Technical, environmental and economic advantages of pavement cold recycling technology are good signs of an efficient method for asphalt concrete pavements rehabilitation. Nowadays, additives are used for improving the implementation situation and upgrading the performance of cold recycled mixtures. The increasing costs of preparing the common additives such as cement and lime, and also the pollutants that result from their production processes were among the most important reasons for widely using waste additives like fly ash. In this study cold waste powder in its natural and ash form was used as an additive in the cold recycled mixture with bitumen emulsion. In addition, lime powder was separately and as a compound was used in the cold recycled mixtures. The performance of the studied mixtures was assessed by Marshall, indirect tensile strength, moisture sensitivity and resilience modulus tests. The test results showed that using coal waste and its ash, improved the mechanical features of the mixture in a way that Marshal stability, tensile strength and resilience modulus were also increased. As the matter of fact, the effects of using coal waste ash on the mechanical features of the mixtures was obviously related to the existence of more Pozzolanic materials in its chemical compounds. Further, the application of coal waste ash, reduced the moisture sensitivity of the mixture, while using coal waste caused an increase in the mixture's moisture sensitivity. Moreover, the results showed that adding 3% of lime to the recycled mix significantly caused a decrease in the moisture sensitivity. Also lime can be used as a complement for coal waste and its ash because the results showed improvement of the mechanical features and the durability of the mixture due to the occurrence of cementitious reactions specifically in the long-term.

The widespread application of bitumen emulsion, especially in surface treatment as the commonest approach to road maintenance in the world, indicates the necessity of finding ways to improve the bitumen emulsion performance. The present research is aimed at investigating the effect of polyphosphoric acid (PPA), as an admixture, on rheological characteristics of the bitumen emulsion. For this purpose, PPA was used at different dosages (i.e., 0.4, 0.8, 1.2, and 1.6 wt.% by weight of the residual bitumen emulsion) to modify the bitumen emulsion. Evaluation of the modified bitumen emulsion samples was performed based on a number of physical parameters (Saybolt Furol viscosity, softening point, penetration, and thermal sensitivity) and dynamic shear rheometer (DSR) and multiple stress creep recovery (MSCR) tests. Results of the bitumen tests showed that the use of PPA improved the bitumen emulsion characteristics in terms of reduced penetration, increased softening point, and decreased thermal sensitivity. With increasing the PPA dosage to up to 0.8 wt.% by weight of residual bitumen emulsion, the resultant changes in the penetration and softening point were significant and improved the bitumen emulsion performance. It was also observed that the value of G*/sin ( ), as a measure of resistance to bleeding in hot weather, increases with PPA dosage in all samples, with the best performance obtained with the samples containing PPA at 0.8 and 1.2 wt.%. An increase in the operating temperature of the PPA-modified samples was seen, so that the sample containing PPA at 0.8 wt.% exhibited 28.6% higher operating temperature than the control sample. The values of R% and %Rdiff parameters increased with the PPA dosage. The observed reduction of percent recovery due to increased temperature in the modified sample indicated the lower sensitivity of the modified bitumen emulsion to temperature rise. The value of Jnr parameter decreased with increasing the PPA dosage, indicating a boost in the resistance of the bitumen emulsion to bleeding.

Three types of chemical additives were used to modify the recycled mixture with emulsion bitumen.   These chemical additives are composite port land cement (CPC), hydrated lime (HL), and a combination of hydrated lime and ballast blast furnace slag (GGBF).   The presence of different additives in the performance of the recycled mixture was investigated by volume and strength tests, humidity sensitivity test, rutting test and bending test at low temperature. The test results show that the performance improvement of emulsion recycled mixture depends on the types and percentages of chemical additives. Several recommendations are given for the selection of chemicals.

