scholarly journals Alternative patch repair materials for rebar corrosion damage

2018 ◽  
Vol 199 ◽  
pp. 07017
Author(s):  
Primesh Jassa ◽  
Hans Beushausen ◽  
Ines Tchetgnia Ngassam
Keyword(s):  
Drying Shrinkage ◽  
Corrosion Damage ◽  
Point Of View ◽  
Patch Repair ◽  
Common Belief ◽  
Cement Concrete ◽  
Premature Failure ◽  
Repair Materials ◽  
Repair Procedure ◽  
Patch Repairs

One of the most common methods adopted in the rehabilitation of corrosion-damaged concrete is the patch repair procedure. However, in practice this method has shown to often be unreliable as a consequence of the widespread occurrence of shrinkage induced cracking and poor substrate-patch adhesion leading to debonding of the patch repair. From a practical point of view, such failed repair systems essentially restore the repaired concrete back to a deteriorated state. There is a common belief that repairing concrete with specialised proprietary repair materials would guarantee durability. However, the widespread premature failure of patch repairs conducted using such materials has proven the contrary. This paper presents an understanding of the materials and issues concerning the durability and serviceability of concrete patch repairs, with the aim of identifying alternative non-structural patch repair materials for the effective repair of corrosion-damaged concrete structures. The potential patch repair materials researched were polymer-cement concrete (copolymer of vinyl acetate and ethylene with 5% cement replacement) and 60%, 80% and 100% fly ash (FA) mortar. Patch repairs were conducted on substrate moulds to test application and observe cracking/debonding occurrence. Furthermore, compressive strength, durability index, accelerated drying shrinkage, restrained shrinkage, workability and scanning electron microscopy (SEM) tests were conducted to determine the properties of the materials developed with reference to performance requirements of durable concrete repairs. It was concluded that the 60% FA and polymer-cement concrete repair materials had the best overall performance. This research established that innovative alternative repair materials such as a 60% FA or polymer-cement concrete material, can be developed for non-structural patch repairs with improved long-term performance relative to conventional materials.

scholarly journals Characterization tools for shrinkage-compensating repair materials

2018 ◽  
Vol 199 ◽  
pp. 07002
Author(s):  
Benoît Bissonnette ◽  
Samy-Joseph Essalik ◽  
Charles Lamothe ◽  
Marc Jolin ◽  
Luc Courard ◽  
...  
Keyword(s):  
Effective Strain ◽  
Drying Shrinkage ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Test Procedures ◽  
Expansive Agent ◽  
Change Behavior ◽  
Repair Materials ◽  
Field Quality ◽  
Volume Change Behavior

Achievement of dimensional compatibility is one of the most important considerations in order to consistently achieve lasting repair works that do not undergo harmful cracking. Drying shrinkage of Portland cement concrete is generally inevitable and, although its magnitude can be reduced by optimizing or modifying the composition parameters, it remains significantly larger than its ultimate tensile strain. Conversely, the use of shrinkage-compensating concrete (ShCC) may allow to achieve a zero-dimensional balance with respect to drying shrinkage, through the use of a mineral expansive agent. The experimental work carried out in recent years at Laval University to evaluate the potential of shrinkage-compensating concretes (ShCC) for use as repair materials has in fact yielded quite promising results. Nevertheless, more research is required to turn ShCC systems into a truly dependable and versatile repair option. Among the issues still unresolved, suitable tests methods must be developed, not only to better characterize ShCC, but also to guide the specifications and perform field quality control. Efforts have thus been devoted to adapt or develop test procedures intended to better capture the particular volume change behavior of ShCC’s. The paper presents two test procedures intended to assess the shrinkage-compensating potential and the effective strain balance of ShCC in restrained conditions.

Macrocell Corrosion Formation in Concrete Patch Repairs - A Laboratory Study

2016 ◽  
Vol 711 ◽  
pp. 68-75
Author(s):  
Choorackal A. Eldho ◽  
Ominda Nanayakkara ◽  
Jun Xia ◽  
Stephen W. Jones
Keyword(s):  
Field Application ◽  
Patch Repair ◽  
Steel Bar ◽  
Repair Materials ◽  
Steel Bars ◽  
Patch Repairs ◽  
Macrocell Current ◽  
Macrocell Corrosion ◽  
Chloride Contaminated

Corrosion of reinforcement steel bars is a major threat to the durability of concrete structures exposed to chloride contaminated environment. Patch repairing is widely practiced in affected structures to avoid further damage due to corrosion. Macrocell formation within the patch repair is identified as one main reason for the failure of patch repairs. In the present study, a group of patch repairing materials is tested for their potential to form macrocell corrosion after repaired in a chloride contaminated environment. The influence of parameters such as level of chloride contamination, type of repair materials and the area of steel bar receiving repair are presented based on macrocell current measurements. The selected repair materials for study were cement based, GGBS based and polymer based in its composition. It is found that the severity of macrocell depends on the driving potential existing between the repair and substrate concrete. The quality of substrate concrete and repair material influences the macrocell formation. The surface area of the steel bar that receives the repair also affects the macrocell current. The study will be used for the evaluation of repair materials for macrocell corrosion formation potential before their field application in a chloride contaminated environment.

