Cementitious binders and reclaimed asphalt aggregates for sustainable pavement base layers: Potential, challenges and research needs
TL;DR: In this article, the use of RAP aggregates with cementitious materials for pavement foundation layers is discussed, and a review of the properties of fresh and hardened RAP in cementitious matrices, as well as changes in the microstructure.
About: This article is published in Construction and Building Materials.The article was published on 2020-12-30. It has received 15 citations till now. The article focuses on the topics: Cementitious & Literature survey.
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TL;DR: In this paper, the effect of milling speed on the RAP particle agglomeration rate was evaluated through a pavement maintenance project and the size-susceptibility of the aggloomate d particles, gradation deviation of the recycled mixture, and morphology classification of RAP particles were discussed.
18 citations
TL;DR: In this paper , the use of residues from the processing of bauxite and glass powder as precursors for the preparation of geopolymers was evaluated using compressive strength tests.
Abstract: In this study, the use of residues from the processing of bauxite and glass powder as precursors for the preparation of geopolymers was evaluated. The route used was an alkaline solution of NaOH with three different molarities. Nine compositions of the percussion (waste) and the activator used were verified. XRF, XRD, laser granulometry, SEM, FTIR, BET, DTG, and compressive strength tests were used to verify the physical and chemical characteristics of the residues used and the geopolymers obtained. Some geopolymers developed efflorescence on their surfaces, indicating a higher alkali content. The compressive strength increased with the addition of small amounts of Portland cement (5%). The composition with the best performance exhibited a compressive strength of 11.35 ± 1.23 MPa after 28 days. The results of the chemical analysis showed the formation of the characteristic gel of the geopolymers. However, the primary finding was that the amount of activator (sodium hydroxide) proved to be inefficient because of the intrinsic alkaline properties of the red mud, which were already effective in the alkaline activation process.
17 citations
TL;DR: In this article, the authors evaluated the impact of the combination of these two aspects on CO2 emissions mitigation of road life cycle is less known even though it is critical to the longer-term road transportation decarbonization and long-range policy making for transportation sector, especially under latest worldwide net-zero carbon emission goal.
14 citations
TL;DR: In this paper , the authors presented the properties of alkaline-activated pastes using sugarcane bagasse ash (SCBA), granulated blast furnace slag (BFS) and metakaolin (MK) as precursors.
Abstract: BFS-MK-based alkali-activated materials are well established as an alternative for sustainable and green construction. This work aims to collaborate and encourage the use of biomass ashes, such as sugarcane bagasse ash (SCBA), as a precursor in alkali-activated materials (AAM). This ash is a rich source of aluminosilicate, which is a primary requirement for this application. In addition, this waste is still an environmental liability, especially in developing countries, and with a large volume of annual production. Thus, in this research, alkali-activated pastes (AA) were produced using sugarcane bagasse ash (SCBA), granulated blast furnace slag (BFS) and metakaolin (MK) as precursors. In addition, environmental gains were encouraged with energy savings, with no extra reburn or calcination steps in the SCBA. Thus, the precursors were characterized by laser granulometry, X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The pastes were produced by mixing the precursors with the activator, composed of a mixture of sodium hydroxide 8 mol/L and sodium silicate. Aiming to study the incorporation of SCBA, all samples have a precursor/activator ratio and a BFS/(BFS + MK) ratio constant of 0.6. The compressive strength analysis, FTIR, XRD, TGA, SEM and isothermal calorimetry analyses pointed out the occurrence of alkaline activation in all proposed samples for curing times of 7, 28 and 91 days. The sample GM0.6-BA0 (15% SCBA) achieved the highest compressive strength among the samples proposed (117.7 MPa, at 91 days), along with a good development of strength throughout the curing days. Thus, this work presents the properties of alkaline-activated pastes using SCBA as a sustainable and alternative precursor, seeking to encourage the use of raw materials and alternative waste in civil construction.
12 citations
TL;DR: In this paper, the feasibility of using industrial waste (i.e., magnesium industry waste (MW) and red mud (RM) as supplementary cementitious materials was evaluated, and a PC/MW/RM mixture containing 75% PC substituted with 25% of MW and RM was developed as a ternary binder.
8 citations
References
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TL;DR: A brief history and review of geopolymer technology is presented with the aim of introducing the technology and the vast categories of materials that may be synthesized by alkali activation of aluminosilicates as mentioned in this paper.
Abstract: A brief history and review of geopolymer technology is presented with the aim of introducing the technology and the vast categories of materials that may be synthesized by alkali-activation of aluminosilicates. The fundamental chemical and structural characteristics of geopolymers derived from metakaolin, fly ash and slag are explored in terms of the effects of raw material selection on the properties of geopolymer composites. It is shown that the raw materials and processing conditions are critical in determining the setting behavior, workability and chemical and physical properties of geopolymeric products. The structural and chemical characteristics that are common to all geopolymeric materials are presented, as well as those that are determined by the specific interactions occurring in different systems, providing the ability for tailored design of geopolymers to specific applications in terms of both technical and commercial requirements.
3,302 citations
TL;DR: In this paper, the effect of mineral properties on the compressive strength of the synthesized geopolymer was investigated, and it was shown that a wide range of natural Al-Si minerals could serve as potential source materials for the synthesis of geopolymers.
1,424 citations
TL;DR: Aluminosilicate-based alkaline cements have been classified into five categories as discussed by the authors, and the key advances made in the understanding of synthetic gels are discussed, which ultimately finds hybrid cements to be technologically viable materials for contemporary construction.
1,104 citations
TL;DR: In this paper, a brief discussion of the class of cementing materials known as "alkali-activated binders" is provided, which are identified to have potential for utilization as a key component of a sustainable future global construction materials industry.
1,052 citations
TL;DR: In this article, a statistical study of the effect on the polymerization process of the molar ratio of the component oxides and the water content of the mixture showed the latter to be a critical parameter.
933 citations