Evaluation of the ability of alkalophilic bacteria to form a biofilm on the surface of Portland cement-based mortars

2020 ◽  
Vol 108 (3) ◽  
pp. 304
Author(s):  
Heriberto Martinez Hernandez ◽  
Marielle Gueguen Minerbe ◽  
Yoan Pechaud ◽  
Thierry Sedran
Keyword(s):  
Bacillus Subtilis ◽  
Calcium Carbonate ◽  
Genetic Information ◽  
Biofilm Formation ◽  
Recycled Concrete ◽  
Bacillus Halodurans ◽  
Homogeneous Precipitation ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Bacterial Development

This paper investigates bacteria colonisation through biofilm formation, based on the premise that biofilm helps bacteria to have a better development. The aim is to homogenize bacterial growth on recycled concrete aggregates (RCA) to obtain a homogeneous precipitation of calcium carbonate (CaCO3). In previous studies, Bacillus halodurans C-125 was selected to perform biocarbonation on RCA to generate a coat of CaCO3 and diminish water absorption. Contrary to expectations, its poor development led to an heterogeneous CaCO3 precipitation, resulting in an inefficient treatment. Within the framework of this criterion the genetic information of B. halodurans C-125 was compared with a homologous specie “Bacillus subtilis str. 168” to know if it possessed the genes to encode Tas A and Tap A proteins. These proteins consolidate a robust biofilm in Bacillus subtilis str. 168, which promotes bacterial development and adhesion to a surface. Remarkably, B. halodurans C-125 lacks the genes to produce Tas A and Tap A. B. halodurans C-125 was also compared with a group of bacteria isolated from RCA to produce biofilm on MSgg media. Curiously, B. halodurans C-125 did not form a robust biofilm while the bacteria isolated from RCA did. Because of the capacity of the isolated bacteria to form biofilm, they were inoculated on a mortar disk with nutrient and MSgg broth. The results showed traces of bacterial development and precipitation of CaCO3 in form of calcite.

Green Concrete made with Recycled Concrete Aggregates: Fresh and Hardened Properties

2018 ◽  
Author(s):  
Driton R. Kryeziu ◽  
Armend Muja ◽  
Fisnik Kadiu ◽  
Visar Krelani ◽  
Besian Sinani ◽  
...  
Keyword(s):  
Recycled Concrete ◽  
Green Concrete ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Hardened Properties

scholarly journals Characterisation and Life Cycle Assessment of Pervious Concrete with Recycled Concrete Aggregates

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 209
Author(s):  
Adilson C. Paula Junior ◽  
Cláudia Jacinto ◽  
Thaís M. Oliveira ◽  
Antonio E. Polisseni ◽  
Fabio M. Brum ◽  
...  
Keyword(s):  
Environmental Performance ◽  
Treatment Plant ◽  
Recycled Concrete ◽  
Pervious Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Positive Contribution ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates

The search for environmental preservation and conservation of natural resources gives rise to new concepts and viable technical solutions on the path to sustainable development. In this context, this study’s main objective is to analyse the influence of recycled concrete aggregates (RCAs) on the development of pervious concrete, whose use as a floor covering represents an excellent device to mitigate the urban soil sealing phenomena. For this, mechanical and hydraulic tests were carried out, in addition to microstructural analyses and the assessment of its environmental performance. The results obtained were compared to reference studies also involving the incorporation of recycled aggregates. A pilot-scale case study was conducted, involving a parking space lined with pervious concrete moulded “in situ”. In laboratory tests, permeability coefficients and mechanical strengths compatible with the literature and above the normative limit for light traffic were found. The case study demonstrated higher permeability than in the laboratory, but the flexural strength was lower, being indicated only for pedestrian traffic. The environmental assessment showed that the RCA represents a positive contribution to the environmental performance of pervious concrete. Still, attention should be given to the recycled aggregate transport distance between the concrete plant and the RCA treatment plant.

scholarly journals Effect of Fiber Volume Fraction on Behavior of Concrete Beams Made with Recycled Concrete Aggregates

2019 ◽  
Vol 253 ◽  
pp. 02004
Author(s):  
Wael Alnahhal ◽  
Omar Aljidda
Keyword(s):  
Fiber Volume Fraction ◽  
Concrete Beams ◽  
Volume Fraction ◽  
Recycled Concrete ◽  
Flexural Behavior ◽  
Beam Specimen ◽  
Rc Beam ◽  
Fiber Volume ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates

This study investigates the effect of using different volume fractions of basalt macro fibers (BMF) on the flexural behavior of concrete beams made with 100% recycled concrete aggregates (RCA) experimentally. A total of 4 reinforced concrete (RC) beam specimens were flexural tested until failure. The parameter investigated included the BMF volume fraction (0%, 0.5%, 1%, and 1.5%). The testing results of the specimens were compared to control beam specimen made with no added fibers. The experimental results showed that adding BMF improves the flexural capacity of the tested beams.

scholarly journals Strength and Water Absorption of Sustainable Concrete Produced with Recycled Basaltic Concrete Aggregates and Powder

2021 ◽  
Vol 13 (11) ◽  
pp. 6277
Author(s):  
Ibrahim Sharaky ◽  
Usama Issa ◽  
Mamdooh Alwetaishi ◽  
Ahmed Abdelhafiz ◽  
Amal Shamseldin ◽  
...  
Keyword(s):  
Water Absorption ◽  
Edge Length ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Partial Substitution ◽  
Small Reduction ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Sustainable Concrete

In this study, the recycled concrete aggregates and powder (RCA and RCP) prepared from basaltic concrete waste were used to replace the natural aggregate (NA) and cement, respectively. The NA (coarse and fine) was replaced by the recycled aggregates with five percentages (0%, 20%, 40%, 60% and 80%). Consequently, the cement was replaced by the RCP with four percentages (0%, 5%, 10% and 20%). Cubes with 100 mm edge length were prepared for all tests. The compressive and tensile strengths (fcu and ftu) and water absorption (WA) were investigated for all mixes at different ages. Partial substitution of NA with recycled aggregate reduced the compressive strength with different percentages depending on the type and source of recycled aggregate. After 28 days, the maximum reduction in fcu value was 9.8% and 9.4% for mixtures with coarse RCA and fine RCA (FRCA), respectively. After 56 days, the mixes with 40% FRCA reached almost the same fcu value as the control mix (M0, 99.5%). Consequently, the compressive strengths of the mixes with 10% RCA at 28 and 56 days were 99.3 and 95.2%, respectively, compared to those of M0. The mixes integrated FRCA and RCP showed higher tensile strengths than the M0 at 56 d with a very small reduction at 28 d (max = 3.4%). Moreover, the fcu and ftu values increased for the late test ages, while the WA decreased.

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