The Evolving Identities of HSI and Differentiated Funding

To achieve Higher Education Act Title V funding goals, policymakers must reconsider approaches, respond to Hispanic-Serving Institution (HSI) diversity, and prioritize servingness. This study investigated HSI heterogeneity across traditional performance metrics and student-engagement indicators using data sources previously only examined independently. A multi-step TwoStep cluster analysis revealed six clusters of HSIs. The two most important predictors of cluster membership were years with an HSI designation (transitioning and established) and institution type (associate, bachelor, and special focus). Key quantitative metrics may be useful for policy actors seeking an equity-minded Title V award strategy that considers HSI heterogeneity and prioritizes HEA Title V policy aims

Towards arresting reinforced concrete corrosion-a review

© 2018 The Authors, published by EDP Sciences. This work reviews developments in the understanding of chloride induced corrosion of steel in concrete from both a kinetic and thermodynamic perspective. Corrosion damage is at least in part attributed to the production of acid at sites of corrosion initiation. Solid phase inhibitors provide a reservoir of hydroxyl ions to inhibit damage. Pit re-alkalisation is identified as an important protective effect in electrochemical treatments used to arrest corrosion. A process like pit re-alkalisation is achieved more easily by impressing current from sacrificial anodes using a power supply which may then be followed by low maintenance galvanic protection to prevent local acidification. Methods for monitoring the steel corrosion rate in electrochemically treated reinforced concrete have been developed and used to assess corrosion risk. Some of these concepts have been adopted in the recent international standard on cathodic protection, ISO 12696:2016, some of the amendments of which are considered in the work presented here

Incipient anodes in reinforced concrete repairs: A cause or a consequence?

Patch repairs are a common repair technique for corrosion-damaged reinforced concrete structures. However, this repair method is sometimes associated with limited durability and in many cases further corrosion damage has been noted around the repaired patches, a phenomenon known as the “incipient anode” effect. The diagnosis of this problem is widely reported to be macrocell activity. It is deemed that the cause of incipient anodes is the loss of the natural cathodic protection provided by the corroding steel to the steel in the parent concrete adjacent to the patch repair. This diagnosis is based on very limited data. Indeed potential measurements on field structures repaired with proprietary materials have provided data that suggest that macrocell activity is not a cause of incipient anode formation but it is a consequence. Alternative mechanisms that may cause incipient anode activity include repair/parent material interface effects, residual chloride contamination within the parent concrete, and/or vibration damage to the steel/parent concrete interface during repair area preparation. The aim of the work presented here was to assess the impact of macrocell activity on the formation of incipient anodes around the perimeter of repairs in patch-repaired reinforced concrete structures. This was examined based on a major multi-storey car park and a bridge structure both located in the UK. The analysis challenges the view that macrocell activity is a cause of incipient anode formation. Indeed this work shows that the data supporting the existing diagnosis is not convincing and suggests that macrocell activity is primarily a consequence of incipient anode formation and the cause probably, results from other factors

Corrosion management of reinforced concrete structures

Corrosion management of reinforced concrete structure

Diagnosing the cause of incipient anodes in repaired reinforced concrete structures

The incipient anode (or halo) effect often occurs on repaired reinforced concrete structures. The diagnosis of this problem is widely reported to be macrocell activity. This diagnosis is based on very limited data. Indeed potential measurements on field structures repaired with proprietary materials have provided data that suggest that macrocell activity is not a cause of incipient anode formation. Alternative mechanisms that may cause incipient anode activity include repair/parent material interface effects, residual chloride contamination within the parent concrete, and/or vibration damage to the steel/parent concrete interface during repair area preparation

Assessing the long term benefits of Impressed Current Cathodic Protection

This experimental field study interrupted the protection current offered by Impressed Current Cathodic Protection (ICCP) to ten in-service reinforced concrete structures. The study aimed to identify the longterm effects of ICCP after it was recognised that some of the systems are now reaching the end of their design life and require a significant level of maintenance. It was found that after five or more years of ICCP, the steel remained passive for at least 24 months after interrupting the protection current despite chloride contamination that would represent a corrosion risk

