Use Of Supplementary Cementitious Materials Research Articles

Mixture design and environmental impact analysis of cement-metakaolin-sugarcane bagasse ash ternary composite

The use of supplementary cementitious materials (SCMs) is an effective way to reduce CO2 emissions within the cement industry. In this paper, the Cement-Metakaolin (MK)-Sugarcane Bagasse ash (SCBA) ternary composite was designed based on the simplex centroid design method. The influence of MK and SCBA on mechanical properties of ternary composite was investigated. In addition, the hydration products and microstructure of ternary composite were analyzed by Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), low-field nuclear magnetic resonance (LF-NMR). At the same time, the life cycle assessment (LCA) method was used to quantitatively analyze the environmental impact and economic cost of the ternary composite system. A multi-performance indicator was used to optimize the mix ratio of the ternary composite based on the simplex centroid design method, and it was concluded that the Cement: MK: SCBA ratio was 75%: 20%: 5% (by weight) to achieve the optimal synergistic effect. The findings of this study can offer a design methodology that considers both performance and environmental factors, while also providing a theoretical foundation for the utilization of SCBA in cement-based materials.

Efficiency of self-compacting concrete made with variable sustainable cementitious materials: A TOPSIS algorithm approach

The use of supplementary cementitious materials as a partial replacement for cement is taking the lead in the concrete production industry. Being known as by-products from various manufacturing properties, concrete produced with such materials is considered a sustainable alternative to normal concrete. Three different by-product materials have been investigated in this study for the production of sustainable self-compacting concrete (SCC), namely, ground granulated blast furnace slag (GGBS), fly ash (FA), and silica fume (SF). Compressive strength, production cost, and global warming potential (GWP) were the main testing parameters for the mixes' performances. Multi-criteria decision-making algorithm was implemented using the TOPSIS model to investigate the ultimate performance of those SCC mixes considering all tested parameters simultaneously. Results showed the best SCC performance can be attained when using about 60 % of GGBS as a partial replacement for cement.

The influence of selected mineral ingredients on the technological properties of sealing slurries

Sealing slurries used to modify the subsoil should meet a number of requirements, including: rheological properties, setting time, appropriate mechanical strength and durability. The study determined the technological properties of sealing slurries prepared with ordinary Portland cement and blended binders containing appropriately selected mineral additives. The tests used granulated blast furnace slag, silica fly ash and ash obtained in the fluidized bed combustion of coal. The assessment of the technological properties of fresh slurries included the selection of an appropriate rheological model and the assessment of the rheological properties of the sealing slurry, such as: plastic viscosity, apparent viscosity and yield point. The research determined the factors causing improvement of the technological properties of fresh slurry. The use of supplementary cementitious materials, also in systems with fluidizing admixtures, allowed for a significant modification of the rheology of the tested sealing slurries. The obtained results indicate their beneficial effect on the functional properties of slurries, enabling their use as binder components replacing Portland cement, while limiting or even eliminating the addition of superplasticizers.

Heat-resistant composites based on ternary binders with a low cement content: Characterization and performance

A reduction in cement consumption can be achieved through the use of supplementary cementitious materials (SCMs). In addition, the utilization of more than one SCM can show a beneficial synergic performance. In this paper, a combination of calcium aluminate cement, alumina admixtures and one other type of SCM was investigated. Namely: microsilica, ferrite powder, ceramic dust, calcined shale and sintered mullite were employed. The phase compositions of the designed binders were primarily characterized by XRD, XRF, DSC and SEM. Subsequently, the basic physical and mechanical properties as well as thermal expansion of the ternary binder-based composites up to 1400 °C were determined. The results revealed the synergic performance of used components. Calcined shale and ceramic powder were the most promising admixtures, exhibiting compressive strength of 80 MPa at room temperature and 117 and 128 MPa for ceramic powder and calcined shale, respectively, after exposure to 1400 °C.

