DESIGN AND PROPERTIES OF HOT MIXTURE POROUS ASPHALT FOR SEMI-FLEXIBLE PAVEMENT APPLICATIONS

Abstract Semi-flexible pavement consists of selected porous asphalt mixture filled with cementitious slurry. This new type of pavement has prospects to be designed as a high deformation resistant pavement (Setyawan et al, 2001). Porous asphalt, as the skeleton of the composite has been de-signed to have a porosity of 30% by selected the aggregates gradation, type of bitumen, bitumen content and fibre content. This investigation concerned with the design and properties of porous asphalt to be used as the skeleton for grouted macadam. The ranges of mixtures were evalu-ated by using different type of bitumen, bitumen content, filler addition and aggregate gradation. This investigation concluded that porous as-phalt manufactured by using specified gradation utilising 50-pen bitu-men is appropriate to be used as skeleton for grouted macadam. Keywords: cellulose filler, grouted macadam, polymer modified, porous asphalt, semi-flexible pavement

Pembinaan konstruk instrumen penilaian pasca penghunian untuk perumahan bertingkat yang dibina menggunakan kaedah Sistem Binaan Berindustri (IBS)

Post Occupancy Evaluation (POE) is an activity of the building evaluation process with a focus on quality, operational performance and satisfaction of the occupants. The POE is important to evaluate completed and occupied buildings to identify weaknesses and potential for future improvement. To date, there have been various variations of POE instruments and tools to evaluate occupied buildings. However, the POE instrument for assessing high-rise housing constructed using the industrialized building system (IBS) method has not been developed specifically. In this regard, this study aims to discuss the construction of an effective POE instrument to measure the quality and performance of high-rise housing built using the IBS method. For this purpose, the 3 round Delphi method was adapted by involving 15 experts selected based on their background and experience related to IBS. The results of a three-round Delphi study found that 33 out of all sub-constructs were dropped because of low mean scores (<4.2 in two rounds) while 75 sub-constructs were identified as final items. The results of the Delphi study also found that all 10 constructs were 1) Spatial; 2) Design and aesthetics; 3) Physical; 4) Building materials; 5) Quality of work; 6) Comfort and well-being; 7) Environment and health; 8) Maintenance; 9) Value and 10) Cost is the most significant construct for developing PPP instruments. Accordingly, an effective Post-Occupancy Assessment Instrument for measuring the quality, performance and value of a home built using the IBS method should include all of these constructs

A Review of Characteristics of Bio-Oils and Their Utilization as Additives of Asphalts

Transforming waste biomass materials into bio-oils in order to partially substitute petroleum asphalt can reduce environmental pollution and fossil energy consumption and has economic benefits. The characteristics of bio-oils and their utilization as additives of asphalts are the focus of this review. First, physicochemical properties of various bio-oils are characterized. Then, conventional, rheological, and chemical properties of bio-oil modified asphalt binders are synthetically reviewed, as well as road performance of bio-oil modified asphalt mixtures. Finally, performance optimization is discussed for bio-asphalt binders and mixtures. This review indicates that bio-oils are highly complex materials that contain various compounds. Moreover, bio-oils are source-depending materials for which its properties vary with different sources. Most bio-oils have a favorable stimulus upon the low temperature performance of asphalt binders and mixtures but exhibit a negative impact on their high-temperature performance. Moreover, a large amount of oxygen element, oxygen-comprising functional groups, and light components in plant-based bio-oils result in higher sensitivity to ageing of bio-oil modified asphalts. In order to increase the performance of bio-asphalts, most research has been limited to adding additive agents to bio-asphalts; therefore, more reasonable optimization methods need to be proposed. Furthermore, upcoming exploration is also needed to identify reasonable evaluation indicators of bio-oils, modification mechanisms of bio-asphalts, and long-term performance tracking in field applications of bio-asphalts during pavement service life

Assessment of recycled concrete aggregates for road base and sub-base

Population increase and economic developments can lead to construction as well as demolition of infrastructures such as buildings, bridges, roads, etc and used concrete is the main waste product of them. Recycling of waste concrete to obtain the recycled concrete aggregates (RCA) for base and/or sub-base materials in road construction is a foremost application to be promoted to gain economical and sustainable benefits. As the mortar, bricks, glass and asphalt present in different constituents in RCA, it exhibits inconsistent properties and performance. In this study, six different types of RCA samples were subjected classification tests such as particle size distribution, plasticity, compaction test and California Bearing Ratio (CBR). Results were compared with those of the standard road materials used in Queensland, Australia and found that ‘RM1-100/RM3-0’ and ‘RM1-80/RM3-20’ samples are sitting in the margin of the minimum required specifications of base materials while others are lower than that

Characterization of the Structure of Saudi Crude Asphaltenes by X-ray Diffraction

Structural characterization studies have been carried out on four commercial Saudi Arabian crude oils. The aromaticity and crystallite parameters of the asphaltenes were studied by X-ray diffraction methods and compared to the average structural parameters calculated from nuclear magnetic resonance spectra

Asphalt toughness effect on bituminous mixture fatigue behavior

One of the most important parameters to define bituminous mixture behavior in service is the toughness that the bitumen provides when binding the aggregate particles; that is; the dissipated energy during the materials fracture process. The greater the dissipated energy in fracture, the better the bituminous mixture quality is. Hence, a relationship will have to exist if the toughness is removed during one load cycle (direct tension) or during many cycles along time (fatigue). The purpose of this study is to determinate relationships between the toughness of different bitumens and the fatigue behavior of their corresponding bituminous mixtures, for which, the toughness has been obtained by means of direct tension test and has been compared with the value of the fatigue law and dissipated energy obtained by fatigue bending test. Results showed that, this study expect to give important means for further research to predict fatigue life from a static test.Peer ReviewedPostprint (published version

Studies of the microstructure of polymer-modified bitumen emulsions using confocal laser scanning microscopy

Polymer-modified bitumen emulsions present a safer and more environmentally friendly binder for enhancing the properties of roads. Cationic bitumen emulsion binders containing polymer latex were investigated using confocal laser scanning microscopy. The latex was incorporated into the bitumen emulsion by using four different addition methods and all emulsions were processed with a conventional colloid mill. The emulsion binder films were studied after evaporation of the emulsion aqueous phase. We show how the microstructure and distribution of the polymer varies within the bitumen binder depending on latex addition method, and that the microstructure of the binder remains intact when exposed to elevated temperature. It was found that a distinctly fine dispersion of polymer results when the polymer is blended into the bitumen before the emulsifying process (a monophase emulsion). In contrast, bi-phase emulsion binders produced by either post-adding the latex to the bitumen emulsion, or by adding the latex into the emulsifier solution phase before processing, or by comilling the latex with the bitumen, water and emulsifier all resulted in a network formation of bitumen particles surrounded by a continuous polymer film. The use of emulsified binders appears to result in a more evenly distributed polymer network compared to the use of hot polymer-modified binders, and they therefore have greater potential for consistent binder cohesion strength, stone retention and therefore improved pavement performance