Supplementary Cementitious Materials Research Articles

Shrinkage and Creep Properties of Low-Carbon Hybrid Cement.

Hybrid cements combine clinker with large amount of supplementary cementitious materials while utilizing hydration and alkali activation processes. This paper summarizes shrinkage and creep properties of industrially produced H-cement, containing only 20% of Portland clinker. In comparison with a reference cement CEM II/B-S 32.5 R, autogenous shrinkage is smaller after 7 days, and drying shrinkage is similar at similar times. A different capillary system of H-cement leads to faster water mass loss during drying. Basic and total creep of concrete remains in the standard deviation of B4 and EC2 creep models. The results demonstrate that shrinkage and creep properties of concrete made from H-cement have similar behavior as conventional structural concrete or high-volume fly ash concrete.

Geothermal Nano-SiO2 Waste as a Supplementary Cementitious Material for Concrete Exposed at High Critical Temperatures.

The partial replacement effect of Portland cement by geothermal nano-SiO2 waste (GNSW) for sustainable Portland-cement-based concrete was investigated to improve the properties of concrete exposed at high critical temperatures. Portland cement was partially replaced by 20 and 30 wt.% of GNSW. The partial replacement effect on Portland-cement-based concrete subjected to 350, 550, and 750 °C was evaluated by measuring the weight changes, ultrasonic pulse velocity, thermogravimetric and differential thermal analysis, X-ray diffraction, surface inspection, and scanning electron microscopy under residual conditions. The ultrasonic pulse velocity results showed that the GNSW specimens maintained suitable stability after being heated to 350 °C. The SEM analysis revealed a denser microstructure for the 20 wt.% of partial replacement of Portland cement by GNSW specimen compared to the reference concrete when exposed to temperatures up to 400 °C, maintaining stability in its microstructure. The weight losses were higher for the specimens with partial replacements of GNSW than the reference concrete at 550 °C, which can be attributed to the pozzolanic activity presented by the GNSW, which increases the amounts of CSH gel, leading to a much denser cementitious matrix, causing a higher weight loss compared to the reference concrete. GNSW is a viable supplementary cementitious material, enhancing thermal properties up to 400 °C due to its high pozzolanic activity and filler effect while offering environmental benefits by reducing industrial waste.

Report of RILEM TC 281-CCC: A critical review of the standardised testing methods to determine carbonation resistance of concrete

The chemical reaction between CO2 and a blended Portland cement concrete, referred to as carbonation, can lead to reduced performance, particularly when concrete is exposed to elevated levels of CO2 (i.e., accelerated carbonation conditions). When slight changes in concrete mix designs or testing conditions are adopted, conflicting carbonation results are often reported. The RILEM TC 281-CCC ‘Carbonation of Concrete with Supplementary Cementitious Materials’ has conducted a critical analysis of the standardised testing methodologies that are currently applied to determine carbonation resistance of concrete in different regions. There are at least 17 different standards or recommendations being actively used for this purpose, with significant differences in sample curing, pre-conditioning, carbonation exposure conditions, and methods used for determination of carbonation depth after exposure. These differences strongly influence the carbonation depths recorded and the carbonation coefficient values calculated. Considering the importance of accurately determining carbonation potential of concrete, not just for predicting their durability performance, but also for determining the amount of CO2 that concrete can re-absorb during or after its service life, it is imperative to recognise the applicability and limitations of the results obtained from different tests. This will enable researchers and practitioners to adopt the most appropriate testing methodologies to evaluate carbonation resistance, depending on the purpose of the conclusions derived from such testing (e. g. materials selection, service life prediction, CO2 capture potential).

