Supplementary Cementitious Materials Replacement Research Articles

The Effects of Waste Ceramic Powders and Waste Glass Powders on the Rheological and Mechanical Properties of Self-Compacting Concrete

Two key axes dominated this experimental research. The first was developing self-compacting concrete from ceramic waste powder (CWP) and glass waste powder (GWP), which met and followed the recommended European specification and guidelines for self-compacting concrete (EFNARC) standards. The second axis indicated the self-compacting concrete's rheological and mechanical performance. Sixteen different mixtures were produced using supplementary cementitious materials (SCMs) to replace cement partially. The replacement levels of SCMs were 5%, 10%, and 15% (by weight of cement), divided into three series: Series A (containing ceramic waste powder), Series B (containing glass waste powder), and Series C (containing combinations of ceramic waste powder and glass waste powder). The SCC rheological properties for all mixtures with different levels of SCMs replacement in the mixture gradually decreased as the substitution ratios increased. The reduction in flowability for substitution, ranging from 5% to 35%, was approximately 0% to 12%, respectively. However, the reduction was insignificant; the fresh properties remained within the limits specified by EFNARC. Regarding the mechanical properties, at an early age, the strength of mixtures decreased with increasing alternative ratios. However, after 90 days, the strength increased by about 11% and 9% of the compressive and flexural strengths, respectively, over the control mix, indicating that SCMs improve the concrete strength over time and are suitable to contribute to an eco-friendly concrete industry without compromising strength.

Durability of Ternary Blended Concrete Incorporating Rice Husk Ash and Calcined Clay

Research on the combined substitution of supplementary cementitious materials (SCMs) has already demonstrated that it might be one of the few viable options to produce low-carbon concrete at scale. This paper presents an experimental investigation on the performance and durability of rice husk ash (RHA) and calcined clay (CC) in ternary blended concrete exposed to chloride attacks under wet/dry cycles. Portland cement (PC) was replaced by RHA and CC up to 50% by weight to produce low-carbon concrete. Samples were subjected to wet/dry cycles in 3.5% NaCl water, with mineralogical composition and microstructure development before and after exposure analysed by TGA-DSC, MIP, XRD, and SEM. The durability of the concrete against wet/dry cycles was investigated in terms of compressive strength, water absorption, open porosity, density, thermal conductivity, and electrical resistivity. The results showed that concrete mixes with CC and RHA up to 60% exhibited an increase of 33% in compressive strength, followed by minimal changes in water absorption. While a decrease in electrical resistivity was measured in all samples with RHA and CC, increasing the CC content to 50% resulted in improved resistance to chloride penetration. Increasing the CC content resulted in a more refined microstructure, with an overall decrease in porosity of up to 32% compared to the control series. While RHA alone did not contribute to significant improvements after wet/dry cycles, the combined substitution of RHA and CC at SCM replacement levels of 60% showed an overall improvement in hardened properties and durability. This investigation provides valuable insights into the long-term performance and strength of innovative low-carbon concrete.

Modelling and optimization of multiple replacement of supplementary cementitious materials for cement composite by response surface method

Supplementary cementitious materials are beneficial in improving performance and lessening the cement consumption with highly lessening CO2 emission. Many researchers used blast furnace slag, bentonite, and active limestone separately or two of them together to improve the performance of cementing materials, however, it is not well known how all react together in cement composite materials. So, the present study used modeling and optimizing the replacement of blast furnace slag, raw bentonite, and active limestone each by the doses of 0 to 20% to maximize strength and minimize the fresh bulk density of cementing materials by central composite design-response surface method (CCD-RSM). The results found, the employment of blast furnace slag, bentonite, and active limestone in the cement composite materials generally lessens the early strength compared to the control mixture. However, the replacement of blast furnace slag and active limestone by 20% significantly improves the 28-days compressive strength while employing raw bentonite by 20% reduced compressive strength by 6.45% compared to the control mixture. However, blending raw bentonite with active limestone by half improved the compressive strength. Besides these, the substitution of bentonite and active limestone reduces the fresh bulk density and flexural strength than the control mixture. Generally, the study optimized depending on the criteria of maximizing strength and minimizing fresh density and found the mix design replacement of blast furnace slag 1.01%, raw bentonite 5.30%, and active limestone 20% that improves 28 days compressive strength simultaneously reduces fresh bulk density in addition to replacing more than 54 different optimized design mix results.