Concrete incorporating supplementary cementitious materials: Temporal evolution of compressive strength and environmental life cycle assessment

The use of Supplementary Cementitious Materials (SCMs) or industrial wastes as a partial replacement for cement in the production of concrete is an urgent need in the construction industry due to cement's growing environmental challenges and rising cost. In respect of this, we conducted research work on proportioning binary concrete mixes. Fly ash (FA) replaced 10 %, 20 %, and 30 % of the cement, while silica fume (SF) replaced 5 %, 10 %, and 15 % of the cement. A control concrete mix was also developed with 100 % cement and no SCM. The results showed no increase in compressive strength for FA concrete compared to control at the early age of 3–28 days, but a maximum increase in compressive strength of 4 % was discovered at a later age of 56 days for concrete with 20 % FA. For 5 % SF concrete, a considerable strength increase of 15 % was seen at the early age of 3 days. Like with FA concrete, 2 % improvement in strength was recorded at the later age of 56 days for 10 % SF concrete. This study further focused on the concrete's temporal evolution of compressive strength by developing a strength evolution model (SEM) using nonlinear regression analysis at a 95 % confidence level. Pearson correlation coefficient was used to determine the correlation between the model values and the experimental results. For comparison, the fib Model Code 2010 was applied to the experimental data, and a good agreement was observed among the proposed model, the fib Model values, and the experimental results. The proposed model can be expanded to address further regression-related problems. Finally, environmental life cycle assessment revealed that utilizing 10 %, 20 %, and 30 % of FA lowered Global Warming Potential (GWP) by 9 %, 19 %, and 29 %, respectively. Likewise, using 5 %, 10 %, and 15 % of SF reduced the GWP by 5 %, 9 %, and 14 %.

Effect of wheat straw ash as cementitious material on the mechanical characteristics and embodied carbon of concrete reinforced with coir fiber

The use of supplementary cementitious materials has been widely accepted due to increasing global carbon emissions resulting from demand and the consequent production of Portland cement. Moreover, researchers are also working on complementing the strength deficiencies of concrete; fiber reinforcement is one of those techniques. This study aims to assess the influence of recycling wheat straw ash (WSA) as cement replacement material and coir/coconut fibers (CF) as reinforcement ingredients together on the mechanical properties, permeability and embodied carbon of concrete. A total of 255 concrete samples were prepared with 1:1.5:3 mix proportions at 0.52 water-cement ratio and these all-concrete specimens were cured for 28 days. It was revealed that the addition of 10 % WSA and 2 % CF in concrete were recorded the compressive, splitting tensile and flexural strengths by 33 MPa, 3.55 MPa and 5.16 MPa which is greater than control mix concrete at 28 days respectively. Moreover, it was also observed that the permeability of concrete incorporating 4 % of coir fiber and 20 % of WSA was reduced by 63.40 % than that of the control mix after 28 days which can prevent the propagation of major and minor cracks. In addition, the embodied carbon of concrete is getting reduced when the replacement level of cement with WSA along with CF increases in concrete. Furthermore, based on the results obtained, the optimum amount of WSA was suggested to be 10 % and that of coir fiber reinforcement was suggested to be 2 % for improved results.

Fast set GGBS Binder

AbstractTo reduce CO2 emission producing Ordinary Portland cement (every ton of Portland cement accounts for roughly 850 kg CO2) the use of supplementary cementing materials (SCM's) are becoming todays standard in the cement and construction industry.Although some SCMs are used on their own, most of them are used in combination with Portland cement clinker.Aim was to accelerate the setting time of a pure GGBS binder and improve its early strength development. From different publications we learned that fast setting cements contain C11A7. CAF2 similar to the phases calculated from our Type II GGBS.