Long-Term Performance of Mortars with Combined Incorporation of Ladle Furnace Slag and Metakaolin

Ladle furnace slag (LFS) is used as a supplementary cementitious material (SCM) due to its high calcium oxide (CaO) content. Its binding properties are enhanced in the presence of siliceous materials, such as metakaolin (MK), forming a ternary mixture that can directly replace ordinary Portland cement (OPC). However, despite this blend having already been evaluated in alkali-activated mixtures, knowledge about this mixture in situations of direct replacement of OPC by slag is still lacking. This study evaluates the synergistic effects of combining LFS and MK in cementitious mortars. Due to an insufficient hydration reaction observed in the short term, this study focuses on assessing the long-term performance of these mortars. Both the fresh and hardened states at 28 and 180 days are evaluated, and the resulting microstructural characteristics and constituent phases are also examined. After 180 days of curing, the mortar with MK exhibits superior binding activity compared to the results at 28 days. Although the nominal resistance does not show a clear advantage with the application of MK, a significant reduction in the porosity of the mortar is observed. Microstructural analysis indicates that the addition of MK increases the hydration compounds when mixed with LFS. Importantly, the sample containing MK and LFS showed a 42% reduction in cement consumption, highlighting the potential for resource efficiency. Thus, this study contributes to promoting a circular economy between the steelmaking and civil construction sectors.

Multi-objective optimization of seawater mixing in cement-based materials with supplementary cementitious materials using response surface methodology

Seawater instead of freshwater to produce concrete is an effective measure to save freshwater resources. However, the presence of harmful ions in seawater restricts its broader application. The incorporation of supplementary cementitious materials (SCMs) has the potential to significantly mitigate these adverse effects. Consequently, there is a growing interest in understanding the mechanisms by which SCMs function in seawater-mixed cementitious systems. In this study, a quadratic polynomial prediction model with the mechanical properties and dry shrinkage of the composite matrix as the response target was analyzed by the response surface method (RSM). Tests and analytical techniques elucidated the effects of metakaolin (MK) and ground granulated blast-furnace slag (GGBS) on the hydration process of the pastes after seawater mixing. The results revealed that the compressive strength and dry shrinkage were influenced by single-factor or multi-factor interactions. The optimal mix design (MK=20.2 % and GGBS=10.0 %) was experimentally validated, showing an absolute error of 1.5 %. The microstructural analysis indicated that MK and GGBS expedited essential pozzolanic reactions. Enhanced strength in mixtures before 3 d was attributed to cation exchange and initial flocculation. In the 28 d specimens, the increase in strength was related to the growth of Friedel’s salt crystals and C-(A)-S-H gels. Due to the presence of the C-(A)-S-H gels and AFm phases, chloride ions were efficiently immobilized, and the shrinkage of the matrix was reduced.

Recycling of waste glass powder: Effects on microstructure, mechanical properties and sustainability of seashell powder calcined sludge cement

The massive accumulation of waste seashells, waste sludge and waste glass not only occupies a large amount of land resources, leading to a shortage of land resources, but also causes serious soil-water-air composite pollution over a long period of time with the role of the surrounding environment, which poses a serious hazard to the ecological environment and public health. In this study, the effect patterns of waste glass powder (WGP) on the workability, mechanical properties, microstructure and carbon emission of seashell powder calcined sludge cement (SCSC) slurries prepared using waste sludge and waste seashells as supplementary cementitious materials in place of part of the cement clinker were investigated. The hydration process and microstructure of the materials were characterized by heat of hydration tests, thermogravimetry (TG-DTG), infrared Fourier transform (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the addition of WGP improved the fluidity of SCSC slurries and reduced the shear stress of SCSC slurries without changing the flow pattern of SCSC slurries, and all the slurries conformed to the power law model. The compressive strength of SCSC slurries increased by 25.26 % with 5 % WGP addition. The CO2 emissions per cubic meter of SCSC slurries were reduced by 4.43 %, 8.81 %, 13.5 % and 18.23 % for WGP additions of 5 %, 10 %, 15 % and 20 %, respectively. These results can provide a new way for the efficient resource utilization of waste seashells, waste sludge and waste glass, and reduce the CO2 emission during the cement production process, promoting the clean production of cement.

