Properties Of Asphalt Concrete Research Articles

Assessing the Marshall Properties of Porous Asphalt Concrete

Porous asphalt paving is a modern design method that differs from the usual asphalt pavements' traditional designs. The difference is that the design structure of porous pavements allows the free passage of fluids through their layers, which controls or reduces the amount of runoff or water accumulated in the area by allowing the flow of rain and surface runoff. The cross-structure of this type of paving works as a suitable method for managing rainwater and representing groundwater recharge. The overall benefits of porous asphalt pavements include environmental services and safety features, including controlling the build-up of contaminated metals on the road surface, rainwater management, resistance to slipping accidents, reduced splashing, and spraying pedestrians and drivers.
 In this study, the porous mixture's volumetric and physical properties were tested, and the use of carbon fibers as a type of mixture improver. The results were compared after performing the following steps: Selecting the best gradient for the porous asphalt mixture by selecting the largest proportion of air voids from three gradations group according to specifications (ASTM 7064), then choosing the optimum asphalt ratio according to the standard specifications, which are the value of drain down % and the Cantabro abrasion loss % value, as well as the ratio of air voids. After obtaining the optimum asphalt ratio, samples of the asphalt mixture were prepared. Carbon fibers were added to it at a rate of (0.3%) by weight of the total mix and a length of (2 cm) and prepared samples without additives. They were tested by a Marshall device to calculate the stability and flow value and show the effects of fibers on porous asphalt concrete properties. An increase in the stability value and a decrease in the flow and reduction in the drain down rate during exposure to high temperature were observed for the samples containing carbon fibers, by 48.8%, 44%, and 72%, respectively

The effects of porosity, asphalt content and fiberglass incorporation on the tensile strength and resilient modulus of asphalt concrete blends

Asphalt concrete is the prevailing material used for road surface construction. Its adequate characteristics in providing stability, durability and driving safety are controlled by complex interactions between its components. Thus, it is important to estimate the sensitivity of asphalt concrete mechanical properties as a function of its volumetrics. For this study, different combinations between asphalt content (3.5, 5 and 7.5%) and porosity values (above 4%) were used in order to disassociate these properties. The influence of mixing in fiberglass (0.5%) was also analyzed. It was found that porosity is significantly more relevant than the asphalt content in the prediction of tensile strength and resilient modulus of fiber-free asphalt concretes. In fiber-reinforced mixtures, the mechanical properties are improved by increasing the asphalt content, which suggests a better bonding between fibers and aggregates. For both cases, decreasing porosity is beneficial. By grouping both sets of results, it was possible to create a unique theoretical curve for both the tensile strength (qt) and the resilient modulus (RM). The RM/qt ratio was 5800 for the fiber-free group, and 3900 for the fiber-reinforced group - suggesting a better fatigue life indicator for asphalt concretes when fibers are added.

ОПРЕДЕЛЕНИЕ ПОКАЗАТЕЛЕЙ ВЗАИМОДЕЙСТВУЮЩИХ ПОДСИСТЕМ ПРОМЫШЛЕННЫХ ПРЕДПРИЯТИЙ ДЛЯ ДОСТИЖЕНИЯ ЦЕЛЕЙ В ОБЛАСТИ КАЧЕСТВА

Highways are the most important component of country's economic development. They are a complex of engineering structures that are subject to various kinds of deformations during operation. The causes of premature defects are outdated technologies, poor quality materials, high traffic loads, and weather conditions. On average, after 2–3 years of the new road operation, pits, overflows, potholes, cracks, rutting occur on asphalt concrete pavement, its presence worsens the traffic conditions on the road and violates the unimpeded passage of cars. To extend the life cycle of a transport object, there are preventive measures that prevent the destruction of road surfaces. Such activities include regular maintenance and repair work. One of the effective measures is the use of road impregnation materials (RIM). Road-impregnation materials are used in case of need to prevent aging of the organic binder in the composition of asphalt concrete in the coating, as well as to reduce the impact of external factors. In this article, the influence of the basis of the impregnating material of two manufacturers on the indicators of the properties of asphalt concrete of various degrees of destruction is investigated. Among the considered impregnating compositions, solvent-based road impregnation materials proved to be the most effective. It has been established that the abrasive effect on samples of asphalt concrete significantly reduces the effectiveness of impregnating materials, especially based on bitumen emulsion.

