Aspekt Laboratorium Sp. z o.o. and KPRM Infrastruktura Sp. z o.o. are two companies working in synergy in the Polish construction
market for many years. The effect of their collaboration is the mutual transfer of experiences and good practices in research, development and building. The positive image of both companies and continuing reinforcement of their position in the construction market are the consequences of their professional attitude, high quality of offered services, timely performance, as well as compliance with customer requirements, competitive prices and responding to customer expectations. These objectives were accomplished thanks to continuing development and the implemented quality management systems. However, a particularly noteworthy factor was the contribution of high-skilled managerial staff working as one team in a single-level structure consisting of:
marketing and sales, design, purchasing, production, quality control, warehouse, project and financial and administration departments.
Aspekt Laboratorium is a unit with the status of an R&D centre. It specializes in testing of civil engineering structures, and in particular bridge structures. It has operated since 1999 conducting tests for more than two thousand bridge, road and railway structures characterized by various static properties and different spans. It performs bridge load testing for the needs of general contractors of works on national roads, expressways, motorways and railway routes, as well as directly for the branches of the General Directorate for National Roads and Motorways based in Kraków, Warsaw, Bydgoszcz, Lublin and for the railway carrier PKP PLK (bridge testing for speeds up to 200 km/h; 250 km/h on the Central Main Line). The laboratory specializes in dynamic testing. It performs acceptance testing of bridge structures according to the requirements of ISO:17025. Aspekt also provides road and bridge design services and prepares expert opinions, issues technical opinions and performs periodic inspections of bridges. The staff comprises researchers and engineers with road and bridge design and construction licenses. The company collaborates with numerous scientific centres and specialists in the field of technical infrastructure. The laboratory has its own specialist certified testing and measuring equipment. It is accredited by the Polish Accreditation Centre and holds certificate no. AB 1359, which complies with the strict requirements of the General Directorate for National Roads and Motorways and of the railway carrier PKP
PLK concerning bridge load testing. The company develops dynamically and it enters new areas related to improvement of safety and strength of bridges. One of such areas is SHM – Structural Health Monitoring. It is multi-layer monitoring which covers, among other things, registration of environmental changes such as: temperature, humidity, wind, as well as changes in the bridge structure allowing detection of damages at very early stages. Aspekt Laboratorium applied such monitoring on A4 motorway. It also implements systems based on radar and fibre optic technologies.
KPRM Infrastruktura Sp. z o.o. is a leading Polish producer of elements of bridges and bridge structures. It specializes in manufacturing structural bearings and bridge expansion joints. The key product of KPRM is composite expansion joints characterized by innovative structure. The company also designs the abovementioned elements as well as transports them to and installs them on the construction site.
KPRM pot bearing is a spatial joint that enables rotation around any horizontal axis by deforming the elastomeric cushion inside
a cylindrical steel casing (so-called pot), closed with a plate performing the role of a piston. The elastomeric cushion maintains a fixed volume under the impact of triaxial Compression. As a result, the bearing does not settle under the load. The bearing pot is made by means of rolling from a single block or by welding a ring to the bottom of the pot. The elastomer cushion placed inside the pot is additionally protected against compression by a vulcanized pressure gasket. In sliding pot bearings, the upper surface of the piston is coated with polytetrafluoroethylene (PTFE) on which the top bearing plate equipped with a polished austenitic sliding sheet at the bottom moves. KRPM pot bearings are protected against corrosion by means of sandblasting and spray metallization. In addition, sealing paint sets are used.
KPRM spherical bearing is a spatial joint consisting of three parts: the top plate with austenitic sheet, the planoconvex lens with PTFE plate on a flat surface, and the chromium-plated polished spherical surface of plano-concave lens with an embedded PTFE layer. All the components are made of high quality materials with relevant certifications for special applications in bridge construction. As compared to other types of bearings (that is, pot and elastomeric bearings), they are distinguished by being made from a durable core material – steel. They also offer the possibility of achieving a large degree of angular rotation as well as the possibility of transferring high vertical loads. The bridge construction is not loaded with the fixing moment after its rotation. The bearings with unidirectional sliding construction permanently transfer the horizontal force from the top plate directly onto the bottom plate without involving the lens.
KPRM elastomeric bearings are built of elastomeric layers additionally reinforced with steel sheets. The durable combination of metal sheet and rubber ensures consistent rigidity and high capacity of the bearing. They are mainly used in bridge structures, providing horizontal displacements in all directions and limiting rotation while shifting the support reactions from the load-bearing structure onto bridge supports. Uncomplicated construction makes elastomeric bearings durable, reliable and easy to assemble. They provide linear and angular displacement of the structure by deforming the elastomeric block. Depending on the degree of linear displacement and rotation the bearings are supposed to ensure, the vertical load transfer capacity respectively increases or decreases.
KPRM modular expansion joints are a means of tight covering of the expansion gap in the bridge structure and transferring the load of motor and passenger traffic through expansion gaps changing their width when the bridge is in use. Changes in the width of expansion gaps are caused, among other factors, by changes in ambient temperature and by the load of vehicles passing through
the bridge. Expansion joints make it possible to compensate the displacement of the edges of bridge expansion gaps. KPRM expansion joints are designed as modular expansion joints. A characteristic feature of modular expansion joints is that total displacement of the edge of the expansion gap is split between deformations of a number of modules in the expansion joint. Modular expansion gaps for bridges are assemblies with internally variable geometry, which are freely deflected under the influence of displacement of the edges of a span of the bridge. At the same time they maintain the required rigidity under the load of motor vehicles passing through the bridge. KPRM modular expansion joints consist of two steel sections with one elastomeric sealing
section being wedged in the steel cavities between them in order to form a module enabling the transfer of nominal displacement
of 80 mm (± 40 mm). The wheels of motor vehicles run on the steel sections, and the displacement of the edge of the bridge expansion gap is compensated through the altering width of the gaps between the steel sections.
KPRM composite expansion joint is a device developed by a team of designers from KPRM in 2015 as an innovative solution. The prototype passed the required approval tests carried out by the Road and Bridge Research Institute. A characteristic feature of the composite expansion joint is that all its components that are directly exposed to weather/environmental conditions are made from corrosion-resistant materials. After a serial production of the device was launched, such expansion joints have been installed on many bridges on expressways as well as on railway routes. The composite expansion joint is composed of three materials having
- structural non-alloy steel – this is the core of the section transferring the loads
- stainless alloy steel – it forms an effective barrier to corrosion
- bonding layer – it is also used for separating two dissimilar metals.
The products of KPRM can be found all over the world. The company successfully entered the exotic market of the United Arab Emirates where it carries out inspections and replacements of old bridge expansion joints.
Monitoring of the condition and efficiency of bridge equipment – KPRM Infrastruktura Sp. z o.o. and its partner company Aspekt Laboratorium Sp. z o.o. developed systems for monitoring the condition and efficiency of bridge bearings and expansion joints. Measurements are carried out in order to ensure an adequate level of safety and strength of the specific elements. The measurements cover characteristics such as: stress, displacement, deformation, vibrations, and noise level. Fixed detectors immediately detect any alerts and emergencies. The system continuously filters the signals it receives; every deviation from the standard, depending on the degree of risk, activates a set of pre-programmed measures. It has a direct influence on the safety and comfort of every road traffic participant.
The companies Aspekt Laboratorium and KPRM Infrastruktura are undoubtedly among the leaders of the Polish infrastructural building sector. Through their engineering aptitude and scientific reliability they cocreate the history of Polish road engineering, making an important contribution to the development of the sector.