Evaluation of textile effluent treatment plant sludge as supplementary cementitious material in concrete using experimental and machine learning approaches

The growing demand for readymade garments is leading to the production of a large amount of textile effluent sludge (TES) from wastewater treatment plants, which is currently disposed of as backfill, causing land and groundwater contamination. This scenario has prompted researchers to explore the use of industrial waste, such as TES, as a supplementary cementitious material (SCM) to mitigate the carbon footprint of cement production. Therefore, this study aims to investigate the fresh, mechanical, non-destructive characteristics, and predictive modeling of mechanical strengths of TES-based concrete. Machine learning models, including random forest (RF) and artificial neural networks (ANN), were utilized to predict compressive and tensile strengths from various input variables. This study also evaluated the alkalinity, specific gravity, oxide content, and surface area of TES. The findings showed a pH of 9.4 and a CaO content of 33.3 %, indicating TES's potential as an SCM. The research further investigated the properties of concrete with 5–20 % cement-replaced TES, using a total binder content of 488.1 kg/m3 and a water-binder ratio of 0.32. The fresh state properties of the 5–15 % TES incorporated concrete produced normal density concrete, with a slump of 100 ± 20 mm, Kelly ball penetration of 45 ± 7 mm, a compaction factor of 0.92 ± 0.05, and a fresh density of 2464 ± 152 kg/m3. At 28 days, concrete with 15 % TES replacement showed a compressive strength of 25.6 MPa and a tensile strength of 2.88 MPa, achieving 76 % of the strength activity index and 72 % of the relative tensile strength. However, the 15 % TES concrete displayed a water permeability coefficient of 4.4 × 10−12 m/s and an electrical resistivity of 31.5 kΩ cm, compared to the control mix's 2.0 × 10−12 m/s and 37.7 kΩ cm. However, the hardened properties declined significantly after replacing 15 % of cement with TES. The mechanical properties were also estimated using ultra pulse velocity and rebound hammer tests, showing a coefficient of determination (R2) higher than 0.87. The RF model demonstrated superior performance with an R2 value of 0.8802 for compressive strength and 0.8518 for tensile strength, outperforming the ANN model's R2 values of 0.8126 and 0.695, respectively. Scanning electron microscopy confirmed the consistent development of hydration products in the TES-enhanced concrete samples.

Phase quantification analysis in cement-blended slag system with the PONKCS method

The Partial Or No Known Crystal Structure (PONKCS) method, an XRD analysis technique, is widely employed for phase quantification in cement-blended supplementary cementitious materials (SCMs). This study emphasized unsolved factors in applying this method to SCMs blends, including obtaining accurate SCM structure information, accounting for chemical composition variation, and identifying suitable C–S–H profiles. Ground granulated blast furnace slag was chosen as the representative SCM. Results show that four fundamental parameter (FP) type peaks were sufficient to index slag pseudo-structure without Pawley fitting. Slag weight fraction quantification was minimally impacted by slag pseudo-structures from slag with SiO2 content variations up to 3.03%. The C–S–H profile, with negligible clinker residue and a Lorentzian crystallite size of approximately 6.9 nm, was found suitable for PONKCS method application. Combining selective dissolution method with PONKCS method improved its accuracy. This study enhances improving quantification precision and extending the applications of PONKCS method in variable SCMs systems.

Recycling of Waste Granodiorite Powder as a Partial Cement Replacement Material in Ordinary Concrete

Abstract In this study, the effect of using waste granodiorite powder (WGP) as a cement replacement material in percentages ranging from 1 to 9% on various physical and mechanical properties of ordinary concrete was investigated. The resistance of produced concretes with WGP to the high temperature effects on the 28 days compressive strength were studied as well. Granodiorite is one of the well-known igneous rocks that have been used in previous research as a replacement for coarse or fine aggregates due to the hardness of its grains. However, rare studies have investigated its powder as a partial cement replacement material. Results showed the ability of investigated WGP with high surface area to act as a supplementary cementitious material that contributed to enhance the results of mechanical and physical properties of concrete. At traditional room temperature, the optimal replacement percentage was 7%, where the 28 days compressive and tensile strengths were improved by 28.3% and 17.3%, respectively. The optimal replacement ratio varied between 7 and 9% in the case of high temperatures, according to exposure time and temperature degree. Statistical and sensitivity analysis was conducted on 66 available compressive strength value represents all variables before and after elevated temperature exposure. While the regression equation showed good R2 value of 85.3%, sensitivity analysis indicated that compressive strength value is most sensitive to temperature, followed by WGP ratio and exposure time, with importance values of 56, 26, and 18 %, respectively. Results showed also that the setting times and consistency was decreased with increasing the replacement ratio with WGP, while the workability was slightly improved up to 5% replacement ratio. Furthermore, microstructure analysis showed that WGP can help to densify the concrete matrix due to its small size and ability to fill the interstitial voids in the concrete matrix.

