Videos, Webinars & More

This study investigated a new approach to dispersion of carbon nanofibers (CNFs) in cement paste by coating rice husk ash (RHA) particles using a natural polymer binder. Light Chitosan with low molecular weight was used to provide bonding between CNFs and SiO2 from the RHA substrate. Mechanical properties namely, compressive strength and flexural properties of paste specimens were assessed to evaluate the efficiency of the applied method. Microstructural analysis was carried out using FTIR, XRD, TGA, and SEM to investigate the effects of the coating process on the hydration products and to explain the mechanical properties of specimens with the modified RHA. The results showed that 15% and 5% modified RHA increased the compressive strength and flexural strength of paste specimens at 28 days by 53% and 187%, respectively. Microstructural analysis showed that the coating process delayed the hydration, however, the physical crosslinking effect of carbon nanofibers enhanced the mechanical properties at all ages.

Two approached to reducing the carbon footprint of concrete are to, 1. Reduce the clinker content of the cementitious binder and, 2. Reduce the total binder content. For the first, combinations of supplementary cementitious materials can be combined with Type IL cements while still attaining early-age strength development with at least a 40% reduction in clinker content. For the second, optimizing aggregate gradations with at least three components can result in savings of up to 15% of the required cementitious materials content while also reducing concrete permeability and shrinkage. The methodologies for combining both of these approaches will be discussed.

Finding a sustainable alternative to cement is crucial to mitigate climate change. This presentation introduces an innovative approach to investigate alkali-activated binders and monitor kinetic reaction using Raman spectroscopy. The dissolution of precursors by alkalis was continuously monitored for 24 hours immediately after mixing, which was found to be especially helpful to optimize the appropriate mixing procedure. Coupled with a new method for predicting the final products of alkali-activated materials using comprehensive phase-analysis, the cost and performances could be better controlled and optimized. Field applications of optimized AAM mixes based on fly ash, slag, or red mud could achieve 1) cement free with more than 80% reduction in carbon footprint, 2) ~25% reduction in cost, 3) cured at ambient temperature with well controlled setting time, flowability and other fresh properties, 4) similar or even superior hardened properties and durability, and 5) mass production ready.

In most emerging economies of the World, such India, major construction is expected during this decade in both infrastructure and housing sectors. This presents a great opportunity for more efficient, responsible, and sustainable technologies to be implemented. This would require the consolidation and research, if needed, in the areas of waste processing, lean technologies, scaling-up and policy changes for large-scale adoption. Waste processing would go beyond fly ash, waste clay and slag, to consider construction and demolition waste, and non-recyclable plastics. Analytical tools, life estimation and demonstration of techniques such as 3D-printing need to be applied for lean philosophies to be applied at the site. Scaling-up would require test beds, simulation, visualization, and adoption management. Policy notes, road maps and influencing stakeholders will be needed for large-scale changes. Though the challenges may appear daunting, international collaboration and strengthening of local centres of excellence could provide the relevant solutions. IIT Madras has initiated a project along these lines with the participation of about 20 of its faculty members, 30 research scholars, and several collaborators from around the globe (https://civil.iitm.ac.in/pcoe/tlc/). The talk would present recent results, goals, and the potential collaboration with entities such as ACI and RILEM in this initiative.

This presentation will be from the concrete contractor's perspective on lower carbon concrete and constructability, a discussion of what has worked on projects and what challenges have been encountered.

This webinar will discuss laboratory testing of portland limestone cement (PLC) based on internal research and projects being conducted by WJE. A brief introduction will be provided on PLC. Microscopic techniques and chemical analysis performed in an attempt to identify, classify, and quantify PLC will be discussed. This talk is intended to provide an industry update on current work-in-progress laboratory research.