Use of Ultra-High-Performance Concrete to Produce Standard Coarse Aggregates

2021 ◽  
Vol 50 (2) ◽  
pp. 20210013
Author(s):  
Késsia da Silva Conceição ◽  
Paulo César de Almeida Maia ◽  
Guilherme Chagas Cordeiro
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Ultra High Performance Concrete ◽  
Coarse Aggregates

An Evaluation on the Restrained Shrinkage of Ultra-High Performance Concrete

2012 ◽  
Vol 525-526 ◽  
pp. 449-452 ◽  
Author(s):  
Jung Jun Park ◽  
Doo Yeol Yoo ◽  
Sung Wook Kim ◽  
Young Soo Yoon
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Tensile Creep ◽  
Ring Test ◽  
Early Age ◽  
Restrained Shrinkage ◽  
Reinforcing Bars ◽  
Ultra High Performance Concrete ◽  
Shrinkage Cracking ◽  
Coarse Aggregates

Since ultra-high performance concrete (UHPC) is subject to large occurrence of shrinkage at early age due to its low water-to-cement ratio, the mixing of large quantities of powdered admixtures and the absence of coarse aggregates, UHPC presents large risks of shrinkage cracking caused by the restraints provided by the form and reinforcing bars. Accordingly, this study intends to evaluate the shrinkage behavior of UHPC under restrained state by performing restrained shrinkage test using ring-test. The test results reveal that increasing thickness of the inner ring increases the tensile creep at early age leading to the reduction of the average strain and residual stress of the inner ring.

Influence of the Type of Silica Fume on the Rheological and Mechanical Properties of Ultra-High Performance Concrete

2011 ◽  
Vol 488-489 ◽  
pp. 274-277 ◽  
Author(s):  
Kyung Taek Koh ◽  
Jung Jun Park ◽  
Su Tae Kang ◽  
Gum Sung Ryu
Keyword(s):  
Mechanical Properties ◽  
Surface Area ◽  
Silica Fume ◽  
High Performance ◽  
High Performance Concrete ◽  
Cementitious Materials ◽  
Ultra High Performance Concrete ◽  
Coarse Aggregates ◽  
Surface Areas ◽  
Compressive And Flexural Strengths

Ultra-high performance concrete (UHPC) is a new generation of concrete developed through microstructure enhancement techniques for cementitious materials. UHPC exhibits extremely high compressive and flexural strengths exceeding 180 and 30 MPa, respectively, and remarkable durability compared to normal concretes. The fabrication of UHPC requires very low W/B ratio reaching merely 0.2, the use of large quantities of fine binder and superplasticizer without coarse aggregates, and the incorporation of steel micro-fibers. This study investigates the effect of the type of silica fume on the rheological and mechanical properties of UHPC. The adopted silica fume presents various contents of SiO2 and surface areas. From the experimental results, UHPC using silica fume with 94% of SiO2 3% of ZrO2, and surface area of 80,000 g/cm3 shows better flowability than UHPC using silica fume with 98% of SiO2and surface area of 200,000 g/cm3 by lowering the viscosity of the cementitious composites without decreasing the compressive strength. Therefore, the fabrication cost of UHPC can be reduced by smaller dosage of superplasticizer when using silica fume with Zr content .

scholarly journals Static mechanical properties and mechanism of C200 ultra-high performance concrete (UHPC) containing coarse aggregates

2020 ◽  
Vol 27 (1) ◽  
pp. 186-195 ◽  
Author(s):  
Lv Yujing ◽  
Zhang Wenhua ◽  
Wu Fan ◽  
Wu Peipei ◽  
Zeng Weizhao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Coarse Aggregate ◽  
High Performance Concrete ◽  
Maximum Size ◽  
X Ray Diffraction ◽  
Ultra High Performance Concrete ◽  
Coarse Aggregates ◽  
Static Mechanical ◽  
Static Mechanical Properties

AbstractIn this paper, C200 ultra-high performance concrete (UHPC) containing coarse aggregate was prepared. Firstly, four different maximum size and three different type of coarse aggregate having significant differences in strength, surface texture, porosity and absorption were used to prepared the mixtures. Secondly, the effect of maximum size and type of coarse aggregate on the workability of the fresh UHPC and the mechanical behaviour of harden UHPC were investigated. Finally, a series micro-tests including mercury intrusion porosimetry (MIP), scanning electron microscope (SEM), X-ray diffraction (XRD) were conducted and the mechanism of the C200 UHPC were discussed.The results show that the type and maximum size of coarse aggregate have significant effect on the workability and mechanical properties of C200 UHPC. The basalt coarse aggregate with maximum size of 10mm can be used to prepare the C200 UHPC. The compressive strength and flexural strength of the C200 UHPC is 203MPa and 46MPa at 90 day, respectively. Besides, the micro-tests data show that the C200 UHPC has a compacted matrix and strong interface transition zone (ITZ), which make the aggregate potential strength fully used.

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