Indirect Tensile Strength Values Research Articles

Accelerated Pavement Testing of Re-Recycled Cold Central Plant Recycled Asphalt Mixtures

Cold central plant recycled asphalt mixtures (CCPR) have been shown to provide a high-quality, economical, and environmentally conscious asphalt base mixture. Existing literature, however, does not indicate what would be an appropriate future rehabilitation method for a pavement that includes CCPR. Given the previously cited benefits of CCPR, it is logical to ask whether a CCPR can be re-recycled and, if so, how will it perform? This paper presents a study of a test section containing a re-recycled CCPR placed at the National Center for Asphalt Technology Test Track. CCPR from a Virginia Department of Transport study on the Test Track was recovered, re-recycled, and placed at 5-in. thick with a 2-in. asphalt concrete (AC) overlay. In preparing for a re-recycled CCPR layer, milling an existing CCPR layer resulted in a coarser gradation and lower indirect tensile strength values. Initially, the re-recycled CCPR test section did not perform well owing to moisture in the aggregate base present during construction of the re-recycled CCPR layer. It is suspected that this moisture negatively affected the curing of the re-recycled CCPR layer. Thus, the re-recycled CCPR layer was milled and re-recycled again (3rd generation re-recycled CCPR) and placed at 5-in. thick with a 2-in. AC overlay. The 3rd generation re-recycled CCPR performed well through 3 million equivalent single axle loads (ESALs), the same number of ESALs that resulted in fatigue cracking and rutting failures in the initial re-recycled CCPR.

Effects of utilization of rejuvenator in asphalt mixtures containing recycled asphalt pavement at high ratios

This study investigated the properties of asphalt mixtures, including recycled asphalt pavement, at high ratios. In addition, to improve the properties of asphalt mixtures containing recycled asphalt pavement, bitumen was modified with a rejuvenator at proportions of 2, 4, and 6% and used together with 35, 40, and 45% recycled asphalt pavement. Based on test results, the strength of asphalt mixtures increased as the ratio of recycled asphalt pavement added to asphalt mixtures increased. In addition, all combinations of recycled asphalt pavement and rejuvenator agent had higher indirect tensile strength values according to the reference mixture. The rutting resistance of asphalt mixtures increased as the ratio of recycled asphalt pavement added to the asphalt mixtures increased. Asphalt mixtures containing 45% recycled asphalt pavement and 2% rejuvenator-modified bitumen showed the best rutting resistance. The significance of the obtained results was determined with appropriate statistical analysis. So, it has been determined that the rejuvenator used in this study can effectively improve the properties of asphalt mixtures containing recycled asphalt pavement. Finally, the rejuvenator agent used in this study allowed the utilization of recycled asphalt at a higher ratio than the amount specified in the Highway Technical Specification.

Performance evaluation of grouted porous asphalt concrete

Abstract Semiflexible pavement (SFP) is considered a composite mixture, as it consists mainly of a porous asphalt mixture with high air voids grouted with highly flowed cementitious grout. Numerous benefits have been attributed to this technology, including exceptional slip resistance, a high static bearing capacity, and rutting resistance. In this study, two different types of semiflexible paving mix were produced by using two different types of grouting materials (GMs). There is a discrepancy between the compressive strengths of the two GMs used, as the compressive strength of the first mixture, which consisted of 96% cement and 4% silica fume (SF), was approximately twice the compressive strength of the second mixture, which consisted of 75% cement and 25% sand. The mechanical and durable properties of the two SFPs were studied, in addition to the effect of variation in the compressive strengths of the two GMs and their effect on the final performance of the pavement. The results of Marshall and rutting tests show that the SFP material exhibits good high-temperature stability. The effect of the variation in the compressive strength of the two mixtures was evident in the results of the tests compared with the sand mixture at a strength of 20.8 MPa, the SF at a strength of 48.1 MPa witnessed a 39.54% increase in the Marshall stability at 28-day curing age. Also, the composite material (CM) showed better rutting performance than traditional asphalt mixtures, which did not exceed 2 mm. The results of the indirect tensile strength (ITS) test showed a discrepancy between the two types of CM, as the ITS value of the grouting material of SF (GMSF) mixture increased by 14.91% compared with the grouting material of sand (GMSN) for the curing age of 28 days for unconditioned samples and by 20.22% for the conditioned samples for the same curing age, while the durability of two types of CM was measured by Cantabro abrasion loss and tensile strength ratio. The results were acceptable and within the specification limits. With a variation for the two types of CM, the GMSF mixture showed an increase in the value of Cantabro loss by 11.52% over the GMSN mixture for ageing samples and 6.59% for non-aging samples of 28 days of curing age.

