scholarly journals Acoustic Emission Characteristics of Normal and Layered Concrete Blocks during Dilating/Static Fracture

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Ji Ma ◽  
Feng Du ◽  
Shuai Zhang
Keyword(s):  
Acoustic Emission ◽  
Surface Displacement ◽  
High Strength ◽  
Engineering Construction ◽  
Strength Concrete ◽  
Soft Interlayer ◽  
Fracturing Process ◽  
Concrete Blocks ◽  
Static Fracture ◽  
Experimental Reference

Static fracturing technology is one of the most effective methods for localized breaking of rock and concrete. Layered concrete and rock structures are commonly seen in engineering applications such as breaking of concrete buildings, stone cutting, and excavation of rock in underground spaces. Therefore, it is essential to study the static fracturing characteristics of layered concrete to ensure the safety of engineering construction processes. In this paper, using acoustic emission (AE) technology and surface displacement monitoring, the deformation and fracturing of ordinary-strength concrete, concrete with a soft interlayer, and layered concrete (with strength decreasing successively by layer) were studied under the effect of a static (or soundless) cracking agent (SCA). The experimental results indicated that (1) AE activity of the two layered concrete test blocks during static fracturing showed a gradually increasing trend, while that of the ordinary-strength concrete tended to first increase and then decrease; (2) for the concrete test block with a soft interlayer sandwiched by high-strength layers, the AE events reached a maximum in the transfer of expansion pressure stage, which accounted for 47.11% of the total value in static cracking; the macroscopic damage to layered concrete test blocks comprising multiple interlaid layers with different strengths mainly occurred in the fracturing stage, during which the AE events and AE energy accounted for 76.22% and 66.94%, respectively, of those in the whole static fracturing process; and (3) the duration of static fracturing prolonged with the increase of the overall strength of the concrete test blocks. The results provide a useful experimental reference for the application of static fracturing technology in the breaking of layered concrete and rock.

scholarly journals Compressive strength of masonry constructed with high strength concrete blocks

2017 ◽  
Vol 10 (6) ◽  
pp. 1273-1319 ◽  
Author(s):  
E. S. FORTES ◽  
G. A. PARSEKIAN ◽  
J. S. CAMACHO ◽  
F. S. FONSECA
Keyword(s):  
Compressive Strength ◽  
High Strength Concrete ◽  
Strain Curve ◽  
High Strength ◽  
Masonry Walls ◽  
Strength Ratio ◽  
Stress Strain Curve ◽  
Strength Concrete ◽  
Concrete Masonry ◽  
Concrete Blocks

Abstract Although the use of high strength concrete blocks for the construction of tall buildings is becoming common in Brazil, their mechanical properties and behavior are not fully understood. The literature shows a gap in experimental studies with the use of high strength concrete blocks, i.e., those with compressive strength greater than 16 MPa. The work presented herein was conducted in order to study the behavior of high strength structural masonry. Therefore, the compressive strength and modulus of elasticity of concrete block walls tested under axial load were assessed. The specimens included grouted and ungrouted walls and walls with a mid-height bond beam; ungrouted walls were constructed with face-shell and full mortar bedding. The walls were built and tested in the laboratory of CESP and in the Structures Laboratory of the UNESP Civil Engineering Department in Ilha Solteira (NEPAE). Concrete blocks with nominal compressive strength of 16 (B1), 24 (B2) and 30 (B3) MPa were used. Ungrouted masonry walls had a height of 220 cm and a width of 120 cm while grouted masonry walls had a height of 220 cm and a width of 80 cm. Traditional Portland cement, sand and lime mortar was used. The testing program included 36 blocks, 18 prisms, 9 ungrouted walls (6 with face-shell mortar bedding and 3 with full mortar bedding), 9 grouted masonry walls, and 12 ungrouted walls with a bond beam at mid-height. The experimental results were used to determine the compressive strength ratio between masonry units, prisms and masonry walls. The analyses included assessing the cracking pattern, the mode of failure and the stress-strain curve of the masonry walls. Tests results indicate that the prism-to-unit strength ratio varies according to the block strength; that face-shell mortar bedding is suitable for high strength concrete masonry; and that 20% resistance decrease for face-shell mortar bedding when compared with full mortar bedding is a conservative consideration. The results also show that using a bond beam at the mid-height of the wall does not lead to a compressive strength decreased but it changes the failure mode and the shape of the stress-strain curve. In addition, the results show that estimating E = 800 fp is conservative for ungrouted masonry walls but reasonably accurate for grouted masonry walls and that there is no reason to limit the value of E to a maximum value of 16 GPa. Furthermore, the results show that, for design purposes, a wall-to-prism strength ratio value of 0.7 may be used for high strength concrete masonry.