Fundamentally understanding carbonation-induced corrosion of steel in environmentally friendly concretes

Reducing greenhouse gas emissions in concrete production is crucial to achieve sustainability goals. One of the primary solutions is employing environmentally friendly cements with lower clinker content, such as those containing supplementary cementitious materials. However, concretes produced with some of these cements are vulnerable to fast carbonation, which raises durability concerns regarding corrosion of the steel reinforcement. While traditional approaches focus on preventing concrete carbonation and corrosion initiation, evidence shows that corrosion rates of steel in carbonated concrete do not necessarily compromise durability. In this context, the fundamental understanding of the kinetics of carbonation-induced corrosion must be improved, considering the role of the concrete pore solution, pore structure, and moisture content, as discussed in this paper. Open questions and promising approaches to clarify them are also discussed. Based on this knowledge, corrosion propagation can be properly included in the service life design of reinforced concrete structures, reconciling the goals for both sustainable and durable structures.

Phase evolution and heavy metal solidification of cement desulphurized electrolytic manganese residue composite cementitious system under steam curing conditions based on thermodynamic simulation

The mechanical properties and microstructure of desulphurized electrolytic manganese (D-EMR) cement mortar under steam curing at 80 °C for 7 h and 7 days and standard curing for 3 days and 28 days were studied. The hydration products, microstructure and pore distribution were studied by Quantitative X-ray diffraction analysis (QXRD), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), thermogravimetric-differential thermal analysis (TG-DTA) and backscattered electron (BSE). At the same time, the evolution of hydration products with age and the existence form of heavy metals under different curing conditions were simulated by GEMS thermodynamics. The results show that steam curing can promote the hydration reaction of cement and the secondary hydration of D-EMR. With the extension of steam curing time, the mechanical properties of the early stage are significantly improved. At a D-EMR content of 15 %, the compressive strength of D-EMR cement mortar after steam curing for 7 days is 1.15 times that of the control group under the same conditions, and the content of calcium hydroxide (CH) is 65.91 % of the control group. Steam curing can significantly improve the degree of C3S hydration of cement clinker and the secondary hydration of D-EMR, and increase the degree of polymerization of hydrated calcium silicate (C-S-H) gel. In addition, thermodynamic simulation showed that when the pH value was greater than 7.5, Mn2+ was mainly stable in the form of Mn(OH)2, MnOOH and Mn3O4, and there was no leaching risk. This will provide theoretical support for the use of D-EMR as a new type of supplementary cementitious material (SCM).

Optimizing Amorphous Silica Recovery from Rice Husk Cultivated under Different Soils for Supplementary Cementitious Material Application

Optimizing Amorphous Silica Recovery from Rice Husk Cultivated under Different Soils for Supplementary Cementitious Material Application

Physico-Mechanical Properties of High-Strength Concrete Containing Supplementary Cementitious Materials Subjected to Acid Attack

Physico-Mechanical Properties of High-Strength Concrete Containing Supplementary Cementitious Materials Subjected to Acid Attack

Properties and hydration mechanism of slow-setting and expansive cement based on CFB ash and slag

Aiming at the problems of long construction time and easy shrinkage cracking of pavement base, the slow-setting and expansive cement (SEC) was prepared using circulating fluidized bed ash and slag (CFBA and CFBS), S95 ground granulated blast furnace slag (GGBFS), and silica fume (SF) as supplementary cementitious material in this paper. By adjusting the content of supplementary cementitious material, the ratio of ash and slag, the performance of SEC was evaluated by the indexes of water consumption of standard consistency, setting time, flexural and compressive strength. The hydration products of mortar samples and the influence mechanism were studied by means of XRD, TG-DTG, FTIR, and SEM-EDS. The results showed that when the SF content was 6 %, the compressive strength of the mortar specimens reached its maximum (35.19 MPa) at 28 days, which increased by 23.04 % compared to the control group. Meanwhile, the free calcium oxide and gypsum in CFBA reacted under alkaline conditions to form ettringite (AFt) and C-S-H gel, which caused the volume expansion of cement and led to a decrease in shrinkage within the cement system. SEC has higher mechanical properties and much smaller shrinkage cracks than ordinary cement. Therefore, replacing part of the cement by solid waste such as CFBS to prepare SEC to compensate for the shrinkage of the pavement base is an effective way to reduce pavement cracking.