Assessment of Traditional Asphalt Mixture Performance Using Natural Asphalt from Sulfur Springs

This research utilized natural asphalt (NA) deposits from sulfur springs in western Iraq. Laboratory tests were conducted to evaluate the performance of an asphalt mixture incorporating NA and verify its suitability for local pavement applications. To achieve this, a combination of two types of NA, namely soft SNA and hard HNA, was blended to create a binder known as Type HSNA. The resulting HSNA exhibited a penetration grade that adhered to Iraqi specifications. Various percentages of NA (20%, 40%, 60%, and 80%) were added to petroleum asphalt. The findings revealed enhanced physical properties of HSNA, which also satisfied the requirements outlined in the Iraqi specifications for asphalt cement. Consequently, HSNA can serve as an asphalt binder to produce asphalt mixtures for flexible paving construction. Notably, HSNA mixtures exhibited greater Marshall stability and stiffness index when compared to traditional mixtures. The results from indirect tensile strength (ITS) and tensile strength ratio (TSR) tests indicated that the 80NA mixture displayed the highest ITS values and a TSR of 81.36%, surpassing the TSR of the mixture incorporating petroleum asphalt by 0.57%.

Effect of Natural Bitumen on the Performance of Hot Asphalt Mixture‏

Globally, for more than a century, large quantities of asphalt binder have been consumed in the production of asphalt mixtures. There are two types of natural asphalt (NA) deposits in the Heet region: rock asphalt and sulphur spring asphalt. NA from sulphur springs was used in this study to assess NA performance and determine the suitability of using NA in local asphalt mixtures. The NA was treated by heating it to 163 °C for several hours. NA was subjected to laboratory testing after industrial treatments, and it was found that the physical properties of NA can conform to Iraqi specifications by heating it for 20 hours. The results showed that treated NA is better suited to hot climates because it is less temperature sensitive than traditional petroleum asphalt. NA was discovered to be highly effective in improving mechanical properties. In addition, the NA mixture had the highest indirect tensile strength values and a tensile strength ratio of 81.2%, which was 0.37% higher than the TSR of the conventional mix. NA will play an important role in the production of flexible pavements and provide a significant economic benefit without compromising the overall performance of the mixture because it is less expensive than conventional asphalt and is available in large quantities in Iraq.

Performance of Hybrid Asphalt Mixture through the Stability and Tensile Strength

Introduction: The stability and tensile strength of asphalt mixtures play a crucial role in pavement durability, primarily due to the challenges associated with cracking. This study investigates the utilization of a hybrid asphalt mixture comprising hybrid materials: Palm Oil Fuel Ash (POFA), garnet waste and sawdust to enhance the modified asphalt performance. Aims: The objective is to examine the hybrid materials’ influence towards the mechanical properties of the hybrid asphalt mixture, specifically focusing on the Indirect Tensile Strength (ITS) as well as the Marshall stability test. Methods: To achieve this, hybrid materials were finely ground and sieved to 25µm before being incorporated into the mixture. The Marshall mix design procedure was conducted, utilizing hybrid binders at concentrations of 0% (control), 3% 6%, and 9%. The effects of the hybrid asphalt mixture on stability, flow, stiffness, and ITS were assessed at the optimal binder content. Results: The findings indicate that the hybrid asphalt mixture reveals enhanced Marshall stability, stiffness, flow, and ITS values compared to conventional asphalt mixtures. Notably, hybrid asphalt mixtures with 6% binder concentration demonstrate the most significant enhancement in terms of Marshall stability and ITS. Conclusion: This correlation suggests that the incorporation of POFA, garnet waste, and sawdust as hybrid materials in the hybrid asphalt mixture possesses a positive effect on the overall mechanical properties of the pavement. Highlights: • POFA, garnet waste, and sawdust increased the stability of the hybrid asphalt mixture. • POFA, garnet waste, and sawdust increased the tensile strength of the hybrid asphalt mixture. • Hybrid asphalt mixture performs positively towards flow and stiffness.

