Cement Consumption Research Articles

Experimental study on the mechanical properties and cementation mechanism of microbial cemented fine tailings backfill

The extensive exploitation of metal mines has resulted in the generation of vast quantities of fine tailings, posing significant environmental challenges such as surface subsidence and deposition. The conventional cemented backfill technology, which has been widely used for tailings processing, requires substantial cement consumption and thus leads to escalated economic costs and carbon emissions. In this paper, we propose a pollution-free alternative, Microbial-Induced Calcite Precipitation (MICP) technology, as a promising solution for sustainable mine filling. The study employs microscopic and macroscopic analysis techniques, including laser diffraction particle size (LDPS) analysis, scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), to investigate the inner structure and mechanical properties of the microbial cemented fine tailing backfill (MCFB). Key parameters such as unconfined compressive strength (UCS), CaCO3 content and porosity are examined, with a focus on the effects of bacterial solution dosage and curing time. The results reveal that the MICP-processed fine tailings exhibit an increase in particle size by approximately 292.1% compared to their original size. Furthermore, MCFB specimens demonstrates significantly enhanced UCS and decreasing porosity under comparable conditions, surpassing the performance of traditional cemented fine tailings backfill (CFB) specimens. Microscopic analysis highlights that the strength development in MCFB predominantly arises from the cementation effects of MICP-induced CaCO3, primarily in the form of calcite, rather than the cementation effects resulting from hydration products (C-S-H) in conventional CFB.

Neural Network-Based Estimation of Flexural Performance for Polymer Permeable Concrete

Pervious concrete is increasingly used to reduce runoff water and improve water quality near pavements and parking lots, but highway pavement structures cannot use it due to its high porosity and reduced strength. To address the issue of lower flexural strength in permeable concrete, this study designs and conducts 11 different tests with varying mix ratios. The objective is to ensure that the resulting concrete satisfies both permeability and compression resistance requirements. The uniform test method is employed to measure the flexural strength of the concrete after a period of 28 days. This study employs neural networks to analyze the flexural performance of polymer permeable concrete by considering various input factors such as cement consumption, water consumption, STA (4.75 to 9.5 mm stones), STB (9.5 to 16 mm stones), VAE (vinyl acetate-ethylene) polymer content, and SAP polymer content. The objective is to optimize the mix proportion of polymer permeable concrete and identify a suitable ratio that satisfies the requirements of pavement structural flexural performance.

SECONDARY RESOURCES IN PRODUCTION OF COMPOSITE BUILDING MATERIALS BASED ON CEMENT

Link for citation: Kopanitsa N.O., Demyanenko O.V., Kulikova A.A., Tkach E.V., Shestakov N.I., Stepina I.V. Secondary resources in production of composite building materials based on cement. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 10, рр. 49-60. In Rus. The relevance of the research is caused by the importance of the problem of rational use of natural resources in production of composite building materials. The possibility of partial replacement of natural non-renewable raw materials used in the production of multi-ton concrete and mortar mixtures based on cement with secondary products from the production of various industries will solve the problems of: resource saving, energy consumption and ecology. The construction industry is the largest consumer of by-products of mining enterprises: overburden and waste from mining and processing enterprises, which is hundreds of millions of tons per year. The most studied are the issues related to their use as fine and coarse aggregates in concrete and mortar mixtures for various purposes. The expansion of the possibility of using secondary products of mining enterprises in the production of composite building materials is associated with the production of active mineral additives, fillers in concrete and mortar mixtures, as well as energetically active nanomodifiers. The use of by-products of different chemical composition and dispersion makes it possible to control the processes of structure formation and hardening of composite materials based on cement and to obtain composite materials with the required performance properties. The main goal of the research is to scientifically substantiate and investigate the possibility of using waste from mining enterprises as components in concrete and mortar mixtures based on cement. Objects: modifying additives based on secondary products; composite materials with enhanced performance properties. Methods: determination of the mobility of mixtures, normal density, hardening time, flexural and compressive strength according to SS; thermal analysis; electron microscopy, x-ray phase analysis, colorimetry. Results. The paper introduces the results of studies necessary for the scientific substantiation, development and implementation in the construction industry of the technology for production of building mortar mixtures obtained using secondary products of mining enterprises as well as the comparative results of studies on the effect of a complex additive of microcalcite and nano-SiO2 on the properties of cement systems. It is shown that the introduction of a complex additive increases the compressive strength of cement stone, reduces the consumption of cement without reducing its standard characteristics and improves the performance properties of concrete.

