Materials

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22 pages, 8304 KiB

Open AccessArticle

Carbonation Behavior of Mortar Made from Treated Recycled Aggregates: Influence of Diammonium Phosphate

by Diana Gómez-Cano, Yhan P. Arias-Jaramillo, Roberto Bernal-Correa and Jorge I. Tobón

Materials 2023, 16(3), 980; https://doi.org/10.3390/ma16030980 - 20 Jan 2023

Viewed by 1254

This research aims to improve the quality of recycled concrete fine aggregates (RFA) by using diammonium hydrogen phosphate (DAP). We aimed to understand the effect of DAP treatment on durability performance due to the carbonation action of mortars with the partial and total [...] Read more.

This research aims to improve the quality of recycled concrete fine aggregates (RFA) by using diammonium hydrogen phosphate (DAP). We aimed to understand the effect of DAP treatment on durability performance due to the carbonation action of mortars with the partial and total substitution of treated RFA. The results showed a maximum reduction in the RFA water absorption of up to 33% using a minimum DAP concentration due to a pore refinement as a consequence of the formation of calcium phosphates such as hydroxyapatite (HAP). The carbonation phenomenon did not have a significant effect on the durability of mortars with DAP-treated RFA, as we did not find a decrease in the compressive strength; the carbonation depth of the mortars with 100% treated RFA decreased up to 90% and 63% for a w/c of 0.45 and 0.50, in comparison with mortars with 0% treated RFA. An inversely proportional relationship was found between the accelerate carbonation and the compressive strength, showing that higher percentages of treated RFAs in the mortar promoted an increase in compressive strength and a decrease in the carbonation rate, which is behavior associated with a lower permeability of the cement matrix as one of the consequences of the microstructural densification by DAP treatment. Full article

(This article belongs to the Special Issue Properties and Novel Applications of Recycled Concrete and Mixed Aggregates)

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21 pages, 12640 KiB

Open AccessArticle

Deicer Salt-Scaling Resistance of Concrete Using Recycled Concrete Aggregates Pretreated by Silica Fume Slurry

by Hossein Sasanipour, Farhad Aslani and Javad Taherinezhad

Materials 2022, 15(24), 8874; https://doi.org/10.3390/ma15248874 - 12 Dec 2022

Viewed by 1436

Abstract

Concrete wastes such as recycled concrete aggregates (RCA) make up a significant part of construction and demolition waste (C&DW) which can be used to minimize usage of natural aggregates and reduce carbon footprint. This paper studies the salt-scaling resistance of recycled aggregate concrete [...] Read more.

Concrete wastes such as recycled concrete aggregates (RCA) make up a significant part of construction and demolition waste (C&DW) which can be used to minimize usage of natural aggregates and reduce carbon footprint. This paper studies the salt-scaling resistance of recycled aggregate concrete produced with pretreated RCAs. The test method for evaluating salt-scaling resistance in concrete according to DIN EN 1340: 2003 was performed. Four series of concrete mixes using natural aggregates, RCAs, manually pretreated RCA, and modified RCA in a desiccator were subjected to the different tests in terms of bulk electrical resistance in two directions (X and Y) before and after freeze-thaw cycles, ultrasonic pulse velocity, and weight loss of the surface layer of concrete specimens. Moreover, Scanning Electron Microscopy (SEM) of mixes was conducted and the microstructure of mixes considering the interface transition zone was studied. Results show that after exposure to cycles of freezing and thawing, the quality of concrete regarding ultrasonic pulse velocity did not change. The electrical resistance of specimens decreased significantly in X-direction and slightly in Y-direction after applying freeze-thaw cycles in all mixes. Nevertheless, surface modification of RCAs can increase electrical resistance and improve durability of concrete. SEM images show that the interface transition zone before and after freeze-thaw cycles remained unchanged which means strong bond between aggregate, new mortar, and old mortar. An estimation of the total charge passed indicated that all recycled aggregate concretes can be classified in a safe area and with very low chloride ion penetrability according to ASTM C1202. Full article

