Marshall aggregates

The hot mixes are designed by using a standard laboratory compaction procedure to develop a composition reflecting estabUshed criteria for volume percent air voids, total volume percent voids between aggregate particles, flow and stabdity, or compressive strength. Tests such as the Marshall, Unconfined Compression, Hubbard-Field, Triaxial Procedure, or the Hveem stabdometer method are used (109). 

Hounslow, M.J., Ryall, R.L. and Marshall, V.R., 1988. A discretized population balance for nucleation, growth and aggregation. American Institution of Chemical Engineers Journal, 34, 1821-1832. 

Filip Z, Hattori T (1984) Utilization of substrates and transformation of solid subtrata. In Marshall KC (ed) Microbial adhesion and aggregation. Dahlem Konferenzen, Springer-Verlag, Berlin, Germany, pp 251-282... 

SAS mixes are optimized using a slightly modified Marshall Method (ASTM Method D 1559) and represent a series of trade-offs between stability and flow, air voids content and permeability and fatigue life [15]. The major departure from the Marshall Method is that only 2 hammer blows rather than the conventional 75 blows per face are used. The light compaction is used only to expel entrapped air and to achieve more uniform sample configurations without disturbing sulfur soldification within the aggregate voids. 

Optimum Marshall Binder Contents Sulphlex-233 and AC-20 Asphalt Cement With a Well-Graded Diabase Aggregate... 

Examination of Sulphlex-233 mixtures with other types of aggregates generally have confirmed the results presented here. Sulphlex-233 mixtures can meet or exceed most Marshall design and compressive strength criteria at either equal volume or equal weight replacement of asphalt cement, but "optimum" mixtures are obtained at or near the equal volume replacement level. The Sulphlex-233 mixtures are in many cases susceptible to water damage, and the use of tall oil as an anti-strip additive has been recommended where indicated. 

Marshall, K. C. Microbial Adhesion and Aggregation Springer Berlin, Germany, 1984 pp 317-330. 

Laboratory experiments show that micrometer-sized dust grains, like those in proto-planetary disks, readily stick together during collisions, forming porous aggregates up to 1 cm in size (Poppe et al. 2000 Marshall Cuzzi 2001 Krause Blum... 

Sulfui>-Aggregate Interaction. Substantial increases in stiffness of SA binder-based mixes, as measured by the Marshall test, tensile strength, and resilient modulus of elasticity, have been observed with increasing sulfur-asphalt ratio of the binder used (11, 15, 16). Such increases can, of course, be attributed in part to the increase in viscosity of the SA... 

Use of Low-Quality Aggregate. Good-quality aggregates are costly and in short supply in certain areas. Laboratory investigations have shown that some low-quality aggregates can be improved greatly especially with respect to Marshall stability. For example, the Marshall stability (ASTM D1559) of 608 for a sand mix, as shown in Table VI, is increased to 2608 when an SA binder is used. 

Direct Substitution Method. Sulfur and asphalt were poured together at 300°F and were added to the heated aggregate at 300°-320°F. The three materials were mixed in the Hobart mixer for 2 min. Standard Marshall test samples for Marshall and dynamic stiffness tests were prepared as in the emulsification method. Bar samples for fatigue testing were prepared by kneading the mix into 3 X 3 X 12-in. bars to obtain compaction equal to the Marshall compacts. 

Figure 4. Marshall stability vs. compaction tem-perature—limestone aggregate...

A temperature sensitivity study was made to establish the workability of the paving materials with increasing sulfur contents in the binders. Marshall compaction samples were prepared in quadruplicate for all the mixtures shown in Table II, and the effect of compaction at 10 temperatures was determined. Figures 4 and 5 show the results of the temperature sensitivity study on the Marshall stability of both methods of mixing with each aggregate. Figures 6 and 7 give the void content of the same... 

Table III. Comparison of Marshall and Hveem Stability Results for Mixture Designs of Various Type Binders and Aggregates...

Figure 6. Effect of curing time on Marshall stability for mixes with sulfur-extended binders prepared in high-shear blender ana by aggregate shear...

Mix design is the choice of the best combination of aggregate, binder, and compaction effort to produce desirable pavement material properties. The choice has been made normally based on the results of simple indicator and control tests such as the Marshall stability, Marshall flow, Hveem stability, resilient modulus, and indirect tension tests. 

For the screening test phase, three replicate specimens of each combination of independent variables were made, and each of the indicator or control tests was run on the specimens of sulfur-asphalt concrete. These indicator tests (dependent variables) included bulk specific gravity, air voids, voids in the mineral aggregate (VMA), resilient modulus, Hveem stability, Marshall stability, and Marshall flow. Table II presents the range of dependent variables determined during the screening test for the AAS system mixtures. 

Hirokawa Y, Tanaka T, Katayama S (1984) In Marshall KC (ed) MicrotU adhesion and aggregation. Springer, Berlin Heidelberg New York, p 177... 

Marshall, N., 1968. Observations on organic aggregates in the vicinity of coral reefs. Mar. Biol., 2 50—53. 

Marshall properties, dynamic stability, bending strength and strain at failure of the asphalt mixtures with each of the plastics aggregates were compared with those of a conventional asphalt mixture. Results showed that dynamic stability of asphalt mixture with a plastics aggregate which softened at the mixing temperature was higher than the conventional mixture. 

Hounslow MJ, Ryall RL, Marshall VR (1988) A Discretized Population Balance for Nucleation, Growth, and Aggregation. AIChE J 34 1821- ... 

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