Issue 53

M. Ameri et alii, Frattura ed Integrità Strutturale, 53 (2020) 177-186; DOI: 10.3221/IGF-ESIS.53.15 179 E XPERIMENTAL METHODS ypically, aggregate forms 90% to 96% of the total weight of the asphalt mixture; hence, the structural, chemical and physical properties of these stone materials have a significant effect on the strength of asphalt mixtures [20, 21]. The crushed limestone aggregates used in this study were obtained from the Asbcharan quarry located in the north- eastern part of Tehran province, Rudehen. The gradation and specifications of aggregates are shown in Tab. 1. a) Grading limit used in the research study Sieve Number Sieve size (mm) Weight percentage passing through each 4.0 GPA scale Average value 1" 25 - - 3.4" 19 100 100 1.2" 12.5 90-100 95 3.8" 9 - - #4 4.75 44-74 59 #8 2.36 28-58 43 #16 1.18 - - #30 0.5 - - #50 0.3 5-21 13 #100 0.15 - - #200 0.75 2-10 6 Aggregate Test Aggregate Test Method Bulk specific gravity 2.484 ASTM C127 Absorption course aggregate (%) 2.1 ASTM 127 Absorption fine aggregate (%) 4.3 ASTM 128 Los Angeles abrasion Loss (%) 23 AASHTO T96 Tow Fracture faces (%) 93 ASTM D5821 b) Engineering properties of aggregate source Table 1: Gradation and specifications of the aggregates Asphalt binder is an essential component of asphalt concrete mixture, and it is the binder that holds aggregate together. The quality of the asphalt binder is directly related to the performance of the asphalt mixture [22]. In this experimental investigation, a 60-70-penetration-grade binder obtained from Tehran’s Pasargad Oil Company was used. To characterize the properties of the asphalt binder, conventional tests including penetration, softening point and ductility test were carried out. Tab. 2 presents the basic properties of the base bitumen. Test Method criteria Result Penetration of 25 c ,100gr, (0.1mm) ASTM D5 60-70 68 Softening Point (C) ASTM D36 45-54 48 Ductility of 25 (cm) ASTM D113 100 100 Flash point (C) ASTM D92 250 300 Fire Point (C) ASTM D70 230 315 Specific gravity at 25 C ASTM D70 1.05-1.06 1.048 Kinematic viscosity 120C (cSt) ASTM D2170 - 815 Kinematic viscosity 135C (cSt) ASTM D2170 - 425 Kinematic viscosity 150C (cSt) ASTM D2170 - 235 Penetration index (PI) - െ2 ൑ ൑ 2 -1.15 Penetration viscosity number (PVN) - - -0.55 Table 2: Basic properties of the 60-70 penetration-grade asphalt binder T