Effect Of Aggregate Gradation Research Articles

Effect of Aggregate Gradation on the Properties of 3D Printed Recycled Coarse Aggregate Concrete

Effect of Aggregate Gradation on the Properties of 3D Printed Recycled Coarse Aggregate Concrete

Optimizing self-sensing performance of conductive mortar via gradation of graphene coated aggregate

With the increasing focus on structural health monitoring of concrete during its service life, self-sensing functional concrete has emerged as an effective method for real-time detection and assessment of structural conditions. We recently proposed a new methodology of preparing conductive cementitious mortar with graphene-coated aggregates (Gr@Ag). Instead of the traditional approach, where conductive fillers are directly intermixed and uniformly distributed in the binding matrix, the development of Gr@Ag has created a more efficient path for electron transport through the connections of aggregates. The main objective of this study is to understand the effect of aggregate gradation on the electrical performances of conductive mortars, and the piezoresistivity is optimized by adjusting the aggregate packing. Electrochemical impedance spectroscopy was employed to investigate the underlying mechanisms of how aggregate gradation affects the mortar's electrical conductivity. It was found that both the internal resistance and resistivity of the conductive mortar considerably decreased with the reduction in Gr@Ag particle size. The contribution of conductive sand to the conductivity of mortar can reach 80.89–92.36 %, effectively transforming the conductive path from a disconnected state to a connected state. Reducing the particle size of the conductive aggregates contributes to an increase in particle contact rate, with the particle contact rate reaching up to 59 %. The presence of completely isolated conductive aggregates is noticeably reduced. As the particle size decreases, there is a significant reduction in mechanical performance. The conductive aggregates become relatively isolated from the matrix, and both the size of the conductive aggregates and the interfacial transition zone play vital roles to affect the mechanical properties.

Investigation of aggregate gradation on air voids distribution in porous asphalt concrete using X-ray CT scanning images

Porous asphalt concrete (PAC) is typically used as a paving material for porous asphalt pavement in rainy areas due to its abundant interconnected pores structure. Not all interconnected pores in PAC are valid for permeability, mainly influenced by the composition of aggregate gradation. The main purpose of this paper is to investigate the effect of aggregate gradation on pores structure distribution in PAC by X-ray computed tomography (CT) system and digital image processing (DIP) techniques. The distributions of porosity, number and average equivalent diameter of air voids in middle part are much more evenly compared to the both ends in PAC specimens, accounting for about 70 % of the total of specimen height. The average equivalent diameter of interconnected air voids mainly ranges from 0.5 mm to 5 mm in PAC, accounting for about 80 % of the total numbers. For PAC with similar porosity, the larger the normal maximum aggregate size (NMAS), the less the number and the larger the average equivalent diameter of air voids (interconnected air voids), the smaller the difference between the interconnected porosity and porosity. For PAC with same NMAS, as the porosity increase, the number and average equivalent diameter of air voids (interconnected air voids) are respectively decreased and increased gradually, the difference between the interconnected porosity and porosity is also showed a decreasing trend. And then, the correlated equation is established among porosity, interconnected porosity and the composition of aggregate gradation. The distribution of air voids (interconnected air voids) size could be well described by the two-parameter Weibull model, and the relationships are explored and developed between Weibull model parameters and the composition of aggregate gradation.

Experimental Investigation on the Properties of Sustainable Pervious Concrete with Different Aggregate Gradation

Pervious concrete (PC) as a green infrastructure material has been increasingly used due to its positive environmental impacts, such as controlling storm water runoff, removing water pollutants and reducing heat island effect. The aggregate gradation is a critical factor influencing the physical properties of PC. Therefore, this paper represents an attempt to determine the effects of aggregate gradation on the various physical properties of PC, and then to explore relationships between them. To this end, three aggregate gradations 4.75–9.5 mm, 9.5–19 mm and 19–31.5 mm were recombined with various proportions (20–80%) to obtain five different gradations named as A, B, C, D and E. PC mixtures were prepared with these five aggregate gradations. Then, physical and mechanical properties of PC including porosity, permeability, compressive strength and water stability were investigated, according to the available specification. The results suggested that it was feasible to use waste concrete for permeable pavement, because all the specimens provided required specification requirements. Different linear relationships were also found between the maximum aggregate size and porosity, permeability coefficient, compressive strength and its loss rate. That is, porosity and permeability increased with the proportion of larger size aggregate increased, however, compressive strength reduced. Thus the compressive strength had an inverse correlation with the porosity and water permeability. Among five different aggregate gradations, group C (20% of 4.75–9.5 mm aggregate, 50% of 9.5–19 mm aggregate and 30% of 19–31.5 mm aggregate) can be seen as the optimum gradation and is suitable for base layer materials of permeable pavements.

