Experimental Research on High Performance Concrete under Drying-Wetting Cycles in Saline-Lake Environment

2011 ◽  
Vol 368-373 ◽  
pp. 1561-1565
Author(s):  
Wei Kong ◽  
Yi Hong Wang ◽  
Gang Zhou ◽  
Tian Hua Li
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Saline Lake ◽  
Salt Lake ◽  
Concrete Structures ◽  
Lake Area ◽  
Corrosion Performance ◽  
Dual Action ◽  
Corrosion Problem ◽  
Single Factor Experiment

Aiming at the corrosion problem of concrete structure of bridges in Chaerhan salt lake area, the paper puts forward a new method of using multi-defense lines against salt erosion, helpful to improve the durability of concrete structures. Single factor experiment of salt erosion and a dual-action experiment of salt erosion and drying-wetting cycles were conducted, using 3 kinds of concrete specimens, including simple high performance concrete (HPC), HPC coated with waterproof material outside and HPC mixed with waterproof material. Results of experiments show that high performance concrete prepared in the experiments has good anti-corrosion performance. Moreover, HPC with multi-defense lines application effectively delays salt erosion to concrete, and lengthens service life of concrete structures in saline-lake environment.

Temperature Control and Anti-Cracking Measures for a High-Performance Concrete Aqueduct

2013 ◽  
Vol 405-408 ◽  
pp. 2739-2742 ◽  
Author(s):  
Zhen Hong Wang ◽  
Shu Ping Yu ◽  
Yi Liu
Keyword(s):  
Temperature Control ◽  
Temperature Difference ◽  
High Performance ◽  
High Performance Concrete ◽  
Concrete Structures ◽  
Apparent Temperature ◽  
Mass Concrete ◽  
Water Pipe ◽  
Thin Walled ◽  
Water Pipe Cooling

To solve the problem of cracks developing on thin-walled concrete structures during construction, the authors expound on the causes of cracks and the crack mechanism. The difference between external and internal temperatures, basic temperature difference and constraints are the main reasons of crack development on thin-walled concrete structures. Measures such as optimizing concrete mixing ratio, improving construction technology, and reducing temperature difference can prevent thin-walled concrete structures from cracking. Moreover, water-pipe cooling technology commonly used in mass concrete can be applied to thin-walled concrete structures to reduce temperature difference. This method is undoubtedly a breakthrough in anti-cracking technology for thin-walled concrete structures, particularly for thin-walled high-performance concrete structures. In addition, a three-dimensional finite element method is adopted to simulate the calculation of temperature control and anti-cracking effects f. Results show the apparent temperature controlling effect of water-pipe cooling for thin-walled concrete structures.

Material and Structural Properties for Creating High Performance Concrete Structures

2014 ◽  
Vol 629-630 ◽  
pp. 21-27
Author(s):  
György L. Balázs
Keyword(s):  
Structural Properties ◽  
Material Properties ◽  
High Performance ◽  
High Performance Concrete ◽  
Concrete Structures ◽  
Structural Elements ◽  
Design Rules ◽  
Existing Structures ◽  
New Codes ◽  
Specific Material

HPC and UHPC concretes are finding their ways both to new structures and to retrofitting of existing structures. Herein specific material properties as well as structural examples are discussed. New Codes and Recommendations provide description of material properties and design rules for HPC/UHPC structures and structural elements.

Usage of Heat Pretreatment for Reduction of Explosive Spalling of High Performance Concrete

2014 ◽  
Vol 1054 ◽  
pp. 37-42
Author(s):  
Iveta Nováková ◽  
Ulrich Diederichs ◽  
Lenka Bodnárová
Keyword(s):  
Compressive Strength ◽  
Water Vapour ◽  
High Performance ◽  
High Performance Concrete ◽  
Mercury Porosimetry ◽  
Concrete Structures ◽  
Explosive Spalling ◽  
Polypropylene Fibres ◽  
Rapid Reduction ◽  
Micro Cracks

Fire resistance of concrete structures could be improved by add of polypropylene fibres in to the concrete mixture in butch from 1 to 2 kg per 1 m3 of fresh concrete. This method is effective, but it is not possible to use it for existing concrete and existing reinforced concrete structures. The new method which has good potential for fire protection of existing structures is based on creation of capillary pore and micro cracks system, which allowed water vapour evaporate from concrete. This study deals with determination of appropriate temperature in which is created adequate network of capillary pores and micro cracks which has no influence on strength and durability of the concrete. The formation of macro cracks and bigger pores could cause rapid reduction of compressive and tensile strength, decrease of resistance to aggressive substances and decrease of the frost resistance. The high performance concrete (HPC) has very low porosity, which can cause explosive spalling while the water vapour tries to evaporate from concrete structure during the fire. The HPC concrete has high compressive strength and high density. The HPC samples were exposed to temperatures 150, 250, 350 a 450°C, and after cooling down to normal ambient were carried out tests to define changes in porosity by mercury porosimetry, mass looses and compressive strength changes. The heated HPC concrete is regaining humidity into its structure from surrounding atmosphere, which can cause rehydratation of some chemical compounds. [1] For verification of these hypotheses the HPC samples were kept in water storage for 4 weeks and then tested.

