Repair, Protection and Waterproofing of Concrete Structures

P. Perkins

• Publisher: CRC Press
• Year: 1997
• eBook ISBN: 9781135820411
• Topic: Architecture
• Subtopic: Architecture Methods & Materials

A wealth of recent research into the continued deterioration of reinforced concrete structures has led to a review of methods of investigation and repair techniques. This thoroughly revised and updated new edition brings together the fundamental aspects of this world wide problem and offers advice on how investigations, diagnosis and consequent remedial work should be carried out.

1
General observations

1.1 INTRODUCTION

While reinforced concrete structures which have been properly d esigned and constructed are resistant to deterioration, they should not be considered as maintenance free. Regular and careful inspection and the implementation of a sensible maintenance programme are essential. Reference can usefully be made to BS 8210: Guide to Building Maintenance and Management. ‘Maintenance’, ‘useful life’ and ‘design life’ are commented on in the Introduction to Chapter 3.

It is important that the lessons learned by the investigation of deteriorated structures should be taken into account when designing and constructing new structures. These ‘errors’ generally arise from inadequate and poorly drafted specifications and poor workmanship on site, but very seldom consist of structural inadequacy arising from errors in original design.

1.2 THE RESPONSIBILITIES OF THE ENGINEER OR OTHER PROFESSIONALS

An engineer who is instructed to investigate and report on a deteriorated concrete structure, and to prepare recommendations for necessary remedial work, should be clear in his own mind on the extent of his responsibilities to his client.

If he is responsible for the inspection of the remedial work to ensure that the requirements of the contract are complied with and the certification of payments-on-account to the contractor, then it is in the interests of his client that good relations with the contractor are maintained. These ‘good relations’ will be reflected in the standard of work, and its completion within the contract period.

The use of proprietary methods of repair can introduce problems in clearly defining the responsibilities of the engineer. For example, cathodic protection and, to a lesser extent, realkalization of concrete have come into use in the UK in the last few years. Both repair systems are highly specialized and unless the engineer happens to be well experienced in the use of such system(s), he would be well advised to make it clear in writing to his client that while he will accept responsibility for the integration of the specialist system(s) with other work in the contract, he will not be responsible for the efficacy of such systems, which must then be the contractural responsibility of the specialist firms concerned. The engineer’s fees should clearly reflect this ‘opt-out’.

The contract would then have to be drafted in such a way that the specialist contractor would be responsible for both the design and execution of the sections of the specialist work covered by the contract. This may sound rather academic to those who have not had experience with the law, but I refer to the High Court Case No. 1980-P-1364, known as Pirelli v. Oscar Faber. The Judgment by His Honour Judge Stabb, QC is dated 1 August 1980, and consists of some 32 pages, including the following statement which is relevant to the point being emphasized here:

consulting engineers…were not entitled to divest themselves of the duty of design entrusted to them unless expressly so agreed by their client.

1.3 BASIC PROCEDURE FOR INVESTIGATIONS—LITIGATION NOT INVOLVED

In cases where litigation is not contemplated, the basic procedure recommended to be adopted by the engineer following his appointment by the building owner is set out in Chapter 4 which deals with investigations and diagnosis of defects in reinforced concrete structures.

1.4 PROCEDURE WHEN LITIGATION IS CONTEMPLATED

The amount of litigation arising from the need to repair defects in reinforced concrete buildings has increased considerably in the last 20 years. This is reflected in the very high premiums charged by insurance companies for professional indemnity policies. The very real possibility of litigation arising from the need to carry out remedial work to existing structures must be taken into account by an engineer instructed to investigate a deteriorated structure. The engineer should realize that his report may well be used as the basis for legal action as the wording of the report will contain an opinion on the cause of the defects, which would indicate where responsibility probably lay.

Should the engineer’s client initiate legal action to recover the cost of the remedial work, the engineer would normally be required to give evidence in court or before an arbitrator. Some comments on the engineer as an expert witness are given in section 1.5.

My experience suggests that it is always prudent to enquire at the time of appointment whether litigation is likely to be contemplated. The answer will influence the conduct of the investigation and the wording of the report. When litigation is contemplated or is already under way, the suggested approach is outlined below.

The engineer should, with the agreement of his client, ensure the following.

1. That all interested parties have been informed of his appointment and the reasons for it;
2. He should seek to reach agreement with the parties concerned on the details of the sampling and testing he proposes to carry out, and the testing laboratory he proposes to use. This is common sense, but is frequently neglected. Clause 4.2 in BS 60890:1981: Assessment of Concrete Strength in Existing Structures, states:
   Before any programme is commenced, it is desirable that there is complete agreement between the interested Parties on the validity of the proposed testing procedure, criteria for acceptance, and the appointment of a person or laboratory to take responsibility for the testing.
   The idea that there may be ‘complete agreement’ is in my experience, over-optimistic and is seldom achieved.
   While the Standard quoted only refers to the investigation of concrete strength in existing buildings, the principles are valid for all investigations involving the likelihood of a serious dispute.
3. There should be complete openness on the reasons for the investigation; all reasonable steps should be taken to avoid confrontation as this invariably results in a hardening of attitudes and resistance to objective discussion.
   Should it become clear that the only way to resolve the dispute in such a way that the building owner obtains reasonable compensation for the rectification of the defects in the building, then ‘some form of legal action’ is likely. ‘Some form of legal action’ means arbitration under the Arbitration Acts or the issue of a Writ in the High Court.