Mechanical activation for sulfidic tailings treatment by tailings: Environmental aspects and cement consumption reduction

Sulfidic mine tailings are one of the massive hazardous solid wastes, containing large amounts of toxic heavy metals. Poor management of tailings can lead to the production of acid mine drainage and the heavy metal transfer emissions into the environment. Thus, in this study, mechanical activation was used to reuse a combination of carbonate tailings (TC) and sulfidic tailings (TS) for concrete construction purposes and to effectively immobilize heavy metals. The results showed that after tailings treatment, the heavy metal leaching rate was significantly below the allowed criteria based on the toxicity characteristic leaching procedure (TCLP). The mercury intrusion porosimetry (MIP) test results on the specific surface area and porosity after the activation pointed out increase and reduction, respectively. In the concrete sample containing 20 % cement-replacing activated tailings, the critical pore diameter after 28 curing days was 60 nm, which was less than that of the control sample with a critical pore diameter of 150 nm. According to X-ray diffraction (XRD) and scanning electron microscopy (SEM), ettringite and calcium silicate hydrate gel acted as hosts for heavy metals ions and played an inevitable role in stabilizing metal pollutants. Results revealed that the compressive strength of the sample containing 20 % of the activated tailings after 28 curing days was 31.2 MPa, which was higher than the strength of the control sample (26.99 MPa). Overall, it was concluded that the combined mechanically activated mine tailings can be a viable substitute for cement (up to 40 %) for constructing concrete samples. The utilized combined approach led to diminish adverse effect of sulfide content in concrete samples besides the cement consumption reduction.

Geopolymer mortars for use in construction 3D printing: Effect of LSS, graphene oxide and nanoclay at different environmental conditions

The environmental impact of concrete 3D printing (C3DP) has become a concern due to its large cement consumption and over-exploitation of natural resources. This study investigates the viability of using geopolymer mixtures in C3DP prepared with fly ash (FA)/ground granulated blast furnace slag (GGBS) and underutilised aggregate as substitutes for ordinary Portland cement (OPC) and natural aggregate, respectively. This paper focuses on the rheological, mechanical, and shrinkage properties of FA/GGBS-based geopolymer mortar with lead smelter slag (LSS) as natural sand (NS) substitute and the impact of adding nanoclay (NC) and graphene oxide (GO), as thixotropy agents, on the yield stress development and viscosity recovery properties of the mixtures. The effect of various outdoor environmental conditions of 24 °C -50 %RH, 35 °C -90 %RH and 35 °C -50 %RH on pore water evaporation and 28-day drying shrinkage of 3D printable geopolymer mortar was studied, considering the effect of NS, LSS, NC and GO in free-formed and control conditions. LSS GO-modified mortars exhibited superior viscosity recovery capacity and yield stress evolution compared to their NC-modified counterparts. Moreover, using LSS instead of NS resulted in increased 28-day compressive strength under various environmental conditions, and LSS mortars exhibited lower drying shrinkage in both conventional casting and free-formed conditions. The findings of this paper will serve as a benchmark for further studies on the effect of different curing techniques (internal or external) on the hardened state dimensional stability of 3D printed products using alkali-activated binder systems to improve the structural integrity by controlling the water evaporation and drying shrinkage development.

Investigation of the Cementing Efficiency of Fly Ash Activated by Microsilica in Low-Cement Concrete.

This paper presents experimental results on the influence of concrete composition factors on the criterion characterizing the ratio between the compressive strength of activated low-cement concrete and clinker consumption. The investigation was carried out using mathematical planning of the experiments. Experimental and statistical models describing the influence of the fly ash, activating additive (microsilica), consumption of cement and aggregates, as well as the superplasticizer on the strength of low-cement concrete under normal hardening conditions and after steaming were obtained. The values of the clinker efficiency criterion and the mineral additive cementing efficiency coefficient were calculated, and models of these parameters were obtained for the investigated concrete compositions. It was shown that the activating effect of microsilica yields an increase in ash cementing efficiency and clinker efficiency criterion in concrete. Using the obtained models, an example for calculating the ash cementing efficiency coefficient is given.

