Proportion Of Aggregates Research Articles

Experimental and numerical investigation on I–II mixed-mode fracture of concrete based on the Monte Carlo random aggregate distribution

This paper presents the result of an experimental and numerical investigation on I–II mixed-mode meso-scale fracture behavior of concrete by the Monte Carlo Simulation (MCS) random aggregate numerical simulation method, involving the tests of 6 four-point shear notched concrete beams with different coarse aggregate. Simultaneously, the effects of volume fraction and specific surface area (SSA) of coarse aggregate on fracture characteristics and peak load were discussed at the meso-level. The results showed that the crack growth patterns of four-point bending concrete beams with separate coarse aggregate volume fraction and SSA were basically consistent under the same loading condition. The actual path of fracture propagation is determined by the difference of the aggregate distribution, and with an increase in the volume fraction of coarse aggregate, the fracture surface is rougher, and I–II mixed-mode fracture of concrete required more fracture energy, which is corresponded to a higher peak load. Also, with an increase in the proportion of small size coarse aggregate, the contact surface area between aggregate and mortar increases, and consequently, peak load increased by the proportion of small size coarse aggregate increase.

Soil wet aggregate distribution and pore size distribution under different tillage systems after 16 years in the Loess Plateau of China

In the Loess Plateau of China, conventional tillage is defined as the tillage without crop residues left on the soil surface and ploughed twice a year. The use of alternative practices is a way to reduce soil erosion. Our objectives were to assess the long-term impacts of different soil tillage systems on soil physical and hydraulic characteristics, emphasizing management practices to improve the soil physical qualities (reduce bulk density and increase stability of aggregate) under the conservation tillage system in the Loess Plateau of China. Conventional tillage (CT), no tillage (NT), and sub-soiling (SS) were applied in this experiment. Soil wet aggregates distribution and stability, soil organic carbon (SOC) content, soil water retention curves and pore size distributions were measured. The results showed that in the 0–10 cm and 10–20 cm depth soil layers, NT and SS treatments showed a significantly higher proportion of wet aggregates >250 μm (macroaggregates) compared to CT. In these two layers, the proportion of wet aggregates <53 μm (microaggregates) was significantly higher in CT with respect to NT and SS. SOC content increased as the aggregate fraction size increased, and was higher within wet aggregates >250 μm than within the 250–53 μm and < 53 μm (silt + clay) fractions at both depths. In addition, the conservation tillage (NT and SS) can result in improved total porosity and reduced soil bulk density compared with CT in the surface layer. Pore size distribution in CT soil was unimodal, with the maximum in the 10–30 μm matrix pores of the surface layer. However, in the surface layer the pore size distributions from NT and SS showed a dual porosity curve, with two peaks in the matrix and structural pore areas. The 10–20 cm layer showed similar pore size distributions in each treatment. After scanning the soils by micro-computed tomography, we visualized the pore characteristics. The images showed that CT reduced the long and connected macropores compared with conservation tillage. Overall, soil aggregate stability and soil macropores are most improved under conservation tillage. Conservation tillage with crop residues should be adopted instead of conventional tillage, as an effort to improve crop yield and control soil erosion in the Loess Plateau of China.

Valorization of marble waste in the manufacture of concrete

The building materials manufacturing industry generates a lot of waste and their landfill has many problems (including the place occupied by the storage sites, the importance of the costs and the impact on the environment). This industry does not pose problems only at the end of the life cycle of these materials. It is imperative to find means of recovery and reuse of these wastes and therefore to propose another alternative to the depletion of aggregate sources. The main objective of this study is to show technically the possibility of using the aggregates from the manufacture of marble as a substitute in hydraulic concrete. The article presents the methodology of study and characterization of marble scrap, as well as the different formulations of concretes; series of tests have been developed, with a constant W / C ratio for a variable recycled aggregate content. The study consists of analyzing the results obtained and its comparison with a control concrete (100% natural aggregates); the rheological properties in the fresh and mechanically hardened state of concretes with different proportions of aggregates from marble waste (25%, 50%, 75%, 100%). The results show that marble waste is ready to be used as substitute material.