Use of microgrid fibre as a new reinforcement additive to improve compressive and tensile strength values of cemented rock fill mixes

ABSTRACT In this study, use of microgrid fibre (MGF) was tested as a new polypropylene fibre additive for cemented rock fill (CRF) mixes and compared with the conventional polypropylene fibre type geosynthetics. Changes in the uniaxial compressive strength and indirect tensile (splitting) strength values of CRF specimens were investigated for the use of different fibre types. In this experimental study, cemented basalt aggregate type rock fill materials were tested in case of using different amounts of fibre additives and cement contents. According to the results obtained from this experimental study, it was determined that MGF type new fibre additives can supply better increases in strength values in comparison with the conventional polypropylene fibre products. It was assessed that MGF type novel additives can be used to make better adherence in the CRF mixes and reinforcement performances under both compression and tension cases than those of the conventional fibre additive products.

Effect of Aggregate Proportion and Skeleton on the Strength of Porous Asphalt Mix

Investigating the skeleton behaviour of dry aggregates and the characteristics Of Indirect Tensile Strength (ITS) of various open-graded bands is the prime focus of this study. The skeleton band has an impact on mechanical characteristics. To make porous asphalt mixes’ skeletal strength greater, aggregate proportion studies are necessary before evaluating its performance. So, the current research on how the gradation band behaves concerning aggregate proportions is studied in this paper. The coarse and fine aggregate percentages on the gradation that affect tensile strength values vary in this paper. The coarse content effect on the ITS value lower side and fine proportion on the gradation significantly affect and indicates the compacted sample’s binding property. In this paper, different couple conditions also effect the ITS values. The porous asphalt mixture’s main mote is to improve air void content and drainage facility while improving durability and strength parameters.

The Effect of Recycled Material and Buton Granular Asphalt (BGA) on Asphalt Concrete Mixture Performance

Pavement recycling is an appropriate technology for constructing and restoring road pavement structures due to the limited supply and high cost of pavement materials. This study aims to improve the recycled mix's performance by replacing the fine aggregate in the recycled mix for road pavement with Buton Granular Asphalt (BGA). The percentage of recycled material (Reclaimed Asphalt Pavement/RAP) in the mixture was limited to 20% and 30% by weight of the total mixture. BGA was added by 3%, 6%, and 9% in each mixture with the RAP variation. Mixture performance was obtained through Indirect Tensile Strength (ITS) testing. The ITS test results showed that the ITS value of the mixture with RAP and BGA increased by an average of 4.7–15% compared to the mixture without RAP and BGA. The Toughness Index (TI) value increased by 3.5–19.8% with the addition of RAP. With the addition of 3% BGA, the TI value tends to increase and subsequently decrease up to 9% BGA levels. The result indicated that adding 30% RAP and 3% BGA to the mixtures improved pavement performance and could be a solution to increase the elasticity and fracture resistance of the mixture. Doi: 10.28991/CEJ-2023-09-06-09 Full Text: PDF

Investigation of changes in geomechanical properties of sandstones under different saturation and anisotropy conditions: Example from Gümüşhane (NE Türkiye)

In this study, the changes in various geomechanical properties were studied for sandstones cropped out at the Mescitli region of the Gümüşhane city under different saturation and anisotropy conditions. For this purpose, 225 specimens were prepared considering the lamination planes of those were chosen to have orientation of 0, 30, 45, 60 and 90° relative to loading direction. Index properties of the sandstones such as dry unit weight (dry), saturated unit weight (sat), water absorption by weight (Aw) and water absorption by volume (Av) were assigned. In accordance with the objective of study P wave velocity, uniaxial compressive strength and indirect tensile strength values were determined based on different saturation and anisotropy conditions. It was noted as a result of the observations carried out that specimens parallel to lamination have higher wave velocities in general when compared with specimens that are perpendicular to lamination planes. While uniaxial compressive strength values for sandstones are high for specimens which are parallel and perpendicular to lamination, the lowest strength value was observed in specimens with an anisotropy angle of 30°. In addition, it was also observed that the strength values decrease at a significant level with increasing saturation conditions. Strength anisotropy ratio (RUCS) for sandstones varies between 1.28–1.49 based on different saturation conditions. Similarly, while indirect tensile strength values were higher in specimens that were parallel and perpendicular to lamination, they were lower for other anisotropy orientations. Indirect tensile strength values also decreased with increasing degree of saturation.