Increasing the Durability of Asphalt Pavement - the Road to Road Safety

Based on literature data, the paper analyzed the impact of transport operational indicators related to the quality of road surface coverage on road safety. It presented the results of experimental studies on the effect of the road adhesion cationic thermostable additive on the properties of bitumen and asphalt concrete. The authors identified that the introduction of this additive leads to an increase in the viscosity and softening temperature of bitumen, its adhesion to mineral materials, which has a positive effect on strength, water resistance, shear stability, crack resistance, fatigue durability of asphalt concrete. The conclusion was made about the regularity of improving road safety, related to the improvement of the quality of the pavement, arranged from asphalt concrete with the application of the tested additive.

ДРУГИЙ СТАНДАРТ УКРАЇНИ НА БІТУМИ НАФТОВІ ДОРОЖНІ В’ЯЗКІ: ЗМІСТ ТА ПЕРСПЕКТИВИ

The first Ukrainian standard ДСТУ 4044 “Viscous petroleum road bitumens. Technical conditions” was implemented in 2002. According to its content and list of indicators, it met the level of the oil refining industry of Ukraine and the state of the road industry. In addition to conventional indicators, it included additional indicators of adhesion and mass content of paraffins. The indicator for paraffin remained unregulated, because there was neither acceptable method nor necessary equipment, and in generally an intention of manufacturers and users to apply it. The standard referred to in the article differs from the previous one by the principle of assigning indicators and their list. This is largely due to Ukraine’s accession to the European Free Trade Association and the deepening of scientific knowledge on predicting the behavior of bitumen under different conditions and their impact on the properties of asphalt concrete. Accordingly, the limits of normalization of bitumen grades on the depth of needle penetration were changed, which led to an increase in amount of grades from 4 to 5. Using the dependence of the penetration index on the softening point temperature, its new normative values are ordered. The Fraas breaking temperature provided by the standard is slightly lower than that normalized EN 12591 which is due the climatic conditions of Ukraine. The rate of adhesion of bitumen to the surface is normalized, which quantitatively characterizes the adhesion of bitumen to the mineral substrate, the least favorable for interaction. It is proposed to determine the indicators of technological aging by the RTFOT method. The standard contains additional indicators to be determined according to the harmonized European standards ДСТУ EN 12607-1 and ДСТУ EN 13302 (methods for determining the dynamic viscosity). Additional standards include equal viscous heating temperatures of bitumen in the production of asphalt mixtures and their compaction. The first is the temperature, which corresponds to a bitumen viscosity of 0.5 Pas, the second is 10 Pas. Elongation at a temperature of 0 ºC is included in the standard as a certain analogue of the breaking temperature. Based on the fact that at this time the next European standard is in the final stage before approval, the values of additional indicators can be included into this standard after adjusting their values with European ones based on the characteristics of bitumen used in Ukraine. Keywords: bitumen, depth of needle penetration, softening point temperature, adhesion, ductility, cohesion, heating.

Simulation on heat transfer of phase change material modified asphalt concrete for delaying black ice formation

PURPOSES : This study aims to determine the type (e.g., melting point, freezing point, latent heat fusion) and optimal content of phase change material (PCM) based on the numerical and experimental analyses evaluating the effects of heat transfer in PCM-modified asphalt pavement systems. METHODS : The effect of PCM on the thermophysical properties of PCM-modified asphalt concrete can be taken as an effective volumetric heat capacity. The volumetric fraction of PCM was calculated using an iterative method. The numerical model was established and computed using the MATLAB 2020 software. The optimum PCM design tool was developed to select the type and contents of the PCM. The PCM was chosen based on the following criteria: black-ice-formation delay time, minimize temperature increase, and increase temperature area. To validate the numerical model, asphalt mixtures were modified with varying PCM contents, and the temperature response of the PCMmodified asphalt samples was examined via temperature test. RESULTS : The numerical results showed that incorporating PCM into the asphalt mixture can slow the cooling rate of the pavement system. The predicted results from the optimum PCM design tool were highly consistent with the measured values from the laboratory temperature test. CONCLUSIONS : The temperature of PCM-modified asphalt pavement can be predicted via numerical method. The effect of PCM on the thermophysical properties can be considered as effective volumetric heat capacity; while the volume fraction of PCM can be calculated via an iterative method. The accuracy of the numerical model was confirmed by a high agreement between the measured and predicted values.

