COMPARATIVE ANALYSIS OF LOW TEMPERATURE STRENGTH OF MODIFIED ASPHALT CONCRETES
Authors:   Doctor of Chemical Sciences, Professor, Academician, President of NAS RK, Almaty, Kazakhstan, Zhurinov M. Zh. ,   nanrk.mzh@mail.ru, https://orcid.org/0000-0001-5314-1219, Teltayev B. B. ,   Doctor of Technical Sciences, Corresponding Member of NAS RK, Professor, President of JSC “Kazakhstan Highway Research Institute”, Almaty, Kazakhstan; bagdatbt@yahoo.com, https://orcid.org/0000-0002-8463-9965, Amirbayev Ye. D. ,   Chief of Road Construction Materials Division of JSC “Kazakhstan Highway Research Institute”, Almaty, Kazakhstan; https://orcid.otg/0000-0001-8508-8803, Elschibayev A. O. ,   Chief of Road Structures and New Technologies Division of JSC “Kazakhstan Highway Research Institute”, Almaty, Kazakhstan; https://orcid.otg/0000-0002-6197-8905
Published: December 2020

A comparative analysis has been performed in this work for low temperature strength of 31 types of the conventional (non-modified) and modified road asphalt concretes. The neat bitumens of the grades BND 70/100, BND 100/130 and BND 130/200 have been produced by the Pavlodar petrochemical plant from the crude oil of the Western Siberia (Russia) by the method of direct oxidation and they satisfy the requirements of the standard ST RK 1373-2013. The polymers Elvaloy 4170, Elvaloy AM, Kraton, Calprene 501, Butonal NS, SBS (L 30-01 A), KUMHO KTP and crumb rubber have been used for the modification of the bitumens. The modification of the bitumens has been performed in the laboratory of Kazakhstan Highway Research Institute. The modified bitumens satisfy the requirements of the standard ST RK 2534-2015. The conventional and modified asphalt concretes satisfy the requirements of the standards ST RK 1225-2019, ST RK 1223-2019, ST RK 2028-2010, ST RK 2373-2019 and GOST 31015-2002. The strength of the asphalt concretes at uniaxial direct tension at a constant strain rate of 1 mm/min at the temperatures of -10 °С, -20 °С and -30 °С determined in the device TRAVIS under the standard EN 2697-46 has been accepted as a characteristic of their low temperature strength. It is found out that various modifiers affect the asphalt concrete strength in different ways: a degree of impact depends both on a type of an asphalt concrete and a modifier, as well as on a negative temperature value. Some modifiers increase, and some of them decrease the strength of the asphalt concretes at low temperatures compared with the original asphalt concretes. Among the modifiers the polymer Elvaloy AM has been found to be the most efficient at low temperatures. The asphalt concretes of type B with the bitumens of grades BND БНД 100/130 and BND 130/200 at modification by the polymer Elvaloy AM had the biggest strength at all the considered low temperatures: at -10 ºC – 6.79 MPa and 6.43 MPa; at -20 ºC – 7.57 MPa and 7.87 MPa; at -30 ºC – 7.35 MPa and 8.86 MPa. The stone mastic asphalt concretes 15 and 20 with the polymers and without them at all the considered low temperatures practically had the strength not higher than the basic asphalt concretes of type B with neat (original) bitumens of grades BND 100/130 and BND 130/200.