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A recently used material that shows environmental and technical advantages for use as an asphalt binder modifier is biochar (BC). Different biomasses can be converted into BC by pyrolysis. One agro-industrial biomass that is abundant in copious quantities is oil palm mesocarp fiber (OPMF) obtained from African palm cultivation. In the present study, the use of a BC obtained from OPMF (BC-OPMF) as a modifier of asphalt binder (AC type) to produce a hot mix asphalt (HMA) was evaluated. This type of BC has not been investigated or reported in the reference literature as a binder and/or asphalt mix modifier. Initially, AC was modified with BC in three ratios (BC/AC = 5, 10, and 15%, with respect to mass) to perform penetration, softening point, and rotational viscosity tests; rheological characterization at high and intermediate temperatures; and scanning electron microscope (SEM) visualization. Based on this experimental phase, BC/AC = 10% was chosen to manufacture the modified HMA. Resistance parameters under monotonic loading (stability—S, flow—F, S/F ratio of the Marshall test, and indirect tensile strength in dry—ITSD and wet—ITSC conditions) and cyclic loading (resilient modulus, permanent deformation, and fatigue resistance under stress-controlled conditions) were evaluated on the control HMA (AC unmodified) and the modified HMA. Additionally, the tensile strength ratio (TSR) was calculated to evaluate the resistance to moisture damage. Abrasion and raveling resistance were evaluated by performing Cantabro tests. BC-OPMF is shown to be a sustainable and promising material for modifying asphalt binders for those seeking to increase stiffness and rutting resistance in high-temperature climates, resistance to moisture damage, raveling, and fatigue without increasing the optimum asphalt binder content (OAC), changing the volumetric composition of the HMA or increasing the manufacturing and construction temperatures. [ABSTRACT FROM AUTHOR]

Significant amounts of blast furnace slag (BFS) are generated daily as by-product from iron and steel industries. This waste material usually has interesting physical properties and mineralogical and chemical composition, which can be useful as granular aggregate in the production of hot mix asphalt (HMA). In this study, an experimental program was designed to evaluate the effect on the resistance of a HMA due to the replacement (in mass and volume) of the coarse fraction of a natural aggregate (type limestone; LS) by a BFS. Total aggregate replacement was also evaluated. The mechanical properties were evaluated by carrying out the following tests: Marshall stability, indirect tensile strength (ITS), Cantabro abrasion, resilient modulus, permanent deformation, and fatigue resistance. Water sensitivity or moisture damage was evaluated by determining the ratio of indirect tensile strength (TSR) in wet and dry conditions. X-ray diffractometry (XRD), X-ray fluorescence (XRF) tests, and imaging processing in a scanning electron microscope (SEM) were carried out on particles of LS and BFS. The results revealed a remarkable enhancement in the properties of the HMA mixture when the coarse fraction of the LS was replaced in volume by BFS. When such a replacement was made in mass, the adhesive properties of the asphalt-aggregate system worsened. Total replacement of the LS led to unsatisfactory mechanical behavior. [ABSTRACT FROM AUTHOR]

A relatively recent development in asphalt pavement technology, warm mix asphalt (WMA) offers a number of benefits. We present a comparison of some mechanical properties of warm mix asphalt (WMA) made in an asphalt plant batch with a traditional Hot Mix Asphalt (HMA). WMA mixture was made with asphalt cement CA 60-70 and a chemical additive that foams the asphalt at 80 °C. WAM was mixed and compacted at 120 °C and 110 °C, respectively. The control mixture (HMA) was a Dense Graded Mixture MDC-19 proposed by [1], was made with the same materials and mixed and compacted at 150 and 140 °C. Mechanical properties were evaluated under two loading modes: monotonic load (Marshall and indirect tensile test) and dynamic loads (resilient modulus, permanent deformation and fatigue). Results showed that mechanical properties of Warm Mixed Asphalts are better than control mixture. [ABSTRACT FROM AUTHOR]

A relatively recent development in asphalt pavement technology, warm mix asphalt (WMA) offers a number of benefits. Although its most important advantage is environmental in nature, it also shows technical and economic benefits. This paper presents and discusses results for the laboratory evaluation of a WMA, which were compared to traditional hot mix asphalts (HMA). Two samples of WMA and two samples of HMA with nominal maximum aggregate sizes of 10 mm and 19.0 mm were evaluated. A liquid chemical solution was used to make WMA (Patent pending for this additive). The purpose of this additive was to induce foaming of the asphalt binder AC 60-70 (PG 58-22). Moisture susceptibility and strength under monotonic and dynamic loading were studied. In addition, a set of tests were performed: Marshall, resilient modulus, permanent deformation and indirect tensile strength. The research led to the conclusion that the WMA chemical additive decreases mix temperatures by 30° C, which in turn, translates into better workability and volumetric composition. Furthermore, the WMA showed higher levels of resistance to both moisture damage and high service temperatures under monotonic and dynamic loading. [ABSTRACT FROM AUTHOR]