Bitumen Modification Research Articles

Qualitative Evaluation for Asphalt Binder Modified with SBS Polymer

Solutions for safer, more durable infrastructure are required in light of increasing traffic and severe weather in Iraq. The most significant road conservation and maintenance challenges are the pavement's low resistance to dynamic loads and short service life. As a result, vast sums of money are spent annually to enhance the road service capacities in Iraq. Thermoplastic electrometric polymers for bitumen modification create long-lasting, cost-effective roadways. This study aims to determine how the mechanical properties of neat asphalt binder change when styrene butadiene styrene (SBS) is added as a modifier. The current research investigates adding three percentages of SBS (3, 5, and 7% of the weight of bitumen). Both neat and polymer-modified bitumen (PMB) were subjected to a series of physical laboratory and Superpave tests, including a dynamic shear rheometer tester (DSR) and a storage stability test. In addition, a chemical analysis test was conducted to identify any change in the neat binder chemical composition due to the addition of SBS polymer. The results indicated that 5% of SBS polymer was the optimum addition percentage to the local asphalt in Iraq. Additionally, it reduced the susceptibility of bitumen to temperature changes and enhanced its characteristics in all laboratory tests. The obtained PMB significantly improved rutting and fatigue factors compared to the neat asphalt binder. Based on the DSR tester and the storage stability test, the ratio of 5% SBS met the requirements of class PG76-10, used in the central and southern governorates of Iraq. Using SBS polymer on the surface course in Iraq reduces road damage due to the scorching summer sun, reduces the likelihood of rutting and fatigue cracking, and works well in hot regions, resulting in roads that last longer, provide comfortable riding, and require less maintenance.

Effects of the Mixing Process on the Rheological Properties of Waste PET-Modified Bitumen

This paper analyses the key findings of a study devoted to PET-modified bitumen. The research program was run according to the D-optimal experimental plan based on a factorial design. Five factors, i.e., the type of polymer (source), the type of bitumen (qualitative factors), PET amount, mixing rate, and mixing temperature (quantitative factors), controlled the bitumen–polymer mixing process. The experiment included a series of determinations of bitumen’s rheological characteristics obtained by MSCR (Jnr, R) and G*/sin(δ) at 50 °C, 60 °C, and 70 °C. The low-temperature properties of the composite (critical temperature) were evaluated using a BBR test. The findings showed that bitumen modification with PET primarily reduced the creep susceptibility of the bituminous–polymer mixture. The low-temperature characteristics of the modified bitumen played a secondary but essential role. The amount of polymer and the mixing rate interacted with the temperature, significantly reducing the stiffness of the composite, while the type and amount of bitumen had a substantial effect on the results obtained in the BBR test. It is worth noting that when combining bitumen and plastomer, special attention should be paid to ensuring a high level of homogeneity of the mixture by controlling the parameters of the mixing process accordingly. The tests and analyses provided crucial models (GLM), which allowed for the prediction of the plastomer-modified bitumen’s low- and high-temperature properties. The resulting relationships between factors and the identification of their impact on the bitumen properties enable a better understanding of the process of bitumen modification with PET. The conclusions presented here serve as a basis for future optimisation of the modified bitumen composition. The performed studies indicate that the use of >3% plastomer in bitumen 70/100 allows for a reduction in its susceptibility (MSCR) to below 0.5 kPa−1, making it suitable for bituminous mixtures for high-traffic roads. No significant increase in critical temperature (BBR) was observed.

Waste motor engine oil – the influence in warm mix asphalt

Employing Hot Mix Asphalt (HMA) technology for asphalt pavement construction results in the emission of greenhouse gases and other harmful pollutants, contributing to significant air pollution due to extensive energy consumption. Consequently, the adoption of Warm Mix Asphalt (WMA) is recommended, given its potential for enhanced energy efficiency and reduced emissions due to lower mixing and production temperatures compared to HMA. This research delves into the impact of incorporating waste motor engine oil (WMEO) as a bitumen modifier in warm mix asphalt. The investigation involved adding WMEO at various percentages, specifically 0%, 3%, 4%, and 5% based on the weight of bitumen. The study assessed the performance of the samples in terms of penetration, softening point, stability, flow, and stiffness. The findings revealed that the incorporation of WMEO in warm mix asphalt led to a substantial improvement in penetration and softening point. Moreover, the results indicated that incorporating WMEO as a bitumen modifier could enhance the performance of WMA in terms of stability, flow, and stiffness.

