FE 08.0270/2022/ARB - Process-reliable production of low-noise road surfaces in exposed concrete construction

The production of concrete pavements with exposed concrete surfaces has been the standard construction method in Germany since 2006. Various projects and publications have looked at the causes of the ranges of noise reduction actually achieved. As a result, among other things, influencing variables on the acoustic performance of the exposed concrete surface were described and the fulfilment of the individual parameter texture depth according to ZTV Beton StB 07 was assessed as insufficient. Since then, there has been no further and new development of relevant parameters and approaches for the reproducible achievement of these target values in the manufacturing process, based on the previous investigations.

The primary objective of this project is therefore the formulation of practical measures for the process-safe achievement of the full noise reduction potential of exposed concrete surfaces. In the context of the expected reduced availability of CEM I cements in the future, the laboratory tests are to be extended to clinker-reduced cements (CEM II/B M).

In the project, the specific noise-reducing surface properties are to be quantified on the basis of insitu measurements. For this purpose, investigations with different measuring systems (2D, 3D, flow resistance, etc.) on acoustically favourable exposed concrete sections are planned. Based on this, existing characteristic values will then be validated and, if necessary, modified. The identification of the relevant influencing and control variables from the formulation and manufacturing process on the optimally noise-reducing exposed concrete texture should serve as a basis for the development of practical construction measures to increase process reliability.

The production of an optimal and quantifiable noise-reducing exposed concrete surface by means of additional texture characteristics is to be investigated first with a standard CEM I cement and, based on this, with clinker-reduced composite cements on a laboratory scale. Subsequently, a large-scale laboratory test is to be carried out with a suitable clinker-reduced cement.

With the publication of ARS 04/2022, a great simplification for the use of alternative, clinker-reduced cements compared to .dem long-standing standard CEM I 42.5 N has already been achieved. However, only a few of these cements have extensive practical construction experience, including cements containing blast furnace sand, such as CEM II/A S and CEM III/A (with max. blast furnace slag content: 50%). The clinker-reduced cements with several main components, such as CEM II/B-M (V-LL), are currently still excluded from use in concrete road construction. Due to the expected release of further cements for concrete road construction in the coming years, investigations must therefore be carried out on the process-reliable production of concrete pavements with exposed concrete surfaces with clinker-reduced cements that go beyond ARS 04/2022.

The benefit lies in the fact that, if the research project is successfully implemented, the process reliability in the production of the low-noise exposed concrete can be increased. By identifying the relevant influencing and control variables from the formulation and manufacturing process on the optimally noise-reducing exposed concrete texture, practical construction measures can be developed to increase process reliability. In view of the fact that the availability of CEM I cements will continue to decrease in the future and that less blast furnace slag will be available due to the upheavals in the steel industry, the release of further clinker-reduced cements for concrete road construction is to be expected. As a result, resources can be conserved and environmental compatibility in concrete road construction can be improved.