Improving asphalt emulsion mixtures properties containing cementitious filler by adding GGBS

Production and use of sustainable cold asphalt emulsion mixtures (CAEMs) that are comparable to traditional hot mixtures and relevant for roads and highway construction might achieve several benefits such as reducing energy consumption, CO 2e emissions, and total expenses. Furthermore, some of by-products and waste materials could be incorporated in these mixtures to enhance their properties. The purpose of this investigation is to produce CAEM incorporated by producing material(s) with mechanical properties and water sensitivity comparable to conventional hot asphalt mixtures. The mechanical properties have been evaluated by conducting indirect tensile stiffness modulus (ITSM) test and uniaxial compressive cyclic tests (UCCTs), while water sensitivity was evaluated by determining the indirect tensile strength ratio (ITSR). A waste fly ash (WFA) has been incorporated instead of mineral filler with different percentages (0-6% by weight of aggregate), while ground-granulated blast-furnace slag (GGBS) was added with dosages ranging from 0-3% by total mass of aggregate to produce the novel CAEMs. The results revealed a considerable enhancement in the performance of the new CAEM mixtures as a result of using WFA and GGBS in comparison with the conventional hot asphalt mixture properties. © 2016 American Society of Civil Engineers

Investigating the effects of cement and cement kiln dust as a filler on the mechanical properties of cold bituminous emulsion mixtures

The application of cold mixes is lagging behind in the research field, which is quite obvious in a developing country. Furthermore, cold mixes have more economic and environmental advantages than hot mixes. This is the principal motivation for the present research, which aims to improve the mechanical properties of cold mix asphalt. Ordinary Portland cement (OPC) and cement kiln dust (CKD) were used as filler in cold bituminous emulsion mixtures (CBEMs) to compare the obtained results with those for CBEMs with conventional limestone. Indirect Tensile Stiffness Modulus (ITSM), fatigue, and resistance to rutting tests were used in the comparison. The experimental results showed that CBEMs with CKD and OPC had comparative mechanical properties to CBEMs with limestone and hot mix asphalt of the same grading and materials. Thus, this research introduces a new cold mix with CKD or OPC, which is able to meet more than the mechanical characteristics' requirements, reduce costs, and provide environmental benefits. © IAEME Publication

Characterizing Cold Bituminous Emulsion Mixtures Comprised of Palm Leaf Ash

Abstract Cold bitumen emulsion mixtures (CBEMs) are a promising substitute for hot mix asphalt (HMA) due to their low environmental impact, cost effectiveness, and low energy production costs. Nevertheless, conventional CBEM has some disadvantages, mainly related to the long curing time required to reach its full strength and its higher susceptibility to moisture. This paper reports the experimental test results of research that aimed to investigate and develop a new CBEM containing a waste biomass material, palm leaf ash (PLA), a waste material produced by burning palm leaves. The new CBEM was compared with a conventional cold mix (CCM) as a control. The tests to assess the mixtures’ mechanical properties were the Marshall test, indirect tensile strength, and wheel track test. Durability was evaluated by water sensitivity and aging tests. The results revealed noticeable improvements in the mechanical properties of the CBEMs comprising ordinary portland cement (OPC), and raised the possibility of replacing some of the OPC with PLA without compromising said improvements. Results have shown that the new CBEMs with PLA achieved outstanding results in comparison with traditional CBEM, with and without the addition of OPC. There was also a significant improvement in water sensitivity when using PLA. This paper therefore opens the door for the development of new CBEMs that have outstanding mechanical characteristics when made with biomass ash material

To investigate the fundamental causes of utility air voids content failures in asphalt layers to achieve Specification for the Reinstatement of Openings in Highways (SROH) compliant performance

The linkage between air voids content and durability in footways reinstatements with the limits currently in SROH is non-proven and unsupported by evidential research or trial data. Compounding of errors, particularly in density measurement of core samples and subsequent variability, generate biased air void content results that make the compliance largely a matter of chance. This led to a very wide range of predicted outcomes, putting both the contractor and the client at unacceptable risk. The use of a measured in situ air voids content criteria in a specification for footway reinstatements, where the entire operation is in restricted areas with hand laying process using recipe mixed materials, cannot be sustained on technical grounds with respect to relevant British Standard and Transport Research Laboratory (TRL) guide. Taking account of the service loads, nature and scale of works in footways, an in-service guarantee by the undertaker for an agreed extended period, linked to an allowable intervention level, could be a simple, realistic and acceptable solution, ensuring a durable reinstatement that removes the financial risk of failure from the highway authority

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 (BBCF)