Effect of aggregate gradation on the mechanical strengths and permeability properties of porous concrete

Porous concrete (PC) is a very popular construction material in developed countries and is now finding application in India in parking lots. In this investigation, an effort was made to study the various performances of PC in the laboratory. Different gradations of coarse aggregates namely 4.75–10 mm, 10–12.5 mm, and 12.5–16 mm are considered to characterize PC adopting conventional compaction by tamping rod, additional 5 and 10 compactions by proctor hammer. The effect of varying compaction and the coarse aggregate gradation is studied on axial compressive, flexural tensile, and splitting tensile strengths of PC. In addition, a simple method is proposed to determine the permeability of all PC mixes. The work was extended to know the influence of low-grade fly ash and GGBS as supplementary cementing materials (SCMs) on the strengths and permeability of PC. Though the strength of PC in the presence of SCMs has decreased, the permeability and the estimated porosity of all mixes decreased compared to the 100% cement counterpart. A wide range of PCs were developed to suit several combinations of mechanical strength, density, and permeability depending on the type of application leading to a sustainable solution. The simple test method proposed to determine the permeability of the PC gives satisfactory results.

Simultaneous evaluation of rutting-stripping performance and cracking resistance for asphalt mixtures

In this study, the influence of volumetric properties on viscoplastic (VP) deformation, stripping, and cracking performance of asphalt mixtures and the corresponding correlations between these three performance indices were comparatively investigated based on the Hamburg Wheel Tracking Test (HWTT) and Overlay Test (OT) results. A total of 20 different types of asphalt mixtures were comparatively evaluated and divided into two groups, namely: one group for the asphalt mixtures with stripping and another group for the asphalt mixtures without stripping. It was observed that the aggregate gradations of asphalt mixtures prone to stripping were mostly fine graded, and that, the effect of aggregate gradation was more pronounced than that of the asphalt binder content. Additionally, even though the average OT peak loads for all the asphalt mixtures were similar, the numbers of OT load cycles to failure for the fine-graded asphalt mixtures were over twice higher than those with coarse aggregate gradations. Also, whilst the VP deformation and cracking of the asphalt mixtures with stripping were positively correlated, the response-trends for the non-stripping asphalt mixtures were indeterminate. In general, the stripping characteristics were found to be related to the cracking resistance potential, further suggesting that the occurrence of stripping could be largely due to adhesive fracturing between the asphalt binder and the aggregates. Overall, the test results and study findings indicated a potential feasibility to predict and estimate the performance indices (i.e., deformation, rutting, stripping, cracking resistance, etc.) from amongst each other for the asphalt mixtures that are prone to stripping.

Refined simulation of bond-slip behavior between ribbed steel and concrete: Effects of initial stress and temperature

The bond performance between steel and concrete exposed to fire is influenced by many factors, including the presence of an initial load before the temperature increase. To investigate such effect, a 3-D refined simulation model is presented accounting for the heterogeneity of concrete at the mesoscopic level and the external geometry of ribbed steel bars. The rationality and validity of the refined simulation model and of the multi-step analysis were verified by comparison with existing experimental data. Subsequently, the effects of aggregate gradation and distribution, initial loading level and temperature on the bond behavior were analyzed. The load transfer mechanism at the steel–concrete interface as a function of temperature under different loading levels is captured and discussed. It is found that the influence of aggregate grading and distribution on the bond-slip curve can be ignored under the aggregate volume fraction set in this work. Additionally, results show that the damage initially concentrates at the rib tip of the deformed steel bars, with an increase across the concrete section as the slip increases, as it could be expected. However, the bond stress and both stress and strain of steel at the same position decrease as the temperature increases. Finally and most importantly, it is found that the heating and loading sequence induce a different damage evolution inside the specimen, with a significant effect on the bond stiffness, the plateau portion of the bond stress-slip curve and the bond strength associated to a given critical temperature.