Rheological Evaluation and Life Cycle Cost Analysis of the Geopolymer Produced from Waste Ferrochrome Electric Arc Furnace Fume as a Composite Component in Bitumen Modification

Rheological Evaluation and Life Cycle Cost Analysis of the Geopolymer Produced from Waste Ferrochrome Electric Arc Furnace Fume as a Composite Component in Bitumen Modification

Effect of recycled vegetable oil on the performance of nanomarl-modified asphalt mixtures

In response to the demand for a greener approach to pavement infrastructure and the economic benefits associated with alternative materials, the modification of neat binders has been a consistent focus. This research aimed to enhance the characteristics of asphalt binders and mixtures by incorporating recycled vegetable oil (RVO) and nanomarl. RVO was added to 60/70 penetration bitumen at concentrations of 1%, 3%, and 5% by weight, while nanomarl was kept constant at 5% by weight of the bitumen. Various physical, rheological, and microstructural properties of the modified binders were evaluated, including penetration, softening point, viscosity, rutting resistance, fatigue resistance, creep, stiffness, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). Furthermore, the moisture susceptibility and rutting resistance performance of asphalt mixtures incorporating these modified binders were investigated through analyses of tensile strength ratio and Hamburg wheel tracking. The test results revealed that the incorporation of RVO in bitumen led to a gradual increase in the penetration value of the modified bitumen. Simultaneously, the softening point and viscosity of the modified bitumen decreased, indicating that the addition of oil rendered the modified bitumen softer. However, the inclusion of nanomarl in RVO-modified bitumen improved its viscoelastic behavior and positively influenced its rheological properties under both unaged and aged conditions. Specifically, the addition of 5% nanomarl resulted in reduced penetration value, increased softening point, viscosity, rutting resistance, fatigue resistance, creep stiffness, and improved relaxation behavior at low temperatures. The most favorable outcomes were observed when incorporating 1% RVO with 5% nanomarl. Moreover, SEM and FTIR analysis demonstrated successful blending of the additives into the bitumen, without any evidence of phase separation. This indicates a homogeneous distribution of the additives within the bitumen matrix.Practical application: The modification of bitumen with waste or recycled oils for the production of asphalt mixture has been successfully studied in numerous researches. However, this study introduces a novel approach by synergistically combining recycled vegetable oil (RVO) modification with the incorporation of nanomarl particles into asphalt mixture. The innovation aspect lies in the integration of two sustainable and environmentally friendly components, RVO and nanomral, to enhance asphalt performance. The findings offer a blueprint for incorporating sustainable materials and approaches in road construction projects. Pavement engineers can adopt the use of RVO modification and nanomarl particles to create longer-lasting and environmentally friendly asphalt pavements. In regions with challenging climatic conditions, the use of this modified asphalt can lead to improved infrastructure resilience. Roads built with these materials can better withstand temperature fluctuations. The integration of RVO and nanomarl particles offers improved performance, cost-effectiveness, reduced environmental impact, and also opens avenue for further exploration and optimization of asphalt mixtures incorporating innovative additives.

Effects of solvent-free bentonite fluid on physical, rheological and aging properties of SBS modified bitumen