Towards modern sustainable construction materials: a bibliographic analysis of engineered geopolymer composites

Engineered cementitious composites (ECC) exhibits impressive tensile strength but has significant environmental drawbacks due to high cement consumption. Recently, engineered geopolymer composites (EGC) have gained attention as a potential ECC alternative. This comprehensive study reviews the latest EGC advancements, encompassing mix design, design theory, engineering properties, environmental benefits, and durability. It emphasizes how factors like activators, precursors, fibers, additives, and aggregates impact EGC properties, making it a cost-effective material for fire, chemical resistance, and dynamic loads. To address limitations in traditional literature reviews, innovative research methods, including scientometric analysis, were employed to provide a cohesive analysis. This review aims to facilitate knowledge dissemination and collaboration by summarizing EGC advances and highlighting remaining challenges in developing practical applications. It is revealed from the review that various manufacturing methods enhance geopolymers, especially in geopolymer concrete, where replacing 50% of ordinary Portland cement with fly ash boosts strength. Geopolymer concrete excels in pre-cast applications, offering durability and resistance to harsh conditions as an eco-friendly alternative to Portland cement. It suits highway pavement, walls, marine coatings, and tiles, reducing carbon emissions and promoting efficient waste management. EGCs find broad use in construction due to their strong, durable, and eco-friendly qualities, supporting sustainable infrastructure development.

Innovations and applications of Laterized concrete in sustainable construction

This comprehensive discourse examines the innovative construction material known as laterized concrete, which combines sustainability with local resource utilization. The exploration encompasses its composition, mix design, strength, durability considerations, case studies, challenges, guidelines, global impact, and future prospects. Laterized concrete leverages the distinctive attributes of laterite soil to achieve enhanced performance, reduced cement consumption, lower carbon emissions, and improved durability. It highlights its role in transforming construction practices towards more sustainable and eco-friendly approaches. Through case studies, challenges, and guidelines, the material's potential is illuminated, serving as an invitation to further research, development, and widespread implementation in the pursuit of a greener built environment.

A Locally Available Natural Pozzolan as a Supplementary Cementitious Material in Portland Cement Concrete

For several decades, class F fly ash has been an attractive supplementary cementitious material, at least in part, due to its ability to reduce Portland cement consumption and mitigate alkali-silica reactions in concrete. However, fly ash availability is becoming uncertain as the energy industry decommissions coal burning power plants as it transitions to renewable energy production. This situation creates a need to identify viable and sustainable alternative supplementary cementitious materials. There are several types of supplementary cementitious materials, such as natural pozzolans, metakaolin, or ground granulated blast-furnace slag, which appear to be potential alternatives to fly ash in concrete. In this research, a locally available natural pozzolan (pumicite) was selected to replace fly ash in concrete. After conducting alkali-silica reaction tests on mortar mixtures, rheological and strength properties, shrinkage, resistance to freezing and thawing, and chloride ion permeability of concrete mixtures containing different amounts of fly ash and natural pozzolan were evaluated. The results showed that pumicite was more effective than fly ash at mitigating the alkali-silica reaction, and a pumicite content of 20% was necessary to mitigate the alkali-silica reaction. Ternary mixtures containing both pumicite and fly ash were the most effective cementitious materials combinations for mitigating the alkali-silica reaction expansion. Additionally, pumicite provided acceptable compressive strength and modulus of rupture values (greater than 4.0 MPa) that exceeded the flexural strengths provided by established mixtures containing only fly ash. Shrinkage and durability factor values for all mixtures were less than 710 μstrain and greater than 75, which are generally considered acceptable. Additionally, all mixtures with acceptable alkali-silica reaction expansions had very low chloride permeability. These results indicate that pumicite can be a reliable alternative for fly ash.

