Developing a more Sustainable Cement
WACKER contributes to sustainability through a diverse array of products. In this effort, WACKER specialists targeted new fields of application like cement manufacturing where silicones have been not considered until recently. Cement is an essential construction material used across in North and Central America including areas with seasonally or increased relative humidity. WACKER’s new family of cement additives is designed according to cement strength and grinding productivity requirements.
Enabling a more Sustainable Cement
The SILRES® BS 8083 US is a cement stabilizer designed for maintaining the durability of cement manufactured and/or stored especially in hot and humid areas. Depending on the process set up, it may be used as is or diluted and mixed with other chemicals during the manufacturing of diverse types of cements. Benefits of silane-siloxane emulsions used as additives are confirmed by manufacturers of Portland cement by avoiding unwanted wastes or additional costs of frequent cleaning shutdowns related to the caking or clumping of the cement.
A newly developed strength enhancer is the SILRES® BS 8166 that can be used as performance additive in various type of hydraulic cements. This highly effective concentrated material must be diluted to 5-10% actives in water before using, in addition it can be combined with traditional grinding aids (compatibility tests are strongly recommended) prior to using in the cement manufacturing process. With a view to reducing the clinker component in the cement formulation, WACKER specialists were able to achieve same level of compressive strength in different types of cements.
Analyzing the curing mechanism, WACKER specialists have found that the performance aid can boost not just the compressive strength depending on the cement mix, but also can make the curing behavior less sensitive to the environmental humidity conditions.
Inhibiting pre-hydration
Image showing water droplets on dry cement powder treated with silane-siloxane cement stabilizer (0.05% on cement weight) on the right and untreated powder on the left. The water droplets on the left-hand side immediately soaks into the lower layers of the untreated powder, while the droplet on the right keeps afloat on the treated base without wetting the cement grains beneath it. A subsequent parallel compressive strength test on mortar specimens showed comparable results.
Enhancing the curing
Cement manufactured with the SILRES® BS 8166 enhancer (in diluted form 50 g actives to one metric ton of cement) shows a more robust curing mechanism that is less influenced by the environmental conditions. The diagram shows similar values of compressive strength measured at 7 days and 28 days on standard mortar specimens made of cement produced with and without cement strengthener and kept during the curing at 50% relative humidity, and fully immersed in water, respectively.
Both the OPC (Ordinary Portland Cement) and the treated OPC were ground from the same raw materials (clinker and gypsum) under identical conditions at the company’s Technical Center for Cement & Concrete.
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The cement and concrete industry is taking significant strides towards reducing greenhouse gas emissions, with a goal of achieving net zero emissions by 2050. Key initiatives include the shift from Ordinary Portland Cement (OPC) to Portland Limestone Cement (PLC) and the use of supplementary cementitious materials (SCM) to extend the life cycle of concrete.
Innovations such as oligomeric siloxane strength enhancers or stabilizers are improving cement shelf life and maintain or improve compression strength, while also enhancing concrete durability against environmental factors. Authored by WACKER's experts Dr. Dmitry Davydov, James D. Greene, and Dr. Wei Cai, this article delves into these advancements and their critical role in promoting sustainable construction practices.
