The effect of maize resistant starch (MRS) and transglutaminase (TG) on rheological and thermal properties of pan bread dough was studied. The MRS was added as an alternative to increase the fiber ingestion while TG supplies the gluten dilution, catalyzing protein bonds. A second order Central Composite Design (2²) with three central and four star points was applied and the results were compared to those of pan bread dough prepared without MRS and TG, as control. The presence of MRS and TG significantly (P<0.05) influenced the maximum resistance to extension achieving the highest value for the dough formulated with 8.8 g/100g of MRS and 0.12 g/100g of TG. A modified power-law model was fitted to the stress-strain data obtained from biaxial test, indicating that partial substitution of wheat flour by MRS resulted high n index (degree of strain hardening). Only starch gelatinization enthalpy significantly changed (P<0.05) by MRS and TG contents, increasing with the increase of TG. The temperatures obtained from thermograms are compared to those obtained from DSC curves from aqueous suspensions of MRS, indicating gelatinization temperatures above 100 ºC.

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This paper evaluates the mechanical properties and performance of the Fine Aggregate Matrix (FAM) existing within full RAP asphalt mixtures, in terms of their rheological and fatigue deterioration properties. The RAP material was produced in the laboratory to control its properties and to reduce the effects of variability associated with these materials. Four FAM mixtures were analysed, including a virgin HMA, a 100%RAP and two mixtures containing 50% RAP in combination with virgin materials using different penetration grade virgin binders.The analysis of the deterioration properties was based on the application of a fracture model that incorporates the viscoelastic properties of the material, the quality of the adhesive bonds developed between the aggregates and the corresponding bitumen present in each mixture, and the rate at which the material dissipates energy when subjected to cycling loading. The input parameters for this model include the results obtained from Dynamic Mechanical Analysis (DMA) and Surface Free Energy (SFE) tests. In general, the results showed that the incorporation of 50%RAP content increased the stiffness of the final mixtures, as expected. However, this hardening effect did not result in mixtures with inferior fatigue performance of the FAM present in the full mixtures, at the applied strain level.

This paper evaluates and compares the differences in the rheological characteristics of the fine aggregate matrix (FAM) portion of plant produced Foamed Bitumen Mixtures (FBMs) by means of a mechanical foaming process, and by the incorporation of zeolites in combination with Reclaimed Asphalt Pavement (RAP) material. This evaluation explores, for the first time, the impact of plant production variations for half-warm, warm and hot processes (i.e. mixing temperatures around 90, 120 and 160 o C, respectively) on their rheological response. A fine Virgin-HMA, a fine HMA-RAP -no foaming technique -, and a 100% fine RAP mixture were also produced for comparison purposes. Dynamic Mechanical Analysis (DMA) tests were conducted on all evaluated FAM mixtures to determine their linear viscoelastic properties. Results indicate that the rheological response of the fine RAP-FBMs is influenced primarily by the contribution of the RAP binder in the total bitumen blend, and ageing of the fine RAP material, which were a function of the foaming technology and the production temperature of the materials.

The continuous rise in the cost of refined asphalt binders has increased the need for alternative road materials. Natural sandasphalt mixtures, which have been already used in the construction of flexible pavements, constitute a promising nonstandard asphalt material. Unfortunately, most of these mixtures have not been fully characterised or have been characterised using techniques that are unable to predict their performance. This paper proposes the application of the dynamic mechanical analyser (DMA) test to determine viscoelastic material properties of natural asphalt mixtures. The technique is also recommended to evaluate the mechanical deterioration of these materials and the impact of relevant construction factors, such as a compaction temperature, on their mechanical performance. Experimental results of applying DMA testing on a natural sand-asphalt mixture corroborated that this method provides reliable information to support decision-making processes regarding the responsible use of these mixtures in road infrastructure projects.