scholarly journals Nanomodified rapid hardening concretes reinforced with dispersed basaltic fibers

2021 ◽  
pp. 57-63
Author(s):  
Serhiy Korolko ◽  
Bohdan Seredyuk
Keyword(s):  
Crack Resistance ◽  
High Strength Concrete ◽  
High Speed ◽  
Impact Resistance ◽  
High Strength ◽  
Chemical Additives ◽  
Ultrafine Fibers ◽  
Strength Concrete ◽  
Technical Performance ◽  
Increased Strength

The article considers modern perspectives and directions of using fast – hardening high – strength concretes for protection against striking factors of action of different types of weapons. It is shown that the use of concrete materials in weapons and military equipment is one of the important components of defense structures and protective fortifications during hostilities as platoons and bases, and structures for the protection of civilians. The possibility of obtaining such concretes for the creation of special purpose fortifications is shown. Developed concrete structures have increased strength and impact resistance to high-speed impact. Due to the reinforcement of the concrete structure with mineral and chemical additives and ultrafine fibers, high rates of early strength, viscosity, crack resistance and impact resistance are achieved. The paper presents the main indicators of water consumption, strength and impact resistance of high-strength concrete. The results of the experimental study of samples of the destroyed concrete elements are presented and the corresponding conclusions concerning the use of various types of fibers for reinforcement of such concretes and increase of their crack resistance by basalt fibers are made. It is shown that a high-strength concrete with high construction and technical performance can be successfully used to create protective fortifications and fortifications for special purposes.

Pressure Bleeding Rate and Crack Resistance of High-Strength Concrete with Good Fluidity

2021 ◽  
Vol 51 (1) ◽  
pp. 20200679
Author(s):  
Jia-Liang Yao ◽  
Ying-gang Liu ◽  
Hai-Peng Deng ◽  
Wang Yi
Keyword(s):  
Crack Resistance ◽  
High Strength Concrete ◽  
High Strength ◽  
Bleeding Rate ◽  
Strength Concrete

Theoretical Calculation and Experimental Research of Shrinkage of High Strength Concrete an High-Speed Railway Bridges

2014 ◽  
Vol 1079-1080 ◽  
pp. 312-317
Author(s):  
Ming Zhou Gao ◽  
Ji Hua Li ◽  
Ru Deng Luo ◽  
Hai Long Wang
Keyword(s):  
High Strength Concrete ◽  
High Speed ◽  
Field Tests ◽  
High Strength ◽  
Concrete Bridges ◽  
High Speed Railway ◽  
Strength Concrete ◽  
Concrete Shrinkage ◽  
Tests And Measurements ◽  
Shrinkage Effect

Concrete bridges on high-speed railway are usually constructed with high strength concrete. Because of shrinkage of concrete, large stress and deformation always appear in construction and operation process of bridges. It even leads to concrete cracking. So as to guarantee the safety of structures and smoothness of tracks, correct calculation of concrete shrinkage effect must be done. Concrete shrinkage effect is a very complex non-stress strain problem which is influenced by numerous factors and difficult to calculate. According to the factors considered from different emphasis aspects, a variety of patterns or specifications are formed based on different domestic and foreign models of concrete shrinkage calculation. Combined with the construction of Jiangshan Harbor Bridge (75+2×135+75) m prestressed concrete continuous beam bridge on Hangzhou-Changsha high-speed railway, concrete shrinkage field tests and measurements were carried in which the same mix of high strength concrete as that of the bridge was used. The results of tests and measurements were compared with results of different theoretical models. The effects of high strength concrete shrinkage on high-speed railway concrete bridges were studied and some useful conclusions were obtained.