Layered silicate materials were often used for bitumen modification, but their improvement effect on bitumen performance was limited due to their poor compatibility with bitumen. Introducing long-chain organic compounds on the surface of inorganic materials can make them exhibit solvent-free fluid characteristics, which can significantly enhance the compatibility between inorganic and organic materials. In this study, 3-(trimethoxysilyl propyl) dimethyl octadecyl ammonium chloride (DC5700) and nonylphenol polyoxyethylene ether sodium sulfate (NPES) were used to organically treat bentonite (Ben) to prepare solvent-free bentonite fluid (Ben-fluid) so as to effectively improve the overall performance of styrene-butadiene-styrene copolymer (SBS) modified bitumen (SMB). Ben and DC5700 organically treated bentonite (DC5700-Ben) were used as comparative samples. The microstructure, ultraviolet reflectance and lipophilicity of Ben, DC5700-Ben and Ben-fluid as well as fluidization characteristics of Ben-fluid were tested and characterized. The results of X-ray diffraction spectrometer and Fourier transform infrared spectrometer (FTIR) demonstrated that DC5700 intercalated into the layers of the Ben and chemically grafted on the Ben surface, and the NPES was anchored on DC5700 molecules through ionic bonds. Compared with Ben and DC5700-Ben, Ben-fluid had the highest ultraviolet reflectance and the best lipophilicity. As the temperature exceeded 82.3 ℃, the fluidization characteristics of Ben-fluid began to appear. Meanwhile, the effects of Ben-fluid on physical, rheological and aging properties of SMB were investigated. Ben-fluid was more conducive to enhance the high-temperature stability of SMB than Ben and DC5700-Ben, and has less adverse effects on the low-temperature physical and rheological properties. The aging results of different SMBs revealed that the change in physical properties of SMB containing Ben-fluid after thermal and ultraviolet aging was significantly lower than that of SMB containing Ben and DC5700-Ben. In addition, FTIR showed that compared with Ben and DC5700-Ben, the Ben-fluid could inhibit the increase of carbonyl index and the decrease of butadiene index of SMB after aging. Comprehensive analysis suggested that Ben-fluid was more conducive to improve the physical, rheological and anti-aging properties of SMB.

The effect of the crumb rubber type and amount on dry process modified asphalt mixture and on low-temperature cracking and high-temperature rutting

ABSTRACT One of the best examples of circular economy is the application of crumb rubber for asphalt mixture or bitumen modification. The main objective of this study was to determine the effect of crumb rubber type and amount on dry process modified asphalt mixture performance in terms of rutting resistance, water sensitivity, air void content, stiffness, resistance to fatigue and low-temperature cracking. The study shows that the use of untreated crumb rubber increases the air void content by up to 2.7% compared to the reference mixture while the use of treated crumb rubber reduces air void content up to 0.9%. The use of untreated and treated crumb rubber from 0.5% to 3.0% has a negative effect on water sensitivity (strength decreases by 59.5%). The use of crumb rubber up to 1.5% has a positive effect on resistance to rutting, stiffness and resistance to fatigue (proportional rut depth PRDAIR is improved by 0.6–1.1%, stiffness – by 15.4–16.2% and resistance to fatigue – by 24.7–24.9%). This research revealed that the amount up to 3.0% of both types of crumb rubber has a positive effect on the resistance to low-temperature cracking (40.6–52.1%) comparing to the reference mixture with neat bitumen.

Performance of Stone Matrix Asphalt Modified with Crumb Rubber and Fibres

This article investigates the impact of Crumb Rubber Modified Bitumen (CRMB) and fibre additives (aramid fibre and basalt fibre) on the performance properties of Stone Matrix Asphalt (SMA) mixtures. Tests were conducted to evaluate mix design, draindown, cantabro loss, moisture sensitivity, rutting resistance and fatigue behavior. The Marshall method, the draindown parameters (ASTM D6390-11) and the cantabro loss characteristics (ASTM D 7064) were used to examine the mix design qualities. The modified Lottman test was used to assess the moisture sensitivity of SMA mixes. The roller compactor cum rut analyzer was used to assess rutting resistance. Findings showed that CRMB and fibre additives effectively controlled binder draindown and minimized abrasion loss in SMA mixtures. SMA-CRMB mixtures had higher draindown, but comparable cantabro loss than SMA-AF and SMA-BF mixtures. Incorporating CRMB and fibre additives enhanced moisture sensitivity, rutting resistance and fatigue behavior. SMA mixtures with 0.3% fibre addition displayed similar performance properties to SMA with CRMB. Further, substituting fibre additions for CRMB in SMA combinations may yield similar performance. KEYWORDS: Stone matrix asphalt, Crumb rubber-modified bitumen, Fibre additives, Draindown, Cantabro loss, Moisture sensitivity, Rutting resistance, Fatigue behaviour.