Effect of Aggregate Gradation on Asphalt Concrete Properties

Economic expansion is a positive side effect of national highway construction initiatives. So, the plan is to construct these projects rapidly. This calls for premium asphalt. As a result of aggregate gradation variation, numerous asphalt mixes have been rejected and rebuilt on-site in recent decades, resulting in the waste of valuable resources and valuable time. Consequently, the goal of this study was to examine the durability of asphalt mixes where the aggregate gradation ranged from +4% above to 2% below the standard range. The aggregate gradation is inconsistent throughout HMA manufacture. The aggregate is graded at 2, 4, and 6 percent over and below the allowed range. Case in point: the gradation of the control mix design. Marshall There was a quantitative evaluation of mixed properties throughout the design phase. HMA mix performance was evaluated via high temperature and water cycles by vehicle pressure observation and Indirect Tensile Strength (ITS) testing. In hot climates, asphalt with gradations above +4% and 2% of both the higher and lower standard values showed the greatest resilience to water damage and the least rutting. In warm regions, asphalt mixture design will be constrained by the higher aggregate gradation limits.

Investigating the effects of aggregate gradation on Marshall parameters of bituminous hot mixtures

Bu çalışmada, agrega gradasyonunun bitümlü sıcak karışımların fiziksel özellikleri üzerindeki etkilerinin araştırılması amaçlanmıştır. Bu doğrultuda, 2013 yılı Karayolu Teknik Şartnamesinde binder tabakası için tanımlanan gradasyon zarfı esas alınmıştır. Gradasyon zarfına ait ortalama, alt limit, üst limit değerleri ile birlikte alt ve üst limitlerin % 7 oranında ötelenmesiyle elde edilen beş farklı agrega gradasyonu oluşturulmuş ve her biri için ayrı ayrı Marshall tasarımları yapılmıştır. Gradasyon zarfının dışındaki değerler, çalışma esnasında oluşabilecek gradasyon hatalarının bitümlü karışımda meydana getirebileceği performans değişimlerinin öngörülebilmesi amacıyla çalışmaya dahil edilmiştir. Elde edilen test verilerine göre agrega gradasyonunun bitümlü sıcak karışımların stabilite, akma, birim ağırlık (Dp), hava boşluğu oranı (Vh), bitümle dolu boşluk oranı (Vf), agregalar arasındaki boşluk oranı (VMA) ve Marshall katsayısı üzerindeki etkileri değerlendirilmiştir. Agrega dane boyutunun ortalama gradasyona kıyasla artmasının veya azalmasının Dp ve Vf değerlerinde azalma, VMA ve Vh değerlerinde artış meydana getirdiği belirlenmiştir. Bununla birlikte, gradasyon zarfının üst limitine doğru stabilite değerlerinin arttığı görülmüştür.

Effect of aggregate gradation and bitumen type on mechanical properties of semi-flexible asphalt mixtures

Semi-Flexible Asphalt (SFA) mixture is a wearing course in which Open-Graded Asphalt (OGA) mixes having air voids of 20–35% are grouted with cement mortar. The grout consists of cement, sand, superplasticizer, and water. In the present work, an effort was made to assess the effect of the Sand-Cement (S/C) ratio in determining the optimal grout proportions. Taguchi technique combined with Grey Relational Analysis was used to obtain the optimal grout proportion. The optimum grout was found to be the mixture prepared with an S/C ratio of 0.6, a water-to-cement (W/C) ratio of 0.40, and a polycarboxylic ether-based superplasticizer (SP) content of 0.75% by weight of cement. The SP content was the most influencing factor, while the S/C ratio was the second most influencing factor. To investigate the effect of aggregate gradation and bitumen type on the mechanical properties of SFA mixtures, a new aggregate gradation with neat and modified bitumen was used to prepare OGA mixtures and later grouted with optimal grout proportion. The Marshall Stability, compressive strength, Indirect Tensile Strength, Cantabro loss, fatigue resistance, moisture and Oil spillage resistance tests were conducted. The results showed that the SFA mixtures prepared with polymer-modified bitumen and the new aggregate gradation have better mechanical properties, implying the significance of bitumen type and aggregate gradation.