Practical experiences in the use of a combination of calcined clay and limestone as clinker substitute in cement

AbstractThe acceleration of the impact of climate change prompts the cement industry for swift and effective solutions to reduce a large part of the carbon dioxide associated with cement manufacture. The use of Supplementary Cementitious Materials, SCM, such as fly ash and slag have enabled so far, the possibility of partially replacing clinker, the most energy intensive and main responsible component in cement for carbon emissions. However, reserves of both SCM are declining and their price is increasing, and replacing more than 30% clinker with these SCM can compromise early strength. In recent years a global team of scientists from Switzerland, Cuba and India have proven the possibility of dropping clinker content in cement down to 50% or even less through the combined use of calcined kaolinitic clays and limestone, both cheap and abundant materials, to produce a new cement called “LC3”. The resulting cement matches the properties of a CEM I (EN‐197) at all ages, and carbon emission reduction is reportedly around 25‐40%, depending on the cement to compare with. This paper presents the accumulated experience in the investigation of the new cementitious system and the introduction at the industrial level. Issues like the choice of the right clay, calcination technology, product formulation, standardization and economic feasibility will be discussed. The information in this paper is intended to encourage industrial partners to invest in the new technology.

Activation of LC3 binders by C‐S‐H nucleation seeding with a new tailored admixture for low‐carbon cements

AbstractThe use of supplementary cementitious materials is currently the most favorable strategy for reducing CO2 emissions in cements. Limestone Calcined Clay Cements, LC3, are a type of cement that allows the reduction of CO2 emissions up to 40%. The proportions of the mixtures can vary, but the most investigated combination, LC3‐50, contains about 50 wt% clinker, 30 wt% calcined kaolinitic clay, 15 wt% limestone and an optimised calcium sulphate content. However, the mechanical strengths of LC3 at early ages are not good enough and they should be improved. One way of doing this is by employing commercial strength‐enhancing (accelerator) admixtures based on C‐S‐H nucleation seeding. For this work, LC3‐50 cements were prepared with clays with varying kaolinite contents. Mortars and pastes were fabricated using a new PCE‐based superplasticizer developed to avoid the loss of fluidity at early ages typical of LC3 binders. The selected accelerator for this study was Master X‐Seed STE53. The results show that the loss of fluidity of LC3 mortars during the first hours could be solved by a recently developed PCE‐based superplasticizer. The compressive strengths at 1 day for LC3 mortars strikingly improved by using the C‐S‐H seeding admixture and this behavior was maintained for up to 28 days.

Use of Flyash and Plastic Waste as a Constituent in Concrete

Cement production gives rise to CO2 emissions generated by calculations of CaCO3 and by fossil, being responsible for about 5% of the CO2 emissions in the world. This can be substantially reduced if cement replacement materials, either partial or complete such as fly ash are used. Presently large amounts of fly ash are generated in thermal industries with an important impact on the environment and humans. In recent years many researchers have established the use of supplementary cementitious materials (SCM) like flyash (FA) not only improves the various properties of concrete both in its fresh and hardened states but also can contribute to economic construction costs. Plastic bags which are commonly used for packing, carrying vegetables, etc create a serious environmental problem. The safe disposal of plastic bags in the environment is the most challenging issue for solid waste management across the globe. These are non-biodegradable and toxic. Every year at least 15% of total plastic waste remains untreated. Concrete is one of the best choices for construction in many countries today. Waste plastic is being tried in the field of construction as a spatial replacement in fine aggregate, coarse aggregate, or as an additive the concrete. In the present study fly ash (FA) is taken as the partial replacement in cement and low-density polyethylene (LDPE) is used as an additive in the concrete. FA was partially replaced in cement at percentages of 10, 20, and 30. Along with the variation of FA, LDPE was also added from 0.2% to 1% in the concrete by volume. Ample number of samples in M20 grade was prepared with a w/c ratio of 0.55 It was found from the result that the optimum compressive strength for 7 days and 28 days were 28.44 N/mm2 and 33.77N/mm2 obtained at 20% percent replacement of FA with 0.4% addition of LDPE Similarly the optimum split tensile strength for 28 days was 2.49 N/mm2 obtained at 20% replacement of FA with 0.8% addition of LDPE. Thus 20% FA with up to 0.4% LDPE can be adopted so that the disposal of waste plastic and fly ash can be done well as well and the efficiency of the concrete can be managed effectively.