Activity quantification and assessment of recycled concrete powder based on the contributions of the dilution effect, physical effect and chemical effect

Improving the utilization of recycled concrete powder (RCP) is crucial for optimizing the resource utilization of construction and demolition waste (CDW). The assessment of RCP activity is essential for its extended applications. However, regarding RCP with complex compositions and high content of inert materials, the current standard activity index method fails to provide a comprehensive and efficient assessment. This study aimed to elucidate the activity of RCP, correlate the particle characteristics of RCP with its activity, and propose activity quantification and characterization methods applicable to RCP from different sources. Specifically, the type, particle size distribution, and replacement of supplementary cementitious materials were investigated to categorize their influence as dilution, physical and chemical effects on mortar strength. The relationship between the particle size distribution, replacement, and rehydration properties of RCP and these effects was explored. The results showed that the contributions of dilution, physical and chemical effects of the RCP to the activity could be effectively predicted by their fundamental properties, which were also verified by the Random Forest model and the empirical model for accuracy and rationality. Finally, the activity evaluation method based on the fundamental properties of RCP is proposed. The study findings present an efficient means for accessing the activity of RCP from different sources, thereby facilitating their better applications and enhancing the utilization of CDW.

A new supplementary cementitious material: Walnut shell ash

Partial replacement of supplementary cementitious materials (SCMs) for cement is an effective way to boost the long-lasting sustainability of cement-based construction. However, traditionally used SCMs are facing the problem of low availability. In response, a novel SCM – Walnut shell ash (WSA) – was identified. To validate the feasibility of using WSA as an SCM, frattini tests for pozzolanicity, setting time tests for workability, and compression and flexural strength tests for mechanical properties were conducted. The experimental results have demonstrated that cement paste incorporating no more than 20 % WSA possesses satisfactory pozzolanicity and setting times. Furthermore, this mix achieves an optimal long-term compressive strength of 83 MPa, which it maintains for up to a year. To reveal the hidden mechanisms behind the mechanical performance changes, microscopic and nanoscopic techniques, including scanning electron microscope and 29Si nuclear magnetic resonance, were conducted. Microscopically, the strength enhancement originates from the generation of fibrous C–S–H gel, high hydration level, and low porosity in cement paste with 20 % WSA. Nanoscopically, the changes in mechanical performance result from the shift of polymerization degree and the substitution of Al–Si in cement hydrates. These findings enrich the understanding of the role of WSA in manufacturing sustainable and durable cementitious materials that benefit both biomass waste management and cement industry decarbonization. In addition, the proposed multiscale assessment framework can be a tangible paradigm for screening new SCMs, thereby extending the horizon of sustainable materials research.

Carbon footprint of reinforced concrete columns with and without supplementary cementitious materials

The construction sector consumes a large quantity of natural resources and generates a great deal of carbon dioxide emissions and wastes, affecting its sustainability. Replacing Portland cement with supplementary cementitious materials (SCM) could reduce the environmental impact. This paper examines the carbon footprint of reinforced concrete columns. It focuses on the influence of increasing the steel cross-section and reducing the clinker factor by replacing Portland cement with SCM. Eighteen concrete mixtures were selected and classified according to the specified compressive strength at 28 days of curing using binary and ternary blended cements. Columns were designed consisting of such concretes and employing different reinforcing steel cross-sections. The life cycle assessment was conducted on ISO 14040 standard. The embodied carbon dioxide (ECO2) of the reinforced concrete columns was determined. The results show that the higher the compressive strength of concrete, the lower the carbon footprint of the columns. Concretes with a high volume of SCM replacement and low compressive strength at 28 days do not show the lowest carbon footprint since it requires a greater volume of material to withstand the bearing capacity. The carbon footprint of the columns increases as the steel section increases. Furthermore, increasing the compressive strength of concrete is less beneficial for reducing the carbon footprint of the column when the steel cross-section is increased. Portland cement is the component material of concrete that contributes the most to the concrete carbon footprint, and steel has the highest ECO2/tonne. Replacing Portland cement with SCM reduces ECO2 at one point of the life cycle and may increase the material volume and ECO2 at another. The lowest carbon footprint of compressed reinforced concrete elements is achieved for the higher-strength concretes and the minimum steel cross-section.