scholarly journals STUDY ON EXPLOSIVE SPALLING PROCESS OF HIGH-STRENGTH CONCRETE BY MEANS OF ACOUSTIC EMISSION

2009 ◽  
Vol 65 (1) ◽  
pp. 16-29
Author(s):  
Mitsuo OZAWA ◽  
Shinya UCHIDA ◽  
Ruping WANG ◽  
Toshiro KAMADA ◽  
Hiroaki MORIMOTO
Keyword(s):  
Acoustic Emission ◽  
High Strength Concrete ◽  
High Strength ◽  
Explosive Spalling ◽  
Strength Concrete

Influence of joint thickness and strength of mortars on the compressive behavior of prisms made of normal and high-strength concrete blocks

2020 ◽  
Vol 234 ◽  
pp. 117419
Author(s):  
Filipe Emerick Caldeira ◽  
Gustavo Henrique Nalon ◽  
Diôgo Silva de Oliveira ◽  
Leonardo Gonçalves Pedroti ◽  
José Carlos Lopes Ribeiro ◽  
...  
Keyword(s):  
High Strength Concrete ◽  
High Strength ◽  
Compressive Behavior ◽  
Strength Concrete ◽  
Joint Thickness ◽  
Concrete Blocks

scholarly journals Acoustic Emission Monitoring of High-Strength Concrete Columns Subjected to Compressive Axial Loading

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3114
Author(s):  
Rami Eid ◽  
Boris Muravin ◽  
Konstantin Kovler
Keyword(s):  
Acoustic Emission ◽  
High Strength Concrete ◽  
Large Scale ◽  
Axial Loading ◽  
High Strength ◽  
Concrete Columns ◽  
Concrete Cover ◽  
Premature Failure ◽  
Strength Concrete ◽  
High Strength Concrete Columns

Acoustic Emission (AE) nondestructive tests have attracted great interest for their use in the determination of structural properties and behavior of reinforced concrete (RC) elements. One of the applications this method can contribute to is in high-strength concrete (HSC) columns. These elements have a great advantage in the lower stories of high-rise buildings. However, the premature failure of the concrete cover and the brittleness nature of the failure is of a concern for engineers. This paper presents a study on the AE monitoring of HSC columns subjected to compressive axial loading. The study consists of four large-scale reinforced HSC columns with different confinement reinforcement and height. It is shown that the AE distributions in the columns are categorized by three stages. Moreover, the levels of loads reached at the first AE macro event are similar to the lower range levels of the nominal axial compressive strengths of the tested specimens, while the majority of macro AE events are located at the concrete cover. Based on the results of this study, AE monitoring can provide indications for the damage and load levels attained by reinforced high-strength concrete columns subjected to compressive axial loading.

Research on Creep Performance of C60 High Performance Concrete

2009 ◽  
Vol 405-406 ◽  
pp. 400-404
Author(s):  
Jian Yin ◽  
Yi Jin Li ◽  
Ke Ren Zheng ◽  
Shi Dong Luo ◽  
Ai Guo Yan ◽  
...  
Keyword(s):  
High Strength Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Railway Bridge ◽  
Engineering Construction ◽  
Strength Concrete ◽  
Creep Coefficient ◽  
Term Creep

It was tested creep performance of C60 high strength concrete and C60 HPC to calculate the long-term creep of C60 HPC accurately, which was combined with engineering construction of Yichang Chang Jiang Railway Bridge. It was concluded the creep degree and creep coefficient of C60 HPC by means of optimization fit calculation, which gives scientific foundation for the design and construction of this bridge.

Study on Strength Development of High Strength Concrete Containing Alccofine and Fly-Ash

2012 ◽  
Vol 2 (3) ◽  
pp. 102-104 ◽  
Author(s):  
Suthar Sunil B ◽  
◽  
Dr. (Smt.) B. K. Shah Dr. (Smt.) B. K. Shah
Keyword(s):  
Fly Ash ◽  
High Strength Concrete ◽  
High Strength ◽  
Strength Development ◽  
Strength Concrete
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