Diffusion of Chloride Ions in Ultra High Performance Concrete

2015 ◽  
Vol 1106 ◽  
pp. 21-24 ◽  
Author(s):  
Daniel Dobiáš ◽  
Radka Pernicová
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Concrete Surface ◽  
Chloride Ions ◽  
Transport Sector ◽  
Reinforcement Corrosion ◽  
Ultra High Performance Concrete ◽  
Depth Of Penetration ◽  
Chloride Ions Diffusion ◽  
Normal Strength

The article is dealing with study of chloride ions diffusion in ultra-high performance concrete UHPC, which might be potentially dangerous. Life of concrete structures, in particular in transport sector is jeopardized by risk of steel reinforcement corrosion with regards to exposure of the concrete surface to direct impact of de-icing salts. Measured data were examined in relation to the depth of penetration of chloride ions into the concrete structure. Experiment results proved that UHPC concretes are more resistant to penetration of chlorides than normal strength concretes.

Water Transport Properties and Depth of Chloride Penetration in Ultra High Performance Concrete

2016 ◽  
Vol 711 ◽  
pp. 137-142 ◽  
Author(s):  
Daniel Dobias ◽  
Radka Pernicova ◽  
Tomas Mandlik
Keyword(s):  
Water Transport ◽  
High Performance ◽  
Moisture Absorption ◽  
High Performance Concrete ◽  
Chloride Transport ◽  
Chloride Ions ◽  
Chloride Penetration ◽  
Chloride Diffusion ◽  
Ultra High Performance Concrete ◽  
Depth Of Penetration

Properties of water transport and depth of chloride penetration into the Ultra High Performance Concrete (hereafter as UHPC) with mild steel fibres are presented in this paper. The main aim of this experimental part of work is to obtain sufficiently accurate input data for the evaluation of long-term durability of architectural concrete which are connected with water transport and its accompanying effects such as biological degradation or chloride transport. The article also presents the one dimensional chloride diffusion into UHPC which can be potentially dangerous particularly for durability of reinforced concrete structures. For the simulation of aggressive environments the concrete samples were exposed to chloride solution for one year. Measured data were examined in relation to the depth of penetration of chloride ions into the UHPC structure. Comparative measurements with normal strength concrete (hereafter as NSC) are done as well. An about five-time lower value of moisture absorption of UHPC compared to the NSC was observed and further the curve of chloride penetration into the structure is significantly steeper for UHPC samples.

scholarly journals Determination of Axial Capacity for Enhanced Normal and Ultra - High Performance Concrete Columns

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sarmad Shafeeq Abdulqader ◽  
Asmaa Ali Ahmed ◽  
Nawfal Shihab Ahmed
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Peak Load ◽  
Concrete Cover ◽  
Ultra High Performance Concrete ◽  
Concrete Technology ◽  
Compression Load ◽  
Axial Capacity ◽  
Load Carrying ◽  
Normal Strength

Abstract Concrete Technology has been developing for more than a century. One of the most exceptional achievements in concrete technology is the evolving of Ultra-High Performance Concrete (UHPC) which has been a research focus in a wide applications diversity. In this paper, an experimental work has been carried out for investigating the transverse and longitudinal reinforcements’ variation influence on the axial capacity of UHPC columns. Eight columns (five UHPC columns and three Normal Strength Concrete (NSC) columns) have been poured and tested under a concentric axial compression load till a failure is reached. Then, the results are reported herein. The experimental results show that UHPC columns failed in a controlled manner and no concrete chips or a concrete cover spalling are observed. Also, the longitudinal reinforcements have not buckled away beyond the peak load because of the presence of the reinforcing steel fibers in UHPC. Correspondingly, the steel ties spacing proportionally affects the load carrying capacity of columns as presented hereinafter.

scholarly journals Shrinkage in Ultra-High Performance Concrete Overlays on Concrete Bridge Decks

2019 ◽  
Vol 271 ◽  
pp. 07008
Author(s):  
William Toledo ◽  
Leticia Davila ◽  
Ahmed Al-Basha ◽  
Craig Newtson ◽  
Brad Weldon
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Bridge Decks ◽  
Plastic State ◽  
Early Age ◽  
Concrete Bridge ◽  
Ultra High Performance Concrete ◽  
Concrete Overlays ◽  
Concrete Bridge Decks ◽  
Normal Strength

This paper investigates the shrinkage and thermal effects of an ultra-high performance concrete (UHPC) mixture proposed for use as an overlay material for concrete bridge decks. In this study, early-age and longer-term shrinkage tests were performed on the locally produced UHPC. Thermal and shrinkage effects in normal strength concrete slabs overlaid with UHPC were also observed. Early-age shrinkage testing showed that approximately 55% of the strain occurred in the plastic state and may not contribute to bond stresses since the elastic modulus of the UHPC should be small at such early ages. Thickness of the substrate and amount of reinforcing steel were important factors for shrinkage in the slabs. The thickest slab experienced greater shrinkage than thinner slabs. Comparing this slab to a thinner slab with the same reinforcement indicated that reinforcement ratio is more important than the area of steel.

