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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Construction and Building Materials".

Deadline for manuscript submissions: closed (10 November 2024) | Viewed by 18871

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Special Issue Editor

Dr. Jonathan Oti

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Faculty of Computing, School of Engineering, Engineering and Science, University of South Wales, Pontypridd CF37 1DL, UK
Interests: low-carbon technology; sustainability; cement; concrete; bricks; blocks; geopolymers; soil stabilization; suppression of expansion; freezing and thawing; waste utilization; microstructural analysis; life cycle inventory; ground granulated blastfurnace slag; pulverized fuel ash; silica fume
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Dear Colleagues,

The production of cement-based construction and building is set to continue increasing as demand worldwide continues to increase, especially where emerging economies need cement-based materials for housing and infrastructure. In the context of increased regulations to reduce the carbon footprint of the construction industry and to limit greenhouse gas emission associated with cement production, this Special Issue will bring together cutting-edge and economically viable new construction and building materials made from alternative cement replacement materials, even though construction cost and technical barriers, such as insufficient durability data and differentiation for different applications, still hinder the global promotion and utilization of new sustainable construction and building materials development. Within the scope of this research topic, emphasis will be focused on fundamental, experimental, numerical, validation, and application research, inducing proven results in state-of-the-art solutions for sustainable construction. Various single-focused approaches or multidisciplinary combinations are also expected to add to the Special Issue. In general, traditionally, the most widely used construction and building materials are produced with Portland cement (PC); however, there have been some sustainability concerns as it is expensive to make and transport, and the manufacturing process is environmentally destructive, accounting for about 8% of global CO₂ emissions. This has led to the use of several new sustainable alternative materials for PC replacement with significant benefits, to mitigate the environmental damage caused by PC. This Special Issue will also bring together techniques and concepts from various distinct works, to examine, explore, and critically engage with issues and advances in sustainable construction and building materials, that can provide several environmental benefits but also can lead to cost-effective products. The papers collected in this Special Issue can help researchers and practicing engineers, construction and building material scientists, low carbon and sustainability practitioners to find more advanced techniques and alternative approaches towards sustainable construction and building material development.

Dr. Jonathan Oti
Guest Editor

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Keywords

sustainable materials
building materials
durability
recycled materials
cement
concrete
stabilization
life-cycle assessment
bricks
block
mortar
geo-polymer
steel
timber
green building materials
eco-friendly materials
nano- and fiber composites
ceramics
limes
PFA
GGBS

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Functional Cement-Based Composites for Civil Engineering (3rd Edition) in Materials (2 articles)

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Research

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22 pages, 12048 KiB

Open AccessArticle

Experimental Study on Seismic Performance of Dovetail Profiled Steel Concrete Composite Shear Walls with Self-Tapping Screw Connections

by Zhenfeng Huang, Youwen Tan, Zheng Zhong, Sumei Zhang, Lanhui Guo and Yunhe Wang

Materials 2025, 18(1), 49; https://doi.org/10.3390/ma18010049 - 26 Dec 2024

Viewed by 566

Abstract

To achieve the assembled connection between dovetail profiled steel sheets and the boundary members in dovetail profiled steel concrete composite shear walls (DPSCWs), self-tapping screws were employed. Three DPSCW specimens connected with self-tapping screws were tested under combined axial and cyclic lateral loads to evaluate their hysteretic response, focusing on the influence of the number of self-tapping screws and the axial compression ratio. The self-tapping screw-connected DPSCWs exhibited a mixed failure mode, characterized by shear failure of the profiled steel sheets and compression-bending failure of multiple wall limbs divided by ribs on the web concrete. Except for slight deformation at the screw holes located on the profiled sheets at the corners of the wall, the connections exhibited minimal visible damage. The yield drift ratio of the DPSCW specimens in the test ranged from 1/286 to 1/225, and the ultimate drift ratio ranged from 1/63 to 1/94, both meeting the relevant deformation standards specified in the “Code for Seismic Design of Buildings. Increasing the number of self-tapping screws enhanced the development of local tensile fields on the profiled steel sheets, thereby improving the wall’s load-carrying, deformation, and energy dissipation capacities. However, increasing the axial compression ratio improved the initial stiffness of DPSCWs but reduced their load bearing and deformation capacity. Moreover, a design method for the self-tapping screw connections in DPSCWs was proposed. Full article