Exploring machine learning to predict the pore solution composition of hardened cementitious systems

This study explores machine learning (ML) algorithms to predict the pore solution composition of hardened cementitious systems produced with Portland cement (PC) and supplementary cementitious materials (SCM). Literature data on pore solution compositions for different cementitious systems was collected and compiled in a comprehensive database containing >300 entries with >80 features. Improved decision tree regressors were applied to the database. It was found that the trained ML models were capable of predicting OH−, Na+, and K+ concentrations reliably (75–90 % of predicted systems within 25 % relative error). Ca2+ and sulfur species had lower prediction accuracy. The silica content of SCM, the alkalis content of PC, and the SCM replacement level were identified as important features in determining the ion concentrations. When applied to this database, ML performed better than conventional, theory-based prediction models. Thus, ML models are a promising, complementary technique to determine pore solution compositions.

Investigation of different paper mill ashes as potential supplementary cementitious materials

Integrating supplementary cementitious materials (SCMs) in cement-based construction materials is a key strategy for reducing environmental burdens and the greenhouse gas emissions related to cement production. Supplies of commonly applied SCMs such as fly ash and blast furnace slag are becoming limited, and therefore the search for alternative SCMs is of high significance. The present research investigates the viability of four paper mill ashes collected at different stages from the same incineration process as SCMs at different cement substitution rates (5–30 wt%). The ashes were first classified depending on their mineralogical and chemical composition, and their contribution to strength development of the prepared mortars is examined. Furthermore, the effects of the ashes on the hydration kinetics and the fresh and hardened properties of the prepared mortars were studied. The obtained results showed that a high level of SCM replacement accelerates the early hydration reactions and decreases the setting time. In addition, the incorporation of paper mill ashes increased the bound water depending on the ash type and resulted in strength development of the mortars at low replacement percentages (5–10 wt%). This study shows that the ashes belonging to type C medium acid based on bio ash classification could be incorporated as SCMs at a maximum level of 10 wt%, while those corresponding to type C low acid could be used up to 20–30 wt%. • Four paper mill ashes were characterized and classified based on the chemical and mineralogical composition then used as SCM. • Paper mill ashes corresponding to type C low acid based on bioash classification could be used as SCMs up to 20–30 wt%. • The addition rate of paper mill ashes controls the fresh properties and strength development of the mortars.

Durability of concretes exposed to high concentrations of CaCl2 and MgCl2.

In cold regions, calcium and magnesium chloride deicing salts damage concrete pavements due to the formation of certain deleterious chemical phases, including calcium oxychloride. While there is much research at a cement paste-scale, damage in concrete has been less studied. In this study, we evaluate concrete damage due to calcium and magnesium chloride and explain the roles of supplementary cementitious materials (SCM) replacement level, air entrainment, salt type, and exposure conditions in damage development. Various non-destructive test methods including bulk resistivity, mass change, and visual damage assessment were used to monitor the damage over time. Damage was reduced as the SCM replacement level and air content increased, regardless of exposure conditions. Bulk resistivity and visual assessment were promising indicators of damage. The product of 91-day bulk resistivity and the air content predicted concrete performance when exposed to concentrated deicing salts. Based on several criteria, mixtures with 20% fly ash replacement level or 35% slag mitigated damage significantly when the air content was greater than 5% by concrete volume. Damage mitigation mechanisms of SCM and air are discussed.Supplementary InformationThe online version contains supplementary material available at 10.1617/s11527-022-01992-y.

