Influence of low temperature on dynamic behavior of concrete.

Aimed at finding out the influence degree of temperature, strain rate, water to cement ratio (w/c ratio) and maximum aggregate size on dynamic behavior of cement concrete, an orthogonal test on dynamic compressive strength of cement concrete applying a self-designed low temperature split Hopkinson pressure bar (SHPB) apparatus has been conducted on 8 groups of cylindrical cement concrete specimens (74 mm diameter and 34 mm thickness). The dynamic compressive strength of concrete specimens with different w/c ratios (0.5, 0.6) and maximum aggregate sizes (12 mm, 22 mm) have been tested at different temperatures (28 °C, 0 °C, −15 °C, −30 °C) and strain rates (33.5 s −1 , 46.7 s −1 ). The influence sequence of factors is: temperature > strain rate > w/c ratio > maximum aggregate size. According to the results of orthogonal test, a further experimental study concerning the influence of temperature (28 °C, 0 °C, −15 °C, −30 °C, −45 °C, −60 °C, −75 °C) and strain rate (34.33 s −1 , 44.25 s −1 , 63.18 s −1 ) on dynamic compressive strength of concrete has been conducted on 21 groups of cylindrical specimens. Also a mechanical calculation model has been built for force analysis. The results demonstrate that: When −75 °C < T < 28 °C, increase ratio of specific energy absorption (SEA) rises as temperature decreases; the sensitivity of dynamic compressive strength to strain rate increases as temperature decreases; the relationship between dynamic compressive strength and temperature conforms to a growth curve, and finally the increase ratio of dynamic compressive strength stabilizes at a maximum level of 65% at T = −75 °C. [ABSTRACT FROM AUTHOR]