Pilot-scale formation of whey protein aggregates determine the stability of heat-treated whey protein solutions—Effect of pH and protein concentration

Denaturation and consequent aggregation in whey protein solutions is critical to product functionality during processing. Solutions of whey protein isolate (WPI) prepared at 1, 4, 8, and 12% (wt/wt) and pH 6.2, 6.7, or 7.2 were subjected to heat treatment (85°C × 30 s) using a pilot-scale heat exchanger. The effects of heat treatment on whey protein denaturation and aggregation were determined by chromatography, particle size, turbidity, and rheological analyses. The influence of pH and WPI concentration during heat treatment on the thermal stability of the resulting dispersions was also investigated. Whey protein isolate solutions heated at pH 6.2 were more extensively denatured, had a greater proportion of insoluble aggregates, higher particle size and turbidity, and were significantly less heat-stable than equivalent samples prepared at pH 6.7 and 7.2. The effects of WPI concentration on denaturation/aggregation behavior were more apparent at higher pH where the stabilizing effects of charge repulsion became increasingly influential. Solutions containing 12% (wt/wt) WPI had significantly higher apparent viscosities, at each pH, compared with lower protein concentrations, with solutions prepared at pH 6.2 forming a gel. Smaller average particle size and a higher proportion of soluble aggregates in WPI solutions, pre-heated at pH 6.7 and 7.2, resulted in improved thermal stability on subsequent heating. Higher pH during secondary heating also increased thermal stability. This study offers insight into the interactive effects of pH and whey protein concentration during pilot-scale processing and demonstrates how protein functionality can be controlled through manipulation of these factors.

Study on the emulsifying stability and interfacial adsorption of pea proteins

In order to expand the natural food emulsifier applications of pea proteins, the emulsifying stability and competitive relationship of interfacial adsorption were investigated. The protein extracted at 90 °C had the highest nitrogen solubility index and surface hydrophobicity. The molecular weight distributions analyzed by high-performance size exclusion chromatography demonstrated that over 60% of the protein had Mw > 500 kDa. The non-reducing SDS-PAGE results showed that the percentage of aggregates were about 37%, and the proportion of proteins were aggregates > vicilin > legumin > convicilin. Increasing the protein concentration from 1.0 to 30 mg/mL increased the emulsifying ability and stability of pea protein stabilized emulsions significantly. At the same time, the concentration of interfacial adsorbed proteins increased. However, the ratio of adsorbed protein to the protein in the initial dispersion (AP%) was decreased significantly from 84% to 21%. When the protein concentration was higher than 10 mg/mL, the interfacial adsorption of pea proteins would reach the saturated adsorption point. The content of aggregates adsorbed onto the interface at low concentration was higher than its proportion in the initial pea protein. With the increase of protein concentration at the interface, the proportion of adsorbed aggregates decreased, while the proportions of vicilin and legumin increased. At saturated adsorption, the contents of proteins on the interface were vicilin > legumin > aggregates > convicilin, and the proportion of aggregates was lower than its proportion in the initial pea protein extraction.

Piezoelectricity-based self-sensing of compressive and flexural stress in cement-based materials without admixture requirement and without poling

The self-sensing of compressive and flexural stress in cement-based materials (without embedded or attached sensors, without admixture requirement and without poling) by capacitance measurement has been demonstrated. The sensing involves two coplanar electrodes in the form of aluminum foil adhered to the cement-based material by using adhesive tape, which also serves as a dielectric film. The normal force associated with compressive or flexural loading is applied to the region between the electrodes. The stress regimes are the low-stress regime (up to 1500 Pa), the medium-stress regime (1500–7400 Pa) and the high-stress regime (7400–65 000 Pa). The lowest compressive/flexural stress demonstrated for effective sensing is 300 Pa. The fractional decrease in capacitance per unit stress is up to 2.2 × 10−6 Pa−1 and tends to decrease as the regime is changed from low to medium and to high-stress. The sensitivity tends to be greater for the compressive stress than flexural stress. However, when the normal stress (relevant to weighing) is considered, the sensitivity is higher for flexural loading than compressive loading. The strain contributes negligibly to the capacitance decrease, though the near-surface deformability of the cement-based material contributes. The change in capacitance upon stress application is attributed to the direct piezoelectric effect. The sensitivity is comparable for cement paste, mortar and concrete. Capacitance-based self-sensing is advantageous over resistance-based self-sensing in terms of the low-stress sensing effectiveness, absence of admixture or aggregate proportion requirements, essential absence of self-sensing effectiveness reduction by the presence of aggregates, wide applicability to existing concrete structures, and ease of applying electrodes.