Field investigation of material layer properties for emulsion-treated base layer application in low-volume roads

ABSTRACT The study presents the determination of pavement design input parameters-structural layer coefficients and back-calculated layer moduli for Emulsion-Treated Base (ETB) layer materials in a Low-Volume Road (LVR) application. Seven test sections were constructed on a stretch of LVR with varying emulsion contents and 50% Recycled Asphalt Pavement (RAP) aggregate incorporation in ETB mixes. Structural performance of the test sections was periodically observed using a Benkelman Beam Deflectometer (BBD) and the data was used for the estimation of the structural layer coefficient of ETB, based on the effective structural number of the pavement. The deflection bowl data of the test sections were also captured using a Falling Weight Deflectometer (FWD) and the modulus of ETB layer was back-calculated using a back-calculation software. The study proposes a structural layer coefficient of 0.23–0.29 and back-calculated moduli of 578–919 MPa for ETB mixes characterised by Indirect Tensile Strength (ITS) values ranging between 140 kPa and 245 kPa. Traffic level-based ETB mix specifications are also proposed in the study, which enables a mix designer to proportion the mix for a selected design traffic level. For a design traffic level of 1 million standard axles, the target dry ITS specification was found to be 188 MPa.

Improved Fatigue Performance and Cost-Effectiveness of Natural Rubber Latex–Modified Cement-Stabilized Pavement Base at Raised Temperatures

The increased temperature at the early state of curing affects the fatigue properties of pavement base materials. The fatigue properties of stabilized pavement bases and subbases govern the performance and service life of pavement structures. This research study utilized natural rubber latex (NRL) to enhance the tensile fatigue properties of cement-stabilized base materials at various temperatures. The effects of influence factors such as cement content (3%, 5%, and 7%), NRL replacement ratio (0%, 10%, 15%, 20%, 25%, and 30%), and temperature (25°C, 40°C, and 60°C) on indirect tensile strength (ITS), indirect tensile resilient modulus (IT Mr), and indirect tensile fatigue life (ITFL) were studied in this research. NRL replacement was found to improve the UCS, ITS, IT Mr, and ITFL of cement (C)-stabilized soil up to the highest values at the optimum NRL replacement ratios, which were 20%, 15%, and 10% for cement contents of 3%, 5%, and 7%, respectively. The cement-NRL (C-NRL)-stabilized samples were found to have superior ITS, IT Mr, and ITFL values compared with C-stabilized samples for the same cement content but had the same rate of reduction in ITS due to the raised temperature. For the NRL replacement ratio on the dry side of optimum, the C-NRL-stabilized samples had lower rate of IT Mr reduction than the C-stabilized samples, although they had the same ITS due to the higher toughness. Therefore, the rate of ITFL reduction of C-NRL-stabilized samples was lower than that of the C-stabilized samples. It was proven in this research that the NRL replacement could reduce the thickness (superior IT Mr) of a cement-NRL-stabilized base course for a given traffic volume and service life, and therefore the construction (material and operation) cost by 17.26% benchmarked to a C-stabilized base course. Finally, the cost-effective design method for C-NRL-stabilized bases course was proposed, which will promote the use of NRL as an alternative green additive instead of synthetic polymer.

An Experimental Study on the Mechanical Characteristics of Natural and Synthetic Fiber-Reinforced Sandy Soil in Pavement Construction

ABSTRACT The current study investigated the use of polyester synthetic (PES) fiber and basalt (BS) and bagasse (BG) natural fibers on the strength and mechanical behavior of sandy soil in pavement construction projects. A series of California bearing ratio (CBR) and indirect tensile strength (ITS) tests were performed on fiber contents (FC) of 0.5,1 and 2% and fiber lengths (FL) of 2.5, 5, and 7.5 mm. Findings show that the maximum California bearing ratio (by increasing 3.3 times) and indirect tensile strength (by increasing 2.98 times) are obtained in the length of 7.5 mm and the content of 2% for polyester and basalt fibers, respectively, which is also evident in the scanning electron microscope (SEM) test results. Also, based on the analysis of variance (ANOVA) and according to various factors including P-value (<0.05), it was determined that the contrast between the values is statistically significant. Due to California bearing ratio – indirect tensile strength and California bearing ratio – resilient modulus experimental relationships, the relationship between resilient modulus-indirect tensile strength was provided with very good correlation coefficients. Furthermore, sensitivity analysis revealed that California bearing ratio and indirect tensile strength values are noticeably influenced by fiber content variations.

