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Number of results: 5
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Abstract

This article presents test results of cement paste and binders with admixture of hydrophilic or hydrophobic nanosilica. The aim of the study was to determine the influence of nanosilica type and mixing method on compressive strength, porosity, and bulk density of cement paste, also on hydration heat of cement binders. The binder compounds were mixed in high speed mixer in order to provide the highest possible dispersion of nanoparticles in the binder before adding it to mixing water. Two mixing methods were studied. The admixtures increased the reactivity of cement binders. Both nanosilica types increased early compressive strength by 25% in comparison with control series. The increase in 28-day compressive strength was observed with the admixture of hydrophilic nanosilica. The differences in dynamics of binders rate of hydration and development of cement pastes compressive strength denote different reaction mechanisms of both types of nanosilica. Application of higher rotation speeds does not guarantee satisfactory mixing of the binder components. For compressive strength enhancement of cement paste prolonged mixing time occurred to be more important.

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Authors and Affiliations

J. Popławski
M. Lelusz
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Abstract

The aim of this research was to develop a composite material to be used as an elastomeric core of the artificial intervertebral disc. Two types of polyurethane composites with non-modified SiO2 and SiO2 modified NH2 group were obtained. The composites made of these materials have different filler content. The effect of modifying fillers for the structure and properties of these materials were investigated.

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Authors and Affiliations

Bartłomiej Waśniewski
Joanna Ryszkowska
Konstanty Skalski
Marek Pawlikowski
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Abstract

Presently, finding effective, simple, inexpensive, hygienic and safe pest control agents are the biggest challenges in management of stored product insects, where those features are available in most physical factors. The insecticidal efficiency of four diversified physical control agents (ultraviolet and microwave irradiations, thermal remediation and silica nanoparticles) were assayed against the most common coleopteran insect species ( Sitophilus oryzae L. and Tribolium castaneum Herbst) on stored wheat. Exposing tested insects to microwave irradiations (2450 MHz) for 25 sec gave preventive efficiency for stored material, which reached 97.68 and 99.02%, respectively. Sufficient exposure periods to kill 50% of the coleopteran adults (LT50%) were 13 and 14 sec, respectively. For effective control with UV radiations, S. oryzae should be exposed for 12 h and T. castaneum for 24 h. An exposure period of 24 h caused progeny reduction 95.24 and 89.72% and gave preventive efficiency of 94.25 and 93.37%, respectively. Values of LT50% were 56.76 and 74.04 h, respectively. Exposing infested samples of the tested species to 70oC for 10 min killed 100% of adults and caused complete cessation of egg laying. Furthermore, 65°C or 70°C caused full progeny reduction. The lowest level of stored product weight loss (1.15 and 1.35%, respectively) occurred at 70°C, where sufficient exposure temperatures to kill 50% of the coleopteran adults (LTD50%) were 60.95°C and 61.63°C, respectively. Synthetic silica nanoparticles (SSiNPs) were more toxic against the tested populations than bio-silica nanoparticles (BSiNPs) after 48–72 h. A concentration of 1.00 g kg–1 of tested silica nanoparticles caused significant reduction in adult populations, saved wheat grain vitality and gave least lost weights of flour (3.35–6.85%).
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Authors and Affiliations

Khalil A. Draz
1
Magdy I. Mohamed
2
Reda M. Tabikha
1
Adnan A. Darwish
1
Mohamed A. Abo-Bakr
1

  1. Plant Protection Department, Faculty of Agriculture, Damanhour University, Damanhour, Egypt
  2. Stored Product Pests Department, Plant Protection Research Institute, Agricultural Research Center, Alexandria, Egypt
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Abstract

Due to the increasing necessity of building on soils with insufficient bearing capacity, the development of methods for soil improvement is an important geotechnical engineering issue. One of the innovative methods of soil stabilisation is the use of nano-additives. The paper presents the influence of nanosilica on the bearing capacity under the footing under undrained conditions. For this purpose, a simple and quick unconfined compression test was used to evaluate the undrained shear strength of selected silty soil. Tests were conducted for soil without additives and with nanosilica contents of 1, 3 and 5%. All samples were compacted to the maximum dry density in a Proctor apparatus, and strength tests were conducted after 7 days of curing. The results clearly show an increase in undrained shear strength with increasing nanosilica content. Based on these data, a parametric analysis of the bearing capacity under the strip footing was performed for 4 variants of nanosilica content and for 9 loading cases. Thus, the impact of stabilisation in a practical engineering issue was presented. For all load cases the optimal dimensions of the foundation were determined. In addition, for the selected case, calculations were made for a fixed foundation dimension. All computations were performed in accordance with Eurocode 7 with GEO5 software.
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Authors and Affiliations

Matylda Tankiewicz
1
ORCID: ORCID
Jakub Mońka
1
ORCID: ORCID
Zofia Zieba
1
ORCID: ORCID

  1. Wrocław University of Environmental and Life Sciences, Department of Civil Engineering, Norwida 25, 50-375 Wrocław, Poland
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Abstract

This study provides a comparative analysis of natural nanosilica (NSn), which is an extract of natural silica sand processed into nanosilica with commercial nanosilica (NSc) derived from semiconductor industrial waste, in 80 MPa high performance concrete (HPC). The percentage of using nanosilica is (3%, 5%, 10%, 15%) by weight of cement used directly and combined with 5% silica fume. Analysis was carried out through compressive strength test, durability through permeability test, rapid chloride penetration test (RCPT), and microstructure test through scanning electron microscopy (SEM). The results of the analysis show that natural nanosilica is equivalent to commercial nanosilica, in applications it is better to use silica fume incorporation. The optimum percentage of using NSn10% and (SF) 5%, while 5% NSc and 5% SF, in these proportions shows the best compressive strength and durability. It’s just that the use of natural nanosilika is 5% more than commercial nanosilika. The benefit of this research is that natural materials such as silica sand with high SiO2 content, can be processed into nanosilica as an advanced material, which can be used as an eco-friendly construction material.
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Authors and Affiliations

A.R. Indra Tjahjani
1
ORCID: ORCID
Mohamad Ali Fulazzaky
2
ORCID: ORCID
Jonbi Jonbi
1
ORCID: ORCID
Nuryani Tinumbia
1
ORCID: ORCID
Wita Meutia
1
ORCID: ORCID
Daral Suraedi
1
ORCID: ORCID
Prima Ranna
1
ORCID: ORCID

  1. Pancasila Univesity, Faculty of Civil Engineering, Jagakarsa, South Jakarta, 12630, Indonesia
  2. Ton Duc Thang University, Sustainable Development in Civil Engineering Research Group (SDCE), 19 Nguyên Huu Tho, Tân Hung, Quân 7, Hô Chí Minh 700000, Vietnam

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