169 publications from this institution
The article presents the results of a research study aimed at determining the optimum amount of 0/1 mm rubber powder additive for cement-sand mortars (CSM) used in asphalt-cement concretes (ACC), to meet the requirements for mineral-cement-emulsion mixtures (MCEM) due to the lack of regulations concerning these concretes. The study includes test results for indirect tensile strength (ITS) and stiffness modulus (IT-CY method) at 5°C, performed after 7 and 28 days of curing. The regression curves for ITS and IT-CY values in relation to rubber powder content after 7 days were well described by exponential functions, whereas the results after 28 days were best fitted by linear functions. It has been observed that compliance with ITS limit requirements excludes CSR mortars that meet IT-CY requirements, and vice versa. In order to clearly define the requirements for mortar mixtures, minimum and maximum ITS and IT-CY values were proposed so that the samples would meet both requirements simultaneously. Supplementary tests were also carried out to assess water resistance.
The bitumen ageing phenomenon is a crucial factor determining the fatigue cracking resistance of asphalt mixtures. Therefore, a reliable representation of changes in the fatigue life of bitumen binders with ageing is fundamental for flexible pavement performance prediction. This study aims to investigate and select the Linear Amplitude Sweep (LAS) test conditions in terms of rational fatigue life predictions of bitumen binders based on the results of time-sweep (TS) fatigue tests performed in Dynamic Shear Rheometer (DSR). Testing was performed on two neat bitumen binders (35/50, 50/70) and one polymer-modified bitumen (PmB 25/55–60) in the unaged, short-term aged (RTFOT), and long-term aged (PAV) states. The Zero-Slope Strain (ZSS) and Limit Strain (LS) levels were introduced to the data analysis to determine a common strain amplitude to be applied in fatigue life calculations based on LAS testing. Correlations between the fatigue life values obtained in TS (Nf,TS) and LAS (Nf,LAS) tests were analysed considering the influence of strain amplitude, temperature, and the degree of ageing. The statistical analysis confirmed that given the specific LAS test conditions and calculation parameters, the relationship between the Nf,LAS and Nf,TS values can be reliably described, taking into account the impact of ageing processes.