The utilization of municipal solid waste combustion bottom ash as a paving material

A research project was conducted to investigate the potentials of using municipal solid waste combustion bottom ash as a paving material. The effort focused on (i) characterization of the time-dependent properties of the bottom ash, (ii) bottom ash utilization as an unbound material in road subbase and base application, and (iii) bottom ash utilization as an aggregate substitution in hot mixture asphalt. A series of standard or non-standard procedures were employed to evaluate bottom ash behavior. Results indicate that variability of the physical properties of the bottom ash produced during the two years study period is relatively small in view of the fact that the bottom ash is a uncontrolled waste material. In comparison to conventional aggregates bottom ash shows more variation. The bottom ash is a heterogeneous, well graded, highly absorptive, porous and lightweight aggregate material. The abrasion resistance and durability of the bottom ash as measured by the Los Angeles abrasion and sodium sulfate soundness tests pass ASTM requirements. The California Bearing Ratio tests show that the bottom ash has an excellent bearing capacity and would make an excellent subbase and base material in road application. Gyratory Testing Machine (GTM) and Marshall mix design methods were employed to study the properties of hot mix asphalt. Results show that the bottom ash can be used as an aggregate substitute in hot mix asphalt. Results also indicate that GTM and Marshall methods do not make much difference in developing the optimum mix design for the conventional aggregate mix. However, they make a significant difference for the bottom ash mix. The GTM method results in much lower optimum asphalt content than the Marshall method for the bottom ash mix. GTM, unlike Marshall, is a unique tool in predicting the mix performance. It is anticipated that the bottom ash mix developed with the GTM method will perform much better than a mix developed with the Marshall method. A bottom ash test road at 50% substitution designed with the GTM method was successfully installed in Laconia, NH in May of 1993. The long term performance of the test road is being evaluated with various destructive and nondestructive testing techniques

Macromolecular approaches to prevent thrombosis and intimal hyperplasia following percutaneous coronary intervention.

Cardiovascular disease remains one of the largest contributors to death worldwide. Improvements in cardiovascular technology leading to the current generation of drug-eluting stents, bioresorbable stents, and drug-eluting balloons, coupled with advances in antirestenotic therapeutics developed by pharmaceutical community, have had a profound impact on quality of life and longevity. However, these procedures and devices contribute to both short- and long-term complications. Thus, room for improvement and development of new, alternative strategies exists. Two major approaches have been investigated to improve outcomes following percutaneous coronary intervention including perivascular delivery and luminal paving. For both approaches, polymers play a major role as controlled research vehicles, carriers for cells, and antithrombotic coatings. With improvements in catheter delivery devices and increases in our understanding of the biology of healthy and diseased vessels, the time is ripe for development of novel macromolecular coatings that can protect the vessel lumen following balloon angioplasty and promote healthy vascular healing

Modeling of asphalt durability and self-healing with discrete particles method

Asphalt is an important road paving material. Besides an acceptable price, durability, surface conditions (like roughening and evenness), age-, weather- and traffic-induced failures and degradation are relevant aspects. In the professional road-engineering branch empirical models are used to describe the mechanical behaviour of the material and to address large-scale problems for road distress phenomena like rutting, ravelling, cracking and roughness. The mesoscopic granular nature of asphalt and the mechanics of the bitumen layer between the particles are only partly involved in this kind of approach. The discrete particle method is a modern tool that allows for arbitrary (self- )organization of the asphalt meso-structure and for rearrangements due to compaction and cyclic loading. This is of utmost importance for asphalt during the construction phase and the usage period, in forecasting the relevant distress phenomena and understand their origin on the grain-, contact-, or molecular scales. Contact models that involve viscoelasticity, plasticity, friction and roughness are state-of-the art in fields like particle technology and can now be modified for asphalt and validated experimentally on small samples. The ultimate goal is then to derive micro- and meso-based constitutive models that can be applied to model behaviour of asphalt pavements on the larger macroscale. Using the new contact models, damage and crack formation in asphalt and their propagation can be modelled, as well as compaction. Furthermore, the possibility to trigger self-healing in the material can be investigated from a micro-mechanical point of view

Evaluation of hot mix asphalt(HMA) properties compacted at various temperatures

Hot mix asphalt (HMA) mixture compacted at various temperature has always been a concern to researcher. Compaction below the standard compaction temperature may bring reverse effect on HMA properties. Moisture damage of HMA with low temperature referred as striping and this problem become prevalent in recent years. This project is to determine the Marshall properties of compacted mix and moisture susceptibility of mix. In this study asphaltic concrete of wearing course with 14mm nominal maximum aggregate size (ACW14) and 20mm (ACW20) were used and test involved were Marshall Test and AASHTO T283 for moisture susceptibility. Samples were compacted at various temperature namely 85ºC, 100ºC, 115ºC, 130ºC, 145ºC, and 160ºC. Result shown that most samples have low density, low flow value and very stiff when compacted at lower temperature. Tensile strength ratio (TSR) for mixes compacted above 115ºC is more than 80% and this shown that mix still stable at minimum temperature of 115ºC for ACW14. ACW20 has TSR more than 80% when compacted at 130ºC and above. This suggests that as mixes get coarser the minimum compaction should be higher. For Marshall Stability, the result indicates that as the compaction temperature increases, the stability increase. However for compaction temperature above 145ºC, the stability slightly drops. This could indicates that 145ºC is the optimum compaction temperatur

Thermal comfort in the historical urban canyon: the effect of innovative materials

Urban heat island (UHI) can considerably affect the thermal quality of the urban environment, especially within urban canyons, that have typically low sky view factor and limited surface heat re-emission capability. A huge research effort has been registered to develop mitigation solutions for UHI, such as cool materials and greenery. Nevertheless, it is not always possible to apply such strategies in historical urban environments due to constrains for the preservation of their cultural value that do not allow to modify the exterior architectural appearance of heritage buildings. In this scenario, the present paper deals with the analysis of the potential of innovative cool materials characterized by the same appearance of historical ones in mitigating the UHI occurring in the context of a historical urban canyon located in central Italy selected as pilot case study. To this purpose, a preliminary experimental characterization of such innovative highly reflective materials has been performed. Afterwards, an experimental continuous monitoring campaign of the main outdoor microclimate parameters and a numerical modelling of the canyon have been carried out to evaluate the local mitigation capability of such materials when applied over the vertical and horizontal surfaces of the historical canyon. The results show the huge potential of the proposed innovative cool materials in mitigating the local microclimate of the historical urban canyon. In fact, a MOCI reduction up to 0.15 and 0.30 is detected by applying cool red envelope materials and cool red envelope materials plus cool grey paving materials, respectively, on the canyon surfaces

Characterization of industrial by-products as asphalt paving material

Most of the recent research is focusing on the utilization of industrial by-products in road construction. The intention is not only to mitigate the problem of waste being dumped to the landfills but to encourage their use as construction material without compromising quality and performance of the road. Steel slag and bottom ash are the industrial by-products generated in large quantity by industry. This study investigates the characteristics of steel slag and bottom ash to be utilized as aggregate in asphalt pavement. Both materials were characterized in terms of physical, chemical and morphological characteristics compared to the conventional granite aggregate. The results revealed that both materials have much potential to be used as aggregate in asphalt mix. The bottom ash was observed weaker in terms of strength, but the steel slag was found much stronger than the granite. The morphological structure of bottom ash and steel slag disclosed that these are made up of porous and rough-edged granular particles with slightly higher water absorption

Study of Roller Compacted Concrete as a Paving Material

Civil Engineerin

Verification of Job Mix Formula for Alaskan HMA

INE/AUTC 14.1