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17 pages, 5727 KiB

Open AccessArticle

Evaluation of Rice Straw Ash as a Pozzolanic Addition in Cementitious Mixtures

by Samantha Hidalgo, Lourdes Soriano, José Monzó, Jordi Payá, Alba Font and Mª Victoria Borrachero

Appl. Sci. 2021, 11(2), 773; https://doi.org/10.3390/app11020773 - 15 Jan 2021

Cited by 20 | Viewed by 3269

Abstract

Rice husk ash is one of the most widely studied biomass ashes used in pozzolanic addition. Given its lower silica content, rice straw ash (RSA) has been explored less often, despite the fact that, according to the United Nations Food and Agriculture Organization [...] Read more.

Rice husk ash is one of the most widely studied biomass ashes used in pozzolanic addition. Given its lower silica content, rice straw ash (RSA) has been explored less often, despite the fact that, according to the United Nations Food and Agriculture Organization (FAO), rice straw (RS) production is estimated at 600 million tons/year. In this work, RSA was physically and chemically characterized, and its pozzolanic properties were assessed. A controlled conditioning, burning, homogenization and grinding procedure was carried out to obtain RSA from RS. Chemical composition, insoluble residue, reactive silica, chloride content and particle size distribution were assessed for ash characterization. To determine RSA pozzolanicity, Frattini, electrical conductivity and pH measurements in an aqueous suspension of hydrated CH/RSA mixtures were obtained. Portland cement (PC) mortars with 15% and 30% RSA substitutions evaluated. The mechanical tests showed specimens with a strength activity index up to 90% and 80% with 15% and 30% RSA, respectively, after 3 days, and these values grew to 107–109% after 90 curing days. Full article

(This article belongs to the Special Issue Application of Biomass Ashes in Cement-Based Materials)

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11 pages, 2976 KiB

Open AccessArticle

Sulfate Resistance in Cements Bearing Bottom Ash from Biomass-Fired Electric Power Plants

by José M. Medina, María Isabel Sánchez de Rojas, Isabel F. Sáez del Bosque, Moisés Frías and César Medina

Appl. Sci. 2020, 10(24), 8982; https://doi.org/10.3390/app10248982 - 16 Dec 2020

Cited by 4 | Viewed by 1699

Abstract

To address some of the gaps in the present understanding of the behavior of new supplementary cementitious materials such as bottom ash (BA) from biomass-fired electric power plants in cement manufacture, this study explored the effect of this promising material on the sulfate [...] Read more.

To address some of the gaps in the present understanding of the behavior of new supplementary cementitious materials such as bottom ash (BA) from biomass-fired electric power plants in cement manufacture, this study explored the effect of this promising material on the sulfate resistance of the end product. Cement paste prepared with 10% or 20% (previously characterized for mineralogy and chemical composition) BA was Köch–Steinegger tested for sulfate resistance. The hydration products, in turn, were analyzed before and after soaking the reference and experimental cements in sodium sulfate to determine whether the use of the addition hastened microstructural, mineralogical, or morphological decay in the material. The 56 days findings showed that the presence of BA raised binder resistance to sulfate attack. Köch–Steinegger corrosion indices of 1.29 and 1.27 for blended cements OPC + 10 BA and OPC + 20 BA, respectively, were higher than the 1.26 recorded for ordinary Portland cement (OPC). In addition, weight gain was 20.5% and volume expansion was 28.5% lower in the new materials compared to OPC. The products resulting from the external sulfate-cement interaction, gypsum and ettringite, were deposited primarily in the pores present in the pastes. The conclusion drawn is that binders bearing 10% or 20% BA are, a priori, apt for use in the design and construction of cement-based elements exposed to sulfate-laden environments. Full article

(This article belongs to the Special Issue Application of Biomass Ashes in Cement-Based Materials)

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17 pages, 588 KiB

Open AccessArticle

Leaching Characteristics of Wood Biomass Fly Ash Cement Composites

by Ivana Carević, Nina Štirmer, Marija Trkmić and Karmen Kostanić Jurić

Appl. Sci. 2020, 10(23), 8704; https://doi.org/10.3390/app10238704 - 4 Dec 2020

Cited by 13 | Viewed by 2986

Abstract

Wood biomass ash (WBA) represents an environmental and economic problem for energy producers, and there have been extensive studies of using WBA as a raw material in construction products. This study investigates the leaching characteristics of WBA cement composites based on testing results. [...] Read more.