(This article belongs to the Special Issue Properties and Novel Applications of Recycled Concrete and Mixed Aggregates)

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17 pages, 4111 KiB

Open AccessArticle

Effect of Processed Volcanic Ash as Active Mineral Addition for Cement Manufacture

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

Materials 2022, 15(18), 6305; https://doi.org/10.3390/ma15186305 - 11 Sep 2022

Cited by 10 | Viewed by 2338

Abstract

In the last quarter of 2021, there was a very significant eruption of the Cumbre Vieja volcano on the island of La Palma, belonging to the Canary Islands, Spain. It generated a large amount of pyroclastic volcanic materials, which must be studied for [...] Read more.

In the last quarter of 2021, there was a very significant eruption of the Cumbre Vieja volcano on the island of La Palma, belonging to the Canary Islands, Spain. It generated a large amount of pyroclastic volcanic materials, which must be studied for their possible applicability. This work studies the properties and applicability of the lava and volcanic ash generated in this process. The need for reconstruction of the areas of the island that suffered from this environmental catastrophe is considered in this study from the point of view of the valuation of the waste generated. For this purpose, the possibility of using the fine fraction of ashes and lava as a supplementary cement material (SCM) in the manufacture of cement is investigated. The volcanic material showed a chemical composition and atomic structure suitable for replacing clinker in the manufacture of Portland cement. In this study, the cementing and pozzolanic reaction characteristics of unprocessed volcanic materials and those processed by crushing procedures are analysed. To evaluate the cementitious potential by analysing the mechanical behaviour, a comparison with other types of mineral additions (fly ash, silica fume, and limestone filler) commonly used in cement manufacture or previously studied was carried out. The results of this study show that volcanic materials are feasible to be used in the manufacture of cement, with up to a 22% increase in pozzolanicity from 28 to 90 days, showing the high potential as a long-term supplementary cementitious material in cement manufacturing, though it is necessary to carry out crushing processes that improve their pozzolanic behaviour. Full article

(This article belongs to the Special Issue Properties and Novel Applications of Recycled Concrete and Mixed Aggregates)

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15 pages, 4546 KiB

Open AccessArticle

Reusing Construction and Demolition Waste to Prepare Alkali-Activated Cement

by María V. Borrachero, Jordi Payá, Santiago Brito, Yasna Pamela Segura, Lourdes Soriano, Mauro M. Tashima and Jose María Monzó

Materials 2022, 15(10), 3437; https://doi.org/10.3390/ma15103437 - 10 May 2022

Cited by 11 | Viewed by 1881

Abstract

Large amounts of waste are derived not only from construction processes, but also the demolition of existing buildings. Such waste occupies large volumes in landfills, which makes its final disposal difficult and expensive. Reusing this waste type is generally limited to being employed [...] Read more.

Large amounts of waste are derived not only from construction processes, but also the demolition of existing buildings. Such waste occupies large volumes in landfills, which makes its final disposal difficult and expensive. Reusing this waste type is generally limited to being employed as filler material or recycled aggregate in concrete, which limits its valorisation. The present work proposes reusing construction and demolition waste to manufacture alkali-activated cement to improve its sustainability and recovery. Construction and demolition waste (C&DW) from a demolition waste collection plant in Valencia (Spain) was physically and chemically characterised. This residue contained large fractions of concrete, mortar, bricks, and other ceramic materials. X-ray fluorescence (XRF) analysis showed that its chemical composition was mainly CaO, SiO₂ and Al₂O₃. X-ray diffraction (XRD) analysis revealed that it presented some crystalline products, and quartz (SiO₂) and calcite (CaCO₃) were the main components. Blends of C&DW and blast furnace slag (BFS) were alkali-activated with mixtures of sodium hydroxide and sodium silicate. The corresponding pastes were characterised by techniques such as thermogravimetry and scanning electron microscopy (SEM). The alkali-activated mortars were prepared, and the resulting mortars’ compressive strength was determined, which was as high as 58 MPa with the 50% C&DW-50% BFS mixture. This work concluded that it is possible to make new sustainable binders by the alkali activation of C&DW-BFS without using Portland cement. Full article