The effect of cement replacement with metakaolin and sugarcane bagasse ash as supplementary cementitious materials on the properties of concrete

The use of supplementary cementitious materials in the cement and construction industry is growing rapidly owing to the numerous benefits the application of these materials offers. In this study, the effects of metakaolin (MK) and sugarcane bagasse ash (SCBA) used to partially replace cement on concrete are investigated. The experimental plan was designed using a constant 5% MK and 0-20% SCBA contents by weight. The mix design of 1:2:3 and water-binder (w/b) ratio of 0.5 was employed. Samples prepared were tested at the ages of 7, 14, 28, and 60 days respectively. Concrete workability, water absorption, and densities all showed a decrease with an increase in the percentage of SCBA. The compressive strengths at lower percentages of SCBA (5% and 10%) recorded higher values compared to that of 5% MK and 0% SCBA. An increase in the percentage of SCBA above 10% however led to a decrease in compressive strength. The maximum compressive strength of 22.17N/mm2 was obtained at 60 days in concrete containing 5% MK and 10% SCBA. Both the T-statistics and F-statistics values calculated were statistically significant and exceeded their critical values. This suggests that there is a good relationship between the compressive strength of SCBA and the curing period and that the variation in the curing period and SCBA also causes a variation in the concrete compressive strength. From the results obtained, it is concluded that 5% MK and 10% SCBA can be applied to replace cement for structural concrete production.

Relationships between Mortar Spread and the Fresh Properties of SCC Containing Local Metakaolin

Self-compacting concrete (SCC) production is a complex operation that requires finding a good combination and suitable dosages for its constituents. Several formulation methods have been developed to meet the workability requirements of SCC. Mortar spread is used to estimate SCC’s rheological properties, but the use of supplementary cementitious materials, such as metakaolin, could affect the accuracy of the estimation. In this paper, the relationships between the fresh properties of local-metakaolin (MK)-based SCC and the spreading of its mortar portion were investigated. The results showed the existence of good correlations between the spreading of mortar portion of SCC and its fresh state properties. The partial substitution of cement with MK did not affect these correlations. The mortar flow should be chosen according to the required rheological properties of the SCC. This can be achieved by using an appropriate viscosity-enhancing agent (VEA).

Investigating the Effects of Recycled Plastic as Fibers on Bending Behavior of Green Concrete Beams Exposed to Marine Environment.

Due to the noticeable production of greenhouse gases in cement production processes around the world, the use of supplementary cementitious materials (SCMs) like metakaolin/zeolite and the production of green concrete is inevitable, which leads to reducing the amount of environmental pollution and, specifically for maritime environments, improving the mechanical qualities of concrete. In addition, nowadays, the increasing use of plastic materials such as disposable glasses is considered a major problem in environmental pollution. Thus, using metakaolin/zeolite as an SCM and disposable glasses as fibers in concrete production may reduce environmental pollution and improve concrete's properties. To do so, in this paper, the flexural behavior of green concrete beams containing metakaolin/zeolite at 10 and 20% as SCMs at 28, 90, and 180 days in the Oman Sea tidal environment was examined by studying the effects of utilizing 0.5 and 1% disposable-glass fibers in ring and strip forms. The findings demonstrate that ring (RFs) and strip fibers (SFs) in green concrete reduce a beam's maximum load capacity (Pmax) by 31%, while RF and SF enhance green concrete beam flexural toughness by 8-20 times. Furthermore, the SF green concrete beams had 24% greater flexural toughness than RF beams at all ages. Finally, by improving the microstructure (by adding SCMs) and flexural behavior of marine concrete structures, in addition to increasing the load capacity and ductility of marine structures, the cracking and penetration of ions decreases; thus, the service life of the structures will increase.

Durability of concrete incorporating organic light-emitting diode (OLED) display waste as cement binder replacement.