Wood biomass ash (WBA) represents an environmental and economic problem for energy producers, and there have been extensive studies of using WBA as a raw material in construction products. This study investigates the leaching characteristics of WBA cement composites based on testing results. Currently, 70% of WBA is landfilled, and the rest is primarily used in agriculture; therefore, this study also addresses the leaching as a component of environmental safety of these two primary WBA management approaches. An analysis of the leaching characteristics of WBA, monolithic, and crushed cement composites is performed by replacing 15% of the cement with WBA. The study was conducted using three WBA samples collected from different power plants. Increased values of leaching from the WBA itself are indicative of potential issues that could occur in the case of its disposal. The study concluded that the WBA could be potentially environmentally acceptable as a raw material in the concrete industry because the heavy metals are stabilized within the cement matrix. Full article

(This article belongs to the Special Issue Application of Biomass Ashes in Cement-Based Materials)

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12 pages, 3663 KiB

Open AccessArticle

Properties and Mechanism of Hydration of Fly Ash Belite Cement Prepared from Low-Quality Fly Ash

by Yongfan Gong, Cong Liu and Yanli Chen

Appl. Sci. 2020, 10(20), 7026; https://doi.org/10.3390/app10207026 - 10 Oct 2020

Cited by 11 | Viewed by 2388

Abstract

Fly ash belite cement (FABC) is predominantly composed of α′_L-C₂S and C₁₂A₇. It is prepared from low-grade fly ashes by hydrothermal synthesis and low-temperature calcination methods. The formation, evolution process, and microstructure of FABC hydration [...] Read more.

Fly ash belite cement (FABC) is predominantly composed of α′_L-C₂S and C₁₂A₇. It is prepared from low-grade fly ashes by hydrothermal synthesis and low-temperature calcination methods. The formation, evolution process, and microstructure of FABC hydration productions were studied in this work, and the ultimate aim is to give a theoretical foundation and technological support for the application of the new cementitious material made of low-quality fly ash. The results showed that the optimal amount of gypsum was about 7% of cement by weight. The 3-day and 28-day compressive strength of cement pastes with 7% gypsum was 13.6 and 60.2 MPa, respectively. Meanwhile, the 28-day flexural and compressive strengths of mortars with 7% gypsum were 4.6 and 25.9 MPa, respectively. The early hydration heat release rate of this low-temperature calcined cement was higher compared with that of high-temperature calcined cement as Portland cement. FABC hydration pastes contained mostly C-S-H, ettringite (AFt), unreacted mullite, and quartz. It was significantly different from Portland cement in that no calcium hydroxide [Ca(OH)₂] was observed in the hydration products of different ages because all Ca(OH)₂ formed in the hydration reaction could react completely to generate AFt. The ratio of harmful pores (d ≥ 50 nm) reached 55.04% after 3-day hydration. However, it decreased to 6.71%, which was lower than that of Portland cement pastes (35.72%) after 28-day hydration. In the later hydration period from 3 to 28 days, the strength developed rapidly, and a compact microstructure appeared in the hardened paste due to the presence of pores less than 20 nm in diameter. Full article

(This article belongs to the Special Issue Application of Biomass Ashes in Cement-Based Materials)

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13 pages, 2895 KiB

Open AccessArticle

Influence of Milling Techniques on the Performance of Wheat Straw Ash in Cement Composites

by Abdul Qudoos, Ehsanullah Kakar, Atta ur Rehman, In Kyu Jeon and Hong Gi Kim

Appl. Sci. 2020, 10(10), 3511; https://doi.org/10.3390/app10103511 - 19 May 2020

Cited by 13 | Viewed by 2745

Abstract

The worldwide production of cement is growing every year due to its increased use in the construction. Cement production is affiliated with an environmental concern as it contributes to the CO₂ emissions. It is imperative to reduce the cement production by incorporating [...] Read more.

The worldwide production of cement is growing every year due to its increased use in the construction. Cement production is affiliated with an environmental concern as it contributes to the CO₂ emissions. It is imperative to reduce the cement production by incorporating supplementary cementitious materials in the cement composites. In this research study, wheat straw ash (WSA) was used as an alternate of ordinary Portland cement. The ash was ground separately with a ball mill and a disintegrator mill as well as with a combination of both to enhance its pozzolanic efficiency. Mortar and paste specimens were made by substituting cement with WSA (20% by weight). Ash specimens were examined in terms of particle size distribution, X-ray diffraction, and X-ray fluorescence analyses. The performance of the ash specimens in cement composites was examined via compressive and flexural strengths, and ultrasonic pulse velocity (UPV) tests. Isothermal calorimetric, thermogravimetric analyses (TGA), mercury intrusion porosimetry (MIP), and scanning electron microscopy (SEM) were also employed on the specimens. The results revealed that the particle size of the wheat straw ash specimens significantly reduced and specific surface area enhanced when ground with a combination of both milling techniques. Cement composites made with this type of ash demonstrated improved mechanical and physical properties, accelerated hydration reaction at the early ages, reduce calcium hydroxide content at the later ages, and densified microstructure. Full article

(This article belongs to the Special Issue Application of Biomass Ashes in Cement-Based Materials)

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13 pages, 1955 KiB

Open AccessArticle

Rendering Mortars with Low Sand and Cement Content. Incorporation of Sanitary Ware Waste and Forest Biomass Ashes

by Catarina Brazão Farinha, Jorge de Brito and Rosário Veiga

Appl. Sci. 2020, 10(9), 3146; https://doi.org/10.3390/app10093146 - 30 Apr 2020

Cited by 3 | Viewed by 2091

Abstract

The incorporation of wastes in new materials and products is an emerging trend, reducing virgin materials’ consumption and landfill deposition and the associated environmental impacts. Cement-based mortars can encapsulate some wastes, with the benefits stated above. In three previous researches, it was found [...] Read more.