Development of an axial constitutive model for square steel tube–alkali-activated slag recycled concrete columns

Alkali-activated slag recycled concrete (ASRC) can reduce cement consumption and utilize construction waste. Although, it has poor mechanical properties, a square steel tube can significantly improve its mechanical performance. Therefore, this study conducted axial compression tests on square steel tube-ASRC column (SST-ASRCC) considering the effects of recycled coarse aggregate (RCA) and steel fibre (SF). Subsequently, the bearing capacity, peak compressive strain, and load–strain models of SST-ASRCCs based on the analysis of existing models were established. The results provide an experimental basis and theoretical support for the promotion of SST-ASRCCs in practical engineering.

OBTAINING A MODIFYING ADDITIVE FOR BUILDING MIXTURES BASED ON SYNTHETIC FIBER PRODUCTION WASTE

An analysis was made of the possibility of using technical waste in the production of synthetic fiber Nitron-D
 to obtain a modifying additive for building mixtures. An analysis was made of the possibility of using technical waste in
 the production of synthetic fiber Nitron-D to obtain a modifying additive for building mixtures. A comprehensive analysis
 of the effectiveness of a modifying additive for building mixtures based on waste from the production of synthetic
 fibers makes it possible to predict an increase in the plasticity of the mixture and its corrosion resistance, a decrease in
 W / C, an increase in the workability of building mixtures and a simplification of their surface machinability; increasing
 the cohesiveness and non-separability of building mixtures at low cement consumption, as well as their high pumpability
 with concrete pumps. Recycling of waste from the production of synthetic fiber will expand the range of products,
 reduce the amount of waste to be disposed of and recycled, which, in turn, will reduce the negative burden on the environment
 and will allow organizations to become resource-saving, low-waste and waste-free.

Effect of waste binder material usage rate on thixotropic behaviour of cementitious systems

In order to investigate the feasibility of using waste as an alternative binder in cement-based materials, the effects of using recycled concrete powder (RCP), glass powder (GP), marble powder (MP), and limestone powder (LP) in place of portland cement on the rheological and fresh characteristics of cementitious systems were determined. In this regard, the influence of the utilization of waste materials and the substitution ratio (25% and 35%) on the parameters of the cement paste mixtures that change over time, such as setting time, Marsh-funnel flow time, mini-slump value, viscosity, and dynamic yield stress (DYS), were determined. The effect of 4 different type waste powder materials on the rheology and thixotropy of cementitious systems was investigated using two different methods (loop and constant shear strain rate methods). In order to reduce cement consumption, the effect of the use of waste powder materials on the time-dependent behavior of cementitious systems has been examined, and important results have been obtained for cases (such as producing 3D concrete or self compacting concrete) where time-dependent consistency change is important. It was determined that replacing RCP and GP enhanced the DYS values while replacing MP and LP decreased them. In this context, it was understood that regardless of time, MP and LP promote flowability, whereas RCP and GP diminish flowability. RCP35 had the greatest Ithix_shr and Ithix_vis values at the 20th minute, whereas MP and LP-containing mixtures had the lowest values. The mixtures with the highest and lowest thixotropic degrees were RCP35 and LP35, respectively.

Environmental evaluation of 3D printed concrete walls considering the life cycle perspective in the context of social housing

Wall construction is the most common application for 3D concrete printing (3DCP). This construction technique requires a printing material with specific rheological characteristics that are usually achieved through high cement consumptions, reaching more than 1000 kg/m³. It is well known that large-scale cement consumption is a worldwide concern, mainly due to carbon dioxide emissions. Thus, in the context of 3DCP structures, this environmental concern becomes even more relevant. Therefore, this work investigated the environmental performance, by means of the Life Cycle Assessment (LCA) methodology, evaluating 14 environmental impact categories of 3DCP walls, and comparing them with conventional construction techniques in a social housing context of a Brazilian case study. The results confirmed that cement consumption provides the greatest contribution to the impact potentials for most of the evaluated categories, reaching 93% for climate change. So, materials that can be used to replace cement, such as supplementary cementitious materials (SCM), are important alternatives. In general, the comparative results showed that 3DCP can have a similar environmental performance to conventional construction techniques, when, instead of evaluating 1 m³ of concrete, the functional unit evaluated is 1 m2 of wall. Sensitivity analysis carried out showed that the printing parameter variations that most affect the consumption of concrete cause the greatest changes in potential environmental impacts, while alterations in the energy consumption, almost do not influence the total values of the potential impacts. Finally, this study presents a roadmap and a pathway for designers, developers, builders and researchers of 3DCP to decrease the life cycle environmental impacts.