The use of supplementary cementitious materials is customary in contemporary concretes. Different industrial by-products and waste materials have been investigated earlier for such applications. In this paper, the use of organic light-emitting diode glass (OLED) display waste as a partial replacement of cement binder in concretes has been explored. Concretes with 10%, 20%, and 30% substitution (by weight) of ordinary Portland cement (OPC) by OLED powder were developed, and the resulting mechanical properties and durability characteristics were evaluated. The results showed that OLED addition leads to strength improvement of up to 8% after 28-day age. Also, the resistance to chloride-ion penetration and sulfate attack improved considerably. The chloride binding capacity for the developed concretes was also investigated. It was demonstrated that the OLED powder incorporation is beneficial in improving the corrosion resistance of the modified concrete. The enhanced mechanical and durability properties of modified concrete point toward the excellent performance of OLED-incorporated concrete for improved service life. Incorporating OLED display waste in concrete as a partial cement replacement can also reduce environmental burden and concrete cost.

Review on the durability of eco-friendly engineering cementitious composite (ECC)

A comprehensive manual review of the use of slag and fly ash in engineered cement-based composites (ECBCs) was conducted. The extensive use of supplementary cementitious materials and integrated fibers in engineered cement-based composite (ECBCs) in seawater composite structures can help to enhance the durability of infrastructure in marine environments and minimize the extensive use of cement and CO2 emissions in the construction industry. This paper retrieved journal and review articles on slag/fly ash utilization in ECBCs from the Scopus database, mainly from 2015 to 2022, and performed an analysis using a suitable software tool. It also provided an up-to-date review of the literature on eco-friendly engineered cementitious composites’ (ECC) durability, with in-depth discussions on the effects of temperature fluctuation on ECCs, supplementary cementitious material, frost and salt corrosion resistance, pre-cracking, seawater resistance, and microstructural alteration. The durability of ECCs is closely related to the behaviors of the fiber distribution, matrix, and fiber-matrix interface under various environmental conditions. The main factors causing the deterioration of the engineering cement-based composites are fiber orientation and dispersion, frost resistance, corrosion, and alkaline environment. Fiber dispersion is mainly assumed to be highly homogeneous in theory, but in practice, due to the uneven dispersion of the fibers the property of each composite structure is not uniform. Further, among all issue associated with durability, sulfate salt attack considered as the most significant environmental deterioration process that affect the resilience of hydraulic structure. At last, it is necessary to conduct additional research on the durability of ECC under various environmental conditions to comprehend its behavior in the actual world. The experimental data currently available on the short-term durability of ECC fluctuate over time. Which indicates that the mechanisms for the long-term degradation of ECC under specific environmental conditions remain unknown.

Evaluating the efficiency of SCMs to avoid or mitigate ASR-induced expansion and deterioration through a multi-level assessment

It is widely accepted that Alkali-Silica Reaction (ASR)-induced expansion and deterioration may be prevented by the appropriate use of supplementary cementing materials (SCMs). Nevertheless, the correlation between microscopic/macroscopic damage degree and features of SCMs-made concrete is still not fully understood. Moreover, more research needs to be conducted to understand the impact of SCMs on the elastic properties of ASR-secondary products. This research presents the results of a multi-level assessment of ASR-induced damage development in concrete incorporating a wide range of reactive aggregates and SCMs at selected unrestrained expansion levels (i.e., 0.00 %, 0.05 %, 0.12 %, 0.20 % and 0.30 %). Furthermore, a thorough discussion is made on the damage generation and propagation at distinct locations of affected concrete: aggregate particles, ITZ and cement paste. Results indicate that higher volumes of SCMs can slightly change ASR damage development by lowering the formation of cracks in the cement paste and altering ASR reaction products' chemo-mechanical properties.

Role of Zn in aluminosilicate glasses used as supplementary cementitious materials

The cement industry relies on the use of supplementary cementitious materials (SCM) to lower the related CO2 emission. SCM are often amorphous materials containing minor elements, which is why it is important to study the impact of these materials on cement reactivity. Two calcium aluminosilicate glass series as model substances of SCM were synthesized and investigated. In both series Ca was partially replaced by Zn, Sr and Mg in different ratios. Moreover, four cement blends made with CEM I 52.5 R and aqueous solutions of Mg(NO3)2·6H2O, Zn(NO3)2·6H2O and Sr(NO3)2 were investigated. Zn retards the reactivity of both glasses and cements system. This retardation effect is suggested to be related both to the formation of the calcium hydroxozincate hydrate, which affects the portlandite formation and, thus, the pH of the system, and to the formation of surface complexes which retards the dissolution and so the reactivity of the glasses.

