Influence of Silica Fume on Durability of Cement-Based Materials Exposed to Chlorides

The deterioration of cement-based materials used for the civil infrastructure has led to the realization that cement-based materials, such as concrete, must be improved in terms of their properties and durability. The use of admixtures, e.g. silica fume, is a relatively convenient way of improving cement-based materials. This paper is focused on the use of silica fume to improve durability of cement-based materials exposed to hydrochloric acid. Effect of hydrochloric acid attack on the silica fume based cement composites and cement composites of ordinary CEM I Portland cement without any additives was investigated during 180 days under model laboratory conditions. The calcium and silicon contents in leachates were evaluated during the experiments using X – ray fluorescence method (XRF). Silica fume based concrete samples were found to have better performance in terms of calcium and silicon ions leaching for all environments except for distilled water environment. The highest concentrations of leached calcium (619.2 mg/L) and silicon (1581 mg/L) ions were observed for the sample without silica fume addition placed in the solution of hydrochloric acid

Environmental evaluation of family house materials impacts on climate change, land and water use, acidification and ecotoxicity

The construction industry plays a significant role in contributing to various environmental impacts, including climate change, acidification, and ecotoxicity, among others. This research paper presents a scientific analysis focused on the environmental evaluation of a masonry residential house by life cycle assessment (LCA) methodology. Specifically, it investigates the environmental impacts associated with the production phase of materials using the SimaPro software, which employs the Ecoinvent database. The ReCiPe method is utilized to calculate the comprehensive environmental impacts, with particular emphasis on climate change, terrestrial acidification, ecotoxicity, land use, and water use. To accurately determine the environmental impacts of the house materials, an allocation approach is employed, taking into account the function and location of the materials within individual structures. The calculated share of climate change per house materials amounted to 21.59 kg CO2 eq/m2/year, while the share on water scarcity was estimated at 15.87 m3/m2/year. The research findings reveal that vertical structures exhibit the highest environmental impacts across all impact categories, while horizontal structures demonstrate comparatively lower values

INFLUENCE OF SULFURIC ACID ATTACK ON CONCRETE WITH INDUSTRIAL WASTE

The paper aims at investigating cement composites with incorporated wastes such as blast granulated slag, fly ash, or micro silica regarding their durability and resistivity against aggressive acidic environments. An aggressive acidic attack was simulated with H2SO4 with a pH of 1.95. The experiments proceeded under model laboratory conditions over a period of 6 weeks, and the accelerated tank leaching test was applied. Both physical (mass of samples, water absorption, and surface disruption) and chemical parameters of concretes (pH, leachability of main components, chemical composition) were examined. The changes in the mass of samples, surface changes, as well as absorbability increases were observed after exposure to sulfuric attack. The leached-out amounts of calcium, silicon, aluminum, and iron, measured using X-ray fluorescence analysis, varied depending on the composition of the analyzed composite and the kind of waste incorporated. The samples with micro silica and slag were identified to be the most durable, regarding the leaching of basic inorganic compounds of the cement matrix. The sample with fly ash was observed to have the lowest change in water absorbability. The positive effect of incorporating waste into cement composite was confirmed when compared to a concrete sample without any waste adde

Environmental performance of miscanthus-lime lightweight concrete using life cycle assessment:Application in external wall assemblies

