The quality of a concrete structure is vitally important. For one thing, the renovation or replacement of buildings and installations can be very costly. What is more, concrete structures have to meet exacting safety requirements. KEMA has many years’ experience specializing in the inspection, condition monitoring and certification of engineering structures. Building and installation managers and the suppliers of construction products all benefit from our support and advice. Our expertise covers systematic maintenance, economic viability, environmental impact, the durability of materials and the application of process residues in the production of construction materials.

Dedicated inspection techniques are used to determine the condition and residual life expectancy of concrete structures in existing buildings. Inspection-based insight into the condition and maintenance status of a structure has numerous benefits:

• certainty of objective assessment by independent experts
• better specification and planning of maintenance and inspection activities
• integrated approach based on multidisciplinary input

The precise nature and extent of each structural inspection conducted by KEMA is decided in consultation with the client. Information about the condition of the structure obtained from the inspection serves as the basis for developing an effective maintenance plan. Furthermore, inspection and analysis data are used by KEMA’s consultants to recommend various ways of tackling any problems encountered. Where appropriate, the identified options can also be costed.

Inspection is just one of the services offered by KEMA in the field of concrete and construction.

Operational changes at a plant – switching from ‘dry-stack’ to ‘wet-stack’ operation, for example – can mean that the structural materials used in a chimney are subjected to stresses unforeseen by the designers. The result can be accelerated degradation and a range of associated problems.

Chimney maintenance is often seen as an end-of-the-pipe activity. In fact, prompt maintenance has considerable operational benefits, as well as enhancing the safety of the working environment.

By making expert inspections and providing practical advice, KEMA can help plant owners and managers to prevent functional deterioration and the resulting truncation of a construction’s life expectancy that results from tardy maintenance. 

In line with the client’s instructions, KEMA inspects each chimney structure by reference to the CICIND checklist, DIN standards and/or specially developed procedures. A full inspection takes in the chimney’s exterior and lining materials, plus – where relevant – the cavity area.

On the basis of inspection information about the maintenance condition of the chimney, minor repairs can be made immediately or incorporated into a maintenance plan.

To support systematic maintenance programs, KEMA’s consultants can on request produce cost estimates, identify optimal inspection intervals, draw up repair specifications and supervise the implementation of preventive and corrective activities.

Most of the Netherlands’ high-voltage electricity pylons were erected in the 1950s. When they develop problems, simple repair work is usually all that’s called for. Standing beside the A12 highway that links the towns of Driebergen and Veenendaal, angle pylon number 64 proved to be an exception, however. The pylon’s owners – regional energy company REMU – had been worried about number 64 for some years. KEMA studies carried out in 1995 and 1996 revealed that earlier attempts at corrective maintenance had been unsuccessful or had addressed the symptoms of the problem rather than the root cause.

KEMA and REMU therefore developed a method for replacing concrete pylon footings in difficult locations. Then, having struggled with the recalcitrant number 64 for years, REMU called in KEMA to help organize a pilot project to try out the new method. The bottom line was that the work had to be done without interrupting power supplies or interfering with the movement of traffic on the A12.

The engineers had little room to play with. The pylon stood at an angle, on the side on an embankment. As a result, it wasn’t possible to use a guy cable for temporary anchorage. Working from KEMA drawings, REMU accordingly constructed a reusable support frame, designed for easy attachment, detachment and relocation to other sites. This frame was used to secure the pylon while its footings were broken up and replaced. Designing and constructing the support frame was quite an undertaking, involving the development from scratch of a special safety and accommodation protocol. The entire process eventually took four months, spanning design, demolition, concrete mix selection, test block preparation, adhesion surface checking, concrete pouring, removal of the shuttering and hardening of the concrete. Within this period, the realization phase took about two weeks.

KEMA advised REMU on selection of the optimum concrete mix. Dating from 1951, the original concrete simply hadn’t been up to the job. Not only did the workmanship leave much to be desired, but also several different types of cement had been used, not to mention a reactive aggregate (ASR). Following testing of alternatives, two concrete repair mixes were chosen, which underwent performance testing in KEMA’s laboratory.

An impervious floor has to be reliable and an effective barrier to fluids. Owners and managers of buildings and installations with impervious floors need to be sure that they meet their legal obligations. That implies independent inspections by experienced, knowledgeable engineers. KEMA offers assessment and inspection services for soil-protecting structures at industrial sites, factories, facilities for motor vehicles, residue stores, sludge depositories and agricultural establishments. As well as inspecting such structures, KEMA undertakes damage assessments where appropriate and makes technical evaluations. As an independent consultancy and research body, KEMA has decades of experience inspecting and advising on the corrective maintenance of impervious installations.

Compliance with environmental legislation is subject to government supervision. Businesses responsible for impervious installations are required to meet the requirements laid down in the Soil Protection Facilities Plan (PBV), for example. Assessment guidelines and CUR/PBV Recommendation 44 (Assessment of Impervious Facilities) set out what must be done to satisfy these requirements. Drawing on its extensive experience in this field, and acting as one of the sponsors of the VABOR Impervious Facilities (VDV), KEMA is active in the inspection and assessment of facilities covered by the various regulations.

During the inspection of concrete floors, data is recorded on standardized forms. Using an inspection method developed by KEMA, expert engineers carefully assess the durability and (residual) life expectancy of a structure. On request, an inspection report is also prepared for the client, covering repair methods, finishing treatments and structural integrity and stability. Such reports are particularly valuable in the context of proposed property purchases, for example.

Our inspectors meet the expertise requirements of PBV report WF-9801. Where an impervious floor is found not to satisfy the applicable criteria, further tests can be conducted in KEMA’s STERLAB-accredited laboratory on the basis of, for example, CUR/PBV Recommendation 63.

KEMA can prepare a plan covering quality control during the realization phase of a construction project. This plan details what checks are to be performed and when. Once the work starts, site inspections are conducted to ensure that the construction activities are proceeding in accordance with the project’s quality plan. In addition, the contractor’s quality checks are verified on a random basis. Finally, the finished structure is checked against a specification checklist to make sure it meets the client’s requirements.

If problems are detected in the course of the site inspections or verification checks, these are noted on a special nonconformity form and copies are given to both the client and the contractor. The contractor is then asked to indicate the proposed corrective action on the form. Once the proposals are received, KEMA advises the client on the likely effectiveness of the measures and on any financial implications (arising out of work volume discrepancies, for example).

For more information, please contact us.