An overview on the efficiency of different pretreatment techniques for recycled concrete aggregate

Ouyang, Kai; Shi, Caijun; Chu, Huaqiang; Guo, Hui; Song, Baixing; Ding, Yao; Guan, Xiaohong; Zhu, Jianping; Zhang, Haibo; Wang, Yuli; Zheng, Jinju

doi:10.1016/j.jclepro.2020.121264

Cited by 107 publications

(47 citation statements)

References 120 publications

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“…The ability of Hg 0 in entering any kind of surface is also testified by techniques to determine porosity by mercury intrusion [36,37] and references therein. The processes that favor the stabilization and mobility of mercury need to be clarified and require specific investigations that were not within the aims of the present paper.…”

Section: Discussionmentioning

confidence: 99%

A New Low-Cost and Reliable Method to Evaluate the Release of Hg0 from Synthetic Materials

Lazzaroni

Nisi

Rappuoli³

et al. 2020

Processes

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Mercury is a toxic and noxious element and is the only metal that naturally occurs as gas. One of the most challenging topics (included in the United Nations Minimata convention) is to understand the adsorption–release processes of manmade materials (e.g., concrete, bricks, tiles, painting). Adsorption of Hg by construction and demolition waste materials has recently been studied, but investigations on how much Hg0 can be released from these products are rather poor. The abandoned mining site of Abbadia San Salvatore (Siena, central Italy) where, for about one century, cinnabar was roasted to produce liquid mercury, is known for the high concentrations of (i) Hg0 in edifices and structures and (ii) total and leachate Hg in synthetic materials. In the present paper, a new, simple and low-cost method to measure the amount of GEM (Gaseous Elemental Mercury) released from anthropic materials (concrete, wall rocks, and tiles) located in the Hg0-rich environments of the former mining site, is proposed. The efficiency of a specific paint that was supposed to act as blocking agent to Hg0 was also tested.

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Section: Discussionmentioning

confidence: 99%

A New Low-Cost and Reliable Method to Evaluate the Release of Hg0 from Synthetic Materials

Lazzaroni

Nisi

Rappuoli³

et al. 2020

Processes

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“…40 A similar study has found that Pseudomonas aeruginosa species exhibit higher clearing zone with zinc oxide as Zn source, whereas Pseudomonas species produces higher halo zone with ZnO and ZnSO 4. 129.9 ± 0.78 l PSB - 10 10 -6 137.63 ± 0.87 k PSB - 11 10 -6 365.93 ± 0.98 a PSB - 12 10 -4 180.56 ± 0.86 d PSB - 13 10 -6 164.46 ± 1.25 g PSB - 14 10 -6 131.36 ± 0.87 l F=df (2,8) 5.413**…”

Section: Qualitative Estimation Of P Solubilizing Potential Of the Ismentioning

confidence: 99%

“…The limited counts of PSB (Table 2) and less production of Indole-3 acetic acid (Table 10) may be attributed as among the reasons for the stunted growth of agricultural crops in the present study area, and this deserves further investigation by using PSB strains as bioinoculants to overcome the stunted growth. (2,8) 0.642* PSBT - 11 10.166 ± 0.088 PSB -Alone 4.6333 ± 0.088 F=df (2,8) 0.700*…”

Section: Production Of Indole-3-acetic Acid By P Solubilizing Bacteriamentioning

confidence: 99%

“…1 Phosphorus has long been considered the second most limiting nutrient for plant growth in terrestrial ecosystems after nitrogen. 2 The total phosphorus content in the soil of arid zones in India ranges from 560 to 900 kg/ha but the available phosphorus in soil is only 15 -25 kg/ha, it's quite low comparatively with total phosphorus. The release of insoluble and fixed forms of phosphorus is an imperative feature for increasing the P accessibility in soil.…”

Section: Introductionmentioning

confidence: 99%

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Detection of phosphate solubilizing bacteria from rhizospheric soil of agricultural crops in Erode district