(This article belongs to the Special Issue Functional Cement-Based Composites for Civil Engineering (Volume II))

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15 pages, 11152 KiB

Open AccessArticle

The Influence of Mineral Additives on Aggregate Reactivity

by Grzegorz Rogojsz and Tomasz Rudnicki

Materials 2025, 18(1), 7; https://doi.org/10.3390/ma18010007 - 24 Dec 2024

Viewed by 381

Abstract

In this article, the authors present the results of their research on assessing the effect of selected mineral additives on the alkaline reactivity of aggregates. The main objective of this research was to check whether the reactivity of aggregates that do not meet the standard requirements can be reduced. Due to the decreasing availability of crushed aggregates and the decreasing resources of sand used for cement concrete road surfaces, solutions should be sought that allow the use of lower-grade aggregates. Among the available mineral additives, dense microsilica, white microsilica, limestone flour, glass flour, basalt flour, and glass granulate were selected. Laboratory tests were carried out in accordance with the requirements for testing the alkaline reactivity of road aggregates in NaOH solution applicable in Poland. The tests included the use of mineral additives in the amounts of 10% and 20%. Based on the research conducted, it was observed that the most beneficial effect was obtained with the addition of white microsilica, for which a decrease in aggregate reactivity was observed by 76.7% for 10% of the additive and 95.8% for 20% of the content. The least beneficial effect, on the other hand, was the use of compacted microsilica, for which an increase in alkaline reactivity was observed by 9.3% for 10% of the additive and 20.9% for 20% of the additive. The research conducted shows that the alkaline reactivity of the aggregate can be reduced, due to which it is possible to use reactive aggregates for the construction of road surfaces made of cement concrete. Full article

(This article belongs to the Special Issue Functional Cement-Based Composites for Civil Engineering (Volume II))

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15 pages, 930 KiB

Open AccessArticle

Design of Self-Compacting Concrete with Reduced Cement Content by Aggregate Packing Method

by Tomasz Rudnicki

Materials 2025, 18(1), 4; https://doi.org/10.3390/ma18010004 - 24 Dec 2024

Viewed by 647

Abstract

This article presents the procedure for designing self-compacting cement concrete characterized by minimal free space and a maximally compacted mineral skeleton. Such a designed mix allows for lower cement consumption and an increased amount of mineral additives. The paper presents a broad analysis of the influence of different aggregate proportions (36 recipes) and verification of the properties of the concrete mix using CEM I 42.5 R cements and fly ash. As a result of the appropriately compacted mineral skeleton, only 17% free space was obtained, which will allow the amount of cement to be reduced from 500 kg/m³ to 350 kg/m³ while fully maintaining the properties of the mix and hardened concrete. After 90 days of curing, SCC concrete was characterized by a compressive strength above 68 MPa and a small 2.1% decrease in compressive strength after 100 freeze–thaw cycles. Full article

(This article belongs to the Special Issue Functional Cement-Based Composites for Civil Engineering (Volume II))