ИССЛЕДОВАНИЕ БИТУМНОГО ВЯЖУЩЕГО СО СТАБИЛИЗИРУЮЩИМИ ДОБАВКАМИ МЕТОДАМИ ИНФРАКРАСНОЙ СПЕКТРОСКОПИИ И РЕНТГЕНОСПЕКТРАЛЬНОГО АНАЛИЗА

Increasing the volume of crushed stone-mastic asphalt concrete used in the upper layers of road surfaces requires the development of effective stabilizing additives that ensure the uniformity of the asphalt mixture during short-term storage and transportation, as well as improving the properties of asphalt concrete. This additives include a complex stabilizing additive of the following composition: 90 % cellulose fibers from waste paper, 5 % rubber powder, 5 % viscous petroleum bitumen of the BND 90/130 brand. This article presents the results of a study of bitumen with the addition of "Viatop 66" and a complex cellulose-containing stabilizing additive (CSD). Using Fourier-transform spectroscopy, graphical data are obtained. as a result of their analysis, it is found that the interaction of stabilizing additives for crushed-mastic asphalt concrete with bitumen leads to the appearance of additional absorption bands characteristic of aromatic compounds (CH, benzene ring), sulfur-containing functional groups S=O st, R-SO-R, R-SO-OH, R-SO2-R, C=S st, as well as for C-O-H groups. X-ray spectral analysis confirmed the presence of additional sulfur-containing spectra in the composition of stabilizing additives. It is found that depending on the chemical composition of the stabilizing additives, the physical and mechanical characteristics of the bituminous binder and the resulting asphalt concrete change.

Evaluation of palm kernel shell and its nano-variant as aggregates in asphalt concrete

This study investigated the influence of palm kernel shell (PKS) and its calcined nanomaterial (CN-PKS) as aggregates on the volumetric and Marshall Properties of hot mix asphalt concrete. The PKS and CN-PKS were used to replace the coarse aggregates and the filler material at 5, 10, 15, 20 and 25 % each in the same asphalt mix in three replicates. The compositions were mixed together and compacted with 50 blows on both sides to obtain cylindrical samples for the Marshall Stability tests. Volumetric parameters (density, air void, voids filled with bitumen, marshal stability and flow) were carried out on asphalt cores to evaluate the strength of the mixes. Mean values were presented for the tested parameters. All the percent of PKS and CN-PKS mix proportions are within the limits of specification. The optimum stability and percentage air void value was recorded at 20%. Utilizing PKS and CN-PKS at 5% and 15% will most likely cause rutting and bleeding of the flexible pavement due to low percent air void. This study concluded that partial replacement with PKS and CN-PKS as coarse and filler at 20% in the same hot mixed asphalt can improve the properties of asphalt concrete for use in medium traffic roads.

Influence of quality indicators of the surface of mineral particles on the properties of asphalt concrete

Increasing traffic loads are driving the demand for durable asphalt concrete. The creation of new compositions of asphalt concrete mixtures is possible by studying the structure-forming processes at the interface between the phases “surface of mineral particles-organic bindef”. The presented study makes it possible to assess the degree of influence of the specific surface area on the physical and mechanical properties of asphalt concrete. Were considered fine mineral materials with different specific surface (natural sand, quartz sand, waste molding sand). They were matched with the same size modulus. At the first stage, the structure and shape of the surfaces of the particles of mineral materials were determined. At the second stage, the physical and mechanical characteristics of three asphalt concrete compositions were determined. It has been established that a well-developed, rough surface of mineral aggregate particles in asphalt concrete can act as an effective modifying element in the composition of asphalt concrete and achieve the desired physical and mechanical characteristics. An increase in the specific surface area of the mineral aggregate particles, with the same size modulus, makes it possible to proportionally increase the strength characteristics of asphalt concrete.