Compressive Strength and Chloride Ion Permeability Test of Concrete Incorporating Fly Ash and GGBS with Diverse Water Binder Ratio

In this study conventional concrete of M40 grade developed with diverse water binder ratio and fixed optimum dosage of 30% mineral admixture fly ash and GGBS with weight of cement .Compression test has been conducted on cube samples and Rapid Chloride permeability test (RCPT) are conducted on cylindrical specimens to acknowledge durability parameter. Compression test results has been enhanced with replacement of supplementary cementitious materials and chloride ion permeability has been reduced with substitution of fly ash and GGBS .incremental of water binder ratio also reduce the permeability value however compression value increased

Strength and Microstructural Investigation of Quaternary Blended High-Strength Concrete

This research focuses on studying the effect of different supplementary cementitious materials (SCMs) such as waste ceramic powder (WCP), lime powder (LP), and ground granulated blast furnace slag (GGBS) in combination on strength characteristics and microstructure of quaternary blended high-strength concrete. To achieve the aims of the study, necessary physical and chemical composition tests were done for the raw materials. Then, mixes were designed into control mix with 100% Ordinary Portland Cement (OPC) and experimental mixes containing 30%, 40%, 50%, and 60% of GGBS, WCP, and LP in combination. Tests were conducted during casting and at curing ages of 7 and 28 days. Accordingly, the control mix which is concrete grade 50 (C-50) as per American Concrete Institute (ACI) mix design is used as a reference for comparison of test results with those specimens produced by partial replacement of SCMs. The characterizations of high-strength concrete are done using consistency, setting time, workability, compressive strength, flexural strength, and morphological tests. The optimum percentage replacement is 50% OPC replacement by 30% GGBS + 10% WCP + 10% LP. Based on the experimental investigations, the workability increases as the replacement level of SCMs increases from 30% to 60% by weight. Compressive strength and flexural strength results increase up to 11.41% and 20% when the percentage replacement increases from 30% to 50% of SCMs replacement at 28 days of curing time, respectively. There are also improvement in the microstructure and significant cost saving due to replacing OPC partially with SCMs with proportions mentioned above. Therefore, the practice of utilizing increased percentage of SCMs in quaternary blend in concrete can be beneficial for the construction industry and sustainability without compromising the quality of the concrete product.

Evaluation of the chemical index model for predicting supplementary cementitious material dosage to prevent the alkali-silica reaction in concrete

This study investigates the chemical index model effectiveness in predicting the minimum replacement of several types of Supplementary Cementitious Materials (SCMs) to mitigate the potential Alkali-Silica Reaction (ASR) in concrete. The experimental program results evaluating four natural aggregates (AF1, AF2, AF3, and AF4) and two Recycled Concrete Aggregates (RCA1 and RCA2), as presented here, were used in the model predictions. The SCMs used in this study consisted of fly ash class C (FA1), fly ash class F (FA2), ground granulated blast-furnace slag (SL), and silica fume (SF). For each SCMs, three levels of Portland cement replacements were used in the production of mortar bars: 15%-20%-25% for FA1-FA2; 20%-40%-60% for SL; and 5%-8%-10% for SF. The natural aggregates were tested according to the ASTM C1260 accelerated mortar bar test. For the RCA, an alternative preparation procedure was applied in the experimental phase to eliminate variability in the results given the RCA's high absorption.Further testing was then implemented for the aggregates classified as potentially reactive by evaluating different SCMs replacement levels to mitigate ASR using the accelerated mortar bar method, following the ASTM C1567. A Monte Carlo simulation was conducted to evaluate the chemical index prediction uncertainty, based on the model inputs statistical variation. The SCMs evaluated in this investigation were effective in mitigating ASR while used in sufficient proportion. The most effective SCMs in reducing ASR was silica fume, with a 10% replacement of Portland cement's weight, fly ash class F was next (15–25%), and finally ground granulated blast-furnace slag (40–60%). The chemical index has proven to give good results when predicting the minimum replacement of supplementary cementitious materials required to suppress ASR based on its chemical composition.

