EFFECT OF CONSTANT AND VARIABLE TEMPERATURES IMPACT OF DIFFERENT VALUE ON CALCULATED RATES OF DYNAMIC MODULUS FOR ASPHALT CONCRETES AND POLYMER ASPHALT CONCRETES
The paper shows the results for experimental determination of dynamic modulus after a number of frosting-defrosting cycles of the fine-grained hot dense asphalt concrete, traditionally used in road construction of Kazakhstan, and polymer asphalt concretes with polymers Elvaloy, Calprene, SBS (L 30-01 A), KUMHO (SBS KTR-101) and Butonal. Testing of asphalt concrete samples has been performed on the four-point bending device at the constant strain of 50 µε, frequency 10 Hz and temperatures -10, 0, 10, 20, 30, 40 and 50°C. The uniform composition of the grain part of the stone material was adopted for laboratory testing for all asphalt concretes and polymer asphalt concretes from Novo-Alekseyevsk borrow-pit. The selected mix has been prepared in laboratory conditions; asphalt concrete samples have been formed and tested under ST RK 1218 for determination of standard characteristics for physical and mechanical properties. Tests results showed that the characteristics of physical and mechanical properties of the asphalt concretes and polymer asphalt concretes satisfied the standard of ST RK 1225 and ST RK 1223. Using roller compactor of Copper model CRT-RC2S the samples have been prepared in the form of rectangular slab, then it has been cut into samples in the form of beams with dimensions 380x50x50 mm. The value of dynamic modulus for all asphalt concretes and polymer asphalt concretes has been evaluated after 50 frosting-defrosting cycles at various temperatures. The value of dynamic modulus depends greatly on the temperature. Within the range of temperature variation from -10°C to 50°C the dynamic modulus varies more than in 70 times. According to the obtained data the elasticity modulus for asphalt concrete without additive after 50 frosting-defrosting cycles showed the biggest value compared with elasticity moduli of polymer asphalt concretes. Asphalt concrete with addition of the polymer Calprene 501 showed the biggest value for elasticity modulus from all the tested polymer asphalt concretes.