Evaluation of Asphalt Produced from Waste Tyre and Polyethylene Terephthalate-Based Bitumen with Paraffin Wax as Rejuvenator

During pavement construction and rehabilitation, large amounts of bitumen are often required. As such, the need for material diversification in pavement construction is essential to conserve the non-renewable natural resource deposits. This study assessed the use of Polyethylene Terephthalate (PET) waste and grounded tyre combined in varying proportions with aged bitumen modifier, and wax as a rejuvenator in the production of asphaltic concrete. A 10% polymer replacement level was maintained for all modified mix batches with three distinct proportions: 6%-PET:4%-GWT, 5%-PET:5%-GWT, and 4%PET:6%-GWT. The rejuvenator was added in percentages 1, 2, and 3 by the total mass of modified bitumen mix. Results showed that the penetration values of the modified bitumen mixes with wax fall between bitumen grades 20–60, indicating suitability in warmer climates. Ductility results indicate an increase in ductility upon modification compared to the control mix. The 6%PET/4%GWT samples obtained the highest ductility values (M2 = 23.5 cm, M5 = 12.5 cm, M8 = 22 cm, M11 = 24.25 cm). The highest softening point value (84.5°C) was obtained with M3 (5%PET/5%GWT/0%wax). The inclusion of wax as a rejuvenator led to massive increases in viscosity values compared to both the control mix and the mixes without wax. Flash and fire point results fell within the same range, implying that the modification and rejuvenation did not yield significant impact on the flash and fire point properties. Marshall stability results showed that no modified bitumen batch obtained stability up to the control mix. The highest flow value (5.9 mm) was obtained with the M12 (5%PET/5%GWT/3%wax) mix. This was about 47.45% higher than that of the control mix and 23.7% higher than that of the corresponding mix without wax. The study recommends material diversification as well as dosage variation as essential in the drive towards achieving optimum stability in asphaltic composites.

Green synthesis of a broad-spectrum UV-blocking bitumen modifier: Investigation of anti-aging performance and mechanism in bitumen

The popularization of inorganic nanomaterials doping, which serves as an effective method to improve the aging resistance of bitumen, is constrained by suboptimal lipophilicity and limited broad-spectrum UV absorption. To overcome this, we synthesized an environmentally-friendly, broad-spectrum UV-blocking nanocomposite by coating nano TiO2–ZnO (Nano-TZ) with sustainable lignin. TEM, T-IR, and photocatalytic activity test results indicate successful lignin coating on the Nano-TZ surface, with the optimal concentration being 15% (Nano-15L@TZ). Rheological test results demonstrated improved UV- and thermal-oxidative aging resistance of the Nano-15L@TZ-modified bitumen compared to those treated with uncoated nanomaterials. The synergistic modification mechanism of the Nano-15L@TZ composite was elucidated by combining the contact angle with UV–Vis and XPS VB tests. Nano-TZ exhibited broad-spectrum UV blocking properties that mitigated the UV aging of bitumen and lignin, while lignin effectively improved its compatibility with bitumen and captured radicals generated by Nano-TZ and aged bitumen.

Investigating the Potential of High-Density Polyethylene and Nano Clay Asphalt-Modified Binders to Enhance the Rutting Resistance of Asphalt Mixture

This study investigates the potential of two bitumen modifiers, high-density polyethylene (HDPE) and nano clay (NC), to enhance the rutting resistance of asphalt mixture. Four HDPE asphalt binders were prepared by mixing the HDPE at percentages of 2%, 4%, 6%, and 8% with the virgin binder, while four NC asphalt binders were produced by mixing the NC at percentages of 1%, 2%, 3%, and 4%. The consistency and flow of virgin binder, HDPE binders, and NC binders were evaluated by penetration, softening point, and viscosity tests. The results show a gradual increment in the binder stiffness by increasing the percentage of both modifiers. The static creep test was conducted at a temperature of 40 °C to evaluate the rutting resistance. The results confirm that both modifiers can greatly improve the rutting resistance of the asphalt mixture, where 8% HDPE and 3% NC modifications reduce the strains provoked in the asphalt mixture under loading by about 50%. According to the correlation analysis, the mixture rutting performance is highly attributed to the binder stiffness, where the lower the penetration value of the asphalt binder, the lower the strains in the asphalt mixture and the higher the stiffness modulus of the asphalt mixture.