The incorporation of wastes in new materials and products is an emerging trend, reducing virgin materials’ consumption and landfill deposition and the associated environmental impacts. Cement-based mortars can encapsulate some wastes, with the benefits stated above. In three previous researches, it was found that forest biomass bottom ashes (up to 15% by volume of cement), powder of sanitary ware (up to 20% by volume of sand) and sanitary ware particles above 2 mm (100% by volume of sand) can be incorporated in rendering mortars, replacing cement or sand. Several tests were performed, and it was found that each waste’s incorporation presents advantages and limitations, when compared with a reference mortar. In this research, the aim was to take advantage of the best features of each waste, combining them in order to optimize the new mortars’ characteristics. Therefore, mortars with one, two and three wastes were analysed in this research. The ternary mix mortar had a volume of wastes equal to 83%, resulting in a mortar with 15% less cement (by volume) and without any natural aggregate (all replaced with the sanitary ware wastes). The fresh, water and mechanical behaviour of the mortars with and without wastes are presented in this research. It was concluded that it is possible to take advantage of the best features of each waste and achieve mortars simultaneously with high volume of wastes and a better performance than the reference mortar (without wastes). Full article

(This article belongs to the Special Issue Application of Biomass Ashes in Cement-Based Materials)

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10 pages, 2726 KiB

Open AccessArticle

Study on Properties of Waste Concrete Powder by Thermal Treatment and Application in Mortar

by Yuwu Sui, Chuping Ou, Shu Liu, Jinshuai Zhang and Qingbo Tian

Appl. Sci. 2020, 10(3), 998; https://doi.org/10.3390/app10030998 - 3 Feb 2020

Cited by 70 | Viewed by 4318

Abstract

Waste concrete must be crushed, screened, and ground in order to produce high-quality recycled aggregate. In this treatment process, 15–30% waste concrete powder (<0.125 mm) can be generated. Hydration activity and the reuse of waste concrete powders (WCPs) were studied in this work, [...] Read more.

Waste concrete must be crushed, screened, and ground in order to produce high-quality recycled aggregate. In this treatment process, 15–30% waste concrete powder (<0.125 mm) can be generated. Hydration activity and the reuse of waste concrete powders (WCPs) were studied in this work, and the results illustrated that the particle size changed after a series of thermal treatments at temperatures from 400 ℃ to 800 ℃. The particle size of waste concrete powder decreased by 700 ℃ thermal treatment, and by 600 ℃ thermal treatment, it increased. More active elements appeared in WCP heated by 800 ℃. Nevertheless, the activity index (AI) of WCP, measured by the ratio of mechanical strengths between mortar with a 30% replacement of the cement with WCP and normal mortar without WCP, indicated that the WCP by 700 ℃ thermal treatment had an optimal AI value, which meant WCP treated at 700 ℃ could be used in mortar or concrete as an admixture. Full article

(This article belongs to the Special Issue Application of Biomass Ashes in Cement-Based Materials)

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Review

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24 pages, 2424 KiB

Open AccessReview

Eco-Efficient Cement-Based Materials Using Biomass Bottom Ash: A Review

by Manuel Cabrera, José Luis Díaz-López, Francisco Agrela and Julia Rosales

Appl. Sci. 2020, 10(22), 8026; https://doi.org/10.3390/app10228026 - 12 Nov 2020

Cited by 23 | Viewed by 4124

Abstract

In recent years the use of biomass for electricity generation in thermal and cogeneration plants has increased worldwide because it is an environmentally clean fuel whose impact measured in greenhouse gas emissions is practically zero. However, biomass bottom ash, a waste produced during [...] Read more.

In recent years the use of biomass for electricity generation in thermal and cogeneration plants has increased worldwide because it is an environmentally clean fuel whose impact measured in greenhouse gas emissions is practically zero. However, biomass bottom ash, a waste produced during combustion, has also increased considerably, which has both a negative economic and environmental impact, due to landfill transport and management of this by-product. Although biomass bottom ash has potential characteristics for application in the manufacture of construction materials, its full-scale application is difficult because of the wide range in physicochemical properties, depending on the type of biomass burned, such as wood residue, olive waste, waste paper sludge, cocoa shell, etc., and the type of combustion process in the plant. This study reviews the influence on the physicochemical properties, mechanical behavior, and durability of different cement-based materials, such as mortars, concrete, and cement-treated granular material, manufactured from biomass bottom ash. The previous studies demonstrate the feasibility of substituting natural materials for biomass bottom ash in cement-based materials, presenting adequate mechanical behavior and durability properties to comply with the required technical specifications in different building materials. Full article

(This article belongs to the Special Issue Application of Biomass Ashes in Cement-Based Materials)

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