Heart - Dogharoon main road project with 122 kilometers in length was constructed with international donation as a part of support to Afghanistan. Due to special condition in this area, lack of good quality material and over loading passing trucks (70 tons per trailer), this road was designed and executed with special consideration. For design of this road, stabilization method using emulsion bitumen and cement with related special equipments was used. PAVERS and PADS software programs were used to design the thickness of the layers. The quality of stabilized base layer was controlled by Falling Weight Deflectometer (FWD).The results showed that the bearing capacity of stabilized layer was more than twice amount of predicted figure. Also the execution time period was decreased considerably in compare with conventional method. To construct roads and runways with high bearing capacity and to increase the roads life time and bearing capacity for heavier loads, various methods are introduced. Methods such as improvement of pavement materials, increasing the layers thickness, renovation with soil stabilization and Cold Mix Recycling (CMR) using lime, cement, bitumen and etc. are used. Stabilization of materials using emulsion bitumen and cement is a method which introduces a proper way for aggregates improvement. The experiences show that, using emulsion bitumen has successfully increases the bearing capacity of roads and runways. Emulsion bitumen as a stabilizer material is used predominantly in recent years and due to its various benefits such as high bearing strength, environmental and economical goals and ease of use is admired by experts. Furthermore, using emulsion bitumen in cold recycling process has specific acceptability and popularity between the users. Emulsion bitumen with exclusive properties can be used in various quality aggregates and also soil materials with high plasticity index. Besides, one of the most uses of emulsion bitumen is in cold recycling process. High speed in performance, easy to work with emulsion bitumen producing plant, easy and quick compaction of produced layers, possibility of using traffic on the constructed layer immediately after construction, and economic and environmental advantages are attractive factors encouraging road builders and contractors to use emulsion bitumen.In this paper and in a study case, while the method of stabilization using emulsion bitumen and cement is introduced, design method, execution procedures and quality control of 122 kilometers main international transit road constructed in Afghanistan is presented and compared with conventional method from economical points of view. The benefits of this method, mix design procedures and related laboratory tests and pavement design are studied and analyzed precisely. The results show that, not only the bearing capacity is increased in comparison with conventional methods but, the execution period and consequently the costs are decreased considerably. At each stage of stabilization, various laboratory tests such as unconfined compression strength test, indirect tensile strength test, in situ and laboratory densities, moisture content and cement and bitumen emulsion contents were carried out. All tests showed that the results are acceptable and in cases, the results of bearing capacity were more than twice as much that was predicted. To determine the modulus of elasticity and to control the quality of the sections performed, a falling weight deflectometer machine was used. The measuring points were every 50 meters in both traffic lines. Back calculated modulus of elasticity of the sections 0 to 23, 23 to 32.3 and 35.3 to 44.4 kilometers of the Heart - Dogharoon main road were determined. The results showed that the average measured modulus of elasticity is more than twice the figure predicted (the predicted figure in design was 1500N/mm2).It means, the bearing capacity of the sections performed, reached to an excellent result and satisfied the high limit of loading in that area.

Due to maturation, the resilient modulus (Mr) of recycled mixes with bitumen emulsion and cement will increase upon curing. Therefore choosing a design Mr for these mixtures will be more complex than conventional hot mixes. Furthermore the Mr test apparatus is not accessible in many project plants and developing a model for estimating the Mr with an inexpensive and accessible method will be desirable. In this research using the results of indirect tensile strength (ITS) and Mr tests at different temperatures (-10, 5 and 25 oC) and curing times (7, 28 and 120 days), two models have been developed for recycled mixture with bitumen emulsion containing type I and pozzolanic cements. Based on the results, first the relation between ITS and Mr in similar conditions (temperature and curing time) for each cement was correlated by a linear relation. Then by considering the effects of temperature and curing on Mr, the aforementioned models were modified for estimating Mr in different conditions.

Pigmented surface treatments are widely used to organize urban spaces (i.e., bike and pedestrian lanes, special lanes, or traffic mitigation measures) and improve the visibility and traffic safety. The present study was performed to investigate the performance and mix design of pigmented slurry seal containing bitumen emulsion and natural pigments replacing natural filler. In this respect, first, characteristics of the powdery pigment and natural filler were investigated by means of XRF, XRD, BET, and FESEM analyses, with the bitumen-filler interactions examined through FTIR tests. Next, 7 pigmented compounds containing red, yellow, and blue powdery pigments (particle size smaller than 0.075 mm) combined with TiO2 were used to partially replace natural filler. Evaluation and comparison of the asphalt samples were performed through wet cohesion test, wet track abrasion test, loaded wheel-sand adhesion test, and loaded wheel-displacement test, with the colorimetric characteristics determined by a spectrophotometer. Results showed that the mixture containing red pigment exhibits the best performance, as compared to other asphalt samples, producing 8.1 and 7.6% higher cohesion than the control sample upon 30 and 60 min of test time, respectively. It further decreased the moisture sensitivity of mixture by 27.6% and vertical displacement under traffic loading by 11.7%. Colorimetric characterization results showed that the use of the TiO2 led to appropriate results when its dosage was limited to 1 – 3% for the blue and red blends and 1% for the yellow blend.

