scholarly journals Effects of the combined usage of nanomaterials and steel fibres on the workability, compressive strength, and microstructure of ultra-high performance concrete

2021 ◽  
Vol 10 (1) ◽  
pp. 304-317
Author(s):  
Kunhong Huang ◽  
Jianhe Xie ◽  
Ronghui Wang ◽  
Yuan Feng ◽  
Rui Rao
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
Negative Influence ◽  
Ultra High Performance Concrete ◽  
Engineering Structures ◽  
Steel Fibres ◽  
Strength Failure ◽  
Compressive Performance ◽  
Carbon Nanofibre

Abstract Using nanomaterials to enhance concrete performance is of particular interest to meet the safety and functionality requirements of engineering structures. However, there are few comprehensive comparisons of the effects of different nanomaterials on the properties of ultra-high performance concretes (UHPCs) with a compressive strength of more than 150 MPa. The aim of the present study was to assess the coupling effects of nanomaterials and steel fibres on the workability and compressive performance of UHPC. Three types of nanomaterials, nano-SiO2 (NS), nano-calcium carbonate (NC), and carbon nanofibre (CNF), were each added into UHPC mixes by quantity substitution of the binder; two types of steel fibres were investigated; and two mixing methods were used for casting the UHPC. In addition, the effect of curing age (7 or 28 days) on the compressive performance of the mixtures was considered. Comprehensive studies were conducted on the effects of these test variables on the fluidity, compressive strength, failure mode, and microstructure. The results show that the combination of these nanomaterials and steel fibres can provide good synergetic effects on the compressive performance of UHPC and that the addition of CNF results in a greater enhancement than the addition of NS or NC. The addition of NS, not CNF or NC, has a considerable negative influence on the fluidity of the UHPC paste. It is suggested that reducing the agglomeration of the nanomaterials would further improve the performance of the resulting UHPC.

scholarly journals Ultra-high-performance concrete with local high unburned carbon fly ash

DYNA ◽  
2021 ◽  
Vol 88 (216) ◽  
pp. 38-47
Author(s):  
Joaquín Abellán García ◽  
Nancy Torres Castellanos ◽  
Jaime Antonio Fernandez Gomez ◽  
Andres Mauricio Nuñez Lopez
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
High Performance ◽  
High Performance Concrete ◽  
Unburned Carbon ◽  
High Tech ◽  
Ultra High Performance Concrete ◽  
Conventional Concrete ◽  
The Cost

Ultra-high-performance concrete (UHPC) is a kind of high-tech cementitious material with superb mechanical and durability properties compared to other types of concrete. However, due to the high content of cement and silica fume used, the cost and environmental impact of UHPC is considerably higher than conventional concrete. For this reason, several efforts around the world have been made to develop UHPC with greener and less expensive local pozzolans. This study aimed to design and produce UHPC using local fly ash available in Colombia. A numerical optimization, based on Design of Experiments (DoE) and multi-objective criteria, was performed to obtain a mixture with the proper flow and highest compressive strength, while simultaneously having the minimum content of cement. The results showed that, despite the low quality of local fly ashes in Colombia, compressive strength values of 150 MPa without any heat treatment can be achieved.

scholarly journals Mechanical Properties and Environmental Evaluation of Ultra-High-Performance Concrete with Aeolian Sand

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3148 ◽  
Author(s):  
Hongyan Chu ◽  
Fengjuan Wang ◽  
Liguo Wang ◽  
Taotao Feng ◽  
Danqian Wang
Keyword(s):  
Compressive Strength ◽  
Environmental Impact ◽  
Young’S Modulus ◽  
High Performance ◽  
High Performance Concrete ◽  
Young's Modulus ◽  
Ultra High Performance Concrete ◽  
Aeolian Sand ◽  
Binder Ratio ◽  
Water Binder Ratio

Ultra-high-performance concrete (UHPC) has received increasing attention in recent years due to its remarkable ductility, durability, and mechanical properties. However, the manufacture of UHPC can cause serious environmental issues. This work addresses the feasibility of using aeolian sand to produce UHPC, and the mix design, environmental impact, and mechanical characterization of UHPC are investigated. We designed the mix proportions of the UHPC according to the modified Andreasen and Andersen particle packing model. We studied the workability, microstructure, porosity, mechanical performance, and environmental impact of UHPC with three different water/binder ratios. The following findings were noted: (1) the compressive strength, flexural strength, and Young’s modulus of the designed UHPC samples were in the ranges of 163.9–207.0 MPa, 18.0–32.2 MPa, and 49.3–58.9 GPa, respectively; (2) the compressive strength, flexural strength, and Young’s modulus of the UHPC increased with a decrease in water/binder ratio and an increase in the steel fibre content; (3) the compressive strength–Young’s modulus correlation of the UHPC could be described by an exponential formula; (4) the environmental impact of UHPC can be improved by decreasing its water/binder ratio. These findings suggest that it is possible to use aeolian sand to manufacture UHPC, and this study promotes the application of aeolian sand for this purpose.

Design of an Experimental Prestressed Vierendeel Pedestrian Bridge Made of UHPC

2014 ◽  
Vol 587-589 ◽  
pp. 1642-1645 ◽  
Author(s):  
Petr Tej ◽  
Alena Tejová
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Total Width ◽  
Bridge Structure ◽  
Ultra High Performance Concrete ◽  
Pedestrian Bridge ◽  
Main Structure ◽  
Steel Fibres

This paper presents the design of an experimental prestressed Vierendeel pedestrian bridge made of ultra-high performance concrete (UHPC). The structure is designed as a permanent single-span bridge with an intermediate deck. The span of the bridge structure is 61.38 m, the total width is 6.68 m, and the clearance width of the bridge is 5.30 m. The main structure of the bridge consists of two prestressed Vierendeel beams made of UHPC with dispersed steel fibres . The main beams are composed of prefabricated parts, subsequently prestressed.

Study on the Compressive Strength and Mixing of Ultra-High Performance Concrete

2013 ◽  
Vol 357-360 ◽  
pp. 825-828
Author(s):  
Su Li Feng ◽  
Peng Zhao
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Strength Properties ◽  
Test Method ◽  
Test Results ◽  
Concrete Compressive Strength ◽  
Ultra High Performance Concrete ◽  
Mixture Ratio

The test in order to obtain liquidity, higher intensity ultra-high performance concrete(UHPC), in the course of preparation, high intensity quartz sand to replace the ordinary sand,reasonable mixture ratio control low water-cement ratio,the incorporation of part of the test piece ofsteel fibers, produced eight specimens . In the ordinary molding and the standard conservation 28d thecase, the ultra-high-performance concrete compressive strength of more than 170MPa.Thepreparation of the test method and test results will provide the basis for further study of the law of themechanical properties of ultra high strength properties of concrete.

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