Repeated Load Triaxial Testing of Recycled Excavation Materials Blended with Recycled Phyllite Materials

Recycled Excavation Materials (REM) are becoming viable alternative construction resources due to their economic benefits. However, REM may be composed of weak rocks, e.g., phyllites, limiting the use in a base layer. The present paper attempts to further the knowledge of the mechanical performance of REM by performing Repeated Load Triaxial Tests (RLTT). REM are mixed with Recycled Phyllite Materials (RPM) in systematic blends of 0%, 25%, 50%, and 100%. The batches’ resilient modulus (MR) and permanent deformation (PD) characteristics were assessed to establish the maximum RPM allowed into REM while maintaining the required performance. Hicks and Monismith’s and Uzan’s models were used to characterize the stiffness behavior. A wide variation in the stiffness between the two materials was observed. Batches comprised of 0% RPM–100% REM and 25% RPM–75% REM showed high stiffness performance. The Coulomb model assessed the PD behavior, and the results showed a similar response for all batches. Unlike the stiffness, blended mixtures did not show sensitivity to increased RPM content in the PD. This study may help end-users to understand the performance of REM given the documented threshold on the allowable quantity of RPM in REM.

Undrained Deformation Characteristics of Soft Marine Clay Subjected to One-Way Cyclic Loading with Variable Confining Pressure

To gain a better understanding of the undrained deformation characteristic of saturated marine clay soil subjected to vehicle cyclic traffic load, a sophisticated dynamic triaxial was used to conduct a variety of undrained one-way compression cyclic experiments with variable confining pressure (VCP) as well as constant confining pressure (CCP). The results indicate that, compared to CCP test results, VCP is helpful to raise the axial resilient modulus (Mr) and restrain the permanent plastic strain ( ε a p ) development of the specimens. By normalization analysis of the measured data of Mr and ε a p , the virtually unique correlation between normalized average resilient modulus, normalized permanent axial strain after 1,000 loading cycles, and normalized mean normal stress is established, respectively, regardless of the values of CSR. Additionally, the VCP influence on ε a p is quantified and fitted by a power law function, which can be used for subsoil deformation prediction and provides new insights into the mechanics of strain accumulation under undrained cyclic loading conditions.

Effect Of Resilient Modulus on Permanent Deformations Using VESYS 5W Program

Due to high temperatures and increased traffic loads, most of Iraq’s streets suffer from permanent distortion problems, especially in streets where there are checkpoints, therefore, there are needs for reports and researches specialized in improving the pavement layers and increasing their resistance to temperatures and high traffic loads to reduce the rut depth. In this research, the VESYS 5W program was used to find a potential value for rut depth, where ordinary asphalt mixes and improved asphalt mixes were used using SBS polymer at 4% by weight of asphalt were it is evaluated according to different properties of these mixture and the resilient modulus one of these properties for it is importance. The results showed that when the value of the resilient modulus increases, the rut depth decreases, as the rut depth was reduced by 42.5% for the surface layer and 73% for the base layer

Performance Analysis of Resilient Modulus and Fatigue Resistance of AC-BC Mixture with Full Extracted Asbuton and Reclaimed Asphalt Pavement (RAP)

One way to be developed to overcome challenges in providing flexible pavement materials is to apply the green roads principle by reusing some or all of the old road pavement material or Reclaimed Asphalt Pavement (RAP) as a material for new road pavement, which if reused will affect the performance of the mixture, such as decreasing the level of durability and premature pavement damage, so an effort must be made to improve the performance of the recycled material, namely by adding full extracted Asbuton and rejuvenating materials. The RAP material was obtained from scratching the asphalt of the Jagorawi Toll Road. The mixture used was asphalt concrete-binder course (AC-BC) layer using 30%, 40%, and 50% RAP material, using full extracted Asbuton at 6%, and Nichireki rejuvenating material. Then, on mixtures with RAP material, Marshall Test, Resilient Modulus test with UMATTA, and resistance to fatigue with four points loading test with strain control were conducted. The use of RAP material with modified asphalt in the form of an addition of full extracted Asbuton into the Pen 60/70 Asphalt can increase the asphalt stiffness. Marshall test results showed that a mixture with 6% full extracted asbuton content and 0% RAP material content (A6RAP0) gave the highest stability value. The results of the Resilient Modulus test showed that the mixture with 6% full extracted asbuton content and 50% RAP material content (A6RAP50) gave a high Resilient Modulus value at a test temperature of 45oC. The results of the fatigue resistance test showed that the mixture with 6% full extracted asbuton content and 50% RAP material content (A6RAP50) at a strain level of 300 µε gave the longest fatigue life. Keywords: Reclaimed asphalt pavement (RAP), full extracted asbuton, asphalt concrete -binder course, modified asphalt, resilient modulus, fatigue life. Abstrak Salah satu cara dikembangkan untuk mengatasi tantangan dalam penyediaan material perkerasan lentur adalah menerapkan prinsip greenroads dengan memanfaatkan kembali sebagian atau keseluruhan material perkerasan jalan lama atau Reclaimed Asphalt Pavement (RAP) sebagai material untuk perkerasan jalan yang baru, dimana jika digunakan kembali akan mempengaruhi kinerja dari campuran seperti penurunan tingkat durabilitas dan kerusakan dini perkerasan, sehingga harus dilakukan suatu upaya untuk memperbaiki kinerja dari material daur ulang tersebut, yaitu dengan penambahan Asbuton murni dan bahan peremaja. Material RAP didapatkan dari hasil garukan aspal Jalan Tol Jagorawi. Campuran yang dipakai adalah Laston Lapis AC-BC menggunakan kadar material RAP sebanyak 30%, 40%, dan 50%, dengan penggunaan Asbuton murni sebesar 6%, serta bahan peremaja Nichireki, dan kemudian selanjutnya pada campuran dengan penggunaan material RAP dilakukan pengujian Marshall, Modulus Resilien dengan alat UMATTA dan ketahanan terhadap kelelahan (fatigue) metode four points loading test dengan kontrol regangan. Penggunaan material RAP dengan aspal modifkasi berupa penambahan Asbuton murni kedalam Aspal Shell Pen 60/70 dapat meningkatkan kekakuan aspal. Hasil pengujian Marshall menunjukkan campuran dengan kadar Asbuton murni 6% dan kadar material RAP 0% (A6RAP0) memberikan nilai stabilitas tertinggi. Hasil pengujian Modulus Resilien menunjukkan campuran campuran dengan kadar Asbuton murni 6% dan kadar material RAP 50% (A6RAP50) memberikan nilai Modulus Resilien yang tinggi pada temperatur pengujian 45oC. Hasil pengujian ketahanan terhadap kelelahan menunjukkan campuran dengan kadar Asbuton murni 6% dan kadar material RAP 50% (A6RAP50) pada regangan 300 µε memberikan umur kelelahan yang paling panjang. Kata-kata kunci: Reclaimed asphalt pavement (RAP), Asbuton murni, laston lapis antara, aspal modifikasi, modulus resilien, umur kelelahan.

