Advanced Materials Research Vol. 723

Abstract: Nowadays, engineers begin to pay more attention on field-aged asphalt concrete cores because they have more reality than the lab-made cores and the results can tell what happened to the pavement. However, it is not accurate to estimate the full asphalt mixture because as usual the pavement engineers can only extract the binder from it, not the mixture. Now there is a newly developed way to analysis the data more accurately using the Direct Tension Test. Because the field aged asphalt mixtures are not aged uniformly with the pavement depth because of various reasons, there is a modulus gradient going through deeply through the asphalt layer and usually the stiffest layer is the surface because normally the surface is more aged. A method has been developed to analysis this behavior. Tests are both taken on field cores which are Hot Mix Asphalt (HMA) and Warm Mix Asphalt (WMA). During the research, the authors found that it is both applicable for all the field cores. More information about this method and tests are detailed in the following paragraphs.

Abstract: This paper presents a review of harvesting green energy from road. There are three forms of green energy exist in road: light, thermal and mechanical energy. Photovoltaic technology, thermoelectric technology, directly heat transferring and piezoelectric technology are discussed in this paper, as well as the cases studied in Europe, USA, Japan, Israel and China. Solar panels installed along road are current available to harvest light energy from the roadside land. Alternatively, the solar panels can be installed on the road instead of pavement structures, such as the Solar Roadway^TM. This technology is rather conceptual at this moment, and the main challenge is to design and build durable materials and structures that can withstand traffic at a reasonable maintenance and replacement cost. Thermoelectric generators can potentially be embedded in pavements, and generate electric power from the temperature gradient existing in pavements. However, instrument capable of efficiently generate electricity from the relatively small temperature gradient in pavement is still under development. Directly heat transfer solution is to have fluid flow through pavement, and the fluid is heated (in summer) by the pavement. An extra benefit in addition to energy collection is that this method can reduce pavement temperature as well as the associated negative effects on pavement performance and the environment. However how the heated fluid can be utilized was not clear. Electricity can be generated by piezoelectric ceramic generators embedded in pavement, as a result of the compressive stress and deformation induced by moving vehicles. Trials have been reported in Israel and China, and it was estimated that one lane-mile of highway can potentially general electricity of 200 kW.

Abstract: This study inspects the benefits of using RAP on both financial and environmental aspects from life cycle viewpoints. The Life Cycle Cost Saving (LCCS) and the Life Cycle Carbon Reduction (LCCR) of various RAP mixtures (RAP content 10%, 20%, 30%, and 40%) to the virgin mixture are introduced and applied in this study. Carbon emission data of associated materials are obtained from PaLATE database. According to calculations, the RAP mixtures corresponding cost ratio and service life ratio exceed certain thresholds to have advantages over virgin mixtures. From a financial perspective, the service life ratio of RAP mixtures to virgin mixtures must be larger than the cost ratio of these two materials. For environmental benefit, the service life of RAP mixtures must be over 70% (40% RAP) to 90% (10% RAP) of that of the virgin mixture.

Abstract: The aging simulating tests of the SBS and SBS modified asphalt under the conditions of wet and dry are compared and the effect of water on the aging of modified asphalt was investigated by infrared spectroscopy analysis. The results showed that: after aging in the wet conditions the change range of asphalt performance increased. Infrared spectroscopy analysis results showed that the carbonyl content of asphalt and SBS after the aging in wet conditions increased. It was proved that the presence of water accelerated the aging of asphalt and SBS under the action of heat and oxygen. This is mainly due to the substances containing carbonyl groups is further oxidized into carboxylic acids under the action of water, while the double bond in SBS chain can occur the hydration reaction in the coupled WaterHeat condition and become the polar groups.

Abstract: Electric arc furnace (EAF) reducing slag is the by-product of EAF steel-making. Currently, reducing slag is considered a waste material by the industry in Taiwan. Since the chemical content of reducing slag is similar to blast furnace slag (BFS), it is expected that reducing slag exhibits a similar pozzolanic effect as the BFS. This study used alkaline activator consisting of sodium silicate and sodium hydroxide to improve the activity of reductive slag so as to replace Portland cement as binder in concrete. Some BFS was used to blend with the reducing slag to enhance the binding quality of alkali-activated mixes. The results show that a blend of 50% BFS and 50% reducing slag can be activated successively with alkali. Also, the sulfate resistance of concrete made with alkali-activated EAF reducing slag is found to be better than that of concrete made with portland cement, while the drying shrinkage of alkali-activated EAF reducing slag concrete is greater than that of portland cement concrete.

Abstract: This study replaced natural aggregate with a fine aggregate of washed municipal solid waste incinerator bottom ash (WMSWIBA) in the production of compressed concrete paving units to increase the applications of WMSWIBA. The cement-aggregate ratios investigated were 0.1, 0.2, 0.3, 0.4 and 0.5, and the water-cement ratios were 0.20, 0.25 and 0.30. The results showed that the coefficient of permeability of the compressed concrete paving units was less than 2.66×10^-5 cm/sec, the water absorption was 13.55~4.75%, the porosity was 8.05~1.62%, the compressive strength was 12.3~48.5 MPa, the ultrasonic pulse velocity was 1521~3059 m/sec, and the attrition volume loss was 117.7~16.0 cm³/50 cm². The results suggested that the compressive strength and ultrasonic pulse velocity increase with the cement-aggregate ratio, whereas the attrition loss decreases.

Abstract: All day long the transportation infrastructure receives solar energy from the sun rays, storing much of them as heat that is left to dissipate by nightfall. The concept of harvesting solar energy from transportation infrastructure is enticing because it offers a way to collect solar energy by utilizing an extensive infrastructure that already exists. Thus, an attempt was made to investigate novel methods for solar energy harvesting and conversion with potential economic efficiency substantially beyond that of current technology. Particularly, a comparative study was conducted between rigid and flexible solar panels.

Abstract: This The main objective of this study is to evaluate the feasibility of using Permeable Reclaimed Concrete (PRC) for urban roads construction. The PRC can be used at both stabilized base and wearing surface layers for new constructed pavements. The purposes of this paper were focused on the comparison of cost and energy consumption in both material production and pavement construction stages between PRC pavement and conventional hot-mixed asphalt (HMA) pavement. In addition, the potential ecological advantages such as reducing urban heat island effect as well as enrich groundwater table by using PRC pavement in the urban roads was also discussed. The results showed that the PRC pavement could effectively reduce 3 to 5°C surface temperature compare to conventional HMA pavement.

Abstract: The furnace slag are the by-products of the steel industry, the main ingredients are the oxide of calcium, alumina and magnesium, and some silica. Slag used as concrete aggregate could cause the problem of the volume expansion of concrete. The expansion problem may be produced by ASR or free calcium oxide and magnesium oxide in slag. This research stabilizing the non-ASR reactive slag using steam treatment analyzes the effectiveness of steam treating technique inhibiting the expansive problem for slag used in concrete. And this paper also discusses the effect of the steam treating time on the performance of inhibiting the expansive problem.

Abstract: Climate change is one of the most key global topics well-known in international community. Over the past decades years, the change climate and its impact on asphalt pavement in China is very obvious. Many expressways of asphalt pavement come forth severe rutting failure during only a few days of extensive, long-lasting, extreme heat wave in summer, which resulting in the change of asphalt cement specification and the selection practice of asphalt cement. So it is necessary to review climate change and its impact in the past, and forecast the probable situation in the future. The paper focuses specifically on the issue of asphalt binder selection under changing climatic conditions.