Rendering mortars with incorporation of very fine aggregates from construction and demolition waste

2019 ◽  
Vol 229 ◽  
pp. 116844 ◽  
Author(s):  
Sara Jesus ◽  
Cinthia Maia ◽  
Catarina Brazão Farinha ◽  
Jorge de Brito ◽  
Rosário Veiga
Author(s):  
Kamil Krzywiński ◽  
Łukasz Sadowski ◽  
Damian Stefaniuk ◽  
Aleksei Obrosov ◽  
Sabine Weiß

AbstractNowadays, the recycled fine aggregate sourced from construction and demolition waste is not frequently used in manufacturing of epoxy resin coatings. Therefore, the main novelty of the article is to prepare green epoxy resin coatings modified with recycled fine aggregate in a replacement ratio of natural fine aggregate ranged from 20 to 100%. The microstructural properties of the aggregates and epoxy resin were analyzed using micro-computed tomography, scanning electron microscopy and nanoindentation. The macroscopic mechanical properties were examined using pull-off strength tests. The highest improvement of the mechanical properties was observed for epoxy resin coatings modified with 20% of natural fine aggregate and 80% of recycled fine aggregate. It has been found that even 100% of natural fine aggregate can be successfully replaced using the recycled fine aggregate with consequent improvement of the pull-off strength of analyzed epoxy resin coatings. In order to confirm the assumptions resulting from the conducted research, an original analytical and numerical failure model proved the superior behavior of modified coating was developed.


2014 ◽  
Vol 600 ◽  
pp. 297-307 ◽  
Author(s):  
Paulo Roberto Lopes Lima ◽  
Romildo Dias Toledo Filho ◽  
Otávio da Fonseca Martins Gomes

In this work it was studied the influence of recycled fine aggregate obtained from construction and demolition waste (CDW) on the rheological properties of Portland cement mortars. The CDW was initially separate in their main constituents (mortar, ceramic and concrete debris) at the laboratory and then grinded separately to the sand size in order to generate more homogeneous fine aggregates. The characterization of the natural and recycled sands was carried out through physical tests, X-ray diffraction, scanning electron microscopy (SEM), and image analysis (shape and texture description parameters). A conventional mortar and three mortars containing recycled sands were produced with a sand/cement ratio of 4 and consistency index of 255±5 mm. The consistency was kept constant by ranging the water-cement ratio from 0.58 to 1.14. The rheological study was performed using a rotating viscometer to obtain torque-rotation ratio and to calculate the yield stress and plastic viscosity. The results indicate that the presence of recycled aggregate causes a lowering of both yield stress and plastic viscosity with respect to the mortar containing natural aggregate.


Buildings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 81
Author(s):  
Fernando A. N. Silva ◽  
João M. P. Q. Delgado ◽  
António C. Azevedo ◽  
António G. B. Lima ◽  
Castorina S. Vieira

This work aims to study the influence of using construction and demolition waste in the replacement of coarse and fine aggregate to produce recycled aggregate concrete (RAC). A moderate compressive strength concrete made with usual fine and coarse aggregate was used as a benchmark material. Compressive and split tensile tests were performed using 120 cylindrical concrete specimens with 150 mm diameter and 300 mm length. Four-point flexural tests in reinforced beams made with conventional concrete and RAC were performed. The results obtained showed that the use of recycled fine aggregates, in both percentages of substitution investigated—50% and 100%— did not generate any deleterious influence on the values of compressive strength and split tensile strength of the RACs produced. Tin fact, the mechanical strengths of RACs produced with recycled fine aggregate were equal or higher than those from the reference concrete. The same behavior was not observed, however, when the recycled coarse aggregate was used. For this case, decreases in concrete mechanical strengths were observed, especially in compressive strength, with values around 35% lower when compared to the reference concrete. Tensile mechanical tests results confirmed the excellent behavior of all RACs made with replacement of usual fine aggregates by recycled. Bending tests performed in reinforced RAC beams had as objective to evaluate the deformation profile of the beams. The obtained results showed that RAC beams with full replacement of usual fine aggregate by the recycled aggregates have presented little changes in the global behavior, an aspect that encourages its use.


