Papers by Keyword: Cement

Abstract: This study is about a church built at the end of the 19th century, made of burnt brick and lime mortar with sand, inadequately renovated. The objective of the study is to signal about the damages suffered by the old buildings due to the use of inadequate materials in repair. The present building was less than 20 years ago renovated by replacing the old lime-sand plaster with cement mortar, a fact that led to the accumulation of moisture in masonry, resulting the damage of the finishes and affecting the safe health conditions. The article presents temperature, humidity and dew point measurements, a calculation of the comfort index, and a software modelling, as well as the correct solutions.

Abstract: Under the current research project, the feasibility of reducing the carbon footprint of masonry restoration mortars was investigated, by means of replacing a part of cement with emery. A two-fold advantage is offered by following this strategy: (i) to develop more sustainable restoration mortars and (ii) to validate the use of a rock that can potentially offer greater resistance to depletion/ weathering. Emery, a naturally occurring rock was characterized via X-ray fluorescence and stereo microscopy. The reference mortar was prepared according to EN 196-1:2016, with a CEMII/B-M(P-LL)42.5R cement targeting a flow table spread of 12-16±1 mm (in accordance with EN1015-3:1999+A1). Consequently, (i) a 20% and (ii) a 50% CEMII replacement with corundum powder was materialized. The mean compressive strength was reduced, as originally intended, by approximately 50% for the 50% replacement, allowing the mortar to be used for restoration purposes, where natural, low strength materials are preferred, which not exceeding the strength of masonry stones. Interestingly, flexural strength did not fall drastically. A number of complications arise on setting the flow spread as the basic design parameter and discussion on mix design is elaborated upon and correlated with the 7-and 28-day strength tests (in accordance with EN1015-11:1999+A1). Furthermore, the pore structure of the surface of the specimens was investigated via stereo microscopy and interesting observations pave the way for more sustainable mortar design.

Abstract: This review utilizes bibliometric analysis to examine global research trends and the chronological development of studies on the incorporation of mine wastes and tailings in concrete. A total of 345 publications were extracted from the Web of Science (WOS) database, and their analysis revealed a clear upward trajectory in scientific output since 2000. Respectively, China, India, Canada, and the USA were identified as the countries contributing the most to this research area. Among the 1139 author keywords extracted from the collected papers, 103 keywords with a minimum of three occurrences were analyzed using the VOSviewer software. VOSviewer further supports identifying research gaps and emerging trends by visualizing relationships among authors, publications, and keywords, facilitating a deeper understanding of the dynamics within the field. The analysis of keyword occurrences shows convergence towards research that focuses on the development of sustainable and high-performance materials that equate environmental responsibility with industrial economy demands. The current review also uses Biblioshiny, a web-based tool that explores topic timelines. It reflects that, in recent years, research focuses have shifted toward more sustainability, advanced materials, and performance optimization in the use of mine tailings in concrete.

Abstract: The current and significant environmental pollution caused by the use of cement in structural construction highlights the need for more sustainable alternatives. This research evaluates the use of uncalcined scallop shell powder (SP) and recycled glass powder (GP) as partial replacements for cement in conventional concrete mixes with a design strength of f'c = 280 kg/cm². SP and GP were incorporated in a 2:1 ratio at the following replacement levels: 2.5% SP + 5% GP and 5% SP + 10% GP. The analysis conducted on the concrete includes CO₂ emissions associated with its production, workability in its fresh state, and compressive strength in its hardened state. As a result, the mix with the lower replacement percentage proved to be the most optimal, achieving a 1-inch increase in workability and a 2.49% increase in 28-day compressive strength compared to the control mix, along with a 1.08% reduction in CO₂ emissions. This demonstrates the structural and environmental viability of concrete incorporating SP and GP.

Abstract: The changes in the mechanical and physical properties of concrete prepared by incorporating various metal oxide nanoparticles into cement products used in both the oil/gas industry and construction have been analyzed in this review. The study compares the properties exhibited by transition metal oxide and some metal nanoparticles in both isolated and complex forms with polymers in concrete. Analyses were conducted primarily in the direction of changes occurring in properties due to the addition of metal oxide nanoparticles such as magnetite Fe₃O₄, TiO₂, ZnO, Fe₂O₃, Ag, CuO, TiO₂/SiO₂, Al₂O₃, ZrO₂, core/shell Fe₃O₄/SiO₂, in dispersed form as cement powder or in water. It has been showed that appropriate changes occur in properties such as compressive and flexural strength, adhesion, initial and final setting, water absorption, porosity, electrical conductivity, degradation when metal oxide nanoparticles are added to cement. The density and size of nanoparticles affect their response to various influences, alongside the fundamental properties of the material.