Design and performance of bonded patch repairs of composite structures

1997 ◽  
Vol 211 (4) ◽  
pp. 263-271 ◽  
Author(s):  
C Soutis ◽  
F Z Hu
Keyword(s):  
Composite Laminates ◽  
Composite Structures ◽  
Three Dimensional ◽  
Patch Repair ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Premature Failure ◽  
Patch Repairs ◽  
And Performance ◽  
Three Dimensional Finite Element

The compressive behaviour of bonded patch repaired composite laminates is examined. A non-linear stress analysis is performed on a double-lap joint in order to identify critical joint parameters and design an efficient external patch repair. It is found that oversized patches not only increase the structure's weight but also increase the stress concentrations in the repaired region which can cause premature failure. Reducing the patch thickness near the edges of the overlap and increasing the local adhesive thickness decreases the stress concentration in both shear and peel stresses. A three- dimensional finite element analysis is then performed to determine the stresses in the optimum repaired configuration and is used with a stress failure criterion to predict the ultimate failure load. Experimental measurements show that carefully designed bonded patch repairs can recover almost 80 per cent of the undamaged laminate strength.

How Potrero Utililized Flush Patches to Manage Localized Under Deposit Corrosion Damage in Waterwall Tubes

2014 ◽  
Author(s):  
Joseph M. Mazzeo
Keyword(s):  
San Francisco ◽  
Corrosion Damage ◽  
Patch Repair ◽  
High Flux ◽  
Circular Section ◽  
Time Period ◽  
Boiler Tubes ◽  
Patch Repairs ◽  
On Line

Flush Patch repair of boiler tubes, in which a circular section of tube is replaced to repair an isolated flaw, is typically considered to be a temporary repair. This paper reviews the successful flush patch repair program at the Potrero Power Plant in San Francisco. Over an 11-year period, a total of 294 flush patch repairs were utilized to repair isolated locations of under deposit corrosion in high flux areas of the water wall tubes. In this time period, three patches were replaced due to leaks found in hydro testing. Most of the repairs were performed in the early part of a decade when the unit was on line for an average of over 7,100 hours a year.

Interfacial Delamination in Plastic Encapsulated Integrated Circuits (Pics)

1996 ◽  
Vol 445 ◽  
Author(s):  
Nickolaos Strifas ◽  
Aris Christou
Keyword(s):  
Integrated Circuits ◽  
Failure Analysis ◽  
Stress Corrosion ◽  
Integrated Circuit ◽  
Point Of View ◽  
Acoustic Microscopy ◽  
Electrical Performance ◽  
Premature Failure ◽  
Interfacial Delamination ◽  
Die Surface

AbstractThe reliability of plastic packaged integrated circuits was assessed from the point of view of interfacial mechanical integrity. It is shown that the effect of structural weaknesses caused by poor bonding, voids, microcracks or delamination may not be evident in the electrical performance characteristics, but may cause premature failure. Acoustic microscopy (C-SAM) was selected for nondestructive failure analysis of the plastic integrated circuit (IC) packages. Integrated circuits in plastic dual in line packages were initially subjected to temperature (25 °C to 85 °C) and humidity cycling (50 to 85 %) where each cycle was of one hour duration and for over 100 cycles and then analyzed. Delamination at the interfaces between the different materials within the package, which is a major cause of moisture ingress and subsequent premature package failure, was measured. The principal areas of delamination were found along the leads extending from the chip to the edge of the molded body and along the die surface itself. Images of the 3-D internal structure were produced that were used to determine the mechanism for a package failure. The evidence of corrosion and stress corrosion cracks in the regions of delamination was identified.

