Studies on drying shrinkage and water permeability of fine fly ash high performance concrete

Author(s):  
Ponraj Sankar L ◽  
G Aruna ◽  
A Krishna Rao ◽  
K Srinivas Kadrekar
Author(s):  
Hani Nassif ◽  
Nakin Suksawang ◽  
Maqbool Mohammed

Many engineers and agencies have observed that the field implementation of high-performance concrete (HPC) is highly dependent on curing and placing conditions. The effect of curing conditions on the early-age properties and long-term durability of HPC is not fully understood. There is a need to expand the knowledge of early-age properties and of the effect of pozzolanic material (like silica fume and fly ash) on drying shrinkage. Results are presented of a study performed to identify the effect of various curing methods on the early-age (autogenous) as well as drying shrinkage of normal and lightweight HPC. The study included a comparison of available analytical models for predicting early-age and drying shrinkage with results from tests performed on different mixes. HPC mixes were developed and evaluated as part of an overall study for the New Jersey Department of Transportation to develop and implement mix designs and technical specifications for HPC transportation structures, such as pavements and bridges. The effect of using three different curing methods on the early-age performance of HPC is presented. The curing conditions consisted of air-dry curing, burlap or moist curing, and use of a curing compound. Results show that moist (burlap) curing should be applied within 1 h after the placement of concrete to improve early-age performance. For very low water-to-cement plus pozzolan ratios, fly ash and lightweight aggregate improved the autogenous shrinkage performance. Moreover, current shrinkage models need to be revised to address HPC mixes.


2011 ◽  
Vol 99-100 ◽  
pp. 1027-1030
Author(s):  
Lan Fang Zhang ◽  
Rui Yan Wang

High-performance concrete was made with fly ash and polypropylene fiber, the study shows that when fly ash content was 20% and polypropylene fiber was 0.6~1.2kg/m3, it had no significant influence on the workability of concrete, however the changes of 28d compressive strength and drying shrinkage of concrete are within 10%, but it can reduce brittle and improve toughness, and impact resistance of concrete is improved obviously, when polypropylene fiber content was 0.9kg/m3, it can improve over three times.


2013 ◽  
Vol 639-640 ◽  
pp. 364-367 ◽  
Author(s):  
Xiao Bo Chen ◽  
Jian Yin ◽  
Wei Min Song

Based on engineering practice, autogenous volume deformation and creep properties of C60 high performance concrete(C60 HPC) and C60 high strength concrete(C60 HSC) were evaluated in the study. The results showed that the cement partly-replaced with fly ash could significantly decrease the creep deformation, creep coefficient and creep degree. In comparison with C60 HSC, the creep coefficient and creep degree of C60 HPC were decreased 17.9%and15.8% in 28 days, 22.9% and 21.0% in 270 days. For C60 HPC and C60 HSC at the same age, autogenous volume deformation of C60 HPC is greater than that of C60 HSC, but they were both less than 80×10-6 , and the autogenous volume deformation was basically completed in 7 days.


DYNA ◽  
2021 ◽  
Vol 88 (216) ◽  
pp. 38-47
Author(s):  
Joaquín Abellán García ◽  
Nancy Torres Castellanos ◽  
Jaime Antonio Fernandez Gomez ◽  
Andres Mauricio Nuñez Lopez

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.


2018 ◽  
Vol 761 ◽  
pp. 120-123 ◽  
Author(s):  
Vlastimil Bílek ◽  
David Pytlík ◽  
Marketa Bambuchova

Use a ternary binder for production of a high performance concrete with a compressive strengths between 120 and 170 MPa is presented. The water to binder ratio of the concrete is 0.225 and the binder is composed of Ordinary Portland Cement (OPC), condensed silica fume (CSF), ground limestone (L), fly ash (FA) and metakaoline (MK). The dosage of (M + CSF) is kept at a constant level for a better workability of fresh concrete. Different workability, flexural and compressive strengths were obtained for concretes with a constant cement and a metakaoline dosage, and for a constant dosage (FA + L) but a different ratio FA / L. An optimum composition was found and concretes for other tests were designed using this composition.


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