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15 pages, 6531 KiB

Open AccessArticle

Preparation and Performance Study of Novel Foam Vegetation Concrete

by Teng Zhang, Tianbin Li, Hua Xu, Mengyun Wang and Lingling Lu

Materials 2024, 17(24), 6295; https://doi.org/10.3390/ma17246295 - 23 Dec 2024

Viewed by 1436

Abstract

Vegetation concrete is one of the most widely used substrates in ecological slope protection, but its practical application often limits the growth and nutrient uptake of plant roots due to consolidation problems, which affects the effectiveness of slope protection. This paper proposed the use of a plant protein foaming agent as a porous modifier to create a porous, lightweight treatment for vegetation concrete. Physical performance tests, direct shear tests, plant growth tests, and scanning electron microscopy experiments were conducted to compare and analyze the physical, mechanical, microscopic characteristics, and phyto-capabilities of differently treated vegetation concrete. The results showed that the higher the foam content, the more significant the porous and lightweight properties of the vegetation concrete. When the foam volume was 50%, the porosity increased by 106.05% compared to the untreated sample, while the volume weight decreased by 20.53%. The shear strength, cohesion, and internal friction angle of vegetation concrete all showed a decreasing trend with increasing foaming agent content. Festuca arundinacea grew best under the 30% foaming agent treatment, with germinative energy, germinative percentage, plant height, root length, and underground biomass increasing by 6.31%, 13.22%, 8.57%, 18.71%, and 34.62%, respectively, compared to the untreated sample. The scanning electron microscope observation showed that the pore structure of vegetation concrete was optimized after foam incorporation. Adding plant protein foaming agents to modify the pore structure of vegetation concrete is appropriate, with an optimal foam volume ratio of 20–30%. This study provides new insights and references for slope ecological restoration engineering. Full article

(This article belongs to the Special Issue Functional Cement-Based Composites for Civil Engineering (Volume II))

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16 pages, 3004 KiB

Open AccessArticle

New Discovery of Natural Zeolite-Rich Tuff on the Northern Margin of the Los Frailes Caldera: A Study to Determine Its Performance as a Supplementary Cementitious Material

by Jorge L. Costafreda, Domingo A. Martín, Miguel A. Sanjuán and Jorge L. Costafreda-Velázquez

Materials 2024, 17(17), 4430; https://doi.org/10.3390/ma17174430 - 9 Sep 2024

Viewed by 903

Abstract

The release of Neogene volcanism in the southeastern part of the Iberian Peninsula produced a series of volcanic structures in the form of stratovolcanoes and calderas; however, other materials also accumulated such as large amounts of pyroclastic materials such as cinerites, ashes, and lapilli, which were later altered to form deposits of zeolites and bentonites. This work has focused on an area located on the northern flank of the San José-Los Escullos zeolite deposit, the only one of its kind with industrial capacity in Spain. The main objective of this research is to characterize the zeolite (SZ) of this new area from the mineral, chemical, and technical points of view and establish its possible use as a natural pozzolan. In the first stage, a study of the mineralogical and chemical composition of the selected samples was carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray fluorescence (XRF), and thermogravimetric analysis (TGA); in the second stage, chemical-qualitative and pozzolanicity technical tests were carried out at 8 and 15 days. In addition, a chemical analysis was performed using XRF on the specimens of mortars made with a standardized mixture of Portland cement (PC: 75%) and natural zeolite (SZ: 25%) at the ages of 7, 28, and 90 days. The results of the mineralogical analyses indicated that the samples are made up mainly of mordenite and subordinately by smectite, plagioclase, quartz, halloysite, illite, and muscovite. Qualitative chemical assays indicated a high percentage of reactive silica and reactive CaO and also negligible contents of insoluble residues. The results of the pozzolanicity test indicate that all the samples analyzed behave like natural pozzolans of good quality, increasing their pozzolanic reactivity from 8 to 15 days of testing. Chemical analyses of PC/SZ composite mortar specimens showed how a significant part of SiO₂ and Al₂O₃ are released by zeolite while it absorbs a large part of the SO₃ contained in the cement. The results presented in this research could be of great practical and scientific importance as they indicate the continuation of zeolitic mineralization beyond the limits of the San José-Los Escullos deposit, which would result in an increase in geological reserves and the extension of the useful life of the deposit, which is of vital importance to the local mining industry. Full article

(This article belongs to the Special Issue Functional Cement-Based Composites for Civil Engineering (Volume II))