(This article belongs to the Special Issue Properties and Novel Applications of Recycled Concrete and Mixed Aggregates)

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18 pages, 3536 KiB

Open AccessArticle

An Experimental Study on Structural Concrete Containing Recycled Aggregates and Powder from Construction and Demolition Waste

by Jeonghyun Kim, Anna M. Grabiec and Andrzej Ubysz

Materials 2022, 15(7), 2458; https://doi.org/10.3390/ma15072458 - 26 Mar 2022

Cited by 16 | Viewed by 3509

Abstract

For complete utilization of construction and demolition (C&D) waste, an investigation of all size fractions of C&D waste generated during the recycling process should be conducted. In this work, the effects of three recycled concrete materials with different sizes (recycled coarse aggregate (RCA) [...] Read more.

For complete utilization of construction and demolition (C&D) waste, an investigation of all size fractions of C&D waste generated during the recycling process should be conducted. In this work, the effects of three recycled concrete materials with different sizes (recycled coarse aggregate (RCA) with a size of 4.75–25 mm, recycled fine aggregate (RFA) of 0.15–4.75 mm, and recycled powder (RP) smaller than 0.15 mm) produced from concrete waste on the fresh and hardened mechanical properties of concrete were evaluated. The replacement ratios of natural coarse and fine aggregates by RCA and RFA were 30, 60, and 100%, and those of ordinary Portland cement for RP were 10, 20, and 30%. The results showed that the concrete properties deteriorated with increasing replacement ratio regardless of the type of recycled materials. The properties were reduced in the order of the use of RFA, RCA, and the simultaneous use of RCA and RFA. In addition, concrete with 30% RP showed lower mechanical strength than concrete with 100% RCA and 100% RFA. However, all concretes could be applicable for structural purposes under different environmental exposure conditions. In particular, concretes with 10% RP and 20% RP showed better cost-benefits compared to natural aggregate concrete with 100% ordinary Portland cement. These promising findings provide valuable initiatives for the effective and complete recycling of C&D waste. Full article

(This article belongs to the Special Issue Properties and Novel Applications of Recycled Concrete and Mixed Aggregates)

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13 pages, 7370 KiB

Open AccessArticle

Application of Pre-Wetted High Titanium Heavy Slag Aggregate in Cement Concrete

by Tao Zhang and Bei Huang

Materials 2022, 15(3), 831; https://doi.org/10.3390/ma15030831 - 22 Jan 2022

Cited by 3 | Viewed by 1491

Abstract

High titanium heavy slag is one kind of solid waste that exists in large amounts in the southwest of China. In this paper, this high titanium heavy slag is used as natural pre-wetted material in concrete because of its porous structure. Three kinds [...] Read more.

High titanium heavy slag is one kind of solid waste that exists in large amounts in the southwest of China. In this paper, this high titanium heavy slag is used as natural pre-wetted material in concrete because of its porous structure. Three kinds of aggregates are used in this concrete. The first one is natural limestone and river sand. The second one is dry slag fine aggregate and coarse aggregate. The third one is pre-wetted coarse slag aggregate and dry slag fine aggregate. The strength, dry shrinkage, autogenous shrinkage, relative humidity, pore size distribution, stress–strain relationship, micro-hardness and chloride penetration of concrete composed of the above three aggregates are tested in this study. The results show that pre-wetted slag aggregate is a suitable internal curing material. The concrete with pre-wetted slag aggregate shows higher strength, lower shrinkage and smaller porosity. The water absorbed in the slag aggregate can be released effectively to increase the relative humidity, accelerate hydration, improve porosity and increase the interface strength. Full article

(This article belongs to the Special Issue Properties and Novel Applications of Recycled Concrete and Mixed Aggregates)

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16 pages, 4854 KiB

Open AccessArticle

Recycled Aggregates from Construction and Demolition Waste in the Manufacture of Urban Pavements

by Manuel Contreras-Llanes, Maximina Romero, Manuel Jesús Gázquez and Juan Pedro Bolívar

Materials 2021, 14(21), 6605; https://doi.org/10.3390/ma14216605 - 02 Nov 2021

Cited by 11 | Viewed by 2275

Abstract

Construction and Demolition Waste (CDW) is among the largest waste streams in the world. Therefore, within the Circular Economy concept, there is a growing interest in its reuse. The purpose of this work was to study the use of recycled aggregates (RAs) obtained [...] Read more.