2020 ◽  
Vol 10 (3) ◽  
pp. 1018 ◽  
Author(s):  
Hisham Hafez ◽  
Reben Kurda ◽  
Rawaz Kurda ◽  
Botan Al-Hadad ◽  
Rasheed Mustafa ◽  
...  

The aim of this critical review is to show the applicability of recycled fine aggregates (RFA) in concrete regarding technical performance, environmental impact, energy consumption and cost. It is not possible to judge the performance of concrete by considering one dimension. Thus, this study focussed on the fresh and hardened (e.g., mechanical and durability) properties and environmental and economic life cycle assessment of concrete. Most literature investigated showed that any addition of recycled fine aggregates from construction and demolition waste as a replacement for natural fine aggregates proves detrimental to the functional properties (quality) of the resulting concrete. However, the incorporation of recycled fine aggregates in concrete was proven to enhance the environmental and economic performance. In this study, an extensive literature review based multi criteria decision making analysis framework was made to evaluate the effect of RFA on functional, environmental, and economic parameters of concrete. The results show that sustainability of RFA based concrete is very sensitive to transportation distances. Several scenarios for the transportation distances of natural and recycled fine aggregates and their results show that only if the transportation distance of the natural aggregates is more than double that of RFA, e the RFA based concrete alternatives would be considered as more sustainable.


Author(s):  
Er. Tajamul Islam

Abstract: Glass is widely used in our lives through manufactured products such as sheet glass, bottles, glassware, and vacuum tubing. Glass is an ideal material for recycling. The use of recycled glass helps in energy saving. The recycled glass has significant contributions to the construction field for concrete production. The application of glass in architectural concrete still needs improvement. Many experiments were conducted to explore the use of waste glass as coarse and fine aggregates for both ASR (Alkali-Silica-Reaction) in concrete. The accumulation and management of construction and demolition waste, which increases along with the continuous spreading of urbanization and industrialization. Construction and demolition waste can be recycled and used as a raw material for new applications. Recycled brick aggregates recovered from demolished masonry structures can be utilized in the manufacture of new concrete mixtures. Hence, partial replacement of fine aggregate by the other compatible material like sintered fly ash, crushed rock dust, quarry dust, glass powder, recycled concrete dust, and others are being researched from the past two decades to conserve the ecological balance. additional plasticizers have been used for this project for improving their workability. In this project experimental studies on the concrete of M20 grade with partial replacement of fine aggregates by crushed brick powder (replacement by 5%, 10%, 15%,20%,30%) and crushed glass powder (replacement by 5%, 10%, 15%). The compressive strength of M20 grades of concrete at different days (3 days 7 days, 28 days) has been determined along with the measurements of workability in the slump test. The trial cubes were cast and tested at different stages. When fine aggregates are replaced by 30% crushed brick powder. The decrease in strength at the end of 28 days was found to be ranging from 22.2% and 9.81%. when fine aggregates are replaced by 20% crushed glass powder, decrease in the targeted strength at the end of 28 days was found to be ranging between 3.0%and 8.6%. The slump value was found to be decreasing in the case of crushed brick powder, while it was found increasing substantially in the case of glass of glass powder. A combination of both alternatives i.e., brick powder (20%) and glass powder (15%) were also studied and it was found that the compressive strength at the end of 28 days for M20 grade of concrete is 96.13%. Keywords: Glass powder, brick powder, workability, fine aggregate; ASR (Alkali-Silica Reaction); Compressive strength


2019 ◽  
Author(s):  
A.P.K.D. Mendis ◽  
◽  
A. Samaraweera ◽  
D.M.G.B.T. Kumarasiri ◽  
D. Rajini ◽  
...  

2020 ◽  
Vol 6 (9) ◽  
pp. 73169-73180
Author(s):  
Kelly Patrícia Torres Vieira Brasileiro ◽  
Bacus de Oliveira Nahime ◽  
Michell Macedo Alves ◽  
Pâmela Millena Kunan ◽  
Vitor Alvares ◽  
...  

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