Assessing the effect of short and long-term aging on moisture damage of hot mix asphalt using two different methods

ABSTRACT The effects of short-term aging (STA) and long-term aging (LTA) on moisture damage mechanisms were investigated using mechanical and thermodynamic methods. PG58-22 and PG64-16 asphalt binders modified with Dodecylamine (DA) and Wetfix (WT) additives and limestone and granite aggregates were used. The moisture sensitivity was assessed using the indirect tensile strength (ITS) test via the modified Lottman test and the surface free energy (SFE) method. As asphalt binder becomes harder due to aging, ITS values increase in dry conditions. However, ITS values decrease due to the texture and mineralogical properties of aggregates, the reduction of mastic cohesion and asphalt binder-aggregate adhesion because of water infiltration and weakening of the mixture in wet conditions. The tensile strength ratio (TSR) test revealed that TSR values decrease due to aging. The cohesion free energy of the PG64-16 asphalt binder increased by 8.9% in the STA state and by 29.8% in the LTA state compared to the unaged state. This rise in PG58-22 was about the same as that in PG64-16. Asphalt binder aging in all the samples reduced the adhesion energy. These variations indicated that aging reduces the probability of cohesion failure and increases the probability of adhesion failure.

Evaluating the Influence of Carbon Fiber on the Mechanical Characteristics and Electrical Conductivity of Roller-Compacted Concrete Containing Waste Ceramic Aggregates Exposed to Freeze-Thaw Cycling

Traditional methods of removing snow and ice from pavements using chemicals are combined with mechanical removal that involves a lot of manpower, advanced machinery, chemicals that are harmful to the environment, and damage to pavements. Furthermore, annually, large quantities of ceramic materials become waste due to their fragile nature during processing, transport, and installation, and their accumulation in the nature has brought about environmental and health-related concerns. Therefore, the study aims to investigate the effect of using waste ceramic as a replacement for fine aggregate in roller compacted concrete (RCC) and the application of carbon fiber to improve the mechanical properties and electrical conductivity of RCC. To achieve this goal, several tests such as compressive strength, indirect tensile strength, electrical resistance, chloride ion penetration, specific gravity, and skid resistance tests were carried out on the fabricated samples before and after freeze-thaw cycling exposure. The experimental results illustrated that replacing waste ceramics with fine-grained aggregate increased the compressive strength and tensile strength of RCC. Furthermore, carbon fiber increased tensile strength but had no noticeable influence on compressive strength. Freeze-thaw conditioning led to a reduction in the compressive and tensile strength regardless of the aggregate type and carbon fiber utilization. In the samples containing waste ceramic aggregate, the electrical conductivity was reduced, and by adding carbon fiber, its electrical conductivity was increased. Exposure to freeze-thaw cycling resulted in an increase in electrical resistance and the passing charge. Waste ceramic incorporation created a similar mixture in terms of skid resistance, while in contrast, the carbon fiber slightly reduced the skid resistance. In addition, freeze-thaw conditioning resulted in an increase in the skid resistance. Besides, in this study, kernelized support vector regression (KSVR) and radial bias function (RBF) neural network models were proposed to estimate the indirect tensile strength (ITS) and compressive strength (CS) values. The results showed that both models have high performance in estimating these values, but RBF was a more efficient model.

