Stability Marshall

The kind of test that is appropriate in the two cases is different in the first case, load should be increased until failure while in the second, some sort of deformation (or strain) control is appropriate. (A practical case of the latter is the Marshall stability test for evaluating the performance of asphalt concrete). In reality some combination of stress and strain capacity is required. 

The effect of sulfur and asphalt contents in SAS mixtures on Marshall Stability is shown in Figure 3 [15]. The stability values tend to increase with sulfur content but decrease with asphalt addition. It is interesting to note that without the sulfur and asphalt, sand mixes would have little or no stability. The data also indicate a wide variety of mix designs are possible whose stabilities are consistant with Asphalt Institute suggested values for conventional asphaltic mixes. 

Figure 3. Marshall stability as a function of sulfur and asphalt contents in sand-asphalt-sulfur mixes (15,). Materials used were medium-coarse sand and 150/180 pen. asphalt. All specimens were prepared with 2 hammer blows on one face only.

Binder Added, w/o Marshall Stability, lb Flow, 1/100 in Hveem Stability, pet Air Void, pet Dynamic Modulus, psi... 

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. 

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... 

Marshall stability of asphalt concrete dropped 72% after immersion testing in gasoline compared with only a 21% loss with 35-vol % sulfur-asphalt concrete. Jet and diesel fuels had a lesser effect on the Marshall stabilities than did gasoline. The solvent effect on sulfur-asphalt concrete materials decreased with increasing sulfur content in the asphaltic binder in the O-35-vol % substitution range. The greater resistance of sulfur-... 

Binder Sulfur Marshall Stability Flow Voids (%) Coefficient of... 

Marshall Flow Marshall Stability Marshall Flow... 

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

Increasing the proportion of sulfur in the binder, as shown by mixes No. 3, 4, 6, and 7 in Tables II and III, increases Marshall stability. This is attributed to the excess particulate sulfur, dispersed throughout the asphalt phase, which performs similar to a mineral filler. The particular sulfur may be observed using a microscope and is visible as small yellowish specks along broken mix surfaces. 

Figure 8. Influence of sulfur content on Marshall stability...

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. 

Sulfur New Asphalt Soften- ing Agent Resilient Modulus Bulk Air Specific Voids Marshall Stability ... 

The Marshall stability of all asphalt mixtures with plastics was over the lower limit value (=7.35kN) specified in the Munual for Asphalt Pavement. But. the flow value of mixtures with plastics was larger than the conventional mixture and that of some of the mixtures was over the upper limit (=40/10Qmm) specified in the Munual. 

Mixture composition and Marshall stability test results... 

Marshall Stability. A factorial study was made to determine the Marshall stability for mix compositions with asphalt contents of 2-10% and sulfur contents of 0-20 wt % of mix. The mix stability of the two-... 

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