Effect of Aggregate Gradation and Bitumen Type on Mechanical Properties of Semi-Flexible Asphalt Mixtures

Effect of Aggregate Gradation and Bitumen Type on Mechanical Properties of Semi-Flexible Asphalt Mixtures

Effect of aggregate gradation and asphalt mix volumetrics on the thermal properties of asphalt concrete

The objective of this study is to investigate the impact of aggregate gradation and Superpave volumetrics on thermal properties of asphalt mixtures. Thirty asphalt concrete specimens with three different Nominal Maximum Aggregate Sizes (NMAS) of 19.0, 12.5 and 9.5 mm and two levels of gradation coarseness: fine gradation (FG) and coarse gradation (CG) were prepared. The Transient Plane Source (TPS) method was used to determine thermal properties. Based on the analyses performed, it was concluded visually that heat transfer is highly dependent on the contact area which, in turn, is related to air void volume. Unlike NMAS, the gradation coarseness (G) has some effect on thermal conductivity (TC) (p-value = 0.008 < 0.05). On the contrary, the NMAS, unlike gradation coarseness, has a significant effect on thermal diffusivity (TD) with a p-value of 0.025. Both gradation coarseness and NMAS have a significant effect on thermal diffusivity (p-value = 0.029 < 0.05) and do not have much effect on specific heat (SH) where p-value is greater than 0.05. Nevertheless, it was noticed that the thermal diffusivity increased linearly with an increase in aggregate size from 85.64 mm2/s to 125.79 mm2/s at 9.5 NMAS FG and 19 mm NMAS FG, respectively. Whereas the specific heat and thermal conductivity increase as the asphalt content (AC) increases. Consequently, the highest average values of thermal conductivity and specific heat are 2 W/m.K and 0.025 M.J/m3. K, respectively, at the highest asphalt content of 6.1%. Multiple linear regression, non-linear regression and deep learning (MLR, NLR and DL) equations were developed. The non-linear regression resulted relatively in the best predictive power of all equations. Finally, larger datasets are needed to predict thermal properties with higher confidence.

Static segregation of fresh high workable concrete based on an image processing method

Static segregation is a common problem in high workable concrete (HWC). In this study, an image processing method was proposed to evaluate static segregation. By processing cross-sectional images of hardened HWC, the characteristics and distribution of aggregates in the HWC effectively were determined, various quantitative indicators of static segregation were ascertained, and the processing results were evaluated and corrected interactively. The effects of aggregate gradation, maximum aggregate size, and mortar rheology on static segregation in HWC were compared. The results showed that the stress generated by gravity and the buoyancy of large aggregate particles made it easier to overcome the yield stress of the mortar. Thus, increasing the content of large aggregates or the maximum aggregate size made the aggregate distribution more inhomogeneous, which led to more severe static segregation. Furthermore, the increase in the water-cement ratio enhanced the mortar rheology, which decreased the yield stress, gradually destabilized the concrete and made it more prone to segregation.

Effect of Aggregate Size and Water/Cement on Compressive Strength and Physiological Performance of Planting Concrete

Planting concrete, an eco-friendly concrete in which plants can grow directly, has been widely used in roof greening and the slopes of rivers. Porosity and compressive strength are important indicators for evaluating the properties of planting concrete. By preparing planting concrete with different aggregate gradations (10–30 mm, 20–40 mm) and water–cement ratios (0.25, 0.27, 0.29, 0.31, 0.33), the effect of aggregate gradation and water–cement ratio on the porosity and compressive strength of the planting concrete was analyzed, the intrinsic relationship between aggregate gradation and plane pore parameters was studied, the strength growth pattern and microscopic strengthening mechanism were studied, the relationship between porosity and compressive strength of the planting concrete were explored, and a tall fescue planting experiment was carried out to evaluate the plantation performance of the planting concrete. The results show that under the same conditions of water–cement ratio, the smaller the particle size of the aggregate, the smaller the porosity of the plane, and the denser the structure. The average diameter of the planting concrete shows an exponential relationship with the porosity of plane. The early growth of the compressive strength of the planting concrete is rapid; the compressive strength has a linear relationship at the ages of 7 days and 28 days. Compared to polynomial and logarithmic functions, the exponential function gives a better insight into the relationship between the porosity and compressive strength of the planting concrete. Tall fescue seeds germinate and grow well; height, cover, and leaf rootstock and element content of plants can be used as indicators to assess the performance of vegetated concrete planting.