Investigation of the influence of bitumen emulsion and Reclaimed Asphalt Pavement content on the mechanical properties of Bitumen Stabilised Materials with high fine particle content

Cold recycling technology is gaining popularity as an economically and environmentally effective way of pavement rehabilitation. The main benefits of the use of cold recycling mixtures (CRMs) in road base courses are associated with the reduction of raw materials consumption by replacing them with recycled materials such as Reclaimed Asphalt Pavement (RAP), as well as the decrease in energy consumption during production and paving compared to Hot Mix Asphalt (HMA). Bitumen Stabilised Materials (BSMs), described as non-continuously bound CRMs, exhibit granular and viscoelastic materials properties due to the presence of local bituminous bonds and a reduced amount of cement. Their mechanical properties are still being investigated.In this paper, Bitumen Stabilised Materials with bitumen emulsion (BSM-E) were investigated. Mixtures characterised by high fine particle content and designed with different Reclaimed Asphalt Pavement (RAP) and bitumen emulsion contents were subjected to Indirect Tensile Strength (ITS) tests at 25°C. TSR water resistance parameter for the mixtures was calculated. Test results were analysed using two-way ANOVA statistical tests.The laboratory test results showed that BSM-E mixtures exhibited different trends of an increase in ITSdry, ITSwet and TSR values as a function of bitumen emulsion content, depending on the RAP amount used. The statistical significance of the effects of bitumen emulsion content, RAP content, and the interaction between these two factors on the tested ITS values was proven.

Evaluating the engineering properties of asphalt mixtures containing RAP aggregates incorporating different wastes as fillers and their effects on the ageing susceptibility

Ageing of asphalt mixtures occurs by intrinsic variables (properties and quantity of the binder and air voids) and extrinsic variables (environmental factors) during production and service life. This topic has been studied extensively in the existing literature, but the potential of alternate filler on the ageing resistance of asphalt mixes and the influence of the interaction between filler and asphalt binder has not been thoroughly examined. The underlying objective of this study was to evaluate the ageing resistance potential of four waste fillers, Jarosite (JS), Hydrated Lime mud (HL), Fly Ash (FA) and Sugarcane Ash (SA), compared to conventional fillers, Stone Dust (SD) on the recycled mix. The recycled mixes were prepared with 50% Reclaimed Asphalt Pavement (RAP) material, locally available natural aggregate, VG-10 grade asphalt binder and studied fillers. The performance properties, including cracking resistance, moisture susceptibility, resilient modulus, rutting, and fatigue resistance of unaged and long-term aged recycled asphalt mix, were evaluated in this study. The results indicated that the ageing resistance of recycled mixtures was highly affected by filler type. HL possesses the highest ageing resistance potential, followed by JS, FA, SA, and SD. The results demonstrated that JS and HL filler significantly improved moisture, rutting, and crack resistance in unaged and long-term aged recycled mix, which are critical factors in extending the durability of pavement. JS and HL filler showed lower fatigue life of recycled mix while tested at higher strain levels due to their higher stiffness. In contrast, FA and SA fillers resulted in a mixed value of properties of the recycled mix compared to SD filler. SA filler showed the lowest cracking resistance (Indirect tensile strength value 1420 kPa for unaged mix and 1573 kPa for aged mix) and moisture resistance (Tensile strength ratio value 78% for unaged mix and 75% for aged mix) among all fillers. The recycled asphalt mix containing SA was found to be highly susceptible to moisture damage, cracking and ageing. The overall conclusions of this study ascertain that the ageing resistance potential of HL was highest among the studied waste fillers for all the studied properties due to its fineness, higher porosity, presence of calcite and increased asphalt film thickness of the mix. • Ageing resistance potential of hydrated lime mud was highest among the studied fillers due to its fineness and the presence of calcite. • Jarosite and hydrated lime mud filler significantly improved moisture, rutting, and crack resistance. • Hydrated lime mud possesses the highest ageing resistance potential among waste fillers, followed by jarosite, fly ash, and sugarcane ash. • Sugarcane ash filler showed the lowest cracking resistance and moisture resistance.