Influence of Mineral Admixtures on Crack Resistance of High Strength Concrete

2006 ◽  
Vol 302-303 ◽  
pp. 150-154 ◽  
Author(s):  
Shu Hua Liu ◽  
Kun He Fang ◽  
Zeng Li
Keyword(s):  
Fly Ash ◽  
Crack Resistance ◽  
Transition Zone ◽  
Silica Fume ◽  
High Strength Concrete ◽  
High Strength ◽  
Mineral Admixtures ◽  
Mechanism Analysis ◽  
Strength Concrete ◽  
Concrete Crack

As high strength concrete (HSC) is widely used in construction, more and more attention has been paid to crack resistance of it. In order to improve crack resistance of HSC, we study the influence of mineral admixtures (ground slag, silica fume and fly ash) on brittleness and characteristic length as crack resistance’ indexes. Testing researches shows, without admixture, crack resistance of HSC is the lowest; when one of the three mineral admixtures added, crack resistance increases dramatically; when two of the three mineral admixtures are added in the concrete, crack resistance increases a little more and it does not change very much no matter which two are mixed; crack resistance comes out the highest when the three mineral admixtures are added in concrete. Mechanism analysis shows, Adding fine and high active ground slag, silica fume and fly ash into concrete can greatly improve microstructure of transition zone, decrease Ca(OH)2, ettringite and porosity in concrete, increase C-S-H gel and greatly reduce the original micro-cracks in the transition zone.

scholarly journals Hybrid-Fiber-Reinforced Concrete Used in Frozen Shaft Lining Structure in Coal Mines

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3988 ◽  
Author(s):  
Zhishu Yao ◽  
Xiang Li ◽  
Taoli Wu ◽  
Long Yang ◽  
Xiaohu Liu
Keyword(s):  
Reinforced Concrete ◽  
Crack Resistance ◽  
High Strength Concrete ◽  
Coal Mines ◽  
High Strength ◽  
Fiber Reinforced Concrete ◽  
Hybrid Fiber ◽  
Strength Concrete ◽  
Lining Structure ◽  
Shaft Lining

To address the cracking and leaking of concrete in frozen shaft linings in deep and thick topsoil layers in coal mines, hybrid-fiber-reinforced concrete (HFRC) was developed. First, the composition of the reference concrete was obtained by investigating high-strength concrete commonly used in shaft linings, and two dosages of polyvinyl alcohol fiber (PVAF) and polypropylene plastic steel fiber (PPSF) were obtained by the mixing test. Then, tests of early cracks of concrete were conducted; results showed that HFRC could almost avoid early cracks, exhibiting an advantage in early crack resistance. Thus, HFRC can play a significant role in improving the durability of frozen shaft linings in complex underground environments. Furthermore, a series of mechanical property tests were carried out. The results showed that the compressive strength of HFRC was similar to that of the reference concrete, but the tensile and flexural strength of HFRC was 42.7% and 35.1% higher than that of the reference concrete, respectively. Finally, an analog simulation model test of shaft linings was conducted. The new type of shaft lining structure containing hybrid fibers (HFs) exhibited plastic deformation characteristics under load, and the maximum hoop strain was −3562 με. It addressed the problem of high brittleness of frozen shaft lining structures of ordinary high-strength concrete and improved the toughness and crack resistance. HFRC is an ideal material for frozen shaft lining structures in deep and thick topsoil.

Calculation Methods on Crack Resistance Capacity of SRUHSC Column to SRC Beam Joint Subjected to Reversal Cycle Load

2010 ◽  
Vol 152-153 ◽  
pp. 1835-1838
Author(s):  
Ju Zhang ◽  
Chang Wang Yan ◽  
Jin Qing Jia
Keyword(s):  
Crack Resistance ◽  
High Strength Concrete ◽  
High Strength ◽  
Test Results ◽  
Steel Reinforced Concrete ◽  
Strength Concrete ◽  
Concrete Frame ◽  
Seismic Area ◽  
Resistance Performance ◽  
Good Agreement

In the joint core regions of steel reinforced ultra high strength concrete frame, the forces are complicated. In seismic area or under some exceptional conditions, it is difficult to repair for joint when cracks occur, so crack resistance performance is important. Based on the experiment of steel reinforced ultra high strength concrete (SRUHSC) column to steel reinforced concrete (SRC) beam joint subjected to reversal cycle load, the crack resistance capacity is studied and applied calculation method for crack resistance capacity is proposed. Compared with the test results, the calculated results are in good agreement with them.

Sign in / Sign up

Export Citation Format

Share Document