Investigating the effect of Interrupted Cathodic Protection on reinforced concrete structures

Impressed Current Cathodic Protection (ICCP) has been one of the major components of the repair and maintenance strategy on many motorway structures in the U.K. It has helped to prolong the life of more than 700 structures, in a significantly sustainable manner, by reducing the need to remove chloride contaminated (but otherwise sound) concrete. This study was initiated after identifying that some of the ICCP systems were reaching the end of their design life and required a significant level of maintenance (including anode replacement) to operate in accordance with the latest Codes of Practice. In addition, there were a number of structures where the application of ICCP has been interrupted due to severe anode deterioration or vandalism. The objective of this work was to collate evidence from structures to support preliminary laboratory results that the application of ICCP to a reinforced concrete structure over a period of time can transform the environment around the reinforcement, even after the protective current has been interrupted. This experimental field study interrupted the current to ten structures which had been protected with ICCP between 5 and 16 years and corrosion rates were monitored to determine when reinforcement corrosion will initiate again. It was found that after five or more years of ICCP, the steel remained passive for at least 30 months after interrupting the protective current, despite the presence of chloride contamination representing a substantial corrosion risk. In some cases, severe anode deterioration meant that the current was interrupted at an unknown point in time prior to the initiation of the scheme. Four main conclusions are drawn regarding this approach: it can give an indication of when repairs to ICCP systems are likely to be critical; provide new evidence for the design lives attributed to systems using lower cost anodes; reduce the requirement to replace systems at the end of their functional lives; and potentially extend the interval between planned maintenance of existing systems with corresponding reduction in monitoring frequency, cost and disruption

On-site transient analysis for the corrosion assessment of reinforced concrete

A range of methods exist to assess the condition of steel reinforcement in concrete. The analysis of the transient response to a small perturbation has been employed successfully in laboratories to assess corrosion. This work examines a simplified method for the application of transientanalysis to in situ reinforcedconcrete structures. The complex analysis has been simplified and undertaken with the use of common spreadsheet packages. The results illustrate that transient response analysis is a viable technique for use on site and appears to provide a more accurate representation of steel corrosion current densities at very low values than polarisation resistance

Long-term performance of surface impregnation of reinforced concrete structures with silane

Silanes can act as hydrophobic pore liners for reinforced concrete (RC) structures. They can significantly reduce the depth of chloride penetration, a major cause of steel reinforcement corrosion. However, there is little published information on their long-term performance. Thirty-two concrete cores were extracted from eight full-scale RC bridge supporting cross-beams that were treated with silane 20 years ago. Their water absorption by capillarity was measured and compared with sixteen control cores extracted from four non-silane treated RC cross-beams constructed at the same time. Results show that silanes may provide a residual protective effect against water even after 20 years of service

Protecting the UK’s critical infrastructure – impressed current cathodic protection on the midland links motorways network

The Midland Links Motorway Viaducts (MLMV) are located around the UK’s second largest city - Birmingham - and comprise 21 kilometres of elevated bridge motorway structures. Impressed Current Cathodic Protection (ICCP) has been used to prolong the life of more than 700 concrete structures in the MLMV, in a significantly sustainable manner, by reducing the need to remove chloride contaminated (but otherwise structurally sound) concrete. The present study was initiated after identifying that some of the ICCP systems were reaching the end of their design life, whilst others had deteriorated or been vandalised, therefore requiring a significant level of maintenance, and cost. The objective of this work was to collate evidence from field structures to support preliminary laboratory results that the application of ICCP to a reinforced concrete structure over a period of time can transform the protective environment around the reinforcement. The results can indicate when repairs to ICCP systems are likely to be critical; provide new evidence for determining the design life; reduce the requirement to replace systems at the end of their functional life; and the interval between planned maintenance of existing systems may be extended with corresponding reduction in monitoring frequency and costs. The work is unique and novel as it is the only ICCP field trial across Europe on full-scale motorway structures. It also contributes to sustainability as the results form a basis for an improved maintenance strategy