Estimating unconfined compressive behavior of HMA using soft computing

The mechanical properties of materials such as elastic tangential modulus (Et) and unconfined compressive strength (UCS) can be used to predict their performance during service life. This paper utilizes gene expression programming (GEP) as an alternative method to estimate the unconfined uniaxial compression properties of hot mix asphalt. Short-term static compression was used to evaluate modes of failure and stress–strain relationship of cylindrical and prismatic asphalt concrete specimens due to mixture types, specimen shape, height, temperature, binder type and testing orientation. The results show that cubic specimens tested parallel to the direction of compaction achieved higher compressive strength and peak strains than specimens tested to the perpendicular direction. Cylindrical specimens had greater elastic stiffness than prismatic specimens with similar aspect ratios. The GEP and multiple linear regression approaches for the assessment of UCS and Et concluded satisfactory outcomes. The coefficient of determination (R2) for USC-GEP was 0.887 and 0.908 and similarly Et-GEP of 0.785 and 0.648 was more significant than regression models. The models developed provide a cheap, simple and quick methodology of estimating the stress–strain properties of dense-graded asphalt concrete by eliminating the need for the compression test.

Efficiency of using shungite filler for modifying organic binder

Modification of bitumen with various additives, including polymer ones, is one of the most effective ways to regulate the performance properties of asphalt concrete. Due to the high cost of polymers, a promising area of research is to reduce the polymer content, for example, by introducing mineral filler into its composition. A wide range of properties and unique structure of fullerene-containing natural shungite allow it to be used in various branches of science, industry and technology to create a variety of materials and determine the search for new areas of its application. One of the ideas that are currently under development is the use of shungite in conjunction with an organic binder used for the production of asphalt concrete. The work is devoted to the study of the influence of fine shungite on the characteristics of polymer-bituminous binder (PBB) and asphalt concrete. It is shown that the introduction of shungite into the PBB increases its viscosity, adhesive and cohesive properties, and the homogeneity of the mixture. This is due to the unique composition, structure and properties of shungite. The positive influence of the use of polymer shungite binder on the quality of asphalt concrete was established. With the introduction of 5% shungite in the PBB composition, the strength at 20 and 50°C, the strength of water-saturated samples, and the shear stability of polymer asphalt concrete significantly increased. This made it possible to reduce the polymer content of PBB by 10%.

Effect of Hybrid Modification and Type of Compaction on the Cracking Properties of Asphalt Concrete

This paper focused on evaluating the effect of aggregate gradation and polymer modification on indirect tensile strength (ITS) and the static stiffness for hot asphalt mixtures. In particular, data from ITS tests have been processed to obtain stiffness measurements through the application of Hondros theory. The results showed that fine mixtures had a better tensile strength by 26.3% than the coarse mixtures. The effect of compaction also was examined, the results showed that samples compacted with the Superpave gyratory compactor (SGC) had an enhancement in ITS by 36.58 and 23.1% in comparison with Marshall and roller compactor respectively. Polymer modifiers were used to estimate their effect on tensile strength, adding 4, 6, and 8% of Styrene-Butadiene-Styrene (SBS), which can rise the ITS by 3.2,6.14 and 13.3% of the non-modified asphalt mixture. Furthermore, using 4, 6, and 8 percent of SBS could increase static stiffness by 53.9, 209.6, and 302.4% respectively for roller compacted fine mixes and 58, 220, and 379.3% for SGC compacted mixes. Furthermore, SBS raised the stiffness modulus by 52.3, 188, and 295% for Marshall compacted mixes. Using hybrid modifier can improve the stiffness of the asphalt mixture. However, The results indicate that using 1, 2 and 3% polyvinyl chloride (PVC) can magnify the stiffness of mixtures by 41.2, 199.8% and 262.6 for roller compacted mixtures and 133.4, 212.1 and 354% for SGC compacted mixtures, whereas there is a stringent increasing by 133.4, 189.2 and 354% for Marshall compacted mixes. Otherwise, polymer-modification can decrease the fracturing index for coarse and fine mixtures.

Встановлення складу епоксиасфальтобетоних сумішей для їх застосування в якості тонкошарового покриття на автомобільних дорогах та мостах

