Mechanical performance of intelligent asphalt mixture utilizing rejuvenator encapsulated method

In this study, in order to evaluate the effects of heavy vacuum slops (H.V.S) as rejuvenator and nano-Zycosil as an anti-stripping agent on used encapsulation method and mechanical performance of asphalt mixture samples, scanning electron microscopy (SEM), computerized tomography (CT) scan and thermal gravimetric (TG) analyses and also, indirect tensile strength (ITS) and indirect tensile fatigue (ITF) tests were performed. First, an encapsulation procedure to prepare different specimens including modified and unmodified samples with nano-Zycosil was done. In the following, morphology of the nano-Zycosil-modified capsules and aggregates were particularly evaluated. Considering the morphology evaluation and TG analysis diagrams, it was found that most of the capsules resisted the mixing procedure of the asphalt mixture. So, the encapsulation procedure used in this study was a successful technique. In addition, modification with nano-Zycosil as an anti-stripping agent significantly improved the adhesion strength in the matrix of capsules-aggregates-asphalt binder by converting the adhesion type from silanolian to siloxane. Overall, modification of capsules and main aggregates together with nano-Zycosil significantly improved moisture resistance and mechanical performance of asphalt mixture samples

Statistical investigation on plastic waste recycling by reusing in soil

Recikliranje i ponovna uporaba plastičnog otpada ključna je za ublažavanje njegovog negativnog utjecaja na okoliš i gospodarstvo. Ovaj rad predlaže evolucijsku polinomnu regresiju (eng. Evolutionary Polynomial Regression - EPR)) kao snažnu metodu za predviđanje stišljivosti pijeska pomiješanog s polietilenom visoke gustoće (HDPE). U svrhu istraživanja proveden je niz opsežnih pokusa pomoću velikog edometra. Za izradu EPR modela korišteni su rezultati koeficijenta bočnog pritiska tla i modula promjene volumena mješavina. Kako bi se ocijenili parametri modela, provedene su analize osjetljivosti. Rezultati su pokazali da je EPR model učinkovit za procjenu karakteristika mješavine.Recycling and reusing plastic waste are key options for ameliorating its negative effects on the environment and the economy. This paper proposes evolutionary polynomial regression (EPR) as a powerful technique to predict the compressibility behavior of sand and high-density polyethylene (HDPE) mixtures. In the investigation, a series of large-scale oedometer experiments were conducted. The results of the coefficients of lateral earth pressure and volume compressibility coefficients of different mixtures were used to develop EPR models. The model parameters were evaluated by sensitivity analyses. The results showed that the best developed EPR model is robust for estimating the characteristics of sand and HDPE mixtures

Experimental Evaluation of the Strength of Peat Stabilized with Hydrated Lime

This study compares the effects of different hydrated lime contents and curing periods in peat stabilization using unconfined compressive strength (UCS) and consolidated-undrained triaxial (CU) tests which constitutes the first comprehensive experimental study on peat in Iran. Since it includes a novelty comparison between these tests along with providing experimental data for both test types. For this purpose, lime contents of 3, 6, 9, 12 and 15% were used with different curing periods of 7, 14, 28 and 90 days. The results obtained in these tests were then compared. In order to compare, for triaxial tests, a novelty value of equivalent unconfined strength, which is the strength in case of hypothetical zero confining pressure in a triaxial test, is introduced and calculated and then compared with UCS values. Results indicate that the equivalent unconfined strengths of CU tests are always lower than those of the UCS test which can be attributed to pore water pressure generation in CU tests which can decrease the equivalent unconfined strength of soil. Moreover, while the undrained cohesive strength is half of the UCS value, the undrained cohesive strength is 0.35 times the equivalent unconfined strength for peat. Such comparison between UCS test, which is quite common and easily conductible, and triaxial test, which provides the most comprehensive data in soil mechanics, could lead to credible results which can be widely applicable in forest areas and regions with much vegetation which is the case in northern parts of Iran. Moreover, based on the comparison, the optimum lime content for peat stabilization in this study was obtained between nine and twelve percent