Soil texture determines the distribution of aggregate-associated carbon, nitrogen and phosphorous under two contrasting land use types in the Loess Plateau

Organic carbon (OC) and nutrient dynamics are closely related to soil texture, but how texture influences the distribution of OC and nutrients in aggregates in various land use types has not been examined. This knowledge gap precludes our mechanistic understanding of soil biogeochemical cycles at large spatial scales. Herein we compared the contents and stoichiometric ratios of OC and nutrients in both bulk soils and aggregates in cropland and woodland across a clay content gradient (7–31%) in the Loess Plateau. The soil metrics that were measured included the proportions of water-stable aggregates, and the contents of OC, nitrogen (N) and phosphorous (P) in bulk soils and each aggregate fraction. The stoichiometric ratios of carbon (C), N and P were calculated. The relationships between soil metrics and clay content were analyzed. We hypothesize that OC, N and P in aggregates increase with clay content, and these relationships are independent of land use types. In partial support of these hypotheses, the proportion of macroaggregates and the contents of OC, N and P in bulk soils and most aggregate fractions linearly increased with clay content. The slopes of these linear relationships were not affected by land use type. The C/N ratio were minimally affected, while the C/P and N/P ratios in both bulk soils and aggregates increased with clay content, and these relationships changed with land use type. Proportion of macroaggregates, contents of OC and N, and ratios of C/N, C/P and N/P were significantly higher in woodland than in cropland across or within sites. Furthermore, the distribution patterns of OC, N and P contents, and C/P and N/P ratios among aggregates varied with site and land use type. These suggested that soil texture determines the distribution of OC, N and P and their stoichiometric ratios within soil aggregates in the Loess Plateau of China, and most of these determining relationships were independent from land use types.

Effect of Water Stress in Soil Nitrogen Dynamics under Intercropping System with Maize and Sorghum

Global warming, one of the most persistent threats to nature, is expected to result in severe droughts in many parts of the world. Droughts are supposed to effect individual plants and/or plant communities by changing their a/ biotic interactions. The objective of this study was to elucidate drought effects on soil nitrogen allocation in different aggregate sizes. This was done by growing Zea mays and Sorghum bicolor in monoculture and mixture. Nitrogen allocation under drought stress was traced using nitrogen stable isotope 15N. Drought disintegrated soil aggregates into finer aggregates for sorghum monoculture and decreased the aggregate proportion in small macro-aggregate fraction for maize monoculture. For plant mixture, drought increased total nitrogen content in micro-aggregate fraction and uptake of added 15N in bulk soil. Hence, the study showed that mix planting maize and sorghum offer better resistance against changes in plant biomass and nitrogen content which suggests its effectiveness in nitrogen conservation during water stress. Moreover, intergrowing maize and sorghum under agroforestry systems also produce advantageous results.

Influence of straw incorporation-to-planting interval on soil physical properties and maize performance

Abstract Long-term soil disturbance due to regular tillage destroys the soil structure, particularly by reducing the soil organic matter content. This, in turn, can lead to declining crop yields. This study assessed the influence of wheat (Triticum æstivum L.) straw incorporation and timing prior to seeding at 6 Mg ha−1 (S+), relative to no straw (S−), on maize (Zea mays L.) growth and yield parameters, as well as on soil characteristics. There were four intervals between straw incorporation and maize seeding, i.e. 60, 45, 30 and 15 days before sowing. Compared to the S− (control), soil dry bulk density increased (p ≤ 0.05) under all S+ treatments. A significantly greater proportion of undesirable small aggregates (&lt;0.5 mm), and a lesser proportion of desirable medium sized (0.5-8.0mm) aggregates, occurred under S− treatment, as compared to $S_{60}^ +$ treatment. A similar, but less pronounced, trend was observed under $S_{45}^ +$ treatment. This trend was also evident for the $S_{30}^ +$ and $S_{15}^ +$ treatments. Generally, incorporation of straw 60 days prior to sowing led to achieving the best soil structure in terms of aggregation. Compared to S−, the soil organic matter showed a weakly significant (0.05 ≤ p ≤ 0.06) increase under straw amendment. Seedling emergence, plant height, cob length, the number of grain rows per plant, the number of grains per cob, as well as 1000 grain weight and yield were the highest under $S_{60}^ +$ , and the lowest under S−. The present study suggests that more research is necessary over longer time periods between straw incorporation and seeding on different crops, and in different soil types, in order to study the effects on soil properties, and on the growth and yield of crops.