Ideal dosage curves for limestone and EAFS aggregate concretes and their sustainability assessment

Experimental tests, and two conventional grading curves, are used to design a dosing scheme, seeking the best way to enhance the general sustainability of certain types of low-to-medium workability concrete mixes. The aim is to achieve highly compacted aggregate gradations, thereby minimizing the need for Portland cement consumption. Several aggregate mix designs, employing fractions of both commercial limestone and recycled electric steelmaking slag, were prepared and assessed. Nine concrete mixes of structural quality (above 40 MPa as compressive strength) were manufactured to analyze their aggregate packing density and their performance as engineering concrete mixtures. The results obtained after classical testing showed excellent quality homogeneous concrete mixes, considering both the in-fresh and in-hard properties. Subsequently, a sustainability analysis of all the mixes led to the conclusion that they were of low environmental impact, due to their high aggregate content and their low cement consumption which, additionally, included other industrial co-products with hydraulic properties.

Modern AAC additive—A ready tool helping with decarbonization of AAC production by reduction of water, cement, lime and energy consumption

AbstractEuropean Association of AAC producers (EAACA) has set the goal for the AAC industry to become carbon‐neutral by 2050, so it is now more important than ever to explore ways to achieve it. One of the readily available solutions is a dedicated additive for AAC production, production, the effects of which positively affect the reduction of CO2e emissions. The additive is a tool helping the chemical reaction and offers improvements in two key emission sources for AAC. The first one is cement and lime usage, responsible for 74% of CO2e emissions in AAC production. A few percent cutbacks of binders consumption generate direct results in this area. The second one is the production process itself, being accountable for 13% of CO2e emissions. Lowering water content in the mix directly results in a lower requirement for steam during autoclaving, therefore impacting energy usage. Reductions in these two areas can be calculated in terms of CO2e emissions, as well as economical savings. The financial advantages generated by the additive are always higher than the cost of it. The chemical and process background presented in this paper is supported with examples from AAC plants worldwide, and complemented by GHG methodology calculation where 3,6% of CO2e emissions reductions can be achieved solely by using modern additive for production.

Hydration characteristics, structure evolution of marine cement composites with high durability modified by colloidal nano-silica for low carbon footprints

The porous structure of cement composites provides channels for the invasion of chloride ions in marine environment, which limits their service life and low carbon footprints. Colloidal nano-silica (CNS) with the particle size of 10–30 nm theoretically can refine the pore structure, block the chloride ion transport channel. Thus, it is beneficial to improve the service life of cement composites and reduce the consumption of cement and carbon dioxide emission. In this paper, the CNS was introduced to partially replace high sulfate resistance Portland cement (HSRPC) preparing HSRPC-CNS composite. The hydration characteristics, strength property, porous structure and chloride ion resistance were investigated. The results revealed that the addition of CNS was effective in improving the properties of HSRPC-CNS composite, and the most suitable content of CNS was 3 wt%. In this case, the hydration process of HSRPC-CNS composite was accelerated, and the 28-days compressive strength increased by 12.26%. Additionally, as the CNS content increases to 3 wt%, the porosity and chloride diffusion coefficient decreased by 32.39% and 41.99%, respectively. Therefore, CNS can be used as a sustainable nano additive that improved compactness, alleviated chloride ion permeability and reduced carbon dioxide emissions in HSRPC-based composites.

