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Enhancing Optical Performance of Cementitious Composites with Nano-TiO₂ based surface treatment: A Cost-Effective Approach to Boost Solar Reflectance Index
No full textThe Solar Reflectance Index (SRI) is a critical parameter for evaluating a material\u27s ability to reflect solar radiation and release absorbed heat, affecting its surface temperature and thermal performance. Nano-titanium dioxide (NTiO₂) is widely used to enhance SRI in paints due to its high refractive index and light color; however, its high-cost limits large-scale intermixing applications for cementitious composites. This study investigates a cost-effective alternative by applying a NTiO₂-based cationic molecular emulsion as a surface treatment. Cement paste samples (5 × 5 × 1 cm for solar reflectance and 10 × 10 × 2 cm for emittance tests) were cast using Type-1L Portland-Limestone cement and a 0.5 water-to-cement ratio, then cured for 14 days under controlled conditions. Samples were evaluated using a UV-VIS-NIR spectrophotometer and a pyranometer for solar reflectance (SR) and an emissometer for thermal emissivity, with SRI calculated under standard conditions. Results indicate that treated samples exhibited consistent increase in SRI compared to untreated samples, demonstrating the potential of surface treatment as a cost-efficient method for improving reflectance properties in cementitious materials for combating urban heat island effect
Impact of Inter-grinding on the Reaction Kinetics and Physical Properties of One-Part Alkali-Activated Metakaolin
No full textDeveloping alkali-activated materials (AAM) is one of the pathways to decarbonize cement manufacturing that currently contributes 5-8% of global anthropogenic carbon emissions [1]. However, extensive deployment of AAMs in industry has yet to be realized, part of which is due to the reluctance to work with “two-part” activation that requires handling large amounts of concentrated caustic solutions [2]. Here, a “one-part” AAM has been developed using calcined kaolin clay and a solid sodium silicate source. Inter-grinding of the dry mixture is found to increase the kinetics of alkali-activation and improve rheological properties of the paste. The underlying physicochemical properties responsible for these improvements have been explored by analysis of particle size distribution, surface properties, nanostructure, and specific surface area
MDEA-enhanced CO2 Sequestration via Steel Slag Waste: Mechanisms and Microstructural Evolution during Aqueous Carbonation
No full textThe current CO2 sequestration efficiency (CO2 SE) of steel slag waste (SSW) remains relatively low, and the underlying mechanisms of the carbonation reaction are not fully understood, limiting its potential for resource utilisation. In this study, N-methyl diethanolamine (MDEA) was introduced into an aqueous carbonation system to enhance the CO2 SE of SSW, and the associated reaction mechanisms and microstructural evolutions were systematically investigated. The results indicate that the addition of 5 wt.% MDEA increased the CO2 sequestration rate (CO2 SR) to 14.44%, representing a 68.5% improvement over the control group. MDEA enhanced CO2 dissolution and diffusion in the aqueous phase, facilitated the sustained release of Ca2+ and Mg2+ from SSW, and promoted the formation of stable, cauliflower-like calcite structures. These findings provide new insights into improving the CO2 SE of SSW, thereby supporting its potential application in CO2 capture and sustainable material recycling
Revising Specifications to Enable New Materials and Adapting to Performance of Low-Clinker Concretes
No full textTo support the concrete industry’s goals of meeting net-zero carbon-dioxide emissions by 2050, new types of lower-clinker cements are being developed for use. While Portland cement will continue to be used as part of the cementitious materials in the bulk of applications, use of Portland cement as the sole binder in concrete is diminishing globally. Reducing the clinker content of concretes is complicated by the limited and diminishing availability of traditionally used Supplementary Cementitious Materials (SCMs), such as fly ash and ground granulated blast furnace slags, whether added as separate additions to concrete or as components of blended cements. This has spawned increased interest and use of natural pozzolans such as volcanic materials, calcined clays, and other novel activated pozzolans. However, some of these activated or manufactured pozzolans either may not meet the current definition of pozzolans, and some may not meet some of the prescriptive limits in current specification. Performance specifications will help in the adoption of new SCMs and low-clinker cements that are being developed and coming to the market. The rapid changes in the availability of cementitious materials, combined with the need to accelerate the adoption and use of concrete mixtures provided they demonstrate equivalent performance to traditionally specified concretes, requires rapid adoption of performance specifications and test methods
Transition to Net Zero and Low Carbon Technologies: Case Studies from the Second Largest Construction Industry – India
No full textEnhancing the Pozzolanic Reactivity of Bauxite Refinery Residue for Cementitious Applications through Calcination Treatment
No full textBauxite refinery residue (BRR), a byproduct of alumina production, has significant potential for applications in the construction industry due to its favourable chemical composition and abundant availability. However, its use as a supplementary cementitious material (SCM) is limited by its low pozzolanic reactivity. This study investigates the pozzolanic reactivity of BRR through both indirect and direct methods. BRR was used to replace Ordinary Portland Cement (OPC) at 5%, 10%, 15%, 20%, 25%, and 30% by weight. Mortar compressive strength was tested at 3, 7, and 28 days, while pozzolanic reactivity was directly assessed using the modified Chapelle test. BRR characterisation included the analysis of chemical composition and particle size distribution, and amorphous content. Results show that raw BRR contributes significantly to early strength development, with all replacement levels (5–30%) exhibiting higher 3-day compressive strength than the plain cement mortar (13.21 MPa). The strength peaked at 16.92 MPa with 5% BRR replacement and remained relatively high across the full replacement range, from 15.0 to 16.92 MPa. In contrast, 28-day compressive strength showed a declining trend with increasing BRR content beyond 10%, indicating limited long-term pozzolanic activity. To address this, BRR was subjected to calcination at 600 °C, 650 °C, and 700 °C. Among these, the BRR calcined at 650 °C showed the improvement in pozzolanic reactivity compared to raw BRR
Book Review of A Dozen Delicious Donuts: A Sweet Cambodian-American Story
No full textIn A Dozen Delicious Donuts: A Sweet Cambodian-American Story, Chanda Ouk Wolf tells a story about the connection of donut shops and the Cambodian community in southern California while acknowledging the cultural experiences and donut creation that originated in Cambodia. The actual making, and step-by-step process of these donuts, are shared when a baking contest is announced by the main character’s teacher at school
Turfgrass Weed Control for Professionals, 2024
No full textTurfgrass is used on everything from athletic fields, golf courses, and parks, to lawns, sod farms, and roadsides. Unfortunately, information on weed management for professionals maintaining these areas has often been inaccurate or out of date, and applicators are frequently unaware of the most effective methods for controlling weeds in turf. Written by experts in the field and featuring insights from contributors from sixteen states across the US, the 2024 edition of Turfgrass Weed Control for Professionals was developed to provide science-based information for those working in the field. It contains information about turfgrass management, weed biology and management, more than 350 photographs to assist in the identification of a variety of weeds, information on how herbicides work, research-based information on the efficacy of herbicides on target weeds, the use of plant-growth regulators, and other useful tips for those managing turfgrasses. First published in 2012 and annually updated to include the most current information, Turfgrass Weed Control for Professionals has long served as a valuable guide for applicators looking to improve weed control, improve integrated weed management, and reduce maintenance costs for their businesses.https://docs.lib.purdue.edu/purduepress_ebooks/1084/thumbnail.jp