Sharmila¹,

Anusha²,

Vinothini³

et al. 2021

Int J Life Sci Pharm Res

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Phosphorus is a second key plant nutrient and the 'kingpin' in Indian agriculture, occupies an exclusive position both in conventional as well as in alternative agriculture. However, the phosphate solubilizing bacteria (PSB) converts the insoluble phosphate into biologically available form through the production of organic acids. Hence, the present study explored the presence of PSB from the Karavalasu agricultural field, Sivagiri, Erode District. The percentages of bacterial solubilization were 14.40 % to 60.70 % in non rhizospheric and rhizospheric crops adhering to root soils respectively.Out of 14 morphologically distinct isolates of PSB, two isolates (PSB8 and PSB11) displayed high P solubilization efficiency on solid medium amended with tricalcium phosphate Ca 3 (PO 4) 2 as the insoluble source (0.2 %). They were further characterized and continued with identification used by Picovskaya's selective medium. The selective medium was incubated for 48 hours at a temperature of 37°C. The characterization was done for two strains by looking at the colony morphology and biochemical properties. The isolates showed the optimum pH for growth of the organism was pH 7 and the optimum temperature was 37 °C. Two strains exhibited significant release of P at the concentrations of 1.96 and 2.26 mg/l by PSB-8 and PSB-11 respectively on 10 th day of incubation in broth medium amended with Ca 3 (PO 4) 2. The strains released acids as evident by decline in pH of the broth medium. They also secreted IAA with the maximum of 17.06 mg/l by PSB-8 with Ca 3 (PO 4) 2 as a source of P. The potential strains for P solubilization were identified using 16S rRNA as Bacillus megaterium and Pseudomonas aeruginosa for further application as bioinoculants to agricultural fields. Finally we afford some indication that the use of Phosphate solubilising microorganisms will support sustainable agriculture and conclude that this knowledge is ready for commercial utilization in various regions worldwide.

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“…The main difference between Recycled Concrete Aggregate (RCA) and Natural Aggregate (NA) relies on the presence of the existing Attached Mortar (AM) layer on the recycled aggregate surface, and, consequently, the presence of an Interfacial Transition Zone (ITZ) between AM and original aggregate [4,5]. An investigation carried out by Verian et al [4] showed that AM makes the RCA a more porous material compared to NA.…”

Section: Introductionmentioning

confidence: 99%

Effects of Freeze-Thaw and Wet-Dry Cycles on Tension Stiffening Behavior of Reinforced RAC Elements

et al. 2021

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In the last several decades, the growth of Construction and Demolition Waste (CDW) production and the increased consumption of natural resources have led to promoting the use of secondary raw materials for a more sustainable construction. Specifically, the use of Recycled Concrete Aggregate (RCA), derived from waste concrete, for the production of Recycled Aggregate Concrete (RAC) has attracted a significant interest both in industry and in academia. However, the use of RAC in field applications still finds some barriers. In this context, the present study investigates experimentally the effects of freeze-thaw and wet-dry cycles on the stress transfer mechanisms of reinforced RAC elements through tension stiffening tests. First of all, the paper presents a detailed analysis of the degradation due to the aging process of RAC with RCAs obtained from different sources. Particularly, the results of tension stiffening tests are analyzed in terms of crack formation and propagation, matrix tensile strength contribution and steel-to-concrete bond. The results highlight that the pre-cracking elastic modulus, the first crack strength as well as the maximum concrete strength are strongly influenced by the presence of the Attached Mortar (AM) in RCA, as the former affects the concrete’s open porosity. Therefore, the amount of AM is identified as the key parameter for the evaluation of durability of reinforced RAC members: a degradation-law is also proposed which correlates the initial concrete open porosity with the damage observed in reinforced RAC elements.

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An overview on the efficiency of different pretreatment techniques for recycled concrete aggregate

Cited by 107 publications

References 120 publications

A New Low-Cost and Reliable Method to Evaluate the Release of Hg0 from Synthetic Materials

A New Low-Cost and Reliable Method to Evaluate the Release of Hg0 from Synthetic Materials

Detection of phosphate solubilizing bacteria from rhizospheric soil of agricultural crops in Erode district

Effects of Freeze-Thaw and Wet-Dry Cycles on Tension Stiffening Behavior of Reinforced RAC Elements

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