Bio-polymer modified bitumen

Bitumen is a key constitutive material in asphalt pavements. It binds together the rock scaffolding of a pavement. Bitumen provides asphalt pavement with flexibility and enables it to respond to traffic loading and return to its original condition after the loading, i.e. bitumen restores/repairs the damage. In Porous Asphalt (PA) or Stonemastic Asphalt Mix (SMA) asphalt mixtures, due its open graded structure, bitumen modifiers are used to improve or restore bitumen physical and mechanical performance. Traditionally bitumen modifiers are made with products of crude oil, such as: ethylene vinyl acetate (EVA) copolymers and styrene–butadiene–styrene (SBS). As crude oil production declines and the environmental and financial costs of crude oil extraction increase, there is a need to identify environmentally sustainable alternatives to use in bitumen. Bitumen modifiers generated from biological sources offer an environmentally friendly and economically viable alternative to crude oil based bitumen modifiers. This paper describes how PHBV (poly-3-hydroxybutyrate-co-3-hydroxyvalerate), a bio-based co-polymer, might be used as an alternative bitumen modifier. The effect of PHBV on 70/100pen was investigated for this paper. The chemical and physical effect of the PHBV on the bitumen performance was investigated using Gel Permeation Chromatography, Fourier Transformed Infrared Spectroscopy, Differential Scanning Calorimetry, microscopic imaging and Dynamic Shear Rheometer tests. The results indicate that PHBV has significant potential as a bitumen bio-polymer modifier.

Research on the Development of a Way to Modify Asphalt Mixtures with PET Recyclates.

Due to the growing need to recycle plastics, new possibilities for their reuse are intensively sought. In the Asian market, waste polymers are increasingly used to modify road bitumen. This solution is beneficial in many aspects, especially in economic and ecological terms. In this work, recycled poly(ethylene terephthalate) (RPET), obtained from storage points located in Lesser Poland, was subjected to material recycling, and its properties were examined using three analyses: differential scanning calorimetry (DSC), thermogravimetric analysis (TG), and Fourier transform infrared spectroscopy (FTIR). The most important point of this research was the selection of conditions for obtaining modified asphalt mixtures through the addition of RPET. Subsequently, the effect of the polymer on the properties of road bitumens was assessed on the basis of penetration tests, softening point, elastic recovery, and structure. In the last stage of our research work, asphalt mixtures with the addition of modified waste PET (PMA) containing mineral filler in the form of basalt dust were obtained. The properties of the obtained mineral-polymer-asphalt mixtures were compared in terms of frost resistance, structure, and abrasion resistance with the properties of mineral-asphalt mixtures that were taken from damaged road surfaces in four points in the city of Tarnów (Lesser Poland) in the winter of 2022. It has been shown that the modification of road bitumen with the use of recyclate and mineral filler has a significant impact on its performance properties.

MODIFICATION OF BITUMINOUS BINDERS WITH PETROCHEMISTRY WASTE

An analysis was made of the possibility of using sludge from the production of sulfonate additives and low
 molecular weight polyethylene for the modification of bituminous materials. It has been established that the combined
 effect of the components of the proposed combined additive on the structure of the bituminous binder makes it possible
 to increase its heat resistance, plasticity and elasticity, with acceptable adhesion to the surfaces of mineral materials.
 Modification of road bitumen with a combined additive based on sludge from the production of a sulfonate additive and
 low molecular weight polyethylene will expand the range of polymer modifiers for polymer-bitumen compositions,
 reduce the involvement of imported additives, reduce the burden on the environment and obtain a positive economic
 effect.

