Presentation 2 Phase A – Deformation Studies A. Abu Abdo

Phase A: Mix Resistance to Deformation (E* and GS/CEI) Tasks Literature Review Analytical Analysis Agg and Binders Evaluation Preparation and Evaluation of HMA Mixtures Data Analysis Phase A Reports

Experimental Program

Mix Matrix 4 Aggregates Structures (Fine Mix, SP3, SP4 and Coarse Mix). 8 Binders; PG 70-34, PG 70-28, PG 70-22, PG 64-34, PG 64-28, PG 64-22, PG 58-34 and PG 58-28. 7 Field Mixes.

Aggregate Gradation

8 22 13 PG High Grade PG Low Grade -34 -28 -22 70 AC% -0.5 Opt 0.5 Coarse Mix   8 Mix 1 > 30x106 22 13 Mix 2 3 - 30x106 Fine Mix 64 58 17 mixes – Total Number of Lab mix samples = 265 Total Number of Field mix samples = 49

Field Mixes In addition to MnROAD Mixes Mix PG AC% APA E* GS/Jc/Jc* 1. (Jerome IC) 70-28 4.90% 2 3 2. (Topaz to Lava) 60-34 4.35% 3. (Lapwai to Spalding) 5.40% 4. (US 95/SH 6) 58-34 6.20% 5. (US 20) 5.12% 6. (SR270) 5.90% 7. (SR270) 5.10% Total   14 21 In addition to MnROAD Mixes

Tests Binder G*, and Master Curves - Completed Gyratory Stability (GS) - Completed E* and FN - Completed APA (In progress) Image Analysis

Data Analysis

Gyratory Stability, GS

Gyratory Stability Ndesign Gyratory Stability, GS =  SN . de NG1

GS Sensitivity to Binder Content Changes The GS values were calculated for Mix 1 and Mix 2 at different asphalt contents; Optimum and ±0.5AC% from optimum, all these mixes were designed to achieve four percent Air voids. As per Superpave Mix Design, these mixes should perform best at the optimum asphalt content, at which the air voids of the compacted specimen at N-design is four percent. As shown in the Figure, both mixes yielded the highest GS at -0.5% AC from optimum instead of at optimum asphalt content. It is believed that the decrease of binder content led to higher GS values due the increase of friction between aggregate particles.

GS Sensitivity to Different Binder Grades Mix 1 Mix 2 GS sensitivity to binder type (PG grade) was evaluated for these two mixes. It was speculated that GS would not capture the changes in binder grade, since GS is determined while compaction, when all binders are heated to achieve the same viscosity (0.28±0.30 Pa.s) and the difference in grade does not influence the performance of the mix at these temperatures. The results showed as expected that overall GS is not very sensitive to the changes in binder grade.

Lab vs. Field Mixes To evaluate the possibility of utilizing GS as a quality control tool in the field, GS values for lab mixes were compared to field mixes. When tested, Field Mix 1 had different mix properties than the mix design (lab mix). Field Mix 2 exhibited the same mix properties as the mix design. When GS was compared for lab and field mixes, it was found that GS could capture the changes in mix properties as shown this Figure. Results showed that GS for Mix 1 changed with the change of mix properties (e.g. Gmm). Mix 2 GS values were the same for field and lab mix due to no change has occurred in mix properties

Field Mixes GS was evaluated for other five field mixes . A trend has been observed, the lower the asphalt content the higher the GS values, due to the increase of friction and interlocking between aggregate particles

Initial Results Flow Number, FN

FN vs. GS (Field Mixes)

Initial Results Dynamic Modulus, E*

G* - PG 70-28 E* - PG 70-28 (Mix 1)

Master Curves G* - PG 70-28 E* - PG 70-28 (Mix 1)