Linking reactivity test outputs to properties of cementitious pastes made with supplementary cementitious materials

Recently developed reactivity tests for supplementary cementitious materials (SCMs) have shown the ability to differentiate between inert and reactive materials. Two promising SCM reactivity tests were used to study ten different SCMs. The first method involves quantifying the heat release, bound water, and calcium hydroxide consumption of SCMs in a simulated pore solution (modified R3 test), and the second method is a lime strength test that quantifies lime mortar strength development. Tests on cementitious pastes with a 20% SCM replacement level were conducted to determine heat release, calcium hydroxide content, bound water, compressive strength, and bulk resistivity for 35 days. Moderate correlations between the modified R3 heat release at 10 days and 1 day and between modified R3 heat release and bound water were shown, which suggests the possibility of reducing test duration and using bound water, instead of the heat release. The calcium hydroxide consumption measured from the modified R3 test correlates strongly with CaO content in the SCM and moderately to paste bulk resistivity at 35 days, demonstrating the fundamental importance of measuring calcium hydroxide consumption. Correlations between modified R3 heat release and bound water and most other paste properties were generally poor, presumably because of the high acceleration in the modified R3 tests. The compressive strength measured from the lime strength test showed moderate to strong correlation to heat release, calcium hydroxide content, bound water, and bulk resistivity of cementitious paste at 1–35 days. The fundamental importance of these reactivity tests is therefore clearly validated.

Development of sustainable self-compacting concrete using recycled concrete aggregate and fly ash, slag, silica fume

A sustainable Self-Compacting Concrete (SCC) was proposed by replacing natural aggregates with recycled coarse aggregates (RCAs) and cement with supplementary cementitious materials (SCMs). A total of 23 SCC mixes, including binary, ternary and quaternary mixes were prepared with three water to binder ratios (0.35, 0.40, and 0.45) and two RCA replacement levels (50%, 100%) as well as two SCM replacement levels (50%, 75%). The fresh state properties, in terms of filling ability, passing ability, viscosity and segregation resistance were studied as well as the hardened state properties. The effect of RCAs and SCMs on the fresh and hardened state properties of SCC mixes was analyzed as well as the influence of using a combination of fly ash, slag and/or silica fume. The test results indicate that SCC incorporating RCAs and SCMs exhibited superior workability and comparable compressive strength and the combination of fly ash, slag and silica fume can compensate for the detrimental effect of RCAs and increase the compressive strength. Thus, the content of RCAs and SCMs can be maximised by using a combination of fly ash, slag and silica fume, which will optimise the sustainability aspect of SCC mixes by minimising cement and nonrenewable natural resources content.

Impact of physical and physicochemical properties of supplementary cementitious materials on structural build-up of cement-based pastes

Understanding the structural build-up is relevant to new technologies that require workability control, such as 3D concrete printing. The effect of supplementary cementitious materials (SCM) particle size (i.e. specific surface area and particle density) and physicochemical behavior (i.e., chemical reactivity and surface potential) and their interactions with the primary mixture parameters (i.e., water to cement ratio, cement reactivity and SCM replacement) on the structural build up of cementitious paste were studied. The growth of static yield stress with time was used to characterize the structural build up of cementitious pastes. Calorimetric curves were also measured. Results showed that the effect of SCM on structural build up is governed by their particle density and surface potential. The structural build up can be raised by increasing the number of contact points (governed by particle density and w/c), the growth rate of C-S-H bridges (governed by surface potential), or the reactivity of cement.

Strength Behaviour of Blended Self Cured Concrete made with Cement by partial replacement of Supplementary Cementitious Materials (SCM’s)

At Present Water is the most essential material in the modern era. In general, Curing of concrete is retaining moisture in the concrete for the period of early ages precisely within 28 days of placing concrete, to improve anticipated properties. Appropriate curing of concrete is crucial to obtain extreme durability, especially if the concrete is exposed to serve conditions where the surface will be imperiled to excessive wear, assertive solutions, and severe environmental circumstances. Poor curing practices adversely affect the desirable properties of concrete which constitutes a major influence on the permeability of a given concrete.Unpredicted shrinkage and temperature cracks be able to diminish the strength, durability and serviceability properties of the concrete. The surface zone will be critically damaged by increased permeability expected to poor curing. The improvement of shrinkage in concrete is proportionate to the rate of moisture loss in concrete. When concrete is correctly cured, water preserved in concrete would facilitate continuous hydration and enhancement of enough compressive and tensile strength to withstand contraction stresses. The incessant development of strength reduces shrinkage and initial cracks or micro-cracks. As a part of this study, SCMs like Flyash (FA), Ground Granulated furnace Slag (GGBS), Silica Fume (SF). Concrete may be a mixture of cement, aggregates and water with / without suitable admixtures with self-curing agents and various proportions, which resulted in the early strength to reduce the autogenous shrinkage and increase in durability.