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14 pages, 7848 KiB

Open AccessArticle

Performance Research of Cement Concrete Pavements with a Lower Carbon Footprint

by Tomasz Rudnicki and Przemysław Stałowski

Materials 2024, 17(13), 3162; https://doi.org/10.3390/ma17133162 - 27 Jun 2024

Viewed by 917

Abstract

The growing interest in the use of building materials with a reduced carbon footprint was the aim of this research assessing the impact of four different types of low-emission cements on the properties of cement concretes used for the construction of local roads. This research work attempted to verify the strength characteristics and assess the durability of such solutions, which used the commonly used CEM I 42.5 R pure clinker cement and three multi-component cements: CEM II/A-V 42.5 R, CEM III/A 42.5 N-LH/HSR/NA, and CEM V/A S-V 42.5 N-LH/HSR/NA. Cement was used in a constant amount of 360 kg/m³, sand of 0/2 mm, and granite aggregate fractions of 2/8 and 8/16 mm. This research was carried out in two areas: the first concerned strength tests and the second focused on the area of assessing the durability of concrete in terms of frost resistance F150, resistance to de-icing agents, water penetration under pressure, and an analysis of the air entrainment structure in concrete according to the PN EN 480-11 standard. Analyzing the obtained test results, it can be concluded that the highest compressive strength of more than 70 MPa was obtained for CEM III concrete, 68 MPa for CEM V concrete, and the lowest for CEM I cement after 90 days. After the durability tests, it was found that the smallest decrease in compressive strength after 150 freezing and thawing cycles was obtained for CEM III (−0.9%) and CEM V (−1.4%) concretes. The high durability of concrete is confirmed by water penetration tests under pressure, because for newly designed recipes using CEM II, CEM III, and CEM V, water penetration from 17 mm to 18 mm was achieved, which proves the very high tightness of the concrete. The assessment of the durability of low-emission cements was confirmed by tests of resistance to de-icing agents and the aeration structure performed under a microscope in accordance with the requirements of the PN-EN 480-11 standard. The obtained analysis results indicate the correct structure and minimal spacing of air bubbles in the concrete, which confirms and guarantees the durability of concrete intended for road construction. Concretes designed using CEM V cement are characterized by a carbon footprint reduction of 36%, and for the mixture based on CEM III, we even observed a decrease of 39% compared to traditional concrete. Concrete using CEM II, CEM III, and CEM V cements can be successfully used for the construction of local roads. Therefore, it is necessary to consider changing the requirements of the technical specifications recommended for roads in Poland. Full article

(This article belongs to the Special Issue Functional Cement-Based Composites for Civil Engineering (Volume II))

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15 pages, 3726 KiB

Open AccessArticle

Advancements in Heavy Metal Stabilization: A Comparative Study on Zinc Immobilization in Glass-Portland Cement Binders

by Abdelhadi Bouchikhi, Amine el Mahdi Safhi, Walid Maherzi, Yannick Mamindy-Pajany, Wolfgang Kunther, Mahfoud Benzerzour and Nor-Edine Abriak

Materials 2024, 17(12), 2867; https://doi.org/10.3390/ma17122867 - 12 Jun 2024

Viewed by 1239

Abstract

Recent literature has exhibited a growing interest in the utilization of ground glass powder (GP) as a supplementary cementitious material (SCM). Yet, the application of SCMs in stabilizing heavy metallic and metalloid elements remains underexplored. This research zeroes in on zinc stabilization using a binder amalgam of GP and ordinary Portland cement (OPC). This study juxtaposes the stability of zinc in a recomposed binder consisting of 30% GP and 70% OPC (denoted as 30GP-M) against a reference binder of 100% CEM I 52.5 N (labeled reference mortar, RM) across curing intervals of 1, 28, and 90 days. Remarkably, the findings indicate a heightened kinetic immobilization of Zn at 90 days in the presence of GP—surging up to 40% in contrast to RM. Advanced microstructural analyses delineate the stabilization locales for Zn, including on the periphery of hydrated C₃S particles (Zn–C₃S), within GP-reactive sites (Si*–O–Zn), and amid C–S–H gel structures, i.e., (C/Zn)–S–H. A matrix with 30% GP bolsters the hydration process of C₃S vis-à-vis the RM matrix. Probing deeper, the microstructural characterization underscores GP’s prowess in Zn immobilization, particularly at the interaction zone with the paste. In the Zn milieu, it was discerning a transmutation—some products born from the GP–Portlandite reaction morph into GP–calcium–zincate. Full article