Ultra-high Performance Concrete as a Sustainable Structural Composite

The phenomenal strides in the modifications and the use of supplementary cementitious materials in conjunction with superplasticizers and discrete fiber distributions in concrete made it possible to arrive at the structural material termed as “ultra-high performance concretes” (UHPC) or its extension “ultra-high performance fiber reinforced concretes” (UHPFRC). Its development heralded a new era, opening new vistas in structural configurations and forms that could be a serious contender to structural steel constructions. Primarily, the chemistry and physics of concrete constituents and mixture design philosophy have not changed much, though the intricacies that are often neglected were effectively corrected from time to time. The use of materials ranging from the conventional to nanoparticles that could exhibit superior pozzolanic activity along with microfibers resulted in strengths well beyond 200 MPa. This opens up several avenues in structural configurations that are of high strength and durability. However, this isn’t a stipulation of replacing the present-day concrete in all structures with UHPC, but the key is to modulate the structural configurations to suit the needs of the particular application for ensuring sustainability in consonance with the capabilities of UHPC. The paper attempts to look at the possible avenues for such options in materials and structural forms to effectively assure sustainable construction alternates.

New Approach to Determine the Activity Concentration Index in Cements, Fly Ashes, and Slags on the Basis of Their Chemical Composition

The manufacture of Portland cement entails high energy and environmental costs, and various solutions have been implemented in recent years to mitigate this negative impact. These solutions include improvements in the manufacture of cement clinker or the use of supplementary cementitious materials (SCMs), such as fly ash (FA) or slag as a replacement for a portion of the clinker in cement. The incorporation of these SCMs in cement may increase its radiological content as they are naturally occurring radioactive materials (NORMs). The Activity Concentration Index (ACI) is a screening tool established in the European EURATOM Directive 2013/59 to determine the radiation protection suitability of a final construction material. The ACI is determined by the activity concentrations of 226Ra, 232Th and 40K, usually determined by gamma spectrometry. The methodology of gamma spectrometry is accurate and appropriate, but this technique is not available in all laboratories. For this reason, and taking into account that there is a relationship between the chemical and radiological composition of these building materials, a new approach is proposed to determine the radiological content of these materials from a chemical analysis such as X-ray fluorescence (XRF). In this paper, principal component analysis (PCA) is used to establish the relationships between the chemical composition and radiological content of cements, FAs, and slags of different natures. Through PCA it was possible to group the cements based on two variables: CaO content and Fe2O3-Al2O3-TiO2 content. A lower correlation was observed for the FAs and slags, as the sample scores were centered around the origin of the coordinates and showed greater dispersion than the cements. The clusters obtained in the HJ-Biplots allowed the determination, using multiple regression, of models relating the activity concentration of 226Ra, 232Th (212Pb), and 40K to the oxide percentages obtained for the three matrices studied. The models were validated using five cements, one FA and one slag with relative percentage deviations (RSD(%)) equal to or less than 30% for 89% of the activity concentrations and 100% of the ACI determined.

Effect of aluminum on the structure of synthetic alkali-silica gels

The use of supplementary cementitious materials, such as fly ash, ground-granulated blast furnace slag (GGBFS), or metakaolin, in cement and concrete, is known to increase the amount of aluminum in the system and enhance its resistance against the alkali-silica reaction (ASR). It is, however, not yet sufficiently understood to what extent aluminum affects the structure of alkali-silica gels and how such a potential incorporation of aluminum contributes additionally to the beneficial effect of aluminum on ASR. In this study, various alkali-silica gels with different aluminum content were synthesized and structurally characterized. The results show that aluminum can be incorporated into the alkali-silica gel structure in four- and six-fold coordination, thus leading to a structural change. The incorporation of aluminum may increase the connectivity and the degree of polymerization within the gel framework. Based on the results, a 3D structural model for an aluminum-containing alkali-silica gel was created.