Shrinkage Cracking Resistance of a Very High Performance Concrete for 2LCP in Accordance with the Polymer Powder Mixing Rate

2018 ◽  
Vol 20 (2) ◽  
pp. 19-25
Author(s):  
ByeongRim Yun ◽  
Kyongku Yun ◽  
KyeRe Lee ◽  
SeungYeon Han
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Mixing Rate ◽  
Cracking Resistance ◽  
Powder Mixing ◽  
Shrinkage Cracking ◽  
Polymer Powder ◽  
Very High

Roof Structural System Study with Use of UHPC

2017 ◽  
Vol 259 ◽  
pp. 70-74
Author(s):  
Milan Holý
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Construction Materials ◽  
High Strength ◽  
Structural System ◽  
Total Load ◽  
Dominant Component ◽  
Industrial Buildings ◽  
Normal Strength ◽  
Very High

This paper deals with the roof structural system using prestressed girders made of ultra-high performance concrete (UHPC). One of the aims of this study is to verify whether the option of the UHPC girders could be under certain boundary conditions competitive with the commonly used construction materials. Due to its high strength, UHPC enables the design of the structural elements with the high load bearing capacity and with smaller slenderness compared to normal strength concrete elements. The price of UHPC is currently still very high compared to the normal strength concretes or steel. Therefore, its use for the usual designed structures does not recently seem too economically attractive. The effect of material savings is nonnegligible in the case, that a self-weight of the structure forms dominant component of the total load. In addition to the high strength, UHPC has very high resistance to environmental influences. It is therefore likely, that UHPC could be advantageously applied e.g. for the roofing of industrial buildings of chemical plants with high aggressive environments, because there are high demands on the life cycle of the structure.

Strengthening of a Bridge Pier with HPC: Modeling of Restrained Shrinkage Cracking

2016 ◽  
Vol 711 ◽  
pp. 1027-1034 ◽  
Author(s):  
Adriano Reggia ◽  
Sara Sgobba ◽  
Fabio Macobatti ◽  
Cristina Zanotti ◽  
Fausto Minelli ◽  
...  
Keyword(s):  
High Performance ◽  
Mechanical Performance ◽  
High Performance Concrete ◽  
Numerical Models ◽  
Experimental Tests ◽  
Concrete Bridges ◽  
Restrained Shrinkage ◽  
Shrinkage Cracking ◽  
Rc Structures ◽  
Restrained Shrinkage Cracking

After more than fifty years from the opening of the largely discussed “Autostrada del Sole” Highway in 1964, the infrastructure system in Italy appears marked by the passing of time, similarly to what observed in several other countries worldwide. The great heterogeneity of the Italian landscape has determined a great variety of construction types, such as large span concrete bridges over the northern rivers and large arch concrete bridges over the valleys of the central region. Increment of vehicle traffic and new seismic regulations are setting new requirements to adapt the existing infrastructure, which should be otherwise replaced. Moreover, reinforced concrete (RC) aging and deterioration have led to structural and material degradation, including severe cracking and corrosion. Specialized materials such as High Performance Concrete (HPC) could represent a viable convenient solution for repairing, strengthening and retrofitting of RC structures as both structural capacity and durability can be refurbished. However, alongside high mechanical performance, HPC is characterized by a high cracking sensitivity at very early age, due to its high stiffness and shrinkage. Restrained shrinkage cracking, particularly significant in repaired structures where the existing concrete generates a considerable restraint against the free movement of the repair material, may represent a limit to the effective application of these materials. For this reason, shrinkage compatibility of HPC with the existing concrete substrate needs to be experimentally and numerically assessed. A study is herein presented where, based on experimental tests, different numerical models are developed and compared to assess and eventually minimize the risk of shrinkage cracking in bridge piers strengthened with HPC.

Effect of Nano Materials on Durability of High Performance Concrete

2013 ◽  
Vol 742 ◽  
pp. 220-223 ◽  
Author(s):  
Yu Xi An
Keyword(s):  
Water Permeability ◽  
High Performance ◽  
High Performance Concrete ◽  
Shrinkage Strain ◽  
Nano Materials ◽  
Carbonation Depth ◽  
Shrinkage Cracking ◽  
Carbonation Resistance ◽  
Dry Shrinkage

The aim of this study was to study the effect of nanoSiO2 on durability of high performance concrete. Four different nanoSiO2 contents (1%, 2%, 3% and 4%) were used. The results indicate that the content of nanoSiO2 has great effect on the durability of high performance concrete. With the increase of nanoSiO2 content, both of the length of water permeability and the carbonation depth of concrete are decreasing gradually, and the water impermeability and the carbonation resistance of concrete are increasing gradually. However, with the increase of nanoSiO2 content, there is a tendency of increase on the dry shrinkage strain of 90 days of high performance concrete, and the anti-dry-shrinkage cracking property of concrete is decreasing.