A new mixture design methodology based on the Packing Density Theory for high performance concrete in bridge engineering

In this study, a new mixture design methodology based on the 4-parameters compressible packing model (CPM) of Packing Density Theory was proposed to satisfy the specific performance criteria of high performance concrete for prestressed concrete bridge construction. Iterative algorithms were developed to determine the parameter of critical cavity size ratio x0 which reflect the crushed aggregate particles shape property and optimize the proportions of aggregates with different size range. After the optimization of aggregates, all the components in concrete were calculated. Thirty-one concrete mixtures with coarse aggregate from 5 different sources have been formulated according to this method to validate it both in fresh and hardened state. The workability, mechanical, and durability properties are verified during the slump, compressive strength, shrinkage, chloride-penetration resistance, and freeze-thaw resistance tests to characterize the obtained high-performance concrete. It is clear from the study that the proposed method is a successful theory for optimizing composition of high performance concrete.

Producing of eco-friendly lightweight concrete using waste polystyrene particles as aggregates with adding waste plastic

This research includes studying the possibility of producing a new kind of No-fines concrete by replacing granules of coarse aggregates with grains results from the fragmentation of industrial waste of polystyrene. This replacing were with different volumetric proportions of coarse aggregate, and theses volumetric ratios were equal to (5%, 10%, 15% and 25%). Waste plastic fibers (WPFs) resulting from cutting of soft drinks bottles were added for strengthening this new kind of concrete. Mixing ratio was equal to (1:5) (cement: coarse aggregate) by weight. One reference mix was produced for comparative purpose. Compressive strength, flexural strength and density tests were conducted, it was examined three samples of each examination and taking the average. Compressive strength values of the new sustainable concrete were ranged from 10 MPa to 12.4 MPa at age of test equal to 28 days, while the average value of the density of this concrete at the same age reaches 1930 kg/m3. This average value of modulus of rupture was equal to 2.36 MPa at 28-day age test.

Experimental study on behaviour of encased stone column with tyre chips as aggregates

Stone columns are constructed using stone aggregates of typical size ranging from 15 to 75 mm. Alternatively, building debris and shredded tyre chips can be used to replace the stone aggregates either partially or totally, which can be an environment-friendly solution to the disposal of solid waste materials. This paper presents the results of model tests on ordinary floating stone columns (OSC) and encased floating stone columns (ESC) constructed with a mixture of stone aggregates and shredded tyre chips. Tyre chips of 10 mm size, 2 to 3 mm thick after removing steel wires, were used in this study. Large size direct shear tests were also conducted for different mix proportions of tyre chips and stone aggregates to assess their shear strength properties. Model tests were conducted on ordinary and encased floating stone columns of diameter (d) 100 mm and l/d ratio of 4.5. Loading was applied through hydraulic jack and reaction loading frame. Model test results show that an ordinary stone column made of stone aggregates can be replaced by an encased stone column made of 100% tyre chips. This confirms the possibility of either partial or full replacement of stone aggregates with tyre chips in stone columns.

Soil structure and soil organic matter in water-stable aggregates under different application rates of biochar

Soil structure and soil organic matter in water-stable aggregates under different application rates of biochar

Aggregate-related changes in soil microbial communities under different ameliorant applications in saline-sodic soils

Soil ameliorants can improve soil physico-chemical properties and activate microbial communities in saline-sodic soils. However, there has been less focus on how aggregate fractions affect soil microbial communities under different ameliorant applications. Here, we used the phospholipid fatty acid (PLFA) analysis to explore the effects of soil ameliorants on microbial communities within mega-aggregates (diameter of >2 mm, ME), macro-aggregates (diameter of 0.25–2 mm, MA), and micro-aggregates (diameter of <0.25 mm, MI), based on an 8-year rice (Oryza sativa L.) field experiment. The five treatments included CK, non-amended control; SS, amended with sandy soil; DG, amended with desulfurization gypsum; FM, amended with farm manure; and M, amended with a mixture of sandy soil, desulfurization gypsum, and farm manure. Relative to the CK treatment, the SS, DG, FM, and M treatments significantly decreased the soil pH and electrical conductivity and significantly increased the soil organic carbon (SOC) content of the MI, while the FM and M treatments also significantly improved the SOC content of the MA and ME. Irrespective of the ameliorant used, the absolute abundance of total PLFAs and most microbial groups generally varied with the SOC content as follows: MA > ME > MI. Meanwhile, the proportional abundance of arbuscular mycorrhizal fungi (AMF) varied between different aggregate fractions as follows: ME > MA > MI. Additionally, the DG treatment significantly enhanced the soil aggregate stability by increasing the AMF abundance, AMF/saprotrophic fungi ratio, and SOC content of the MI. Furthermore, soil microbial groups were highly correlated with soil SOC (P < 0.001), C/N ratio (P < 0.001), pH (P < 0.01), total nitrogen (P < 0.01), and the proportion of aggregates with a >0.25 mm diameter (P < 0.05). In conclusion, desulfurization gypsum is more effective for improving the properties of saline-sodic soils in the western Songnen Plain.