This is the final version. Available from Elsevier via the DOI in this record. In the UK context, miscanthus is a potential alternative perennial crop for the development of bio-based building materials. This paper presents the environmental benefits of using miscanthus shives in lightweight blocks and their potential application in wall assemblies. A systemic life cycle assessment (LCA) is carried out for miscanthus-lime blocks, and the effects of binder type and binder content are discussed. The environmental performance-based analysis reveals that miscanthus blocks can capture 135 kg CO eq/m for an assumed 100-years life period. The impact analysis using the University of Leiden, institute of environmental science (CML) baseline (v4.4) method shows that 75% of the greenhouse gas emissions are attributable to the production of mineral binders. A reduction of binder to aggregate ratio from 2.0 to 1.5 reduces greenhouse gas emissions by 32.9%. The use of 10 wt% mineral additions can potentially stabilise blocks while having little effect on their overall environmental impacts. The environmental profiles of wall systems incorporating miscanthus-lime blocks have been evaluated in this this study. Combining miscanthus blocks with fired clay bricks enables a potential low carbon retrofitting technique for the current stock of residential buildings in the UK. Timber-framed system filled with miscanthus blocks enables a carbon storage of ~97.3 kg CO eq/m , which presents a potential carbon offsetting strategy in new-build dwellings. Consideration should be given to the potential negative impacts related to agricultural activities for the production of miscanthus shives. The largest negative environmental impact was ozone layer depletion, where a relative difference of 12.8% was recorded between miscanthus timber-framed wall and a typical solid wall insulated with mineral wool. It appears that miscanthus-lime composites can substantially improve the environmental profile of wall assemblies and sustainability be applied in existing uninsulated masonry walls or incorporated in timber- framed new-build houses.Engineering and Physical Sciences Research Council (EPSRC)Natural Environment Research Council (NERC)NERC GW4+ Doctoral Training Partnership studentshi

From science to policy: How European HBM indicators help to answer policy questions related to phthalates and DINCH exposure

Within the European Human Biomonitoring (HBM) Initiative HBM4EU we derived HBM indicators that were designed to help answering key policy questions and support chemical policies. The result indicators convey information on chemicals exposure of different age groups, sexes, geographical regions and time points by comparing median exposure values. If differences are observed for one group or the other, policy measures or risk management options can be implemented. Impact indicators support health risk assessment by comparing exposure values with health-based guidance values, such as human biomonitoring guidance values (HBM-GVs). In general, the indicators should be designed to translate complex scientific information into short and clear messages and make it accessible to policy makers but also to a broader audience such as stakeholders (e.g. NGO's), other scientists and the general public. Based on harmonized data from the HBM4EU Aligned Studies (2014-2021), the usefulness of our indicators was demonstrated for the age group children (6-11 years), using two case examples: one phthalate (Diisobutyl phthalate: DiBP) and one non-phthalate substitute (Di-isononyl cyclohexane-1,2- dicarboxylate: DINCH). For the comparison of age groups, these were compared to data for teenagers (12-18 years), and time periods were compared using data from the DEMOCOPHES project (2011-2012). Our result indicators proved to be suitable for demonstrating the effectiveness of policy measures for DiBP and the need of continuous monitoring for DINCH. They showed similar exposure for boys and girls, indicating that there is no need for gender focused interventions and/or no indication of sex-specific exposure patterns. They created a basis for a targeted approach by highlighting relevant geographical differences in internal exposure. An adequate data basis is essential for revealing differences for all indicators. This was particularly evident in our studies on the indicators on age differences. The impact indicator revealed that health risks based on exposure to DiBP cannot be excluded. This is an indication or flag for risk managers and policy makers that exposure to DiBP still is a relevant health issue. HBM indicators derived within HBM4EU are a valuable and important complement to existing indicator lists in the context of environment and health. Their applicability, current shortcomings and solution strategies are outlined

Study on Cr(VI) Leaching from Cement and Cement Composites

This paper reports an experimental study on hexavalent chromium leaching from cement samples and cement composites containing silica fume and zeolite additions that were subjected to various leaching agents. The water-soluble Cr(VI) concentrations in cements ranged from 0.2 to 3.2 mg/kg and represented only 1.8% of the total chromium content. The presence of chromium compounds with both chromium oxidation states of III and VI was detected in the cement samples by X-ray photoelectron spectroscopy (XPS). Leaching tests were performed in a Britton-Robinson buffer to simulate natural conditions and showed increased dissolution of Cr(VI) up to 6 mg/kg. The highest amount of leached hexavalent chromium was detected after leaching in HCl. The findings revealed that the leaching of chromium from cements was higher by 55–80% than that from the cement composites. A minimum concentration was observed for all cement samples when studying the relationship between the soluble Cr(VI) and the cement storage time

Sustainable Building Materials and Life Cycle Assessment

Today, sustainability principles should be applied to all industries, including the building sector, which ranks among the sectors with the most negative environmental impacts [...