Effect of Degradation on Mechanical Strengths of Alkali-Activated Fines in Stabilized Construction and Demolition Waste Aggregates

2022 ◽  
Vol 34 (2) ◽  
Author(s):  
Luca Tefa ◽  
Marco Bassani ◽  
Bartolomeo Coppola ◽  
Paola Palmero
Keyword(s):  
Construction And Demolition Waste ◽  
Demolition Waste ◽  
Mechanical Strengths ◽  
Alkali Activated

scholarly journals Evaluation of the physical-mechanical properties of cement-lime based masonry mortars produced with mixed recycled aggregates

2020 ◽  
Vol 70 (337) ◽  
pp. 210 ◽  
Author(s):  
R. L.S. Ferreira ◽  
M. A.S. Anjos ◽  
E. F. Ledesma ◽  
J. E.S. Pereira ◽  
A. K.C. Nóbrega
Keyword(s):  
Mechanical Properties ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Demolition Waste ◽  
Long Run ◽  
Lime Mortars ◽  
Binder Ratio ◽  
Mechanical Strengths ◽  
One Way Anova

This study investigated the physical-mechanical effects of cement-lime mortars containing recycled aggregate of construction and demolition waste (CDW). The natural aggregate (NA) was replaced by volume at 25%, 50%, 75% and 100% by mixed recycled aggregate (MRA) obtained from the CDW crushing. Five types of mortars were prepared with a volumetric ratio of 1:1:6 (cement, lime and aggregate) and water/binder ratio based on the fixed consistency of 260 mm. The effects of MRA on fresh and hardened mortars’ properties were analyzed. The results were analyzed using a one-way ANOVA. MRA incorporation improved most of the physical-mechanical properties of mortars tested, except for hardened bulk density, water absorption and porosity. In the long-run, mechanical strengths significantly increased in all compositions, especially those with higher percentages of MRA. The results obtained showed that the use of MRA in masonry mortars is an alternative to reduce the generation of waste and consumption of natural resources.

Construction and Demolition Waste (CDW) valorization in alkali activated bricks

2019 ◽  
pp. 495-499
Author(s):  
I. Lancellotti ◽  
V. Vezzali ◽  
L. Barbieri ◽  
C. Leonelli ◽  
A. Grillenzoni
Keyword(s):  
Construction And Demolition Waste ◽  
Demolition Waste ◽  
Alkali Activated

scholarly journals Preliminary Analysis of the Use of Construction Waste to Replace Conventional Aggregates in Concrete

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
Keyword(s):  
Compressive Strength ◽  
Coarse Aggregate ◽  
Recycled Aggregate Concrete ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Fine Aggregate ◽  
Demolition Waste ◽  
Fine Aggregates ◽  
Mechanical Strengths

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.

scholarly journals Acid Resistance of Lightweight Brick Powder Based Alkali Activated Material from Construction and Demolition Wastes

2018 ◽  
Author(s):  
Kai Tai Wan ◽  
Amende Sivanathan ◽  
Gediminas Kastiukas ◽  
Xiangming Zhou
Keyword(s):  
Acid Resistance ◽  
Strength Loss ◽  
Construction And Demolition Waste ◽  
Demolition Waste ◽  
Construction And Demolition Wastes ◽  
Brick Powder ◽  
Structural Applications ◽  
The Matrix ◽  
Similar Density ◽  
Alkali Activated

The annual construction and demolition waste (CDW) generated from EU construction sector was 850 million tons, which represented 31% of the total waste generation and about 28% of CDW was ceramics (bricks and tiles). In this study, the feasibility of using CDW brick powder as the precursor of alkali activated mortar (AAM) and extruded polystyrene (XPS) as the lightweight aggregates to form lightweight brick powder AAM (LW-BP-AAM) for non-structural applications was investigated. The thermal conductivity of LP-BPAAM was 0.112 W/m·K with density of about 1,135 kg/m3 which was lower than the counterparts with similar density in literature. The acid resistance of LW-BP-AAM is comparable to conventional fly ash based AAM and superior than ordinary Portland cement. From the scanning electron microscopy with energy dispersive X-ray spectroscopy, there was no severe damage on the surface of LW-BP-AAM but aluminate was removed from the matrix which was further verified in Fourier transform infrared spectroscopy. The mass and strength loss of LP-BP-AAM was 1.5% and 33%, respectively. Although the compressive strength of the LP-BP-AAM was low (about 1.8 MPa), it can be improved by optimising the particle size of the XPS aggregates.

scholarly journals Construction and Demolition Waste as Recycled Aggregates in Alkali-Activated Concretes

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4016 ◽  
Author(s):  
Zahra Abdollahnejad ◽  
Mohammad Mastali ◽  
Mahroo Falah ◽  
Tero Luukkonen ◽  
Mehran Mazari ◽  
...  
Keyword(s):  
Construction And Demolition Waste ◽  
Recycled Aggregates ◽  
Demolition Waste ◽  
High Calcium ◽  
High Calcium Concentration ◽  
One Step ◽  
Hardened State ◽  
Global Construction ◽  
Alkali Activated Concrete ◽  
Alkali Activated

The growth of global construction has contributed to an inevitable increase in the amount of construction and demolition (C&D) waste, and the recycling of C&D waste as aggregates in concrete is receiving increased interest, resulting in less demand for normal aggregates and bringing a potential solution for the landfilling of wastes. Recently, several studies have focused on the use of C&D waste in alkali-activated concrete to move one step closer to sustainable concretes. This paper focuses on the main mechanisms of using C&D waste in the resulting physical, mechanical, and durability properties of alkali-activated concrete in fresh and hardened state properties. The main difficulties observed with recycled aggregates (RA) in concrete, such as high levels of water demand, porous structure, and low mechanical strength, occur in RA alkali-activated concretes. These are associated with the highly porous nature and defects of RA. However, the high calcium concentration of RA affects the binder gel products, accelerates the hardening rate of the concrete, and reduces the flowability of alkali-activated concretes. For this reason, several techniques have been investigated for modifying the water content and workability of the fresh matrix and for treating RA and RA/alkali-activated binder interactions to produce more sustainable alkali-activated concretes.

Stabilisation of construction and demolition waste with a high fines content using alkali activated fly ash

2018 ◽  
Vol 170 ◽  
pp. 26-39 ◽  
Author(s):  
Nuno Cristelo ◽  
Ana Fernández-Jiménez ◽  
Castorina Vieira ◽  
Tiago Miranda ◽  
Ángel Palomo
Keyword(s):  
Fly Ash ◽  
Construction And Demolition Waste ◽  
Demolition Waste ◽  
Fines Content ◽  
Alkali Activated
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