scholarly journals An Auto-Calibrating Semi-Adiabatic Calorimetric Methodology for Strength Prediction and Quality Control of Ordinary and Ultra-High-Performance Concretes

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 96
Author(s):  
Marco Viviani ◽  
Luca Lanzoni ◽  
Vincenzo Savino ◽  
Angelo Marcello Tarantino
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Concrete Strength ◽  
Ultra High Performance Concrete ◽  
Structural Element ◽  
Construction Operations ◽  
Equivalent Time ◽  
Normal Strength ◽  
Good Agreement

A timely knowledge of concrete and ultra-high-performance concrete (UHPC) strength is possible through the so-called strength-equivalent time (Et) curves. A timely knowledge of concrete strength is useful, for instance, to precisely determine when the shores of a hardening structural element can be safely removed. At the present time, the preparation of the strength-Et curves requires time-consuming and labor-intensive testing prior to the beginning of construction operations. This paper proposes an innovative method to derive the strength-Et and total heat-Et curves for both normal strength and UHPC. Results confirmed that the proposed method is fast, inexpensive, self-calibrating, accurate and can detect any variation of the concrete mix proportions or components quality. In addition, the quality of predictions of strength–maturity curves can be constantly improved as the specimens’ population increases. Finally, results obtained with the proposed method were compared with those obtained using standard methods, showing a good agreement.

scholarly journals Review of The Cement-Based Composite Ultra-High-Performance Concrete (UHPC)

2019 ◽  
Vol 13 (1) ◽  
pp. 147-162 ◽  
Author(s):  
Edwin Paul Sidodikromo ◽  
Zhijun Chen ◽  
Muhammad Habib
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Cementitious Materials ◽  
Vital Role ◽  
Engineering Industry ◽  
Supplementary Cementitious Materials ◽  
Ultra High Performance Concrete ◽  
Strength Concrete ◽  
Normal Strength

Introduction: Ultra-High-Performance Concrete (UHPC) is an advanced type of concrete in the Civil Engineering industry. It is a cement-based composite which exhibits improved mechanical and durable properties showing a high compressive strength of not less than 150 MPa and high tensile strength of not less than 7 MPa. Objective: In this article, a review of the use of a different type of supplementary cementitious materials (SCMs) including fibers is made for obtaining the desired UHPC. Discussion and Conclusion: For this, it is vital to understand the principles of UHPC. UHPC has several advantages over normal strength concrete (NSC) and high strength concrete (HSC) with some commercially ready UHPC’s available, but the use of it is restricted due to the limited design codes. The influence of the curing type also plays a vital role in the overall performance of UHPC.

Enhancing Resiliency and Delivery of Bridge Elements using Ultra-High Performance Concrete as Formwork

2019 ◽  
Vol 2673 (5) ◽  
pp. 443-453 ◽  
Author(s):  
Atorod Azizinamini ◽  
Sheharyar Rehmat ◽  
Amir Sadeghnejad
Keyword(s):  
Test Specimen ◽  
High Performance ◽  
High Performance Concrete ◽  
Numerical Study ◽  
Concrete Specimen ◽  
Point Load ◽  
Ultra High Performance Concrete ◽  
Normal Concrete ◽  
Element Analysis ◽  
Normal Strength

A feasibility study of the use of ultra-high performance concrete (UHPC) shell as a formwork is presented. The core concept of the research, developed by the first author, is prefabrication of UHPC shell which acts as a stay-in-place formwork. In the proposed approach, after transporting the UHPC shell to site, the construction of structural elements is completed by placing reinforcing cage inside the UHPC shell and post-pouring with normal concrete. The superior properties of UHPC provide excellent means to enhance the service life of bridge elements, while eliminating the need for assembling or stripping of formwork. As a proof of concept, a combination of experimental and numerical studies was conducted, results of which are reported here. Before conducting experimental work, numerical study in the form of finite element analysis was carried out to investigate performance of shell during placement of the normal concrete. To provide a baseline comparison between UHPC shell formwork and conventional methods, two test specimens were constructed and tested under three-point load setup. The shell test specimen demonstrated flexural strength, 14% greater than an equivalent normal strength concrete specimen. The UHPC shell test specimen failure occurred by debonding of shell at the interface and development of a large crack in the shell. The shell test specimen exhibited improved levels of ductility before failure. The preliminary analysis demonstrated that the idea is feasible and useful for accelerated bridge construction applications.

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