Construction and Demolition Waste (CDW) is among the largest waste streams in the world. Therefore, within the Circular Economy concept, there is a growing interest in its reuse. The purpose of this work was to study the use of recycled aggregates (RAs) obtained by a specific separation method from CDW, replacing natural aggregates (NAs) in the manufacture of precast concrete elements, such as kerbstones and paver blocks. The physical and technological properties of precast products formulated with RAs were analysed in accordance with current regulations, comparing them with those of commercial products manufactured with NAs. The results indicated that partial or total substitution of NAs by RAs increased the water absorption and apparent porosity values of the precast elements while reducing the bulk density and compressive strength. However, all units manufactured with RAs showed breaking load values higher than the minimum required by EN 1338 and, in some cases, slightly higher average tensile strength values than the reference material. In addition, some of the compositions including RAs gave rise to pieces that, according to their flexural strength, were classified as class 1 and marked S in accordance with EN 1340. According to abrasion resistance, in most cases, the precast elements are classified as Class 4 and I (≤20 mm). Finally, precast concrete produced from RAs satisfies the tolerance requirements for classification as class 3 (≤1.5 kg m⁻²). Therefore, it could be suitable for use in high pedestrian or traffic areas. Full article

(This article belongs to the Special Issue Properties and Novel Applications of Recycled Concrete and Mixed Aggregates)

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15 pages, 14001 KiB

Open AccessArticle

Performance of Concrete Mixes Containing TBM Muck as Partial Coarse Aggregate Replacements

by Ala Abu Taqa, Mohamed Al-Ansari, Ramzi Taha, Ahmed Senouci, Ghaleb M. Al-Zubi and Mohamed O. Mohsen

Materials 2021, 14(21), 6263; https://doi.org/10.3390/ma14216263 - 21 Oct 2021

Cited by 7 | Viewed by 1483

Abstract

This study investigated the potential utilization of the TBM muck obtained from the Gold Line of the Doha Metro Project as a partial replacement of coarse aggregates in concrete mixes. First, the TBM muck particles were screened to coarse aggregate standard sizes. Then, [...] Read more.

This study investigated the potential utilization of the TBM muck obtained from the Gold Line of the Doha Metro Project as a partial replacement of coarse aggregates in concrete mixes. First, the TBM muck particles were screened to coarse aggregate standard sizes. Then, concrete mixes were prepared using 0%, 25%, 50%, and 75% TBM muck replacement of coarse aggregates. The compressive and flexural strengths were determined for all mixes at 28 and 56 days. Moreover, the results obtained were validated using EDX analysis and SEM images. A t-statistical analysis did not show a significant impact of TBM muck usage on the compressive strength results of the concrete mixes. However, another t-statistical analysis showed that TBM muck replacement of coarse aggregates had adversely affected the flexural strength results. The EDX analysis indicated the presence of Na⁺ ions, which can replace the Ca²⁺ ions in the C-S-H gel, cause discontinuities of it, and hence reduce the strength at later ages. Finally, the SEM images showed that the ettringite and carbon hydroxide (C-H) contents in the mixes with TBM muck were higher than that of the control mix, while the C-S-H gel was less in such mixes. Full article

(This article belongs to the Special Issue Properties and Novel Applications of Recycled Concrete and Mixed Aggregates)

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27 pages, 7673 KiB

Open AccessArticle

Petrographic and Physical-Mechanical Investigation of Natural Aggregates for Concrete Mixtures

by Chiara Telloli, Alessandra Aprile and Elena Marrocchino

Materials 2021, 14(19), 5763; https://doi.org/10.3390/ma14195763 - 02 Oct 2021

Cited by 1 | Viewed by 2476

Abstract

The availability of different lithology with which concrete can be packaged could create substantial questions on the differences that they can provide to the same mixture. Different kinds of aggregates were analyzed individually to investigate their main characteristics, which allowed us to package [...] Read more.