Aeolian sand poses significant challenges to civil engineering projects due to its inherent properties. In this research, a comprehensive experimental program was conducted to investigate the effectiveness of bitumen emulsion and cement in stabilizing aeolian sand. For this purpose, samples were collected from three distinct regions (Northern, Central, and Southern) within the central desert areas of Iran and stabilized with varying percentages of bitumen and cement. After 24 hours of curing in a 60 °C oven, the mechanical properties of these samples, including compressive strength, shear strength parameters, and unconfined compressive strength (UCS), were rigorously evaluated. Results demonstrated that optimal mixture in the Northern region, comprising 6% cement and 10% bitumen, yielded a 130% improvement in compressive strength. For the Central region samples, 6% cement and 6% bitumen resulted in a 57% increase in compressive strength. In the Southern region samples, combination of 6% cement and 8% bitumen provided a 121% enhancement in compressive strength. Direct shear tests indicated significant improvements in shear parameters for the optimal mixtures: A 49% increase in the angle of internal friction and a 125% increase in cohesion. The mixture containing 6% cement and 6% bitumen proved most effective in enhancing the internal friction angle, achieving a 29% improvement. Evaluation of UCS results revealed the greatest increases in this parameter occurred in the Northern and Southern regions for samples containing 6% cement and 10% bitumen, with improvements of 79% and 80%, respectively. In the Central region samples, maximum UCS increase (51%) was observed in samples containing 4% bitumen (alongside the optimal cement content).

In the last few years, several studies have focused their attention on production methods of bitumen emulsion to enhance the cold asphalt properties. Accodrdinly, because of improving some characteristics like temperature susceptibility, ductility and rutting resistance, polymer- modified bitumen emulsion (PMBE) is more sutiable for cold asphalt mixure. Generally, the formulation of PMBE depends on addition methods of the latex. In this study, PMBE is produced based on two types of emulsifier and various manufacturing techniques including soap pre-batching, co-milling, and post-blending. Results showed that soap pre-batching method of type 2 emulsifier and co-milling method of type 1 emulsifier had best performance in physical properties including Saybolt-Furol Viscosity (SFV), softening point and penetration and also rheological properties containing complex modulus (G*), phase angle (δ), rutting parameter (G*/sin δ) and surface performance grade (SPG). Thus, type of emulsifier has an important role in selection of PMBE manufacturing method. So, the design procedure to optimize manufacturing of PMBE is different for each type of emulsifier.

Intelligent methods for predicting some quantities are powerful tools for optimization of predicting models these days. The bitumen emulsion is able to easily mix with wet soil so that the bitumen may be easily distributed and scattered in the soil. The aggregates with PI<6 are quite suitable for stabilization of soils with bitumen emulsion. In this research, two aims are followed, one is Marshal Stability modeling for samples stabilized with emulsion bitumen and cement for roads sub-layers, and the other is cost optimization of using these binding materials in roads construction. 170 stabilized samples were made and tested for training the fuzzy neural network. The Marshal Stability of these samples were modeled by fuzzy neural network and also with using genetic algorithm, the roads execution costs were optimized. For modeling, the MATLAB software programming was used. The results showed that, with presented model, the construction costs decrease considerably.The overall conclusions of this research are summarized as follows:The fuzzy neural network presented, is able to determine the Marshall Stability of the samples stabilized by bitumen emulsion and cement with an accepted error %, and establishes a logical relation between the portions of used cement and emulsion.The fuzzy neural network model is a suitable tool for modeling and estimating the natural problems.The genetic algorithm optimization model presented in this research is able to optimize the performance costs of soil stabilization by cement and bitumen emulsion, and consequently reduces total costs of road projects, considerably.The presented diagram for Marshall Stability – cement and emulsion content is able to specify the required cement and emulsion portions as compared to Marshall Stability.

1. Introduction The pavement engineering approach in recent decades has been to develop the use of cement in pavements, including concrete pavement, in particular roller concrete pavement. Some problems with the implementation and application of this type of procedure have led researchers to focus on the subject matter of this type of pavement. In this respect, one of the problems with the level of roller concrete, which, in technical terms, is “, surface wear”,Known as surface abrasion and surface cracks. Surface abrasion, in addition to reducing the thickness of the pavement layer and defective bearing capacity, in the amount of surface friction and creating a driver safety problem due to the dispersion and throwing of aggregates, it also has a negative effect on the surrounding and passing vehicles. Repair and maintenance is an optimal and economical solution in road pavement management. The use of Chip Seal as preventive maintenance is a two option maintenance for lowvolume traffic in highway pavements (Vaitkus et al., 2018, Khabiri, 2005), In previous studies, micronutrient aggregate has been used more than usual, as an example of research on the effect of surface aggregates and bitumen on the performance of peeled aggregates in chip seal (Aktas et al., 2013). The main purpose of this research is to use a fine grading and emulsion bitumen with a rubber powder additive in roller compacted concrete pavement...