Aging Resistance of Bitumen Modifiers: A Comprehensive Review

Abstract The deterioration of physical and mechanical properties of bituminous materials that are attributable to the aging of bitumen is one of the major causes of reduction in service life of flexible pavements. Thermal-oxidation and photo-oxidation aging are the two major types of aging of bitumen. Heat and oxygen cause thermal-oxidative aging, whereas ultraviolet irradiation and oxygen causes ultraviolet photo-oxidative aging of bitumen. Aging of binder leads to significant changes in the chemical composition of bitumen resulting in reduction of cracking resistance of bituminous mixes because of hardening of bitumen. So, it is quintessential to reduce the rate of hardening of bitumen induced by aging for prevention of premature failure of flexible pavements. The type of bitumen used for production of bituminous mixes have a significant effect on aging resistance of bitumen. The bitumen can be modified by using different types of modifiers such as antioxidants, bio-oils, nanomaterials, polymers, rubber, and ultraviolet absorbers. In addition to this, the modifiers such as fillers, warm mix additives, and rejuvenators also affect the aging resistance of bitumen. However, the effectiveness of these modifiers in preventing the hardening of bitumen because of aging varies with type of aging. The modifiers that exhibit improvement in thermal-oxidative aging resistance of bitumen are found to be less effective in improvement in photo-oxidative aging resistance and vice-versa. So, it is imperative to understand the effectiveness of different types of bitumen modifiers for the prevention of thermal-oxidative and photo-oxidative aging of bitumen. This review documents the resistance of different types of modifiers to thermal-oxidative and photo-oxidative aging. Finally, the scope for future work based on the critical gaps identified from existing works is also provided to assist further research.

MODIFICATION OF PETROLEUM BITUMENS WITH RUBBER WASTE

This article provides an overview of the modification of petroleum bitumen with rubber waste, considers various technologies for the production of rubberized asphalt binders: dry process, wet process with high viscosity and wet process without mixing, shows their advantages and disadvantages.

Evaluation of olive pomace and SBS modified bitumen to the performance characteristics

This study investigated the applicability of olive pomace (OP) waste, a biomass waste, in bitumen modification. The OP modification was compared with styrene butadiene styrene (SBS) modified bitumen, which is widely used in asphalt modification, in terms of performance and cost. The OP and SBS binders were tested with conventional and rheological experiments. For this, modified asphalt binders were obtained by adding OP (wt. 4, 8, 15, 19, 25, 30%) and SBS (wt. 4, 4.5%) to pure B 50/70 penetration bitumen. The conventional test results of OP and SBS modified bitumen are close to each other, both modified bitumen decreased the penetration and temperature sensitivity of pure bitumen and increased the softening point. According to rheological test results, it was seen that the critical OP ratio was obtained from the 19% OP addition, and the critical SBS ratio was obtained from the 4% SBS addition and they exhibited the same performance grade. Then, for the hot mix asphalt (HMA) design, the optimum bitumen content was determined according to the Marshall method by using aggregate and B 50/70 pure bitumen, 19% OP, and 4% SBS modified bitumen. The effects of OP and SBS-modified bitumen on the mechanical properties of HMA mixtures were evaluated using Marshall stability tests. It could be said that OP-modified bitumen behaves like a more elastic solid at high temperatures, due to its lower penetration and higher softening point than pure bitumen. It has been observed that 19% OP additive provides an improvement, especially in rutting resistance, fatigue, and thermal crack resistance and 19% OP modified binder can be considered as an alternative to 4% SBS modified binder in general in terms of performance and cost. As a result, it is evaluated that OP can be used as a remedial additive in asphalt modification and contribute to the increase of pavement performance, and also that the damage of this waste material to the environment can be eliminated.

Laboratory evaluation of the effect of waste materials on mechanical properties of asphalt binder and mixture containing combined natural binder and waste polymer