Conventional hot asphalt mixtures have an impact on global warming and CO2 emissions contributing to debates on environmental issues which have been raised in recent years. As an alternative, cold emulsion asphalt mixtures (CBEMs) provide considerable benefits such as eco-friendliness, energy efficiency and cost effectiveness connected with safety. However, their weak early strength along with the need for longer curing times (usually 2-24 months) and higher moisture susceptibility compared to hot asphalt mixtures, have been cited as obstacles to their wider application. That said, the incorporation of waste materials in CBEM mixtures enhances sustainability by decreasing the amount of industrial waste materials needed and conserving natural resources. A new binary blended cement filler (BBCF) material generated from high calcium fly ash (HCFA) and fluid catalytic cracking catalyst (FC3R) was found to be very effective in providing microstructural integrity with a novel fast-curing cold asphalt concrete for the binder course (CACB) mixture. Laboratory performance tests included the stiffness modulus test by indirect tension to cylindrical samples, wheel-tracking tests and water sensitivity. Regarding environmental issues, a toxicity characteristic leaching procedure (TCLP) test was performed to analyse the leachate from various specimens comprising concentrations of heavy metal. The findings of these tests have demonstrated that CACB performs extremely well compared to traditional hot mixtures. The stiffness modulus of the BBCF treated mixture – 3730 MPa after 3 days – is higher than the traditional hot mixture (100/150 pen). In addition, the BBCF treated mixture offered a superior performance regarding rutting resistance, fatigue resistance and water susceptibility as well as revealing a considerably lower thermal sensitivity. More significantly, the BBCF treated mixture was found comparable to the traditional asphalt concrete binder course after a very short curing time (1 day). Finally, the concentration of heavy metals in the specimens incorporating the BBCF was observed to be less than the regulatory levels determined for hazardous materials and so requirements were satisfied. Consequently, this BBCF treated mixture has significant potential with reference to its application as a binder course in asphalt pavement

Analytical investigation of hydration mechanism of a non-Portland binder with waste paper sludge ash

The development and production of new materials requires advanced analytical characterisation to explain the relation between the physico-chemical structure of the material and its properties. Highly integrated microelectronic structure analysis of surfaces with laser beams and X-ray fluorescence aided devices are found to be helpful for providing important information, including the interrelationships between physical, chemical, mechanical and durability characteristics of the new developed products. In most instances no single technique provides all the needed information and hence simultaneous application of several techniques becomes necessary. This study was aimed for hydration analysis, characterization and evaluation of a new novel non-Portland binder (NPB) with waste paper sludge ash (PSA) using FTIR and TG/DTA. The progressive formation of hydration products within the non-Portland binder was identified and their microstructural characteristics were analysed. The stable and non-expansive nature of secondary ettringite formation was also identified after a period of 365 days curing

High performance cold asphalt concrete mixture for binder course using alkali-activated binary blended cementitious filler

A slow rate of curing and the long time necessary to achieve full strength has led cold asphalt mixes (CAM) to be considered poorer in comparison to hot mix asphalt over the last decades. This piece of research aimed to develop a new fast-curing and environmentally friendly cold asphalt concrete for binder courses mixture (CACB). It has the same gradation as that of traditional hot asphalt concrete mixtures but incorporates a binary blended cementitious filler (BBCF) containing waste, high calcium fly ash (HCFA) and fluid catalytic cracking catalyst residue (FC3R) activated by a waste alkaline NaOH solution. The research concludes that incorporating an alkali activated binary blended cementitious filler (ABBCF) with CACB significantly improves the mechanical properties and water susceptibility. In addition, the high performance ABBCF mixture has a substantial lower thermal sensitivity than traditional hot asphalt concrete binder course mixtures. SEM analysis revealed that the main crystallisation had taken place at an early stage of the new ABBCF. More significantly, the new CACB mixture has a comparable stiffness modulus with the traditional asphalt concrete binder course after a very short curing time (less than one day)

The Impact of Cement Kiln Dust and Cement on Cold Mix Asphalt Characteristics at Different Climate

Cold bitumen emulsion mixtures (CBEMs) are made up of the same materials that are used in hot mixes. However, asphalt emulsion and water are used in such mixes. To date, many countries are still not using these mixes as a structure layer. This can be attributed mainly to their low resistance to rainfall, long curing time and low early strength. The addition of cementitious filler to CBEMs as a clean paving material is a potential technique to achieve superior mechanical qualities. The aim of this research is to compare improved CBEMs that might be used as a wearing surface to hot mix asphalt (HMA). These improvements were carried out through the use of a combination of cement and limestone, or a combination of ordinary Portland cement (OPC) and cement kiln dust (CKD). CBEMs were prepared according to Egyptian and British gradations using different percentages of ordinary Portland cement (OPC), CKD, and limestone. This may offer a new cold bitumen emulsion mixture to be used as a structural pavement layer in such countries. The main tests performed for the assessment of the mixes in this research are indirect tensile stiffness modulus, fatigue resistance, and resistance to rutting at different temperatures (20◦ C, 45◦ C, and 60◦ C). The results show that adding OPC to CBEMs enhanced the results in terms of ITSM, rutting and fatigue resistance. However, significant improvements were made by binary filler made of CKD and OPC to the said mechanical properties in terms of both UK and Egyptian gradations. The ITSM values for both CBEMUK6 and CBEMEg6, which contain 80% OPC + 20% CKD, improved by around 8 and 9 times in comparison to CBEMUK1 and CBEMEg1, which contain 20% OPC + 80% L.S, respectively