Long-term mechanical and shrinkage properties of cementitious grouts for structural repair

Grouts have numerous applications in construction industry such as joint sealing, structural repair, and connections in precast elements. They are particularly favoured in rehabilitation of structures due to penetrability and convenience of application. Grouts for repair applications typically require high-performance properties such as rapid strength development and superior shrinkage characteristics. Sometimes industrial by-products referred as supplementary cementitious materials (SCM) are used with neat cement due to their capabilities to provide binding properties at delayed stage. Micro silica, fly ash and metakaolin are such SCMs, those can modify and improve properties of cement products. This study aims at investigating long-term mass loss and linear shrinkage along with long-term compressive and flexural strength for grouts produced from ultrafine cement and SCMs. A series of mixtures were formulated to observe the effect of SCMs on these grout properties. Properties were determined after 365 days of curing at 23oC and 55% relative humidity. The effect of SCMs on the properties are characterised by statistical models. Response surfaces were constructed to quantify these properties in relation to SCMs replacement. The results suggested that shrinkage was reduced by metakaolin, while micro silica and fly ash had positive effects on compressive and flexural strength, respectively.

Mixture Design Approach to optimize the rheological properties of the material used in 3D cementitious material printing

The Mixture Design Approach was adopted in this report to formulate the correlation between the cementitious material components and material rheological properties (static yield stress, dynamic yield stress) and identify the optimal material composition to get a balance between high cementitious material static yield stress and low dynamic yield stress. Cement, sand, fly ash, water and silica fume were blended to form the test materials according to mixture design and the responses (static yield stress, dynamic yield stress) were logged by the Viskomat. Two non-linear mathematic models for responses were experimentally validated based on the ANOVA (Analysis of Variance) analysis. The results indicated that the optimal replacement of supplementary cementitious materials can be determined according to static yield stress and dynamic yield stress based on the ternary components. The Mixture Design Approach is then proven to be an effective method of optimizing the cementitious materials used in 3D cementitious material printing (3DCMP) application.

Mixture design of concrete using simplex centroid design method

The primary goal of concrete mixture design is to strike a balance among workability, compressive strength, durability, economic efficiency and sustainability. In this paper, for a given strength grade, the optimum paste consisting of cement, fly ash and slag, and the optimum ratio among paste, fine aggregate and coarse aggregate were optimized using the simplex centroid design method based on rheological properties. Results showed that the optimum content of total cementitious materials in concrete could be obtained according to the relationships between the workability, yield stress, plastic viscosity and the paste volume fraction. The optimum replacement of supplementary cementitious materials could be determined according to the rheological properties and compressive strength of concrete with ternary cementitious components. It is an effective way to optimize the mixture design of concrete based on the rheological properties using the simplex centroid design method.

Supplementary cementitious materials to mitigate greenhouse gas emissions from concrete: can there be too much of a good thing?

Abstract Among the many possible strategies for reducing anthropogenic greenhouse gas (GHG) emissions is reduction of emissions associated with the production of concrete, which is responsible for 8–9% of global anthropognic GHG emissions. Using supplementary cementitious materials (SCMs) in concrete to offset demand for clinker in cement is a commonly proposed method to cut GHG emissions from concrete production. The most commonly used SCMs are industrial byproducts, such as fly ash and ground granulated blast furnace slag, but the extent to which these SCMs should be used in individual concrete mixtures is not well examined. This research examines the contribution of fly ash and ground granulated blast furnace slag to compressive strength, the role of allocation in the assessment of environmental impacts, and the impacts of transportation. Quantitative analyses are developed using environmental impact assessments and comparisons are drawn based on changes in GHG emissions for concrete production. The findings of this research show that these three factors can outweigh benefits associated with use of SCMs: depending on SCM type and use of allocation or changes in transportation, high levels of SCM replacement do not consistently result in lower GHG emissions for the production of concrete per unit strength. Limited supplies of these popular byproduct SCMs amplifies the necessity to efficiently use these materials. Within the limitations of this study, this work shows strategic use of SCMs to cut GHG emissions based on regional availability and based on application should be a priority.