Introduction. This paper presents the results of the analysis of world and domestic experience, theoretical and practical research to assess the impact of thermosetting additives on the main indicators of bitumen and physical and mechanical properties of asphalt concrete. The optimal compositions of asphalt concrete with increased physical and mechanical properties for their use as thin-layer coatings on road bridges have been established. Attention is also paid to the technology of preparation of epoxy asphalt concrete with different methods of introduction of epoxy components. Problem Statement. Ensuring increased track resistance, strength and crack resistance of pavements on road bridges today is one of the most important problems facing scientists and road workers in Ukraine. An urgent task is to improve the performance of these coatings in order to extend their service life and minimize the frequency of repair work, which, especially on bridges, cause great difficulties and require significant additional costs. Objective. There is no doubt that when using epoxy asphalt concrete as a thin-layer pavement, we get a strong, flexible surface, resistant to cracking and rutting. However, this is not yet a sufficiently researched material for its possible wide application, as it requires a special approach to the establishment of the composition and technology of its preparation. Materials and methods. Asphalt concrete mixture using thermosetting modifiers for its use as a thin-layer coating on orthotropic or reinforced concrete slab of the carriageway of the bridge. Results. An analytical review of domestic experience and the experience of other countries to improve the quality of pavements on road bridges, increase their durability, as well as improve economic efficiency in the use of epoxy-asphalt mixtures. Comprehensive studies have been conducted to establish their optimal composition. Conclusions. The application of a thin-layer coating on an orthotropic or reinforced concrete slab of the carriageway of the bridge made of epoxy-asphalt-concrete mixture requires special attention in establishing the optimal selection of its composition and cooking technology. Particular attention should be paid to ensure the required viability of the epoxy-asphalt mixture, the use of the desired hardener, which affects its properties, determining the required number of thermosetting modifiers, determining the duration of curing depending on temperature.

Simple Indexes to Identify Fatigue Performance of Asphalt Concrete

Abstract Using indexes based on engineering properties is among the ways to evaluate the quality of an asphalt concrete mix in terms of its resistance to fatigue cracking. These indexes typically are developed based on measuring asphalt concrete or asphalt binder properties in a laboratory test. Among such tests, the semicircular bend (SCB) test has shown potential as a promising test to determine fatigue resistance of asphalt mixtures. In the work presented, this test was explored extensively to determine proper fatigue performance identifiers from the test. Numerous tests were conducted to determine the effect of asphalt mix composition on the SCB fatigue test results. A major index considered from this test for evaluation is the flexibility index (FI), which is defined as the ratio of fracture energy and the post peak slope at inflection point derived from a typical load-deformation or stress–strain monotonic test. This index has been proposed based on extensive research at the University of Illinois. In the work presented in this study, tests were conducted on both short- and long-term aged asphalt mixes to evaluate FI and its reliability as a fatigue resistance indicator. The mix components considered as test variables included binder content, air void, and binder stiffness. The results showed a significant reduction in FI fatigue resistance after long term aging. Reduced FI is believed to associate with reduced fatigue life. The sensitivity of FI and other engineering properties to mix parameters were investigated in this research. It was found that FI could not be used alone and as a sole indicator of fatigue performance. It was determined that two indexes are needed for this purpose—the first presents the mix toughness and ductility, and the second is a strength- or stiffness-based index.

Influence of Iron-Filings on Marshall and Volumetric Properties of Asphalt Concrete

The growth and expansion of road infrastructure had resulted in the continuous use of materials, increased construction costs of flexible pavements and increased environmental impact during the service life of the road. Consequently, many researchers have sought to use methods to maintain these roadways sustain environmental impact and traffic loads. One of these approaches is the use of additives to improve asphalt's volumetric character. In this research, iron filings were used as partial replacement of fine aggregates, and the Marshall and volumetric properties were assessed before and after the implementation of iron filings. Specimens were prepared with iron filings addition of (2, 4, 6 and 8%) by weight of fine aggregates. The Marshall mix design procedure was used to calculate the optimum asphalt content and the volumetric properties, including bulk density, Total voids, voids in mineral aggregates V.M.A., and voids filled with asphalt V.F.A. The Marshall Flow and Stability were calculated. Test results were assessed before and after the inclusion of the iron filings. It was concluded that the addition of iron filings can enhance the Marshall and volumetric properties of asphalt. The stability increased by 15% when replacing fine aggregates by 2%, of iron filings by total weight. Also, the air voids and the VMA decreased by increasing the percentage of iron filings, while VFA was not significantly affected as compared to the conventional specimen. The ideal ratio of iron filings which fulfill the optimal requirements was 5%.