The availability of different lithology with which concrete can be packaged could create substantial questions on the differences that they can provide to the same mixture. Different kinds of aggregates were analyzed individually to investigate their main characteristics, which allowed us to package five types of concrete mixtures. These five mixtures were compared to each other through compressive strength values. Furthermore, it was considered microscopically what possible differences could exist between these different mixtures, for example, differences in the cement/aggregate reaction. The chemical characterization of the aggregates, used as the skeleton of the cement mixes, was proposed as an important investigative phase in order to better understand the differences in the geotechnical and physical-mechanical characteristics and to verify the presence of any harmful phases for the durability of the concrete. Full article

(This article belongs to the Special Issue Properties and Novel Applications of Recycled Concrete and Mixed Aggregates)

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27 pages, 39758 KiB

Open AccessArticle

Selected Strength Properties of Coal Bottom Ash (CBA) Concrete Containing Fly Ash under Different Curing and Drying Conditions

by Ji-Hun Park, Quang-The Bui, Sang-Hwa Jung and In-Hwan Yang

Materials 2021, 14(18), 5381; https://doi.org/10.3390/ma14185381 - 17 Sep 2021

Cited by 9 | Viewed by 1703

Abstract

This study aims to evaluate the effect of curing and drying conditions on the strength properties of concrete containing coal bottom ash (CBA) and fly ash as substitutes for fine aggregates and cement, respectively. The strength properties of the concrete including CBA and [...] Read more.

This study aims to evaluate the effect of curing and drying conditions on the strength properties of concrete containing coal bottom ash (CBA) and fly ash as substitutes for fine aggregates and cement, respectively. The strength properties of the concrete including CBA and fly ash were evaluated under two different curing and drying conditions: saturated surface-dry (SSD) conditions and oven-dried conditions at curing ages of 28 and 91 days. The natural fine aggregates of the mixtures were replaced by CBA fine aggregates at 25%, 50%, 75%, and 100% by volume. In addition, the cement in the mixtures was partly replaced with fly ash at 20% and 40%. The experimental program included the measurement of the unit weight, compressive strength, splitting tensile strength, flexural strength, and ultrasonic pulse velocity of the concrete. The test results showed that the compressive strength, splitting tensile strength, and flexural strength decreased as the CBA content increased under both SSD and oven-dried conditions. The curing and drying conditions of the concrete with CBA and fly ash considerably influenced the reduction in the compressive, splitting, and flexural tensile strengths of the concrete. Additionally, the experimental results showed that fly ash insignificantly contributed to the reduction in the strength properties under both SSD and oven-dried conditions. Finally, the relationships between ultrasonic pulse velocity and the splitting tensile strength, flexural tensile strength, and compressive strength were investigated. Full article

(This article belongs to the Special Issue Properties and Novel Applications of Recycled Concrete and Mixed Aggregates)

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17 pages, 5407 KiB

Open AccessArticle

Recycled Concrete Aggregate for Medium-Quality Structural Concrete

by Dong Viet Phuong Tran, Abbas Allawi, Amjad Albayati, Thi Nguyen Cao, Ayman El-Zohairy and Yen Thi Hai Nguyen

Materials 2021, 14(16), 4612; https://doi.org/10.3390/ma14164612 - 17 Aug 2021

Cited by 18 | Viewed by 2290

Abstract

This paper reports an evaluation of the properties of medium-quality concrete incorporating recycled coarse aggregate (RCA). Concrete specimens were prepared with various percentages of the RCA (25%, 50%, 75%, and 100%). The workability, mechanical properties, and durability in terms of abrasion of cured [...] Read more.