Impacts of Aggregate Gradation on the Volumetric Parameters and Rutting Performance of Asphalt Concrete Mixtures.

The main objective of this study was to determine the effect of aggregate gradation (AG) on the volumetric parameters (VPs) and rutting performance (RP) of asphalt concrete (AC) mixtures. The boundary sieve (BS) between fine and coarse aggregates was 2.36 mm size, and 15 gradation curves of three nominal maximum aggregate sizes (13.2, 19.0, and 26.5 mm) were designed based on the percentage passing of the BS. A vibrating compaction test of coarse aggregates, Marshall compaction and wheel-tracking tests of AC mixtures with various gradations were conducted. It was found that AG had crucial effects on the VPs and RP of AC mixtures. The AC mixture can be designed as a skeletal dense structure provided that the percentage passing of the BS is appropriate. More notably, AC mixtures with a skeletal dense structure showed the best rutting resistance performance. Therefore, it is important to optimize AG for enhancing the high-temperature RP of AC mixtures.

A design method for determining fracture toughness and tensile strength pertinent to concrete sieving curve

The aggregate particle gradation of concrete, which is generally characterized by a sieving curve, is a critical factor affecting the formation of the core stress skeleton of concrete specimens. In this paper, a fracture size and boundary effect model that can describe the effect of aggregate gradation on crack propagation at the micro-level in concrete is developed. The critical points on the aggregate sieving curve are selected as the characteristic values of aggregate particles. The individualized calculation method of the fictitious crack growth length under peak load is provided, while the corresponding design application method of the simplified value of the fictitious crack growth length is given. The micro-level explains the physical nature of the discontinuous and jumping expansion of concrete cracks caused by the different aggregate particle gradations. The formula of the novelty design method can link the aggregate particle gradation at the micro-level with the macroscopic fracture and strength parameters. Further, a simplified two-point method to determine the concrete fracture and strength parameters simultaneously by using only two different specimens has been proposed. The proposed model and design method are not limited to the type of specimens. The concrete parameters and structural failure prediction analysis can be carried out by using notched, un-notched, geometrically similar, as well as non-geometrically similar specimens.

An industrial demonstration study on CO2 mineralization curing for concrete

SummaryA 10,000 ton-CO2/y mineralization curing (CMC) process was demonstrated in Jiaozuo city, China by retrofitting a traditional autoclaved curing plant. An industrial concrete formula with synergistic effects of aggregate gradation, early hydration, and alkali excitation was developed using local solid wastes resources. Approximately 90% of the raw materials, including fly ash, furnace blaster slag, steel slag, and carbide slag, came from coal-based industries. An extraordinary phenomenon of high-temperature accumulation from room temperature to 140°C was first observed in an industrial scale because of the rapid and strong exothermic carbonation reaction. A step pressure-equalizing procedure was developed to achieve a rapid carbonation rate, a high CO2 conversion ratio of >98%, and efficient carbonation exotherm recycling. The global warming potential life cycle analysis revealed that compared with autoclaved curing, CMC showed significantly decreased the emission of 182 kg CO2-Eq/m3-product, with direct CO2 sequestration accounting for ∼65% of the reduction.

Modelling and evaluating moisture susceptibility of laboratory prepared asphalt concrete mixtures

Moisture susceptibility, one of the key reasons of asphalt concrete (AC) pavement deterioration, lowers the durability of AC pavements. Analyzing and evaluating the combined effect of aggregate gradation and asphalt on moisture susceptibility is critical for avoiding and/or minimizing premature failures of AC mixtures; however, evidence of such combined effect is scant. As such, this paper examines the vulnerability to moisture in laboratory-prepared AC mixtures to establish the impact of differential aggregate gradations (both wearing and base) and bitumen grade. Superpave gyratory compacted mixtures are subjected to indirect tensile strength (ITS) test and are evaluated using tensile strength ratio (TSR). Four wearing course gradations, two base course gradations and two binder grades are considered in this study. The findings of the laboratory tests suggests that Asphalt Institute Manual Series (MS-2) wearing course mix and Superpave mix (SP-2) base course mix prepared with 40/50 binder grade result in higher TSR values, implying relatively better resistance to moisture damage of these AC mixtures compared to other tested mixtures. In addition, the study found that wearing mixtures prepared with 40/50 binder grade reveal 40% more tensile strength compared to the same mixtures prepared with 60/70 binder grade. To study the relationship of moisture susceptibility, a first order multiple linear regression model is developed as a function of percent sieve passing, nominal maximum aggregate size and binder grade. The model being proposed captures data variability with high degree of accuracy. The model is also validated and sensitivity analysis is carried out in order to determine changes in TSR with regard to the explanatory variables. The findings of this research will help in selecting the AC mixtures while considering their sensitivity to moisture damage and the developed model will contribute in evaluating moisture susceptibility of AC mixtures without performing hectic experimental tests.