Assessment of the Mechanical and Microstructural Performance of Waste Kraft Fibre Reinforced Cement Composite Incorporating Sustainable Eco-Friendly Additives

This study investigates the influence of limestone powder and metakaolin as sustainable eco-friendly additives on the properties and behavior of cementitious composite boards, with a focus on mechanical strength, physical properties, and microstructural characteristics. The experimental investigation begins with the characterization of the raw materials, including limestone powder, and metakaolin, to assess their particle sizes, elemental composition, and microstructural features. Cement composite boards were fabricated using an innovatively developed lab-simulated vacuum dewatering process, by varying the proportions of limestone powder and metakaolin as partial replacements for cement, along with waste kraft fibres as reinforcement. Mechanical testing was conducted to evaluate the flexural strength and behaviour of the composite boards according to standardized procedures. A microstructural analysis was performed using scanning electron microscopy (SEM) to examine the effect of additives on the cementitious matrix, fibrematrix interaction, and hydration products. The findings from the experimental study reveal insights into the influence of limestone powder and metakaolin on the mechanical properties and microstructure of waste kraft fibre-reinforced cement composite boards. Our analysis of the results shows that adding 9% limestone powder as partial cement replacement produces a 24% and 50% enhancement in flexural strength at 7 and 28 days of hydration, while that of metakaolin as partial cement replacement was optimum at 6% with an enhancement of 4% and 36%, respectively, at 7 and 28 days of hydration. The implications of these findings for the development of sustainable cementitious composite are discussed, including the potential benefits of using limestone powder and metakaolin as supplementary cementitious materials in waste kraft fibre-reinforced cement composite boards. Finally, recommendations for optimizing additive proportions are also provided to enhance the understanding and application of these materials in the construction and building industries.

Pozzolanic Potential of Calcined Clays at Medium Temperature as Supplementary Cementitious Material

Pozzolanic Potential of Calcined Clays at Medium Temperature as Supplementary Cementitious Material

Life Cycle Analysis Comparison of Stabilizing Materials for Expansive Soils

Expansive soils present significant challenges to infrastructure stability, necessitating the use of stabilizing materials. This study conducts a comprehensive life cycle analysis (LCA) research design to evaluate the environmental sustainability of various stabilizing materials for expansive soil. The study uses a quantitative analysis assessing materials, including cement, limestone, natural pozzolana, iron ore tailings, and geopolymers (especially alkali-activated slag cement). The method involves a comprehensive LCA, considering phases from raw material extraction through production, use, and disposal. The analysis reveals distinct differences in environmental impact. Cement and lime, common stabilizers, show a high carbon footprint. Natural pozzolana and iron ore tailings exhibit potential as supplementary cementitious materials with reduced environmental impact. Geopolymers, particularly alkali-activated slag cement, offer promising alternatives with lower carbon emissions. This research contributes insights into sustainable geotechnical practices, guiding material selection aligned with environmental goals for effective expansive soil stabilization.

Performance assessment of pervious concrete incorporated with calcium silicate hydrates (C-S-H) cultivated on rice husk ash substrates – A trend surface analysis interpretation