The current study's objective is to examine the characteristics of waste polymer-incorporated natural binder modified binders and combinations. Recycling and making use of waste polymers has gained interest as a possible environmentally and financially responsible bitumen modification method. The goal of the current study was to explore the rheological and mechanical characteristics of mixes and bitumens modified with natural binder that contained various amounts of waste polymer. Original bitumen modified with 5%, 10%, and 15% weight of asphalt binder as well as varied amounts of RPW (3%, 5%, and 7% weight), were all employed as samples of bitumen in the study. Several asphalt binder tests such as conventional tests and rheological ones were performed on binder samples. The results showed that adding waste polymer to the natural binder modified binders enhanced their high-performance temperature, as seen by the decreased penetration and increased softening point values. Results revealed that binders containing 5%, 10% and 15% gilsonite have fatigue life at 2.5% strain about 1.06, 9, and 9.8 times higher than original binder, respectively. Results revealed that addition of 5%, 10% and 15% gilsonite leads to decrease the Jnr value by 36%, 87%, and 96%, respectively. While addition of 3%, 5%, and 7% RPW leads to increase the fatigue life by 1.12, 3.75, 5 times higher than 5% gilsonite modified asphalt. Additionally, the binders treated with waste polymers performed better at low temperatures as seen by their decreased stiffness and enhanced fracture resistance. However, a substantial proportion of waste polymer caused both low and high temperature performance to decline. Overall, this study indicates that waste polymer has the ability to enhance the performance characteristics of naturally occurring binder modified binders, but it is important to carefully evaluate the ideal waste polymer percentage in order to obtain the required performance advantages.

Physical, Mechanical and Structural Characteristics of Sulfur Concrete with Bitumen Modified Sulfur and Fly Ash

Industrial waste usage in the technology of construction materials is currently in a relevant and promising direction. Materials made of industrial waste have a lower cost and are highly environmentally friendly. The objective of this study is to develop effective compositions of sulfur concrete based on the maximum possible number of various wastes of the local industry for this and to investigate the characteristics of this composite. Test samples of sulfur concrete were made from sulfur, fly ash, mineral aggregates and bitumen additive. The dosages of fly ash, sand and bitumen varied, while the content of sulfur and crushed stone remained constant. The following main characteristics of sulfur concrete were determined: density; compressive strength; and water absorption. Tests of sulfur concrete were carried out after 1 day and 28 days of hardening. The best values of compressive strength (24.8 MPa) and water absorption (0.9%) were recorded for the composition of sulfur concrete at the age of 28 days with the following content of components: sulfur—25%, modified with 4% bitumen of its mass; fly ash—10%; crushed stone—40%; and sand—25%. The optimal composition of modified sulfur concrete showed compressive strength up to 78% more and water absorption up to 53% less than the control composition. The characteristics of the sulfur concrete samples after 28 days of hardening differ slightly from the values after 1 day of hardening (up to 1.8%). An analysis of the structure confirmed the effectiveness of the developed composition of sulfur concrete in comparison with the control.

Research on the Rheological Properties and Anti-Aging Mechanism of Paper-Black-Liquor-Modified Bitumen

The production process of the traditional paper making process produces a large amount of waste water, known as paper black liquor. It is needed to explore new ways of reusing this waste and replacing part of the base bitumen to reduce the consumption of non-renewable resources, such as petroleum, thus obtaining better environmental, economic, and social benefits. This paper analyses the feasibility of using paper black liquor, which contains a large amount of lignin, as a modifier for bitumen in the paper industry. Samples of modified bitumen were prepared with 15%, 30%, and 45% of the base bitumen replaced by paper black liquor, and a control group of base bitumen was prepared for testing. The samples were subjected to an 85 min short-term ageing test, FTIR scanning test, thermogravimetric test, frequency scanning test, MSCR test, and LAS test. The analysis of the FTIR and thermogravimetric tests showed that the paper black liquor was mainly composed of lignin and some cellulose, and contained a small amount of salts with Na ions; based on the results of the frequency scan, the compatibility analysis of the vGP curve showed that the modified bitumen was more compatible in the high-temperature range after short-term ageing, thus inferring that the water content of the concentrate had an influence on the compatibility, making it necessary to further investigate different optimum water contents to achieve the best performance and benefit. The incorporation of paper black liquor improved the rutting resistance and fatigue resistance of the modified bitumen, and also gave the paper-black-liquor-modified bitumen a better ageing resistance than the base bitumen. While demonstrating the feasibility of using paper black liquor as an bitumen modifier, this study also helps to provide a basis for theoretical applications of biomass materials in the field of road engineering.