Technical Investigation of the Usability for Foamed Bitumen Stabilized Materials inAsphalt Pavements

Asphalt recycling efforts are increasing in order to reduce the effects of high energy and rawmaterial consumption in the asphalt sector. One of the most common methods for using oldasphalt material, which still retains some value, is recycling with foam bitumen.In practice, for the preparation and evaluation of cold mixes produced using foam bitumen, ITS(Indirect Tensile Strength) and MR (Resilient Modulus) methods are generally used. Amongthese methods, ITS is mostly applied for the evaluation of the materials optimum percentagesvalues and MR test is also used for the evaluation of mixture performance.In the experimental study, firstly for the cold mixes prepared with foam bitumen, optimum foambitumen values of the production series were determined by ITS test. Then, reproductions weremade for these optimum values and resilient modulus values were determined. It was found thatthe ITS and MR values were significantly affected by the material gradation and this showedthe opposite tendency for the materials with the same gradation. The type of active filler waseffective the same as the values of the mixtures on ITS and MR. Especially, the MR resultswere affected by the bitumen grade. As a result of the study, evaluation limit values; 225 kPafor ITSDRY value, 150 kPa for ITSWET value and 70% for TSR, 400 MPa resilient modulus valueand 0.21 layer coefficient value are recommended for FBSM (Foam Bitumen StabilizedMaterial).

Effect of Sandy Soil Partial Replacement by Construction Waste on Mechanical Behavior and Microstructure of Cemented Mixtures

The large amounts of construction waste (CW) generated yearly and its high landfilled proportion worldwide motivate the search for sustainable solutions. Thus, the effect of sandy soil partial replacement for construction waste in cemented mixtures was assessed in the present work in terms of mechanical behavior and microstructure. Distinct cement contents, compaction efforts, and curing periods were evaluated from soil-waste proportion of S75W25, S50W50, and S25W75. Tests of unconfined compression strength (UCS), indirect tensile strength (ITS), ultrasonic pulse velocity, water absorption, mercury intrusion porosimetry (MIP), and scanning electron microscopy (SEM) were conducted. The presence and increase in the amounts of cement and construction waste increase the optimum moisture content of the mixture. In contrast, only the CW content significantly affects maximum dry density. Both S75W25 and S50W50 mixtures resulted in similar UCS and ITS values, which was proven to be statistically equal by analysis of variance (ANOVA) at a 0.05 significance level, favoring CW replacing soil up to 50%. MIP and SEM results explained the sharp mechanical behavior transition obtained in 75% of CW. Cementation reactions resulted in macropores peak reduction and/or peak area translation to the left of the horizontal axis of the PSD curve, while its translation to the right indicates the cement mainly acting as filler, which was supported by SEM tests.

The laboratory performance of asphalt mixture with thermoplastic polyurethane (TPU) and amorphous poly alpha olefin (APAO) compound modified asphalt binder

• The effect of TPU/APAO on the asphalt mixture performance was explored. • APAO could enhance the rutting resistance of TPU modified asphalt mixture. • TPU has positive impact on the cracking resistance of asphalt mixture. • 2 % TPU + 6 % APAO modified asphalt mixture had superior road performance. The using of waste polymer modified asphalt binder in pavement construction is cost effective and beneficial to the environment. In this paper, the modified asphalt binders are prepared by adding thermoplastic polyurethane (TPU, 0 %, 2 %, 4 %, 6 %, by weight of asphalt binder) and amorphous poly alpha olefins (APAO, 0 %, 2 %, 4 %, 6 %). The conventional physical, rotational viscosity and dynamic shear rheometer (DSR) tests were conducted on the modified binders and the results indicated that the addition of APAO could improve the rutting resistance the TPU modified asphalt binder, and the modified asphalt binder with 2 % TPU and 6 % APAO showed the best rutting resistance among the studied binders. To assess the effect of APAO dosage on the performance of TPU modified asphalt mixture, mechanical performance tests including Marshall stability, dynamic stability, indirect tensile, immersion Marshall, freeze–thaw splitting and long-term aging tests were carried out on asphalt mixtures with various TPU/APAO content combinations. The test results proved that 2 % TPU + 6 % APAO modified asphalt mixture showed better resistance to rutting and moisture damage, the superior long-term aging damage resistance, and the excellent anti-freeze–thaw damage ability, when compared to the unmodified asphalt mixture. According to the indirect tensile test results at −10 °C, despite the indirect tensile strength ( ITS ) value of 2 % TPU modified asphalt mixture decreased after APAO added, the ITS value of asphalt mixture modified with 2 % TPU and 6 % APAO was still improved 5.8 % than base asphalt mixture. Based on the comprehensive analysis of the data, 2 % TPU + 6 % APAO modified asphalt mixture has superior road performance, and the performance characteristic of TPU/APAO compound modified asphalt mixture indicated that it could be applied for warmer regions.