Pervious concrete is a special type of concrete designed to allow water to pass through by omitting fine aggregates from the mix, or by using special techniques to create interconnected voids within the concrete. The current study investigates a novel method of cultivating calcium silicate hydrate (CSH) precipitates on a supplementary cementitious material (SCM), Rice husk ash (RHA), substrate and integrating the RHA substrate into pervious concrete to improve mechanical and durability properties. Scanning electron microscopy (SEM) images indicates the formation of precipitates of calcium silicate hydrates on the surface of RHA particles. The silica to RHA (Si/RHA) ratio and curing age of pervious concrete specimens serve as focal points for assessing the mechanical characteristics. Trend surface analysis is utilized to analyse the results, using a polynomial equation to identify underlying trends or patterns within the dataset. The analysis reveals that the Si/RHA ratio and curing days have minimal impact on permeability, while an increase in RHA substrate volume reduces permeability, indicating microstructure densification rather than macro void filling. For compressive strength, the results show that higher Si/RHA ratios and longer curing times positively correlate with strength, with accelerated hydration suggested by the quadratic coefficients of curing age. In terms of split tensile strength, increasing substrate volume enhances strength, while linear terms of Si/RHA ratio and curing age also exhibit positive correlations, although quadratic terms indicate minimal change in strength gain rates. Flexural strength correlates positively with both Si/RHA ratio and curing age, while abrasion resistance negatively correlates with Si/RHA ratio and substrate volume, suggesting enhanced resistance with increased values. CSH seeds grown on RHA enhances the microstructure of concrete, resulting in a denser material facilitating rapid strength development and improved durability.

Mechanical properties of geopolymer concrete incorporating supplementary cementitious materials as binding agents

This research investigates the environmental impact of cement production by exploring eco-friendly geopolymer binders as alternatives. Geopolymer concrete, developed using silica and alumina-rich precursors such as pozzolanic materials, achieves high compressive strength, up to 43.6 N/mm2 with a 16 M concentration and integrated steel fibers. Utilizing manual mixing and industrial by-products, the study pioneers cast-in-situ geopolymers with innovative curing techniques. The paper presents experimental results on the engineering properties of geopolymer concretes of 40 MPa, cured at 100 °C and 60 °C. The study systematically varies binder content, examining proportions of fly ash, GGBS, metakaolin, and silica fume, along with different mix ratios and molar concentrations. Key findings include increased compressive strength with higher NaOH concentration, peaking at 35.2 N/mm2 and 34.22 N/mm2 for 14 M mixes at 7 and 28 days, and 40.29 N/mm2 for 16 M mixes at 7 days. Optimal results were observed at higher curing temperatures, especially with 14 M and 16 M compositions at 100 °C. The study recommends mechanized mixing for efficiency and calls for further investigation into the microstructure and chemistry of geopolymers to advance sustainable construction practices. This research represents a significant step towards eco-conscious building materials, reducing the environmental impact of the construction industry.

Mineralogical Characterization and Geochemical Signatures of Supergene Kaolinitic Clay Deposits: Insight of Ropp Complex Kaolins, Northcentral Nigeria

This study presents the chemical and mineralogical composition of clay deposits and associated rock types within the Ropp Complex in order to assess the influence of parent lithology on the kaolinization, genesis, and utility of the deposit. Representative kaolin samples from E horizons of the weathering profiles and their bedrocks were collected from six sites in the Ropp Complex. Clay mineralogy was determined via the XRD technique, while a geochemical analysis was conducted using XRF, SEM coupled with EDS, and ICP-MS. The results showed that all kaolins dominantly contain kaolinite with a content of 77%–98% except for the AS1 kaolin with only minor kaolinite (20%) but mainly illite (65%). The notably lower crystallinity of kaolinite (HI value of 0.53–1.1) as well as its markedly small grain size is consistent with the formation of kaolinite from intensive chemical weathering of igneous rocks. The AS1 kaolin was probably formed from hydrothermal alteration in the burial stage due to the heating of groundwater by the late volcanism. Mobile trace elements (Sr, Ba, and Eu) exhibited a depletion trend, while immobile elements (Hf, Ta, Th) showed enrichment. The relatively more zirconium in kaolins implies the formation of low-temperature kaolinization. The notably high kaolinite content, accompanied by reasonable levels of Fe2O3 and TiO2, signifies a medium-grade quality. Furthermore, chondrite-normalized rare earth element (REE) patterns exhibit congruent trends in rocks and kaolin samples, indicating a relative enrichment in light rare earth elements (LREEs) alongside a discernible negative Eu anomaly. The abundant kaolinite and silicon–aluminum composition make the kaolins suitable for refractories, pharmaceutics, cosmetics, and supplementary cementitious material (SCM).