Reducing cement consumption in mortars by waste-derived hydrochars

Reducing cement consumption in mortars by waste-derived hydrochars

The performance and microstructure of alkali-activated artificial aggregates prepared from municipal solid waste incineration bottom ash

In order to reduce the negative environmental impact of municipal domestic waste incineration bottom ash (MSWIBA), it is converted into lightweight aggregates by cold bonding technology. To enhance the utilization of waste materials, minimize cement consumption, and fabricate artificial aggregates with superior comprehensive performance, we designed and synthesized alkali-activated aggregates (AAAs) in this study. This study used MSWIBA and ground granulated blast furnace slag (GGBFS) as precursors for alkali-activated aggregates (AAAs), activated by a mixture of sodium hydroxide solutions and sodium silicate. The physical and mechanical properties of AAAs, including water absorption, apparent density, crushing strength and carbon-resistance, were investigated at different NaOH concentrations. In addition, the microstructure, mineral composition, aggregation, porosity and heavy metal leaching behavior of AAAs were analyzed by SEM, XRD, FTIR, TGA, MIP and ICP techniques. All AAAs exhibited a consistent particle size distribution, characterized by apparent densities spanning the range of 1633–1940 kg/m3. The leaching levels of heavy metals align with the standards established by Chinese regulations. Among the different activator concentrations tested, aggregate (M4) displayed superior single-particle crushing strength (3.90 MPa) and better carbonization resistance. It also used a lower concentration of NaOH, which enabled more cost-effective and eco-friendly production. Overall, the findings suggest that MSWIBA can be a viable precursor for producing sustainable lightweight concrete, with 4 M NaOH being the optimal activator concentration for achieving the best performance.

Evaluation of the mechanical behaviour of representative volumetric elements of 3DCP masonry mixtures with partial replacement of cement by limestone filler and metakaolin

The analysis of 3D printing concrete (3DCP) mixtures as representative masonry volumetric elements (RVE-3DCP) is ideal to better understand the behavior of 3DCP within the masonry typology. Nevertheless, analyzing small pieces might not accurately represent the actual behavior of 3DCP in the intended application, especially as masonry in this specific scenario. This study aims to develop representative 3DCP masonry volumetric elements (blocks, prisms, and mini-walls) produced with 3DCP mixtures with up to 50% cement replacement by limestone filler (LF) and metakaolin (MK). The mechanical behavior of the RVE-3DCP and the small-sized specimens (cubes and prisms) was evaluated in comparison with the pieces made with the reference mixture, only with cement. The RVE-3DCP were also compared to the elements of the hollow concrete block structural masonry system. The properties in the fresh and hardened states were investigated to analyze the influence of LF and MK on the 3DCP mixtures. The results showed that there is a reduction in the compressive strength of RVE-3DCP when compared to the compressive strength of small-sized 3DCP specimens, showing that these cube and prism specimens may not be the ideal typology to analyze the real behavior of 3DCP. Furthermore, these 3DCP mixtures with LF and MK obtained better efficiency indexes about cement consumption per MPa achieved, which proves the good performance of mixtures with reduced cement consumption in the ability to withstand the compressive stresses of 3DCP masonry with sealing or structural function. In addition, the RVE-3DCP in block and prism size may be suitable for analysis of the mechanical behavior of 3DCP mixtures as it represents a reduced geometry of the masonry.

A Study on Experimental Analysis of Strength of Concrete incorporating Ultrafine Slag Mineral

The cement concrete has attained the status of a major building material in the modern construction because of its various advantages such as its adequate plasticity, remolding characteristics. It is used extensively all over world. But, environmental concerns both in terms of damage caused by the extraction of raw material and the emission of carbon dioxide during the manufacturing of cement have brought pressures to reduce consumption of cement by the use of relatively effective substitute materials. The substitute materials can be mineral admixtures such as fly ash, rich husk, etc. or ultra-fine material such as steatite powder, ultra-fine slag. This paper is based on the compilation of the experimental analysis done by various researchers and scientists. This paper reviews the results of an experimental study, conducted by various authors and researchers to evaluate the strengths and strength efficiency factors of hardened concrete, by partially replacing the cement by various ultrafine materials such as blast furnace slag, fly ash, alccofine, steatite powder, ultra fine calcium carbonate. This reports on the study conducted on the effect of ultrafine slag on the strength of concrete and in order to make an approach to reduce the content of Ordinary Portland Cement which ultimately results in the less carbon emission and less carbon footprints to achieve same or relatively better strength and workability.