(This article belongs to the Special Issue Functional Cement-Based Composites for Civil Engineering (Volume II))

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27 pages, 7002 KiB

Open AccessArticle

Effect of Carbon Nanotubes on Chloride Diffusion, Strength, and Microstructure of Ultra-High Performance Concrete

by Mahdi Rafieizonooz, Jang-Ho Jay Kim, Jin-Su Kim and Jae-Bin Jo

Materials 2024, 17(12), 2851; https://doi.org/10.3390/ma17122851 - 11 Jun 2024

Cited by 2 | Viewed by 1152

Abstract

This study delved into the integration of carbon nanotubes (CNTs) in Ultra-High Performance Concrete (UHPC), exploring aspects such as mechanical properties, microstructure analysis, accelerated chloride penetration, and life service prediction. A dispersed CNT solution (0.025 to 0.075 wt%) was employed, along with a superplasticizer, to ensure high flowability in the UHPC slurry. In addition, the combination of high-strength functional artificial lightweight aggregate (ALA) and micro hollow spheres (MHS) was utilized as a replacement for fine aggregate to not only reduce the weight of the concrete but also to increase its mechanical performance. Experimental findings unveiled that an increased concentration of CNT in CNT1 (0.025%) and CNT2 (0.05%) blends led to a marginal improvement in compressive strength compared to the control mix. Conversely, the CNT3 (0.075%) mixture exhibited a reduction in compressive strength with a rising CNT content as an admixture. SEM analysis depicted that the heightened concentration of CNTs as an admixture induced the formation of nanoscale bridges within the concrete matrix. Ponding test results indicated that, for all samples, the effective chloride transport coefficient remained below the standard limitation of 1.00 × 10⁻¹² m²/s, signifying acceptable performance in the ponding test for all samples. The life service prediction outcomes affirmed that, across various environmental scenarios, CNT1 and CNT2 mixtures consistently demonstrated superior performance compared to all other mixtures. Full article

(This article belongs to the Special Issue Functional Cement-Based Composites for Civil Engineering (Volume II))

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17 pages, 7109 KiB

Open AccessArticle

Carbonation Resistance of Ternary Portland Cements Made with Silica Fume and Limestone

by Miguel Ángel Sanjuán, Esperanza Menéndez and Hairon Recino

Materials 2024, 17(11), 2705; https://doi.org/10.3390/ma17112705 - 3 Jun 2024

Cited by 2 | Viewed by 924

Abstract

Ternary blended cements, made with silica fume and limestone, provide significant benefits such as improved compressive strength, chloride penetration resistance, sulfates attack, etc. Furthermore, they could be considered low-carbon cements, and they contribute to reducing the depletion of natural resources in reference to water usage, fossil fuel consumption, and mining. Limestone (10%, 15%, and 20%) with different fineness and coarse silica fume (3%, 5%, and 7%) was used to produce ternary cements. The average size of coarse silica fume used was 238 μm. For the first time, the carbonation resistance of ternary Portland cements made with silica fume and limestone has been assessed. The carbonation resistance was assessed by natural carbonation testing. The presence of coarse silica fume and limestone in the blended cement led to pore refinement of the cement-based materials by the filling effect and the C-S-H gel formation. Accordingly, the carbonation resistance of these new ternary cements was less poor than expected for blended cements. Full article

(This article belongs to the Special Issue Functional Cement-Based Composites for Civil Engineering (Volume II))

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14 pages, 6460 KiB

Open AccessArticle

An Evaluation of the Radioactive Content of Ashes Obtained from the Use of Fuels from Recycled Materials by Co-Processing in the Cement Industry

by José Antonio Suarez-Navarro, Miguel Ángel Sanjuán, Pedro Mora and María del Mar Alonso