It is wrong to believe that arbitration will cost any less than an action in the High Court. In addition to the normal legal costs of solicitors’ and counsel’s fees, the arbitrator charges for his services and there is also the cost of hiring suitable accommodation for the hearings.

Most construction contracts include a compulsory arbitration clause, but the court can overrule this requirement. Also, no third party proceedings are permitted in arbitration.

In court proceedings, difficult technical considerations can arise if a defence of ‘Limitation’ is put forward. This would involve the Limitation Act 1980 and the Latent Damage Act 1984, and the engineer may be asked for his opinion on the following two issues:

1. When did significant damage first occur?
2. What was the earliest date on which the Plaintiff had both the knowledge required to bring an action for damages in respect of the relevant damage, and a right to bring such an action?

My experience is that such questions give rise to very complex technical considerations to which there is seldom a clear-cut answer.

Due to the enormous cost of High Court actions, proposals have been made in recent years to find alternative methods of settling disputes. This is generally known as ‘Alternative Dispute Resolution’. Even when the claim is for hundreds of thousands of pounds, the cost of taking the dispute to court can be disproportionate to the possible financial benefit. While the majority of cases in the Official Referee’s courts and in arbitration settle before trial, few do so early enough to avoid substantial costs incurred in the preparations leading up to trial.

The essence of ADR is to create a framework in which the parties involved in a dispute can reach a solution for themselves. This usually requires the assistance of a neutral third party.

There are a number of ADR techniques, such as:

• conciliation;
• mediation;
• mini trial;
• expert fact finding and adjudication.

The success of ADR depends entirely on the willingness of all the parties to resolve their dispute in a mutually satisfactory way, and this requires considerable give and take. Some references on ADR are included in the ‘Further reading’ section at the end of this chapter.

1.5 THE ENGINEER AS AN EXPERT WITNESS

It is possible that an engineer engaged by a building owner to investigate defects in a concrete structure will, as a consequence of such an investigation, be requested to act as an expert witness in any subsequent legal proceedings arising out of the investigation. This is different to acting as a witness of fact and requires a different approach, and is a complex subject on which quite a lot has been written. The following are extracts from four High Court judgments which highlight important aspects of expert evidence.

The first deals with the admissibility of expert evidence; the second with the necessity for the evidence to be objective and unbiased; the third with the liability of the expert to his client; and the fourth with the rejection of the expert’s evidence on the grounds of partiality and bias.

1. The Times, Law Report, 17 July 1995. Lord Justice Stuart-Smith said that the admissibility of expert evidence was governed by Section 3 of the Civil Evidence Act 1972 and rules of court. An expert was only qualified to give evidence that was relevant if his knowledge and expertise was beyond that of a layman and such evidence had to relate to a factual issue in the case. The opinion of such witnesses could not consist of conclusions in respect of findings of fact which were strictly matters for the trial Judge to determine
   
   
   (House of Lords, Liddell v.Middleton).
   
   
   
2. The Times, Law Report, 5 March 1993; ‘The Ikarian Reefer’ (1993) FSR 563. Mr Justice Cress well said:
   
   Expert evidence presented to the Court should be, and should be seen to be, the independent product of the expert, uninfluenced as to form or content by the exigencies of litigation. An expert witness should provide independent assistance to the court by way of objective unbiassed opinion, in relation to matters within his expertise. He should not omit to consider material facts which could detract from his concluded opinion.
   
   
3. The Times, Law Report, 11 November 1991: Palmer and Another v. Durnford Ford (a firm) and Another. Mr. Simon Tuckey QC (Judgment, 31 October).
   
   
   An expert witness could not claim immunity from suit by his clients for his actions in the course of preparing evidence for a claim or a possible claim.
   
   Mr.Simon Tuckey QC so held in a judgment delivered in open court.
   
   
4. The following judgement illustrates very clearly what an expert witness should not do:
   
   Construction Industry Law Letter, S...

Table of contents

• COVER PAGE
• TITLE PAGE
• COPYRIGHT PAGE
• PREFACE TO THE FIRST EDITION
• PREFACE TO THE SECOND EDITION
• PREFACE TO THE THIRD EDITION
• 1. GENERAL OBSERVATIONS
• 2. BASIC CHARACTERISTICS OF CONCRETE AND MORTAR AND THEIR CONSTITUENT AND ASSOCIATED MATERIALS
• 3. FACTORS AFFECTING THE DURABILITY OF REINFORCED CONCRETE
• 4. INVESTIGATION AND DIAGNOSIS OF DEFECTS IN REINFORCED CONCRETE
• 5. NON-STRUCTURAL REPAIRS TO REINFORCED CONCRETE
• 6. STRUCTURAL REPAIRS TO REINFORCED CONCRETE
• 7. COATINGS (BARRIER SYSTEMS) FOR REINFORCED CONCRETE
• 8. REPAIRS TO CONCRETE FLOORS AND ROOFS
• 9. REPAIRS TO CONCRETE STRUCTURES