scholarly journals Advanced high-performance concrete structures - challenge for sustainable and resilient future

2018 ◽  
Vol 195 ◽  
pp. 01001
Author(s):  
Petr Hajek
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Concrete Structures ◽  
Potential Contribution ◽  
Basic Principles ◽  
Model Code ◽  
Existing Structures ◽  
Impact Reduction ◽  
Development Goals ◽  
Technical Solutions

Development and recent changes in natural and socio-economic environment requires new technical solutions for construction of new and reconstruction and modernization of existing structures. Structures and all built environment should be better prepared for new conditions - they should be sustainable and resilient. Concrete is building material with high potential for new technical solutions resulting in needed environmental impact reduction and consequent social and economic improvements. The paper presents potential contribution of concrete industry, advanced highperformance concrete and concrete structures to Sustainability Development Goals specified in UN 2030 Agenda for Sustainable Development and presents basic principles of implementation of sustainability approach into design of concrete structures and particularly to fib Model Code 2020.

Modeling of Vapor Pressure Build-Up in Heated High-Performance Concrete

2012 ◽  
Vol 204-208 ◽  
pp. 3691-3694
Author(s):  
Jie Zhao ◽  
Jian Jun Zheng ◽  
Gai Fei Peng
Keyword(s):  
High Temperature ◽  
Vapor Pressure ◽  
Prediction Model ◽  
High Performance ◽  
High Performance Concrete ◽  
Dominant Role ◽  
Concrete Structures ◽  
Mechanism Study ◽  
Material Degradation ◽  
Temperature Conditions

Under high temperature conditions, such as fire, high-performance concrete will undergo material degradation or even spalling. Spalling is the most detrimental to concrete structures. To prevent concrete from spalling, the mechanism should be understood. Since the build-up vapor pressure in concrete is supposed to play a dominant role in spalling, a vapor pressure prediction model is proposed in this paper to quantitatively analyze the vapor pressure, which can be used for the spalling mechanism study.

scholarly journals Analysis of Chloride Penetration Into High Performance Concrete

2020 ◽  
Vol 3 (3) ◽  
pp. 295-305
Author(s):  
Silvija Mrakovčić ◽  
Natalija Bede ◽  
Ivan Ušić
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Concrete Structures ◽  
Chloride Penetration ◽  
Reinforced Concrete Structures ◽  
Wetting And Drying ◽  
Chloride Corrosion ◽  
Structure Degradation ◽  
Astm C1202

Corrosion of reinforcement is one of basic destruction mechanisms of reinforced concrete structures. In that sense, the most affected structures are those by the sea, especially their parts subjected to cycles of wetting and drying. Chlorides penetrate to concrete mostly by diffusion, faster if the concrete is more permeable, destructing reinforcement passive protection and causing its corrosion, reduction of reinforcement cross section and bearing capacity of the structure. Retardation of chloride corrosion that causes structure degradation in marine environment can be achieved by the usage of quality concrete with enhanced strength and permeability parameters in regards to ordinary concrete. Mixes of ordinary and high performance concrete with different ratio of silica fume have been made. Compressive strength and resistivity to chloride penetration have been tested on the specimens 28 days after mixing. The resistivity to chloride penetration has been determined by fast chloride penetration test according to ASTM C1202 standard, using appliance that measures electrical conductivity of concrete specimens. Based on test results, the suitability of building reinforced concrete structures by the sea using high performance concrete has been analysed.

New Trends in Prestressed Concrete Bridges

2000 ◽  
Vol 1696 (1) ◽  
pp. 238-272
Author(s):  
Michel Virlogeux
Keyword(s):  
Prestressed Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Concrete Structures ◽  
Concrete Bridges ◽  
Prestressed Concrete Bridges ◽  
External Prestressing ◽  
Different Types ◽  
Composite Bridges ◽  
Cable Stayed Bridges

An overview of the recent evolution in the design and construction of prestressed concrete bridges worldwide is provided. Several major trends are evidenced. Certainly those trends that have had greater influences on the industry because of their wide applications are the development of external prestressing, which is now systematically used in some countries for medium-span bridges; the emergence of high-performance concrete, which extends the possibilities at the same time as it improves the durability of concrete structures; and the more frequent association of steel and concrete for composite bridges of different types and composite elements in bridges, allowing the construction of many innovative structures. For more specific applications, cable-stayed bridges, for which interesting developments have been seen in the last 10 years, and the more extensive use of heavy prefabrication in large projects, with elements up to several thousands of metric tons, are also described. Bridge architecture is also discussed in terms of the fact that good structural designs can produce elegant prestressed concrete bridges.

Local damage to Ultra High Performance Concrete structures caused by an impact of aircraft engine missiles

2010 ◽  
Vol 240 (10) ◽  
pp. 2633-2642 ◽  
Author(s):  
Werner Riedel ◽  
Markus Nöldgen ◽  
Elmar Straßburger ◽  
Klaus Thoma ◽  
Ekkehard Fehling
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Concrete Structures ◽  
Aircraft Engine ◽  
Local Damage ◽  
Ultra High Performance Concrete
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