Materials 2024, 17(10), 2287; https://doi.org/10.3390/ma17102287 - 12 May 2024

Viewed by 1230

Abstract

The co-processing of different wastes as fuels in the manufacture of cement clinker not only meets the objectives of a circular economy but also contributes to the reduction in CO₂ emissions in the manufacture of Portland cement. However, waste used as alternative fuels, such as sludge or organic-rich residues, may contain naturally occurring radionuclides that can be concentrated during the combustion process. In this study, the presence of natural radionuclides (radioactive series of uranium, thorium, and ⁴⁰K) and anthropogenic radionuclides (¹³⁷Cs) in these wastes has been investigated by gamma spectrometry. Possible relationships between the radioactive content and the obtained chemical composition, determined by X-ray fluorescence, have also been studied by applying a principal component analysis (PCA). The results showed that the wastes with the highest radioactive content were sewage sludge with activity concentrations of ²³⁸U and ²¹⁰Pb of 321 ± 38 Bq kg⁻¹ and 110 ± 14 Bq kg⁻¹, respectively. A correlation between radioactive content and Fe₂O₃ concentration was also observed. The annual effective dose rates to workers for the ashes estimated from the ash content ranged from 0.0033 mSv to 0.092 mSv and therefore do not pose a risk to workers as they are lower than the 1 mSv per year limit for the general public (DIRECTIVE 2013/59/EURATOM). Full article

(This article belongs to the Special Issue Functional Cement-Based Composites for Civil Engineering (Volume II))

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12 pages, 4203 KiB

Open AccessArticle

Enhancing Mechanical Properties and Microstructures of Mass-Manufactured Sand Concrete by Incorporating Granite Powder

by Jian Huang, Guangfeng Xu, Shujie Chen, Demei Yu, Tengfei Fu, Chao Feng and Yulin Wang

Materials 2024, 17(10), 2234; https://doi.org/10.3390/ma17102234 - 9 May 2024

Cited by 1 | Viewed by 1251

Abstract

The production of manufactured sand and stone processing can cause dust pollution due to the generation of a significant amount of stone powder. This dust (mainly granite powder) was collected and incorporated as a cement replacement into mass-manufactured sand concrete in order to enhance the mechanical properties and microstructures. The heat of the hydration was measured by adding the granite powder into the cementitious material system. The mechanical properties, autogenous shrinkage, and pore structures of the concrete were tested. The results showed that the mechanical strength of the concrete increased first and then decreased with the increase in granite powder content. By replacing the 5% cement with the granite powder, the 28 d compressive and flexural strength increased by 17.6% and 20.9%, respectively. The autogenous shrinkage was mitigated by the incorporation of the 10% granite powder and decreased by 19.7%. The mechanism of the granite powder in the concrete was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP). The porosity decreased significantly within the 10% granite powder. A microstructure analysis did not reveal a change in the type of hydration products but rather that the granite powder played a role in the microcrystalline nucleation during the hydration process. Full article

(This article belongs to the Special Issue Functional Cement-Based Composites for Civil Engineering (Volume II))

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20 pages, 4340 KiB

Open AccessArticle

Mechanical and Microstructural Investigation of Geopolymer Concrete Incorporating Recycled Waste Plastic Aggregate

by Blessing O. Adeleke, John M. Kinuthia, Jonathan Oti, Duncan Pirrie and Matthew Power

Materials 2024, 17(6), 1340; https://doi.org/10.3390/ma17061340 - 14 Mar 2024

Cited by 3 | Viewed by 1967

Abstract

The effective use of waste materials is one of the key drivers in ensuring sustainability within the construction industry. This paper investigates the viability and efficacy of sustainably incorporating a polylactic acid-type plastic (WP) as a 10 mm natural coarse aggregate (NA) replacement in geopolymer concrete. Two types of concrete (ordinary Portland cement—OPC and geopolymer) were produced for completeness using a concrete formulation ratio of 1:2:3. The ordinary concrete binder control was prepared using 100% OPC at a water/binder ratio of 0.55, while the geopolymer concrete control used an optimum alkaline activator/precursor—A/P ratio (0.5) and sodium silicate to sodium hydroxide—SS/SH volume ratio (1.2/0.8). Using the same binder quantity as the control, four concrete batches were developed by replacing 10 mm NA with WP at 30 and 70 wt% for ordinary and geopolymer concrete. The mechanical performance of the developed concrete was assessed according to their appropriate standards, while a microstructural investigation was employed after 28 days of curing to identify any morphological changes and hydrated phases. The results illustrate the viability of incorporating WP in geopolymer concrete production at up to 70 wt% replacement despite some negative impacts on concrete performance. From a mechanical perspective, geopolymer concrete indicated a 46.7–58.3% strength development superiority over ordinary concrete with or without WP. The sample composition and texture quantified using automated scanning electron microscopy indicated that adding WP reduced the presence of pores within the microstructure of both concrete types. However, this was detrimental to the ordinary concrete due to the low interfacial zone (ITZ) between calcium silicate hydrate (CSH) gel and WP, resulting in the formation of cracks. Full article