Investigating the properties of asphalt concrete containing recycled brick powder as filler

One of the major problems caused by the construction and demolition of buildings is the environmental pollution due to the disposal of the large volume of generated waste materials. In addition to the protection of environment, the recycling and reusing of the waste materials are an economical measure. In this research, the viability of using the recycled brick powder as a partial or full replacement of mineral filler in asphalt concrete has been investigated. The primary natural siliceous aggregate filler, as control filler, has been replaced in different percentages, with the secondary recycled brick powder, and the mixtures have been evaluated in terms of, Marshal Stability, flow, indirect tensile strength, moisture damage and volumetric characteristics. The results show that, the Marshal Stability increases and the flow decreases with increasing the brick powder content in the mixture. The results show that full replacement of the natural filler with brick powder results in the highest resistance against permanent deformation and indirect tensile strength. It is also shown that the mixtures containing brick powder are more resistant against moisture damage than the control mixture. The replacement of the mineral filler with the brick powder does not significantly affect the volumetric properties of the mixture.

Asphalt concrete on the basis of converter slags

The properties of converter slag, its activity and the influence of the degree of decay on the structural and mechanical properties of asphalt concrete are studied. It has been established that asphalt concrete with a degree of decay of converter slag of 1.24 % or less can be used for paving roads. It has increased heat, water and frost resistance, which will significantly increase the service life of roads from the beginning of operation to overhaul.

Evaluación reológica y mecánica de un aglutinante asfáltico modificado por polímeros.

The paper presents a comparative study between the properties of a conventional binder and a polymer-modified binder, as well as some mechanical properties of hot mix asphalt concrete (HMA) made with these binders. The comparation of binder based on conventional indices and advanced dynamic properties obtained with a dynamic shear rheometer (DSR). These include the dynamic modulus |G*|and phase angle ( d ) master curves, the fatigue susceptibility in the LAS (Linear Amplitude Sweep) and permanent deformations in the MSCR (Multi Stage Creep Recovery). The asphalt mixtures dosed and compacted according to the Superpave methodology. The mechanical properties explored in concrete asphalt (CA) specimens subjected to moisture-induced damage and static creep tests. The results show the positive effects of polymer addition in the binder’s and hot mix asphalt concrete properties, especially with regard to elastic resilience and permanent deformation reduction .

The impact that crushed rubber can have on the quality of bitumen and asphalt concrete

The results influence of finale dispersed rubber crumb on the properties bitumen and asphalt concrete are presented in the study. The parameters of the optimal regime of bitumen and rubber crumb mixing are established. The influence on the rubber crumb mixing with bitumen or added directly in the process of asphalt concrete mixing on the properties of asphalt concrete is studied. The effects that fine rubber has on the properties of petroleum bitumen and asphalt concrete are measured. The best options available for combining bitumen and rubber crumb are given. Moreover, it is also described how and to what extend crumb can influence the quality of rubber-bitumen binder for roads and how rubber-bitumen binder is affected when crump is added to this asphalt mixture. The influence that rubber crumbs have on the quality of bitumen and asphalt concrete. In the study, the influence of crumb on the properties of bitumen and asphalt concrete are shown. The conditions at which a high-quality mixture of bitumen and rubber crumb can be produced. Furthermore, the effects of crumb on the rubber-bitumen binder and the direct introduction of crumb into mixture are thoroughly investigated.

Cement concrete modified by fine-dispersed anionactive bitumen emulsion for road construction

Cement concretes are strong and able to resist external adverse environmental factors, have an increased water absorption and, as a result, insufficient frost resistance and deformability. Therefore, wide use of cement concrete in road construction is limited. Modification of road cement concrete with anionactive bitumen emulsions is a current and promising solution. By introducing small concentrations of bitumen emulsions into cement concrete, one gets a material with the basic properties of cement concrete and the properties of asphalt concrete. Rigid crystallization bonds formed as a result of cement hydration are dominantly present in cement systems, while coagulation type bonds with adhesive properties bitumen prevail in asphalt systems. Depending on the quantitative relationship between these bonds, the deformability of concrete tends to change. The main technological and operational properties of the resulting road cement concrete were investigated. Cement concrete was bituminized by introducing the anionic bitumen emulsions into the concrete mixture (from 0.5% to 8.0% of cement weight), which allowed increasing technological properties of concrete mixture and the performance properties of hardened concrete. This increases mobility, improves deformability of hardened concrete, increases its abrasion resistance, water resistance, frost resistance, reduces shrinkage without reducing the strength properties of road concrete.