Effect of Aggregate Gradation and Filler Content on the Rutting Resistance of Modified Colored Hot Mix Asphalt

Rutting is considered as the most generated distress in Iraqi roads as a result of the high temperature and excessive traffic load. So, it is essential to utilize polymer modified binder to increase the performance of pavements. The objective of this paper is to assess the effect of aggregate gradation and filler content on the rutting formation of Colored Hot Mix Asphalt CHMA. The HMA was colored by using iron oxide as filler to produce red HMA. Two blends were used: fine and coarse with two different types of filler iron oxide for CHMA and limestone for conventional HMA with two filler content 6% and 10%. Neat (AC 40-50) and modified asphalt (AC 40-50 + 4%SBS) were used. Tests are held on adding 4% Styrene Butadiene Styrene )SBS( by the weight of neat asphalt (AC 40-50) to raise the performance grade by two grades from PG (64-16) to PG (76-16) [1] and [2]. The wheel tracking test is used to assess the rut depth of the CHMA. The test results showed that the using iron oxide with neat asphalt increase the rut depth resistance by 200 and 400 failure load cycles than mixtures using limestone (cycles that mix reach 25 mm rut depth) for fine and coarse mix respectively. Also, the effect of gradation shows that the fine mixture fails at 4000 cycles while the coarse mixture fails at 1800 cycles for 6% limestone mixtures. Increasing the iron oxide content from 6% to 10% leads to increase the failure load cycles by 2200 and 1200 cycles for fine and coarse mixture respectively using modified asphalt. The fine mixture with 10% iron oxide using modified asphalt gives the best performance with 7000 cycles than the coarse mixture with 10% filler content and modified asphalt with 4000 cycles. irrespective the filler and type of binder, the dense mixtures using iron oxide as filler exhibit better resistance to rutting formation than coarse mixtures.

Effect of aggregate gradation on crack propagation in asphalt mixtures at low temperatures based on the Eshelby equivalent inclusion theory

This paper presents a study to evaluate the mixed-mode crack propagation behavior of several typical asphalt mixtures at low temperatures. Based on the Eshelby equivalent inclusion theory and Griffith micro-fracture theory, the basis for determining the I-II mix mode fracture types during crack propagation was established. A random particle-based growth algorithm was adopted to develop a heterogeneous DEM model for three typical asphalt mixtures: open-graded structure (OGFC-13), gap-graded structure (SMA-13), and dense-graded structure (AC-13) mixtures, and a virtual indirect tensile test was conducted. The characteristics of the development of I-II mix mode fractures for three asphalt mixtures at low temperatures were analyzed in four aspects: changes in the number of micro-cracks, proportions of crack types, energy release rates, and force chain diagrams of crack tip stress fields. The results indicate that: (1) From the perspective of the changes in the number of cracks, the dense-graded asphalt mixture has the largest number of micro-cracks, and the proportion of mode I cracks that are mainly due to tension is dominant, while the proportion of mode II cracks that are mainly due to shear is insignificant; (2) The crack energy release rate G(t) in the time-domain increases as the rate of internal energy consumption increases, along with a reduction in the energy storage rate, as the spatial distribution of aggregates change in the open-graded, gap-graded, and dense-graded asphalt mixtures. From an energy standpoint, it was found that more energy is required when the dense-graded asphalt mixture is fractured; (3) In terms of the stress field distributions in the crack tip regions, compared with the open-graded and gap-graded asphalt mixtures, the interior of a dense-graded asphalt mixture is less likely to develop stress concentrations, which is beneficial in suppressing the occurrence of a shear stress field, thereby reducing the occurrence of mode II low-temperature cracks. The results of this research provide theoretical support for the anti-cracking design of asphalt mixtures based on meso-characteristics.