A study on the economic using of steel slag aggregate in asphalt mixtures reinforced by aramid fiber

Due to the urgent need to conserve natural resources, the researchers have been focused on using plant wastes as an alternative source of natural resources. On the other hand, increasing costs of material and rising consumption of natural resources prompted engineers and researchers to look for other materials to enhance asphalt mixture performance, thus minimizing maintenance and rehabilitation of roads as well as saving costs. In this regard, steel slag aggregate is a by product of steel manufacturing, and it is considered as one of the well-known plant wastes, which is suitable for pavements applications. Although it is useful in terms of improving the performances of asphalt mixtures, it has also disadvantages such as expansion volume and high density. However, fibers could be described as a distinct material in the enhancement of asphalt mixture. This study is aimed to evaluate electric arc furnace (EAF) steel slag aggregate replaced natural coarse aggregate in the asphalt mixture reinforced by aramid fiber in order to reduce asphalt layer thickness, and hence reduce transportation costs resulting from high density of the steel slag aggregate. In addition, steel slag aggregate was immersed in the water for 6 months in order to minimize free lime and free magnesia content, which leads to the expansion volume. Six mixtures with different proportion of aramid fiber by total weight of the aggregate were evaluated. Mix1, Mix2, Mix3, Mix4, Mix5 and Mix6 corresponding to 100% of granite aggregate, coarse steel slag aggregate, coarse steel slag and 0.025% aramid fiber, coarse steel slag and 0.05% aramid fiber, coarse steel slag and 0.1% aramid fiber and coarse steel slag aggregate and 0.3 aramid fiber, respectively. However, the fine granite aggregate kept fixed for all mixtures. Thermogravimetric and XRD tests were used to evaluate the benefit of treatment steel slag aggregate while resilient modulus and dynamic creep were the performed tests of the mixtures. Response surface Methodology (RSM) using design expert6 was used to analyze results obtained in order to investigate the interaction between factor and responses of the dynamic creep. Mechanistic empirical pavement design approach was used to examine the possibility of extend service life or reducing thickness of asphalt layer as well as to assess the benefit of ultra-thin asphalt overlay containing steel slag aggregate and aramid fiber in terms of improving service life of existing asphalt layer. The results indicated that method of treatment steel slag was successful in reducing free lime and free magnesia content. Introducing aramid fiber by 0.05% to the total weight of the aggregate into mixture significantly increased resilient modulus and dynamic creep compared to the other mixtures, and it was the optimum content. The results of Mechanistic empirical pavement design indicated that Mix4 have significantly reduced asphalt layer thickness by around 20% if the service life kept constant, or increased service life by 1.24 if the thickness kept constant. In addition, ultra-thin asphalt layer overlay with Mix4 dramatically improved service life of existing asphalt layer

An overview of bus drivers and accident involvement

Common causes of bus accidents are similar to those causing other vehicular accidents. Bus accidents are rare, but they can cause major life disruption and unexpected expenses. Behavior of the bus driver does not only affect passengers comfort, but are also associated with the risk of road crash. In most driving situations, variations of driving behaviour and whether they get involved with accidents or not are influenced by various factors such as human factor, road and traffic situation, working environment, etc. This paper reviews these factors from previous research

Moisture sensitivity of crumb rubber modified modifier warm mix asphalt additive for two different compaction temperatures

Crumb rubber obtained from scrap tires has been incorporated with asphalt binder to improve the performance of asphalt mixtures in the past decades. Pavements containing crumbrubber modified (CRM) binders present one major drawback: larger amounts of greenhouse gas emissions are produced as there is rise in the energy consumption at the asphalt plant due to the higher viscosity of these type of binders compared with a conventional mixture. The objective of this paper is to calculate the optimum bitumen content for each percentage and evaluate the moisture sensitivity of crumb rubber modified asphalt at two different compacting temperatures. In this study, crumb rubber modified percentages was 0%, 5%, 10% and 15% from the binder weight, with adding 1.5% warm mix asphalt additive (Sasobit) and crush granite aggregate of 9.5mm Nominal maximum size was used after assessing its properties. Ordinary Portland Cement (OPC) used by 2% from fine aggregate. The wet method was using to mix the CRM with bitumen, the CRM conducted at 177°C for 30 min with 700rpm and Sasobit conducted at 120°C for 10 min with 1000rpm. As a result, from this study the optimum bitumen content (OBC) was increased with increased crumb rubber content. For performance test, it was conducted using the AASHTO T283 (2007): Resistance of Compacted Bituminous Mixture to Moisture-Induced Damage. The result was as expected and it was within the specification of the test, the result show that the moisture damage increased with increased the crumb rubber content but it is not exceeding the limit of specification 80% for indirect tension strength ratio (ITSR). For the temperature was with lowing the temperature the moisture damage increased

Readiness in implementing teacher training programmes based on industrial revolution 4.0: evidence from Malaysian public universities

Since its introduction, the concept of Industrial Revolution 4.0 has received massive intention all around the world. Subsequently, this revolution has brought changes in all fields including higher education. Various propositions have been made towards transforming educational settings parallel with the elements of industrial revolution 4.0. However, there are different reactions from educators regarding this transformation. This study aimed to identify the readiness of educators to implement the elements of industrial revolution 4.0 in Teacher Training Programs in Malaysian Public Universities. The respondents involved in this study consisted of 61 lecturers from 14 public universities in Malaysia. Logit value analysis using Rasch Measurement Analysis found that the respondents’ readiness towards the implementation was at a moderate level (logit = 0.156). Specifically, respondents had a higher level of readiness to implement the constructs related to teaching methods as compared to the constructs related to the implementation methods. Overall, it was found that the lecturers’ readiness to implement elements of IR 4.0 was still at a moderate level. Thus, there should be efforts to apply elements of industrial revolution 4.0 in higher education to equip our future teachers with the skills and knowledge for them to impart to the future generation

Characteristics of Warm Mix Asphalt Incorporating Coarse Steel Slag Aggregates

The major goal of sustainable practices is to preserve raw resources through the utilization of waste materials as an alternative to natural resources. Decreasing the temperature required to produce asphalt mixes contributes to environmental sustainability by reducing energy consumption and toxic emissions. In this study, warm mix asphalt incorporating coarse steel slag aggregates was investigated. Warm mix asphalt was produced at different temperatures lower than the control asphalt mixes (hot mix asphalt) by 10, 20, and 30 °C. The performances of the control and warm mix asphalt were assessed through laboratory tests examining stiffness modulus, dynamic creep, and moisture sensitivity. Furthermore, a response surface methodology (RSM) was conducted by means of DESIGN EXPERT 11 to develop prediction models for the performance of warm mix asphalt. The findings of this study illustrate that producing warm mix asphalt at a temperature 10 °C lower than that of hot mix asphalt exhibited the best results, compared to the other mixes. Additionally, the warm mix asphalt produced at 30 °C lower than the hot mix asphalt exhibited comparable performance to the hot mix asphalt. However, as the production temperature increases, the performance of the warm mix asphalt improves