An innovative system for monitoring the mechanical properties of concrete

Powszechnie stosowane metody normowe określania cech mechanicznych betonu nie uwzględniają rzeczywistych warunków dojrzewania betonu. Cechy betonu w konstrukcji różnią się od wartości uzyskiwanych laboratoryjnie. W procesie wiązania betonu wydziela się ciepło, które wpływa na tempo zmian cech mechanicznych betonu w konstrukcji. Drugim czynnikiem jest wpływ zastosowania kruszywa na uzyskiwane wartości modułów sprężystości betonu. W artykule przedstawiono wyniki badań cech mechanicznych betonu wiaduktu WG-4 na obwodnicy Raciborza. Na potrzeby podejmowania decyzji o sprężaniu oraz aktualizacji podniesienia wykonawczego określono laboratoryjnie właściwości betonu pielęgnowanego w warunkach znormalizowanych i odwzorowanych. Zastosowano innowacyjny system monitoringu cech mechanicznych betonu, który uwzględniał rzeczywiste warunki dojrzewania betonu w konstrukcji. Uzyskane wyniki z badań pozwoliły zminimalizować ryzyka związane z podejmowaniem decyzji na budowie.Commonly used standard methods for determining the mechanical properties of concrete do not take into account the actual conditions of concrete maturation. The characteristics of concrete in the structure differ from the values obtained in the laboratory. In the process of setting concrete, heat is released, which affects the rate of changes in the mechanical properties of concrete in the structure. The second factor is the influence of the use of aggregate on the obtained values of concrete elasticity modulus. The article presents the results of research on the mechanical properties of the concrete of the WG-4 viaduct on the Racibórz beltway. For the purposes of making a decision on prestressing and updating the construction technology, laboratory characteristics of cured concrete in standardized and mapped conditions were determined. An innovative system for monitoring the mechanical properties of concrete was used, which took into account the actual conditions of concrete maturation in the structure. The obtained results from the research allowed to minimize the risks related to making decisions on the construction site

Influence of Actual Curing Conditions on Mechanical Properties of Concrete in Bridge Superstructures

This article presents the research on the mechanical characteristics of concrete in the construction of three concrete bridges. A system of recording the internal temperature of concrete and automatic control of laboratory ovens was used for specimen curing. This allowed the specimens to be cured under conditions similar to those occurring in the structure. Before the construction, reference blocks were used to define similar curing conditions. Maximum setting temperatures ranged from 47.6 °C to 62.0 °C and had a favorable effect on the properties of the concrete at an early age. For concretes with the use of CEM I cement, after 3 days of curing, the strength obtained was up to 8.2 MPa (23%) higher than that for specimens cured under standard conditions. The modulus of elasticity was higher up to 4.9 GPa (21%). For concrete with the use of CEM III cement, these differences were 26.9 MPa (174%) and 10.3 GPa (64%), respectively. After 7 days of curing, the results were close to each other and after 14, 28, and 56 days, higher values were obtained for specimens cured under standard conditions. The value of the modulus of elasticity of concrete was determined using the direct method according to Eurocode and the standard A method. A test load of the bridge was carried out to verify the modulus values obtained from laboratory tests. The highest consistency (99%) between the theoretical deflections and those measured in the test load was achieved when using the stabilized modulus values obtained on specimens cured under structure conditions in the FEM model. The research confirms the necessity of determining the mechanical characteristics of concrete with taking into account the curing conditions of concrete in the structure. A procedure for determining the mechanical properties of concrete for the correct construction of a bridge is proposed. These results can also be used in the development of a digital twin for bridge management