composite Columns ◽  
Strength Concrete ◽  
Axial Compressive Strength

To study axial compressive strength of high strength concrete-filled steel tube composite columns, tests of 18 specimens were carried out. Parameters of the specimens were the confinement index of concrete-filled steel tube, the cubic strength and the stirrup characteristic value of concrete outer of steel tube. Test results show that the concrete-filled steel tube and the reinforced concrete deformed simultaneously in the axial direction before and at the peak value of axial compressive force; after failure of the reinforced concrete, the concrete-filled steel tube can still bear the axial load and deformation; the main influential factors of axial compressive capacity are confinement index, the cubic strength and the stirrup characteristic value of concrete outer of steel tube. The accuracy of the formula of axial compressive strength of composite columns provided by CECS 188:2005 is proved by the test results of this paper.

scholarly journals A Study on High Strength Concrete with Moderate Cement Content Incorporating Limestone Powder

2014 ◽  
Vol 61 (1) ◽  
pp. 43-58 ◽  
Author(s):  
Alaa M. Rashad ◽  
Hosam.El Din H. Seleem
Keyword(s):  
Compressive Strength ◽  
High Strength Concrete ◽  
Coarse Aggregate ◽  
Cement Content ◽  
Drying Shrinkage ◽  
High Strength ◽  
Limestone Powder ◽  
Test Results ◽  
Strength Concrete ◽  
The Difference

Abstract This paper presents the results of an investigation to assess the validity of producing high strength concrete (HSC) using moderate cement content to reduce the consumption of the binders. Cement content is lowered from 500 kg/m3 to 400 kg/m3. The difference in cement content is compensated by the addition of fine limestone (LS) powder. Pozzolans were incorporated as an addition to cement. Different coarse aggregate types were employed. Workability, compressive strength, tensile strength, permeability and drying shrinkage were measured. Test results revealed that HSC with a compressive strength up to 79 MPa (at 90 days age) could be produced with moderate cement content. The mixtures consistency and drying shrinkage are greatly enhanced due to employing LS powder and the permeability is satisfactory. To provide better solution to some concrete disadvantages like cracking and drying shrinkage, using an economic rate for cement are believed to reduce these disadvantages.

scholarly journals Strength Properties of High-Strength Concrete Containing Coal Bottom Ash as a Replacement of Aggregates

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
In-Hwan Yang ◽  
Jihun Park ◽  
Nhien Dinh Le ◽  
Sanghwa Jung
Keyword(s):  
Compressive Strength ◽  
High Strength Concrete ◽  
Bottom Ash ◽  
High Strength ◽  
Ultrasonic Pulse Velocity ◽  
Strength Properties ◽  
Pulse Velocity ◽  
Coal Bottom Ash ◽  
Strength Concrete ◽  
Fine Aggregates

Most previous studies on the strength properties of coal bottom ash (CBA) concrete have focused on concrete with a normal compressive strength, and thus, studies on the strength properties of high-strength concrete (HSC) containing CBA are limited. Therefore, the effects of replacing fine aggregates with CBA and variations in the curing age on the strength properties of HSC with a compressive strength of greater than 60 MPa were investigated in this study. The different CBA contents included 25, 50, 75, and 100%, and the different curing ages were 28 and 56 days. The mechanical properties of the HSC with CBA incorporated as fine aggregates were examined. The experimental results revealed that CBA could be partially or totally substituted for fine aggregates during HSC production. The test results also showed that the compressive, splitting tensile, and flexural strengths of the HSC containing CBA fine aggregates slightly decreased as the CBA content increased. Moreover, useful relationships between the compressive strength, splitting tensile strength, and flexural strength were suggested, and the predictions reasonably agreed with the measurements. Compared to those of the control specimen, the pulse velocities of the HSC specimens at various CBA contents decreased by less than 3%. In addition, equations for predicting the strength values of CBA concrete by using the ultrasonic pulse velocity were suggested.

Study of Properties of High Strength Concrete Reinforced with Industrial Waste Steel Fibers

2011 ◽  
Vol 341-342 ◽  
pp. 231-241
Author(s):  
Hosein Rahnema ◽  
Mohammad Hosein Modarresi ◽  
Ali Lashkari ◽  
Mohammad Ali Hadianfard ◽  
Saeid Sedaghat
Keyword(s):  
Compressive Strength ◽  
High Strength Concrete ◽  
Industrial Waste ◽  
Bending Strength ◽  
Fresh Concrete ◽  
High Strength ◽  
Steel Fibers ◽  
The Other ◽  
Test Results ◽  
Strength Concrete

High strength concrete (HSC) farther than high compressive strength, possesses uniform high density and very low impermeability, endowing itself with excellent resistance to aggressive environments and disintegrating agencies. But HSC has low flextural strength. Studies have shown that the lack of enough flextural strength of high strength concrete can be compensated by adding steel fibers to the concrete mixture. On the other hand one of the most important environmental problems is the majority of waste spiral steel chips, collected in industrial poles. In this study waste spiral steel chips have been used as steel fibers to reinforced high strength concrete. Also the properties of mixture have been studied. The main properties in this study are including slump of fresh concrete, density, compressive and bending strength of 28-days old specimens. The chips are classified into three different groups according to their shapes and three different categories of test are performed according to percentage of fibers in the mixture. The test results show that any increase in percentage of fibers, will increase the density of specimens and will decreases the slump of mixtures but it will result different behavior of their compressive and bending strength.

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