Felicite Ruddock

Development of Sustainable Cold Rolled Surface Course Asphalt Mixtures Using Waste Fly Ash and Silica Fume

AbstractThe reduction of hot asphalt mixtures for the usage and development of sustainable supplementary cold asphalt mixtures (CAMs) for the construction of road and highway surface layers is a major issue for researchers around the world. This reduction will benefit environmental impact, cost effectiveness, and energy savings. Furthermore, because CAMs comprise a remarkable portion of industrial waste (the disposal of which consumes virgin lands), they are attractive to road and highway authorities. The primary aim of this investigation is to develop new cold rolled asphalt (CRA) with the same gradation as hot rolled asphalt (HRA), which is usually used as a surface course in the U.K., and to improve its mechanical properties and durability by using waste and by-product materials as mineral fillers and additives. Waste fly ash (WFA) was used as a replacement for conventional mineral filler and a by-product silica fume (SF) was used as an additive to enhance the mechanical properties and durability of CR...

Laboratory studies to investigate the properties of novel cold-rolled asphalt containing cement and waste bottom ash

Cold bitumen emulsion mixtures provide valuable advantages over hot mixture asphalt in terms of economic and environmental points of view. The total energy required for mixing, transportation and laying such mixtures is less compared with the traditional hot mixtures. These laboratory studies describe the results of a new developed cold-rolled asphalt (CRA) to be comparable with the traditional hot-rolled asphalt through the addition of waste bottom ash (WBA) to the CRA containing cement as the mineral filler. The mechanical properties were assessed by stiffness modulus and uniaxial creep tests, while water sensitivity was inspected by evaluating the stiffness modulus ratio before and after samples conditioning. The experimental results have shown a significant improvement in the mechanical properties and a substantial upgrading of material resistance to water sensitivity from the addition of WBA to the cold asphalt containing cement.

Performance Analysis of a Cold Asphalt Concrete Binder Course Containing High-Calcium Fly Ash Utilizing Waste Material

It has been established that cold bituminous emulsion mixtures (CBEMs) have a comparatively low initial strength in comparison to hot mix asphalt (HMA), however its superior performance with regard to carbon emissions, is a significant driver regarding its manufacture. In this research, high calcium fly ash (HCFA) together with a fluid catalytic cracking catalyst (FCC) - a rich silica-alumina waste material - have been incorporated to develop a new cold asphalt concrete binder course (CACB) bituminous emulsion mixture. HCFA was used as a substitute for traditional limestone filler while FCC was the additive used to activate the HCFA. The mixtures’ performance was assessed using the indirect tensile stiffness modulus test (ITSM), assessment of resistance against permanent deformation, temperature and water sensitivity tests. Surface morphology was tested using a scanning electron microscopy (SEM). A considerable improvement was identified by the ITSM test in addition to a substantial enhancement in rutting resistance, temperature susceptibility and water sensitivity. It was also established that the addition of FCC to CACB mixtures was found to improve early strength as well as long-term strength, rutting resistance, temperature sensitivity and durability.

Laboratory Studies to Examine the Properties of a Novel Cold-Asphalt Concrete Binder Course Mixture Containing Binary Blended Cementitious Filler

AbstractConventional hot-asphalt mixtures have an impact on global warming and CO2 emissions, contributing to debates on environmental issues that have been raised in recent years. As an alternativ...

Graphene composites with dental and biomedical applicability

Pure graphene in the form of few-layer graphene (FLG) – 1 to 6 layers – is biocompatible and non-cytotoxic. This makes FLG an ideal material to incorporate into dental polymers to increase their strength and durability. It is well known that graphene has high mechanical strength and has been shown to enhance the mechanical, physical and chemical properties of biomaterials. However, for commercial applicability, methods to produce larger than lab-scale quantities of graphene are required. Here, we present a simple method to make large quantities of FLG starting with commercially available multi-layer graphene (MLG). This FLG material was then used to fabricate graphene dental-polymer composites. The resultant graphene-modified composites show that low concentrations of graphene (ca. 0.2 wt %) lead to enhanced performance improvement in physio-mechanical properties – the mean compressive strength increased by 27% and the mean compressive modulus increased by 22%. Herein we report a new, cheap and simple method to make large quantities of few-layer graphene which was then incorporated into a common dental polymer to fabricate graphene-composites which shows very promising mechanical properties.

Improving the Hydraulic Integrity to Separate the Sewer System in Hilly Regions Using a New Manhole Design

The design of the sewer system in hilly regions has a different concept from other areas due to the high flow velocity generated in the system that characterises a sloped system. The flow velocity of sewage or stormwater in the sewer system is limited by design criteria, using minimum velocity to avoid settlement of suspended solids in the pipes and maximum velocity to keep the solute homogeneous (fluid and suspended solids) and avoid pipe erosion. Maintaining these limits of the velocity within hilly regions is challenging and designers usually use steep cascade manholes to dissipate the fluid flow energy. This paper presents a new manhole design to mitigate stormwater flow energy, which is more critical than sewage flow in such areas, and using the traditional normal steps manhole for the sewage chamber. The new manhole design includes two chambers, an inner chamber used as in the traditional manhole for sewage and an outer chamber used for stormwater flow. The hydraulic properties of the new manhole have been explored using a physical model in laboratory conditions and compared with traditional manhole performance. The laboratory results are used for validation and are compared with computational fluid dynamic model outputs of the new design. The hydraulic performance of the new design reveals improvement in decrease in the flow energy of stormwater and increase in the capacity of storage for the stormwater network.

Investigation into the stiffness improvement, microstructure and environmental impact of a novel fast-curing cold bituminous emulsion mixture

Cold bituminous emulsion mixtures (CBEMs) have environmental advantages over conventional hot mix asphalt as they are cold products and are safe to use whilst also reducing energy. However, their low early strength and long curing time have been cited as the main barriers for their wide utilisation. This study describes the development of a new fast-curing CBEM incorporating binary blended cement filler (BBCF) containing high calcium fly ash (HCFA) and high aluminosilicate waste material (HASW) to replace the commercial limestone filler. In addition, a waste alkaline NaOH solution was used as a replacement for the prewater. The new CBEM needs only ambient temperature curing in order to achieve strengths comparable to the traditional hot mixture in a very short time (less than one 1 day). Water sensitivity of the mixtures was assessed by the Stiffness Modulus Ratio (SMR). Scanning electron microscopy (SEM) was employed to characterise the surface morphologies. Furthermore, the environmental impact of using these waste materials in CBEMs was assessed by using a toxicity characteristic leaching procedure (TCLP).The results indicated a significant improvement in the indirect stiffness modulus (ITSM) test and water sensitivity compared to hot mix asphalt. Moreover, SEM analysis confirmed the formation of hydration products after various curing ages. Furthermore, the TCLP test for environmental impact revealed that the heavy metal concentration in the leachates satisfied the required criteria.

Improving the Mechanical Properties of Cold Rolled Asphalt Containing Cement Utilising by Product Material

Reduction of hot asphalt mixtures for the usage and development of sustainable supplementary Cold Asphalt Mixtures (CAM) for the construction of road and highway surface layers is a hot subject for researchers around the world. This will cover many advantages in terms of: environment impact, cost effectiveness and energy saving.