Recycled glass as a supplementary filler material in spent coffee grounds geopolymers

Recycled glass (RG) is a demolition waste, rich in silica and with a high shear strength and has been used as a replacement material for sand in various construction applications. Spent coffee grounds (CG) is a waste material derived from brewing coffee and has been recently studied as a recycled construction material, due to its physical resemblance to sandy soils. Geopolymerization, is a green process which produces cementitious compounds using aluminosilicate-rich materials and alkaline liquids. In this research, a new geopolymer construction material was produced using RG as a supplementary filler material to stabilize CG. Fly ash (FA) and slag were used as the precursors to induce geopolymerization in this new RG + CG construction product. To maximize the potential strength of the geopolymer, fine RG was added into geopolymer mixes in proportions of 25%, 50%, and 75% to observe the effects on the final RG + CG product strength. The mixes were compressed into cylindrical specimens, cured at room temperature (i.e., 21 °C) and 50 °C for 7 and 28 days, and tested for their unconfined compressive strength (UCS) to observe the effect of the various RG replacement ratio on the strength of CG geopolymers. Scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS) were used to further explain the role of RG in influencing strength development. Higher RG contents were found to lead to higher UCS values. A lower liquid-to-precursor (L/P) ratio was required to achieve a saturation point in strength development. RG was found to provide mechanical strength and supplementary chemical bonding strengths by dissolving and contributing Si + ions to form geopolymeric substances

Recycled glass as a supplementary filler material in spent coffee grounds geopolymers

Recycled glass (RG) is a demolition waste, rich in silica and with a high shear strength and has been used as a replacement material for sand in various construction applications. Spent coffee grounds (CG) is a waste material derived from brewing coffee and has been recently studied as a recycled construction material, due to its physical resemblance to sandy soils. Geopolymerization, is a green process which produces cementitious compounds using aluminosilicate-rich materials and alkaline liquids. In this research, a new geopolymer construction material was produced using RG as a supplementary filler material to stabilize CG. Fly ash (FA) and slag were used as the precursors to induce geopolymerization in this new RG + CG construction product. To maximize the potential strength of the geopolymer, fine RG was added into geopolymer mixes in proportions of 25%, 50%, and 75% to observe the effects on the final RG + CG product strength. The mixes were compressed into cylindrical specimens, cured at room temperature (i.e., 21 °C) and 50 °C for 7 and 28 days, and tested for their unconfined compressive strength (UCS) to observe the effect of the various RG replacement ratio on the strength of CG geopolymers. Scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS) were used to further explain the role of RG in influencing strength development. Higher RG contents were found to lead to higher UCS values. A lower liquid-to-precursor (L/P) ratio was required to achieve a saturation point in strength development. RG was found to provide mechanical strength and supplementary chemical bonding strengths by dissolving and contributing Si + ions to form geopolymeric substances

Evaluation of Strength and Resilient Modulus Characteristics of Fly Ash Geopolymer Stabilized Reclaimed Asphalt Pavement Material

Utilization of sustainable road construction materials has been the focus of research worldwide in recent times. Virgin aggregate is a primary material in the pavement industry; hence, finding an alternative is of extreme importance, concerned with the more prudent use of natural resources and the protection of the environment. The present research explored the usage of a significant portion of reclaimed asphalt pavement (RAP), activated with low calcium fly ash (FA) as a binding material. A liquid alkaline activator comprising sodium silicate solution (Na2SiO3) and sodium hydroxide (NaOH) was used for the alkali activation of the mix. The fundamental design parameters including Unconfined Compressive Strength (UCS) and resilient modulus (Mr) characteristics of the stabilized RAP:VA+FA geopolymer specimens were studied at room temperature. The resilient modulus (Mr) value in mechanistic-empirical analyses has been widely accepted in design/analysis of the pavement structures. Therefore, the present study aims to examine the resilient behaviour of the pavement base material stabilized with alkali activated low calcium Indian fly ashes, obtained from the southern region of India. The effect of additives on the microstructure of RAP:VA+FA blends were verified for one day and 28 days cured samples using X-ray diffraction (XRD) studies. Since the UCS and Mr values met the specified strength requirements, the stabilized mix can be used as a pavement base material

A randomized trial to evaluate the effectiveness of an individual, education-based safe transport program for drivers aged 75 years and older

<p>Abstract</p> <p>Background</p> <p>There are concerns over safety of older drivers due to increased crash involvement and vulnerability to injury. However, loss of driving privileges can dramatically reduce independence and quality of life for older members of the community. The aim of this trial is to examine the effectiveness of a safe transport program for drivers aged 75 years and older at reducing driving exposure but maintaining mobility.</p> <p>Methods and design</p> <p>A randomised trial will be conducted, involving 380 drivers aged 75 years and older, resident in urban and semi-rural areas of North-West Sydney. The intervention is an education program based on the Knowledge Enhances Your Safety (KEYS) program, adapted for the Australian context. Driving experience will be measured objectively using an in-vehicle monitoring device which includes a global positioning system (GPS) to assess driving exposure and an accelerometer to detect rapid deceleration events. Participation will be assessed using the Keele Assessment of Participation (KAP). Data will be analysed on an intention-to-treat basis; the primary outcomes include driving exposure, rapid deceleration events and scores for KAP. Secondary outcomes include self-reported measures of driving, socialisation, uptake of alternative forms of transport, depressive symptoms and mood. A detailed process evaluation will be conducted, including examination of the delivery of the program and uptake of alternative forms of transport. A subgroup analysis is planned for drivers with reduced function as characterized by established cut-off scores on the Drivesafe assessment tool.</p> <p>Discussion</p> <p>This randomised trial is powered to provide an objective assessment of the efficacy of an individually tailored education and alternative transportation program to promote safety of older drivers but maintain mobility. Trial registration: Australian New Zealand Clinical Trials Registry ACTRN12612000543886.</p