Acid Attack Resistance of Magnesium Phosphate Cement

2016 ◽  
Vol 680 ◽  
pp. 392-397
Author(s):  
Zhu Ding ◽  
Meng Xi Dai ◽  
Can Lu ◽  
Ming Jie Zhang ◽  
Peng Cui
Keyword(s):  
Compressive Strength ◽  
Acid Solution ◽  
Portland Cement ◽  
Magnesium Phosphate ◽  
Acid Solutions ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Acid Attack ◽  
High Acid ◽  
Repair Materials

Magnesium phosphate cements (MPC) had been used as repair materials for deteriorated Portland cement concrete structures. In this paper a new MPC was prepared and the basic properties including workability and compressive strength were tested. The acid attack resistance of MPC was investigated by immersing the MPC mortars in solutions at pH 3, 5, and 7, for 14d, 28d and 60d respectively. The compressive strength of MPC mortars after acid attack was tested and the microstructure of MPC were examined. The results showed that the compressive strength of MPC decreased after immersion in acid solution for 14d and 28d, however the strength of MPC with suitable materials mixture can recovered again after 60d immersion. The results indicated MPC has high acid attack resistance in static acid solution. The behavior of MPC in flowing acid solutions is need to be studied further.

EXPERIMENTAL STUDY ON DURABILITY OF ROOM TEMPERATURE CURING UFC MORTAR

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Haruka Murakami ◽  
Hiromi Fujiwara ◽  
Masanori Maruoka ◽  
Takahumi Watanabe ◽  
Koji Satori
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
High Performance ◽  
Room Temperature ◽  
Bending Strength ◽  
High Performance Concrete ◽  
Drying Shrinkage ◽  
Concrete Repair ◽  
Repair Materials ◽  
Low Salt

In recent years, as structures become higher, larger, and more durable concrete whose compressive strength of the concrete is 150 N/mm 2 or more have been put to practical use. It is for this reason that it is necessary to develop strengthening materials with equal or better performance. Furthermore, the development of high-performance concrete repair materials is carried out because demand to seismic strengthening and repair increases. In this study, considering these circumstances, it was conducted an experimental study with the aim of developing a repair material using room temperature curing UFC (R-UFC). A binder composition preparation of the R-UFC has excellent fluidity under pressure. It was achieved that high-grade thixotropy, high compressive strength, and high bending strength. It can also be sprayed continuously because of its high thixtoropy. It was confirmed that the sprayed thickness was reached to 20mm by one work. Durability of this R-UFC was investigated and it was confirmed the high sulfate resistance, small drying shrinkage and low salt permeability.

Bond Strength Characteristic of Concrete Patch Repair Material Made from Unsaturated Polyester Resin (UPR)-Mortar

2015 ◽  
Vol 754-755 ◽  
pp. 442-446 ◽  
Author(s):  
Stefanus Adi Kristiawan ◽  
Ageng Bekti Prakoso
Keyword(s):  
Bond Strength ◽  
Strength Characteristic ◽  
Polyester Resin ◽  
Unsaturated Polyester ◽  
High Strength ◽  
Unsaturated Polyester Resin ◽  
Test Method ◽  
Patch Repair ◽  
Repair Materials ◽  
Bond Plane

Patch repair materials made from unsaturated polyester resin (UPR)-mortar have been investigated to determine their bond strength characteristic by slant shear test method. The relative mechanical properties of UPR-mortar and substrate concrete for composing the specimens are: lower modular and high strength ratio. The experimental results show that the combination of materials causes the observed bond strength are dictated by failure of substrate concrete. The actual bond strength could be higher as most of the specimens fail without separation of the UPR-mortar and substrate concrete at the bond plane.

EXPLORATORY STUDY ON THE MECHANICAL AND PHYSICAL PROPERTIES OF CONCRETE CONTAINING SULFUR

2015 ◽  
Vol 77 (32) ◽  
Author(s):  
David Yeoh ◽  
Koh Heng Boon ◽  
Norwati Jamaluddin
Keyword(s):  
Portland Cement ◽  
Physical Properties ◽  
Ordinary Portland Cement ◽  
Cement Content ◽  
Drying Shrinkage ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Complete Replacement ◽  
Mechanical And Physical Properties ◽  
Ordinary Portland Cement Concrete

This research is an exploratory experiment into sulfur concrete used not as a complete replacement of cement but as an additional material in percentage of the cement content. The aim of this research was to explore the possible appreciation of mechanical and physical properties of concrete containing sulfur with percentages of 1%, 5% and 10% of the cement content. The sulfur used here was not heat-activated, hence the binding effect in sulfur was absent. The experimental results revealed that concrete containing sulfur did not perform better in their strength properties, both compressive strength and flexural strength. The physical properties such as water penetration and water absorption for concrete containing sulfur also showed poor performance in comparison to ordinary Portland cement concrete. Such phenomena are very likely due to the sulfur not being activated by heat. Carbonation test did not show good results as a longer term of testing is required. Drying shrinkage property was found to be encouraging in that concrete containing 10% sulfur had quite significant reduction in drying shrinkage as opposed to ordinary Portland cement concrete. 

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