Development of environmentally extended social accounting matrices for policy analysis in Alberta

ABSTRACTThis paper outlines the development of inputs to an integrated land use and transportation model based on a series of environmentally extended social accounting matrices (SAMs) for the Canadian province of Alberta. A novel form of industry disaggregation is employed, based on aggregate iterative proportion and a unique formulation of location quotients. Social accounts are extended via the inclusion of detailed household consumption broken down by income quintiles. The SAMs are developed from supply-use matrices. Physical flow accounts are framed as derived demands, acting as necessary inputs to the production of downstream goods and services. Applications to regional economic modeling are considered, as planning authorities increasingly seek to model the environmental impacts of policy. The SAMs are then applied to the assessment of two technology change scenarios: a shift in the provincial electricity generation mix and a transition to a fully electric private automobile fleet.

Effect of Filler Type on the Durability of Asphalt Concrete Mixes

Mineral filler is the finest fraction of aggregate (smaller than 75 gm) used in the production of asphalt paving mixed. It is essential for producing a mixture that is dense, cohesive, durable, and resistant to water penetration. In spite of the fact that filler is very small proportion of the total aggregates in the mix, due to its rather high affinity for asphalt, the changes in the type of the filler can cause the paving mixture to perform satisfactorily during the design life or deteriorate rapidly under the effect of traffic and environmental impact. The objective of this study is to investigate the effect of mineral filler types (three types, limestone dust, Portland cement and hydrated lime) in the durability of asphalt concrete mixture. To achieve the objective of this study, Marshall mix design method was utilized to produce asphalt concrete mixes at their optimum asphalt content. The mixes were, then, tested to investigate their durability properties including moisture damage and fatigue characteristics. The results indicated that the mixes prepared with hydrated lime have superior resistance to moisture damage in comparison with Portland cement and lime stone dust. On the other hand, the mixes prepared with Portland cement type of filler showed better resistance to the fatigue failure of asphalt concrete pavement.

Prevalence of tobacco use and perceptions of student health professionals about cessation training: results from Global Health Professions Students Survey

IntroductionHealth professionals play an important role in providing advice to their patients about tobacco prevention and cessation. Health professionals who use tobacco may be deterred from providing cessation advice and...