(This article belongs to the Special Issue Functional Cement-Based Composites for Civil Engineering (Volume II))

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15 pages, 3609 KiB

Open AccessArticle

Wet–Dry Cycles and Microstructural Characteristics of Expansive Subgrade Treated with Sustainable Cementitious Waste Materials

by Samuel J. Abbey, Samuel Y. O. Amakye, Eyo U. Eyo, Colin A. Booth and Jeremiah J. Jeremiah

Materials 2023, 16(8), 3124; https://doi.org/10.3390/ma16083124 - 15 Apr 2023

Cited by 4 | Viewed by 2660

Abstract

This work presents an experimental study on the physico-mechanical and microstructural characteristics of stabilised soils and the effect of wetting and drying cycles on their durability as road subgrade materials. The durability of expansive road subgrade with a high plasticity index treated with different ratios of ground granulated blast furnace slag (GGBS) and brick dust waste (BDW) was investigated. Treated and cured samples of the expansive subgrade were subjected to wetting–drying cycles, California bearing ratio (CBR) tests, and microstructural analysis. The results show a gradual reduction in the California bearing ratio (CBR), mass, and the resilient modulus of samples for all subgrade types as the number of cycles increases. The treated subgrades containing 23.5% GGBS recorded the highest CBR value of 230% under dry conditions while the lowest CBR value of 15% (wetting cycle) was recorded for the subgrade treated with 11.75% GGBS and 11.75% BDW at the end of the wetting–drying cycles, both of which find useful application in road pavement construction as calcium silicate hydrate (CSH) gel was formed in all stabilised subgrade materials. However, the increase in alumina and silica content upon the inclusion of BDW initiated the formation of more cementitious products due to the increased availability of Si and Al species as indicated by EDX analysis. This study concluded that subgrade materials treated with a combination of GGBS and BDW are durable, sustainable and suitable for use in road construction. Full article

(This article belongs to the Special Issue Functional Cement-Based Composites for Civil Engineering (Volume II))

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21 pages, 7298 KiB

Open AccessReview

Recent Developments on the Effects of Micro- and Nano-Limestone on the Hydration Process, Products, and Kinetics of Cement

by Xin Li and Mingli Cao

Materials 2024, 17(9), 2133; https://doi.org/10.3390/ma17092133 - 1 May 2024

Cited by 4 | Viewed by 2337

Abstract

Limestone is commonly used in cement concrete due to its unique nature and type. It has physical effects (nucleation effect and dilution effect) and chemical effects on the hydration process of cement. This paper reviews the effects of three representative limestone materials on the hydration process, hydration products, and hydration kinetics. In the hydration process, the reaction was delayed by limestone powder with a particle size larger than 20 μm and calcium carbonate whiskers due to their dilutive effect. On the other hand, limestone powder with a particle size smaller than 20 m and calcium carbonate nanoparticles facilitated the reaction through nucleation and chemical effects. Limestone has a similar effect on hydration products, promoting the production of C-S-H through nucleation. The mechanism of action for this nucleation effect depends on the differences in crystalline form and particle size of the three types of micro- and nano-calcium. Chemical effects impact the amount of AFt produced, with the generation of new products being the main reaction influenced by the limestone admixture. Full article

(This article belongs to the Special Issue Functional Cement-Based Composites for Civil Engineering (Volume II))

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