scholarly journals State of the Art: Mechanical Properties of Ultra-High Performance Concrete

2017 ◽  
Vol 3 (3) ◽  
pp. 190-198 ◽  
Author(s):  
Mohamadtaqi Baqersad ◽  
Ehsan Amir Sayyafi ◽  
Hamid Mortazavi Bak
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
High Performance Concrete ◽  
State Of The Art ◽  
High Strength ◽  
Structural Members ◽  
Ultra High Performance Concrete ◽  
Conventional Concrete ◽  
The Past ◽  
Very High

During the past decades, there has been an extensive attention in using Ultra-High Performance Concrete (UHPC) in the buildings and infrastructures construction. Due to that, defining comprehensive mechanical properties of UHPC required to design structural members is worthwhile. The main difference of UHPC with the conventional concrete is the very high strength of UHPC, resulting designing elements with less weight and smaller sizes.  However, there have been no globally accepted UHPC properties to be implemented in the designing process. Therefore, in the current study, the UHPC mechanical properties such as compressive and tensile strength, modulus of elasticity and development length for designing purposes are provided based on the reviewed literature. According to that, the best-recommended properties of UHPC that can be used in designing of UHPC members are summarized. Finally, different topics for future works and researches on UHPC’s mechanical properties are suggested.

Temperature Effect on the Mechanical Properties of Very High Performance Concrete

2018 ◽  
Vol 34 ◽  
pp. 29-39
Author(s):  
Mebarek Belaoura ◽  
Dalila Chiheb ◽  
Mohamed Nadjib Oudjit ◽  
Abderrahim Bali
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
Exothermic Reaction ◽  
Physical And Mechanical Properties ◽  
Mass Effect ◽  
Mechanical Tests ◽  
Conventional Concrete ◽  
Very High

This study aims at a better understanding of the behaviour of very high performance concretes (VHPC) subjected to high temperatures. The temperature increase within the concrete originating from the hydratation exothermic reaction of cement is emphasized by the mass effect of the structures and can lead to thermal variations of around 50°C between the heart and the structures walls. These thermal considerations are not without consequence on durability and the physical and mechanical properties of very high performance concrete, such as the compressive strength. This work is an experimental research that shows the effects of temperature on the mechanical properties of very high performance concrete (VHPC) and compares them with those of conventional concrete and HPC. Test specimens in usual concrete, HPC and VHPC are made, preserved till maturity of the concrete, and then subjected to a heating-cooling cycle from room temperature to 500°C at heating rate 0.1°C/min. Mechanical tests on the hot concrete and cooling (air and water) were realized. The results show that the mechanical characteristics of VHPC (density, compressive strength, tensile strength and elastic modulus) decrease with increasing temperature, but their strength remains higher than that of conventional concrete.

Mechanical Behavior and Shrinkage of Algerian Very High Performance Concrete Using Local Materials

2017 ◽  
Vol 29 ◽  
pp. 81-89
Author(s):  
Dalila Chiheb ◽  
Mebarek Belaoura ◽  
Mohamed Nadib Oudjit ◽  
Abderrahim Bali
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Point Of View ◽  
Mechanical Mixing ◽  
Alluvial Deposits ◽  
Crushed Aggregate ◽  
Mechanical Performances ◽  
Local Materials ◽  
Crushed Limestone ◽  
Very High

In some parts of Algeria, the alluvial deposits are depleted. Optimizing the use of available resources, has become gradually urgent need and more and more important. Algeria does not remain on the sidelines of this idea, an approach is part of a sustainable development has been developed to make available to the manufacturer a steady stream of material coming from the exploitation of limestone. The importance of this production can be explained by the activity of the carrier ever growing sector. Research programs have been launched in Algeria to focus on aspects, related to the composition of concrete and influence of the nature of the constituents on the mechanical mixing quality, especially compressive strength remains the point of view of the engineer, the most important property of the material, if we exclude the sustainability indicators. Usual concretes were made using local materials. Results showed that the intrinsic properties of the constituents of concrete, and particularly studied the crushed aggregate, provide the concrete characteristics resistors quite satisfactory. To go further and in a growing cares about improving the mechanical strength of these concretes we tried to formulate a very high performance concrete (VHPC) made from local crushed aggregate, in this case the crushed limestone sands as a resource alternative to over-exploited rolled sands. The objective of this study is to enhance the crushed sand in the formulation of VHPC. The referred physical-mechanical performances are related to defer deformations within time (shrinkage) and instantaneous mechanical compressive and flexural strength.

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.

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