Epothilone D inhibits microglia-mediated spread of alpha-synuclein aggregates

Multiple System Atrophy (MSA) is a progressive neurodegenerative disease characterized by chronic neuroinflammation and widespread α-synuclein (α-syn) cytoplasmic inclusions. Neuroinflammation associated with microglial cells is typically located in brain regions with α-syn deposits. The potential link between microglial cell migration and the transport of pathological α-syn protein in MSA was investigated. Qualitative analysis via immunofluorescence of MSA cases (n = 4) revealed microglial cells bearing α-syn inclusions distal from oligodendrocytes bearing α-syn cytoplasmic inclusions, as well as close interactions between microglia and oligodendrocytes bearing α-syn, suggestive of a potential transfer mechanism between microglia and α-syn bearing cells in MSA and the possibility of microglia acting as a mobile vehicle to spread α-syn between anatomically connected brain regions. Further In vitro experiments using microglial-like differentiated THP-1 cells were conducted to investigate if microglial cells could act as potential transporters of α-syn. Monomeric or aggregated α-syn was immobilized at the centre of glass coverslips and treated with either cell free medium, undifferentiated THP-1 cells or microglial-like phorbol-12-myristate-13-acetate differentiated THP-1 cells (48 h; n = 3). A significant difference in residual immobilized α-syn density was observed between cell free controls and differentiated (p = 0.016) as well as undifferentiated and differentiated THP-1 cells (p = 0.032) when analysed by quantitative immunofluorescence. Furthermore, a significantly greater proportion of differentiated cells were observed bearing α-syn aggregates distal from the immobilized protein than their non-differentiated counterparts (p = 0.025). Similar results were observed with Highly Aggressive Proliferating Immortalised (HAPI) microglial cells, with cells exposed to aggregated α-syn yielding lower residual immobilized α-syn (p = 0.004) and a higher proportion of α-syn positive distal cells (p = 0.001) than cells exposed to monomeric α-syn. Co-treatment of THP-1 groups with the tubulin depolymerisation inhibitor, Epothilone D (EpoD; 10 nM), was conducted to investigate if inhibition of microtubule activity had an effect on cell migration and residual immobilized α-syn density. There was a significant increase in both residual immobilized α-syn between EpoD treated and non-treated differentiated cells exposed to monomeric (p = 0.037) and aggregated (p = 0.018) α-syn, but not with undifferentiated cells. Differentiated THP-1 cells exposed to immobilized aggregated α-syn showed a significant difference in the proportion of distal aggregate bearing cells between EpoD treated and untreated (p = 0.027). The results suggest microglia could play a role in α-syn transport in MSA, a role which could potentially be inhibited therapeutically by EpoD.

Soil organic carbon pool changes in relation to slope position and land-use in Indian lower Himalayas

The increase in the atmospheric abundance of CO2 has raised interest in the potential of soils to sequester carbon (C), which inter alia depends on antecedent C level. While inventories of soil organic carbon (SOC) have been developed for different ecosystems at field or global scales, studies at hill-slope level where SOC redistributes by erosion remain scarce. In addition, quantitative information on the variation in SOC stocks and organic matter quality within hill-slopes would allow to make more realistic estimations of the C sequestration potential of landscapes while suggesting improved land management. The main objective of this study was to evaluate the impact of slope position and land-use (grassland versus cropland) on SOC stocks and organic matter quality (proportion of aggregate associated C and labile pools; water extractable, WEOC; hot water soluble, HWC; potassium permanganate oxidizable, KMnO4-C; microbial biomass, MBC). A total of 108 soil samples from the 0–0.15 m layer were collected from 4 slope positions (forested hilltops, middle slope with bare soils, backslopes under grasslands, cropped bottomlands) at nine catenas with 3 replicates per position. The greatest SOC stocks were found at hilltops and backslopes with respectively 10.1 ± 0.64 and 10.1 ± 0.57 Mg C ha−1. SOC stocks decreased by 17% to 8.4 ± 0.65 Mg C ha−1 in bottomlands and by 58% to 4.2 ± 0.26 Mg C ha−1 at backslopes. The soil organic matter from the hilltops showed the greatest proportion of recalcitrant components (62%) followed by the backslope and bottomland positions with ~42%, and middle slope position with 9%. In addition to showing a greater occurrence of labile C fractions, bare and eroded backslope soils were also depleted in water soluble C (WEOC and HWC), KMnO4-C and microbial biomass C. The results showed that there is considerable potential for C sequestration at middle and backslope position through land rehabilitation by either planting trees or vegetation by grass.

Evaluating the fatigue behavior of asphalt mixtures containing electric arc furnace and basic oxygen furnace slags using surface free energy estimation

Abstract This study evaluated the effects of electric arc furnace (EAF) and basic oxygen furnace (BOF) slags on the fatigue behavior of asphalt mixes. After the initial evaluation of the properties of steel slags, nine sets of laboratory asphalt mixes were prepared. For each set, different proportions of limestone coarse aggregates (≥2.36 mm) were replaced with steel slags. The main laboratory protocol involved determining the fatigue life of the samples at 20 °C. Four-point bending beam fatigue tests were performed under controlled strain mode loading at different strain levels to characterize the fatigue behavior of the asphalt mixtures. The adhesion between asphalt and aggregates were assessed using the free surface energy concept. Results revealed that the addition of slags in the mixtures considerably enhanced fatigue life but that the fatigue life of the specimens containing EAF slag was greater than that of the specimens containing BOF slag. The findings also indicated that fatigue life increased with rising slag content. The surface energy test revealed that the adhesion between asphalt and aggregate was stronger in the slags mixtures than in the limestone mixtures. Such adhesion can explain the increased fatigue life of mixtures containing slags.