Creep coefficient

The target bitumen content should be lower than the maximum permissible bitumen determined by using the creep coefficient procedure, when the mixture is to be used in sections with more than 3000 ESAL (equivalent standard axle load) per day. For details on the procedure used to determine the creep coefficient, see Section 6.3.3.3. 

The creep coefficient, 6, is the slope from the least square linear fit on the log e versus log M-values (n = load applications) determined from the triaxial cyclic compression test in 

The creep coefficient may also be determined by executing the static creep test. In this case, the creep coefficient, b, is the slope of the linear fit on the log 5, versus log 5 ix,creep-The stiffness of the bitumen, is determined from the Van der Poel nomograph, and the static creep stiffness, 5 is determined from the static creep test, at various stages of loading. More information regarding the static creep test is given in Section 7.6.3. 

Two specimens per bitumen content (use five levels of bitumen content), after curing for Marshall testing, are subjected to either the triaxial cyclic compression test or the static creep test at 40°C 0.5 C. 

Cold dense-graded mixtures with bitumen content above the maximum permissible bitumen content are more susceptible to permanent deformation and should be rejected. 

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In general, at low latex dosage levels, the creep strain and creep coefficient of latex modified concrete and mortar are considerably smaller than those of ordinary cement cement, mortar and concrete [94, 98]. The low creep is probably due to the low polymer content which may not affect the elasticity, but increases the strength by improving the binding capacity of the matrix as well as providing better hydration through water retention in the mortar and concrete. The coefficient of thermal expansion at about 9-10 x 10 is very similar to that of concrete, which is 10 x 10 6 [87, 94, 99]. 

As previously noted, this chapter has been concerned mainly with those models for the creep of ceramic matrix composite materials which feature some novelty that cannot be represented simply by taking models for the linear elastic properties of a composite and, through transformation, turning the model into a linear viscoelastic one. If this were done, the coverage of models would be much more comprehensive since elastic models for composites abound. Instead, it was decided to concentrate mainly on phenomena which cannot be treated in this manner. However, it was necessary to introduce a few models for materials with linear matrices which could have been developed by the transformation route. Otherwise, the discussion of some novel aspects such as fiber brittle failure or the comparison of non-linear materials with linear ones would have been incomprehensible. To summarize those models which could have been introduced by the transformation route, it can be stated that the inverse of the composite linear elastic modulus can be used to represent a linear steady-state creep coefficient when the kinematics are switched from strain to strain rate in the relevant model. 

The allowed us to obtain RubCon creep coefficients creep = ocreep/o c. The relationship of creep coefficients to time for the reinforced and plain RubCon samples is shown in Figure 2.56. 

Asymptotes of the curves give an indication of the fibrous RubCon creep limit. It is interesting to note that the creep coefficient of the plain RubCon creep = 0.77-0.78, whereas for fiber reinforced RubCon it is slightly below creep = 0.74-0.75. In this case the creep limit of fiber-reinforced RubCon at compression ccreep = 74.9-78.4 MPa exceeds the creep limit of plain material ccreep = 66-66.8 MPa. This phenomenon is... 

From Table 6.9 it follows that specific creep at 400 days and the creep coefficient for composite beam samples (B1 and B3) are one order of magnitude less than for plain concrete. 

Conflicting data exist on the creep behavior of latex-modified mortar and concrete. The creep characteristics of SBR- and PAE-modified concretes reported by Ohamal l are represented in Fig. 4.40. Like ordinary cement concrete, the relationships between loading time (t) and creep strain (ec) or creep coefficient (< )) (i.e., creq) strain/elastic strain ratio) of the latex-modified concretes fit approximately the expression ... 

Figure 4.40 Loading time vs. creep strain and creep coefficient of latex-modified concretes.

The thermal creep coefficient Gt in both channel and tube is given by... 

The thermal creep coefficient Gj is also obtained from the Navier-Stokes equation, but applying the thermal slip botmdary condition (9). It is verified that this coefficient does not depend on the type of the cross section in... 

Gas Flow In Nanochannels, Fig. 3 Thermal creep coefficient versus rarefaction parameter 6 solid lines, kinetic equation solution [11] pointed line, free-molecular value based on Eqs. 12 and 15 dashed line, Navier-Stokes solution Eq. 19... 

Numerical results on the capillary flow of polyatomic gases can be found in [4]. Comparing these results with the data presented here, it is concluded that the Poiseuille coefficient Gp is slightly affected by the internal structure of molecules. The thermal creep coefficient Gp for polyatomic gases differs from that for monatomic gases. 

Thermal creep coefficient determines a gas flow induced by a temperature gradient... 

The creep coefficient 6 or h is then plotted against bitumen content and a graph similar to Figure 6.2 is obtained. By drawing two tangent straight lines to the concave curve as shown in Figure 6.2, the maximum permissible bitumen content is determined at the point of intersection. 

This method is conducted to determine the volumetric and modified Marshall properties, and together with the creep coefficient procedure, it will help determine the target bitumen content of DGCA. 

The criteria used to determine the target bitumen content are soaked stability, retained stability, total void content, absorbed water and bitumen film thickness. When DGCA is going to be used in pavements with medium to high traffic (ESAL > 3000 per day), the target binder content should satisfy the creep coefficient requirement. Equipment... 

Several BGK analyses have been performed for the thermal-creep coefficient [2.99]. The only BGK analysis of the near-free-molecular regime thermal force (Kn. 1, Kn - 0) appears to be that of BROCK [2.136], Experimental Millikan-cell data were found by SCHMITT [2.97] and others to follow the relation... 

Here Cs. "t, and x are microscopic constants Cs. >. and t are called the slip coefficient, the thermal creep coefficient, and the temperature jump distance, respectively. All four constants have the dimension of a length and their... 

Mating force Modulus (tensile, secant, tensile creep) Coefficient of friction... 

A different expression was proposed by the ACI 209R-92 (2008) and a so-called creep coefficient was used ... 

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