Abstract: The cement production process significantly contributes to greenhouse gas emissions, accounting for 25% of total industrial emissions. This study systematically examined new, underutilized materials—sewage sludge ash (SSA), marble waste (MW), and calcined clay (CC)—to evaluate their effects when partially replacing white Portland cement (WPC) in cement paste formulations. Various replacement proportions (10%, 20%, and 30%) were tested, along with different treatment temperatures (600°C, 630°C, 730°C, and 850°C) for SSA and CC. To gain a deeper understanding of the resulting materials, analyses such as XRF, XRD, and SEM were conducted. The highest compressive strength recorded for the 28-day cured cement paste was 91 MPa when 20% SSA (treated at 600°C) was used, compared to just 53 MPa for the control sample. Conversely, CC exhibited minimal enhancement in compressive strength, while MW had detrimental effects. Additionally, replacing WPC with SSA and CC at 9% and 21% resulted in slight improvements in compressive strength. This research highlights the potential of utilizing underexploited materials like SSA to improve the mechanical and chemical properties of cement paste, indicating that further investigation is necessary to enhance environmental sustainability.

Abstract: This research project focuses on the experimental investigation of using zeolite as a partial replacement for cement in M25 grade concrete. Zeolite, a naturally occurring mineral with pozzolanic properties, has gained attention as a sustainable alternative to cement in concrete production. The study aims to assess the effects of incorporating zeolite on the properties of M25 concrete, such as compressive strength, durability, and workability. Through a series of laboratory tests and analysis, the project intends to evaluate the feasibility and effectiveness of utilizing zeolite in reducing cement content while maintaining the required performance standards of M25 concrete. The findings of this research could contribute to promoting eco-friendly practices in the construction industry by reducing the environmental impact of cement production.

Abstract: Desert soils present some issues that need improvement. Some of these are high permeability and collapsibility potential. These problems are due to the uniform particle size distribution and the lack of particle edges. Soil improvement is required to mitigate these issues. Cement is widely used for soil stabilization but has environmental issues since it is a significant source of CO₂ emissions and requires high energy consumption. In this study, the calcined shale material is utilized as a partial replacement for cement to reduce the permeability and compressibility of soils more sustainably. The study considers three cement doses of 5%, 10%, and 15% and four calcined shale percentages of 10, 30, 50, and 70%. A series of falling head permeability and one-dimensional consolidation tests were conducted to examine the performance of cement and calcined shale as stabilizers. The results of the study indicate that the addition of 30% calcined shale as a partial replacement of cement has the most significant effect on the conductivity and compressibility of the soils. An increase in cement content decreases the permeability and compressibility of the soil due to the hydration of cement. Conversely, the conductivity and consolidation of the soil are initially decreased with an increase in the calcined shale up to 30% and then start to increase. In summary, this study reveals that the presence of CS and cement has a substantial effect on the conductivity and compressibility of the soils.

Abstract: River-carried solids, especially during floods, lead to dam sedimentation. Dredging extends dam life, but excess unusable sediment storage threatens the environment. The aim of this work is to investigate the influence of the recovery of calcined mud from Chorfa dam on the physico-mechanical and chemical characteristics of mortars fiber bundles. The sludge is used as a partial substitute for cement by volume at rates of 10%, 15%, 20% and 25%. All test specimens had water / binder (W/B) ratio and steel fibers ratio. Testing programme included measuring the fluidity, ultrasonic pulse velocity test, dynamic modulus of elasticity, flexural and compressive strengths. Compared to the control mortar, the fluidity represented by the diameter of M0, M15 and M25 mixtures decreased by approximately 11%, 14% and 22%, respectively. The compressive strength of M15 increased by 17.4% at 28 days, compared with the control specimen. At 7 days, the ultrasonic speed of the M25 mixture decreases by 1.7% compared to that of M15. The dynamic modulus of elasticity of M20 and M25 increases by 13% and 12% as the age ranges from 2 to 28 days. At 28 days, the flexural strength of the M20 blends increased by approximately 64%.

Abstract: This research investigated the influence of phosphogypsum (PG) addition to mortar mixture and determined the possibility of utilizing PG in soil stabilization. Originally, the chemical composition and mineralogy of the PG were determined using X-ray fluorescence (XRF) and X-ray diffraction (XRD) tests. The principal constituent of PG becomes calcium sulfate hemihydrate with the presence of some impurities. A total of 9 mixes have been developed: A plain mortar mix is a comparative base, and the other 4 mixes are with 5, 10, 15, and 20 % cement replacement with PG for each type (fresh and stockpiled PG called PGF and PGS, respectively). The experimental program focuses on analyzing the effects of PG on setting time, hardened density, compressive strength, and water expansion of mortar mixtures before its soil stabilization application. Test results indicate that with higher PG, the setting time of the mortar mix is delayed except for the mixture with 20% PG, which experienced an early false set. The results of the compressive strength tests revealed that the 5% PG mixes exhibited higher values compared to the control mix, starting from the 28-day curing period, regardless of PG type. Although the higher PG content and compressive strength lowered, the expansion levels were very low based on the ASTM C 1260 limits for all mixtures, excluding heaving risks.