DETERMINATION OF THE RELATION BETWEEN COMPRESSIVE STRENGTHS OF ASPHALT CONCRETE OBTAINED FROM HVEEM STABILOMETER AND UNCONFINED COMPRESSION TESTS

Unconfined compression test is one of the common experiments to determine the compressive strength of asphalt concrete mixtures. In this test, the asphalt concrete sample is loaded under vertical pressure (oj) and the lateral pressure on the sample (cj) during the loading procedure is zero. It is obvious that this results in a reduction in the compressive strength of the asphalt concrete.In the present investigation, by making asphalt concrete samples with different specifications, the compressive strength values were determined through unconfined compression test and the results were analysed by comparing them with those obtained from Hveem stabilometer test on the same samples. The effect of the elemination of lateral pressure (Os) was clarified and finally, a mathematical model was presented to determine the relation between the compressive strengths obtained from these two tests

The Effect of Wetfix and Nanohydrated Lime Additives on Bitumen Aging and the Cohesion and Adhesion Failure Mechanisms of Hot Asphalt Mixtures

Aging due to sunlight and the passage of time is an effective element in the occurrence of moisture damage in hot asphalt mixtures. Still, the effects of this parameter are scarcely considered in the experiments examining the moisture damage potential. Accordingly, this study investigated the effect of aging on the performance of hot asphalt mixtures and examined the improvement of moisture damage performance by using antistripping additives via mechanism and functional tests. Two types of aggregates (limestone and granite) with different degrees of moisture sensitivity, two types of bitumen (PG64-16 and PG58-22) with different performances, and two additives (Wetfix liquid additive and nanohydrated lime) as bitumen modifiers were used. Bitumen samples and asphalt mixtures were subjected to short- and long-term aging. The pull-off test was performed to explore the aging effect on different failure mechanisms (cohesion and adhesion), and the indirect tensile stiffness modulus (ITSM) test was conducted to study the asphalt mixture’s performance against moisture damage. The results specify that aging, in terms of hot asphalt mixture hardening in dry and wet conditions, decreased the MSR (resilient modulus wet to resilient modulus dry ratio), and this decline was greater in long-term aging. The pull-off test results exhibited that aging, especially in the long term, decreased the asphalt mixture’s adhesive strength in dry and wet conditions; this decline in adhesion was greater in the wet than in the dry state, and this difference decreased the wet-to-dry adhesion strength ratio (the pull-off ratio). The additives relatively improved the yield modulus of the asphalt mixture, but their effect was greater in the wet state. A comparison of the pull-off test results in cohesion and adhesion failure demonstrated that Wetfix was more effective in improving bitumen–aggregate adhesion, whereas nanohydrated lime was more effective in enhancing bitumen adhesion. The resilient modulus (Mr) ratio in wet-to-dry conditions indicated that nanohydrated lime had better effects on the overall performance of the aged asphalt mixture against moisture damage. To investigate the effect of additives on the performance of asphalt mixtures, a t-test was performed in all modes of control, short-term aging, and long-term aging. The findings showed the effect of Wetfix and nanohydrated lime on increasing the modulus of elasticity of the samples

Enhancing ultimate bearing capacity prediction of cohesionless soils beneath shallow foundations with grey box and hybrid AI models

This study examines the potential of the soft computing technique, namely, multiple linear regression (MLR), genetic programming (GP), classification and regression trees (CART) and GA-ENN (genetic algorithm-emotional neuron network), to predict the ultimate bearing capacity (UBC) of cohesionless soils beneath shallow foundations. For the first time, two grey-box AI models, GP and CART, and one hybrid AI model, GA-ENN, were used in the literature to predict UBC. The inputs of the model are the width of footing (B), depth of footing (D), footing geometry (ratio of length to width, L/B), unit weight of sand