This paper reports an evaluation of the properties of medium-quality concrete incorporating recycled coarse aggregate (RCA). Concrete specimens were prepared with various percentages of the RCA (25%, 50%, 75%, and 100%). The workability, mechanical properties, and durability in terms of abrasion of cured concrete were examined at different ages. The results reveal insignificant differences between the recycled concrete (RC) and reference concrete in terms of the mechanical and durability-related measurements. Meanwhile, the workability of the RC reduced vastly since the replacement of the RCA reached 75% and 100%. The ultrasound pulse velocity (UPV) results greatly depend on the porosity of concrete and the RC exhibited higher porosity than that of the reference concrete, particularly at the transition zone between the RCA and the new paste. Therefore, the sound transmission in the RC required longer times than that in the reference concrete. Moreover, a predictive equation relating the compressive strength to the UPV was developed. Full article

(This article belongs to the Special Issue Properties and Novel Applications of Recycled Concrete and Mixed Aggregates)

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18 pages, 3511 KiB

Open AccessArticle

Alkali-Activated Stainless Steel Slag as a Cementitious Material in the Manufacture of Self-Compacting Concrete

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

Materials 2021, 14(14), 3945; https://doi.org/10.3390/ma14143945 - 14 Jul 2021

Cited by 15 | Viewed by 2450

Abstract

This work develops the manufacture of self-compacting concrete (SCC) with 50% cement reduction. As an alternative binder to cement, the viability of using an alkali-activated combination of stainless steel slag (SSS) and fly ash (FA) has been demonstrated. SSS was processed applying three [...] Read more.

This work develops the manufacture of self-compacting concrete (SCC) with 50% cement reduction. As an alternative binder to cement, the viability of using an alkali-activated combination of stainless steel slag (SSS) and fly ash (FA) has been demonstrated. SSS was processed applying three different treatments. Binders were manufactured mixing 35% SSS with 65% FA, as precursors, and a hydroxide activating solution. This binder was replaced by the 50% cement for the manufacture of SCC. The results obtained show good mechanical properties and durability. The study shows a reduction in the use of cement in the manufacture of SCC reusing two wastes. Full article

(This article belongs to the Special Issue Properties and Novel Applications of Recycled Concrete and Mixed Aggregates)

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13 pages, 1901 KiB

Open AccessEditor’s ChoiceArticle

Feasible Use of Recycled Concrete Aggregates with Alumina Waste in Road Construction

by Manuel Cabrera, Mónica López-Alonso, Laura Garach, Javier Alegre, Javier Ordoñez and Francisco Agrela

Materials 2021, 14(6), 1466; https://doi.org/10.3390/ma14061466 - 17 Mar 2021

Cited by 4 | Viewed by 2233

Abstract

The management of different industrial by-products, such as recycled aggregates from construction and demolition waste and alumina by-products, as well as the reduction of landfill deposits by incorporating these products in a second life cycle, were the focus of this work. The aim [...] Read more.

The management of different industrial by-products, such as recycled aggregates from construction and demolition waste and alumina by-products, as well as the reduction of landfill deposits by incorporating these products in a second life cycle, were the focus of this work. The aim of this study was to demonstrate the technical viability of using these waste and by-product as a material for road pavement base layers. For this purpose, a real-scale application was carried out, and the behavior of three types of materials, applied on a section of an experimental road under real vehicle traffic conditions, was studied and compared. Three materials were used in these sections applied in the road sub-bases. First, a control material composed of a type of artificial gravel was used to be compared with the rest of materials; the second material was composed of recycled aggregates, and the third was composed of a mix of recycled aggregates and alumina waste. The results concluded that the effectiveness of the sections built using recycled aggregates and alumina waste was very positive and similar those constructed using natural aggregates. Full article

(This article belongs to the Special Issue Properties and Novel Applications of Recycled Concrete and Mixed Aggregates)

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