Investigating mechanical properties of hot mix asphalt containing iron ore flotation tailing

Studies involving the use of iron ore tailings from the beneficiation process in different market niches are increasingly necessary due to the large environmental damage caused by their disposal in dams, since they are waste generated in high volumes and which have low economic value for mining companies The main purpose of this study was to investigate mechanical properties of hot mix asphalt mixture containing iron ore flotation tailing. For this, a mixture containing iron ore flotation tailing and a control mixture with natural aggregates and stone dust were prepared according to the Marshall methodology and tests of stability and flow, indirect tensile strength, resilient modulus, fatigue test and dynamic creep tests were conducted. Results show that the mixture with iron ore flotation tailing had performed technically appropriate, due to the similarity of mechanical properties of the control mixture. Therefore, the results obtained revealed that the iron ore flotation tailing presented technical characteristics appropriate to its use incorporated into hot mix asphalt. In addition, their use as an alternative material in asphalt pavements can generate environmental benefits by reducing the volume of material deposition in tailings landfills and exploration areas for mineral aggregate mining.

The Effect of Temperature on Dynamic Characteristics of Frozen Clay under Principal Stress Rotation

The foundation soil is always subjected to complex stress, including continuous rotation of the principal stress caused by traffic and earthquake loads. To comprehend the dynamic characteristics of frozen clay under complex stress sate, including continuous rotation of the principal stress, this study investigates the effect of temperature on the dynamic characteristics of frozen clay under principal stress rotation using a frozen hollow cylinder apparatus (FHCA-300). The test results reveal that the cumulative plastic strain of frozen clay samples exponentially increases with the rising of temperature under principal stress rotation. The influence of temperature is more profound with a high cyclic stress ratio (CSR). A decrease in temperature can improve the stiffness of the frozen clay, reduces its energy dissipation, and enhances its ability to resist dynamic loading. However, the principal stress rotation phenomenon may aggravate the damage of frozen clay and increase the energy dissipation and reduces its ability to resist dynamic loading. Based on the experimental data, an empirical expression was proposed to describe the coupling influence of CSRs and temperature on the axial resilient modulus of frozen clay, which can predict the development of axial resilient modulus under different thermal-mechanical conditions.

Developing New Empirical Formulae for the Resilient Modulus of Fine-Grained Subgrade Soils Using a Large Long-Term Pavement Performance Dataset and Artificial Neural Network Approach

Artificial neural network (ANN) has been successfully used for developing prediction models for resilient modulus (Mr). However, no reliable Mr formula derived from these models has been proposed in previous studies, although engineers/researchers need empirical formulae for hand calculation of Mr. Therefore, this study aimed to propose reliable empirical formulae for the Mr of fine-grained soils using ANN. For this purpose, thousands of ANN models were developed using the long-term pavement performance (LTPP) and external datasets. The input parameters were the percentage of soil particles passing through #200 sieve (P200), silt percentage (SP), clay percentage (CP), liquid limit (LL), plasticity index (PI), maximum dry density ([ρdry]max), optimum moisture content (wopt), confining pressure (σc), and nominal maximum axial stress (σz). The ANN models were compared with several constitutive models. The results indicate that the constitutive models failed to predict the Mr, and the best Mr predictions were obtained by the ANN-C9 (P200, SP, CP, LL, PI, σc, and σz), ANN-C10 (P200, SP, CP, [ρdry]max, wopt, σc, and σz), and ANN-C11 (P200, SP, CP, LL, PI, [ρdry]max, wopt, σc, and σz) models. Thus, the structures of these ANN models were formulated and proposed as the new empirical formulae for the Mr of fine-grained soils. Sensitivity analysis was also performed on these ANN models. It was determined that (ρdry)max is the most influential parameter in the ANN-C10 model, and LL is the most influential parameter in the ANN-C9 and ANN-C11 models. On the other hand, σc and σz are the least influential parameters.