Rutting analysis of 100 mm diameter polypropylene modified asphalt specimens using gyratory and Marshall compactors

Compaction technique used in Marshall design does not model the process of actual rolling procedures on site exactly. Carrying out laboratory compaction of dense bituminous mixtures with Superpave gyratory compactors is a more realistic way of simulating actual compaction. In this study, mechanical differences of reference and polypropylene modified asphalt mixtures were compared using Superpave gyratory and Marshall compaction methods by carrying out repeated creep tests utilising universal testing machine. In addition, there is no standard Superpave design procedure for 100 mm diameter samples till date. The other purpose of this study is to propose new standards for the compaction and testing procedures of these 100 mm specimens. Indeed, extensive studies have shown that the design gyration number should be 40 for reference and 33 for polypropylene modified specimens under medium traffic conditions for the similar and specific type of aggregate sources, bitumen, aggregate gradation, mix proportioning, modification technique and laboratory conditions. Moreover, it was shown that, the asphalt samples produced by Superpave gyratory compactor were much resistant to destructive rutting effects than the asphalt specimens prepared by Marshall design

Rumination time around calving: An early signal to detect cows at greater risk of disease

The main objective of this experiment was to evaluate the use of rumination time (RT) during the peripartum period as a tool for early disease detection. The study was carried out in an experimental free-stall barn, and involved 23 Italian Friesian cows (9 primiparous and 14 multiparous). The RT was continuously recorded with an automatic system (Hr-Tag), and data summarized in 2-h intervals. Blood samples were collected from 30 days before calving to 42 DIM to assess biochemical indicators related to energy, protein, and mineral metabolism, as well as markers of inflammation and some enzyme activities. The Liver Functionality Index (LFI), which includes some negative acute-phase proteins or related parameters (albumin, cholesterol and bilirubin), was used to evaluate the severity of inflammatory conditions occurring around calving. The cows were retrospectively categorized according to the level of RT observed between 3 and 6 DIM into the lowest (L) and highest (H) RT. The average RT before calving (-20 to -2 d) was 479 min/d (range 264 to 599), reached the minimum value at calving (30% of RT before calving), and after 15 DIM was nearly stable (on average 452 min/d). Milk yield in early lactation (on average 26.8 kg/d) was positively correlated with RT (r = 0.33). After calving, the L cows compared with H cows had higher values of haptoglobin (0.61 and 0.34 g/L at 10 DIM in L and H) for longer time, had a greater increase of total bilirubin (9.5 and 5.7 \u3bcmol/L at 5 DIM in L and H), had a greater reduction of albumin (31.2 and 33.5 g/L at 10 DIM in L and H) and paraoxonase (54 and 76 U/mL at 10 DIM in L and H), and had a slower increase of total cholesterol (2.7 and 3.2 mmol/L at 20 DIM in L and H). Furthermore, a lower average value of LFI was observed in L (-6.97) compared with H (-1.91). These results suggest that severe inflammation around parturition is associated with a slower increase of RT after calving. Furthermore, above 90% of the cows in the L group have shown clinical diseases in early lactation in comparison to 42% of the H cows. Overall, our results demonstrate the utility of monitoring RT around calving and in particular the first wk of lactation as a way to identify in a timely-fashion those cows at a greater risk to develop a disease in early lactation