Effect of Corrosion Inhibitors on In Situ Leak Repair by Precipitation of Calcium Carbonate in Potable Water Pipelines

2017 ◽  
Vol 51 (15) ◽  
pp. 8561-8568 ◽  
Author(s):  
Fei Wang ◽  
Christina L. Devine ◽  
Marc A. Edwards
Keyword(s):  
Calcium Carbonate ◽  
Corrosion Inhibitors ◽  
Potable Water ◽  
Water Pipelines

A TEM study of the microstructure of avian eggshells

1992 ◽  
Vol 50 (2) ◽  
pp. 1102-1103
Author(s):  
S. Q. Xiao ◽  
S. Baden ◽  
A. H. Heuer
Keyword(s):  
Electron Microscope ◽  
Calcium Carbonate ◽  
Nucleation And Growth ◽  
Growth Mechanisms ◽  
Shell Surface ◽  
Thin Sections ◽  
Polycrystalline Metals ◽  
Transmission Electron ◽  
Nucleation And Growth Mechanisms

The avian eggshell is one of the most rapidly mineralizing biological systems known. In situ, 5g of calcium carbonate are crystallized in less than 20 hrs to fabricate the shell. Although there have been much work about the formation of eggshells, controversy about the nucleation and growth mechanisms of the calcite crystals, and their texture in the eggshell, still remain unclear. In this report the microstructure and microchemistry of avian eggshells have been analyzed using transmission electron microscope (TEM) and energy dispersive spectroscopy (EDS).Fresh white and dry brown eggshells were broken and fixed in Karnosky's fixative (kaltitanden) for 2 hrs, then rinsed in distilled H2O. Small speckles of the eggshells were embedded in Spurr medium and thin sections were made ultramicrotome.The crystalline part of eggshells are composed of many small plate-like calcite grains, whose plate normals are approximately parallel to the shell surface. The sizes of the grains are about 0.3×0.3×1 μm3 (Fig.l). These grains are not as closely packed as man-made polycrystalline metals and ceramics, and small gaps between adjacent grains are visible indicating the absence of conventional grain boundaries.

scholarly journals A comparative study of trenchless technologies versus traditional open trenching for the replacement of ageing potable water pipelines

2014 ◽  
Author(s):  
◽  
Shanley Hay
Keyword(s):  
South Africa ◽  
Potable Water ◽  
Survey Questionnaire ◽  
Support Tool ◽  
Total Cost ◽  
The Public ◽  
Pipe Bursting ◽  
Water Pipelines ◽  
Pipeline Networks ◽  
Close Fit

The urgent need to rehabilitate or replace ageing deteriorated buried potable water pipeline networks is one of the many critical service utility provision challenges faced within the municipalities in South Africa. The majority of these unreliable deteriorated pipeline networks consist of un-dipped (not coated with bitumen) AC piping which have long passed their planned economic and technical lifespan. Traditionally, the open trenching method has been utilised for the replacement of aged and deteriorated piping. However, this traditional open trenching method has shown to be expensive and difficult to implement, particularly in congested high traffic use urban areas. The need to rehabilitate or replace the ageing deteriorated buried potable water pipelines in South Africa, taking into account the above mentioned expensive factors has a solution. This solution is termed ‘trenchless technology’ and sometimes also termed ‘no dig’. Recent advancements in trenchless technologies now include innovative methods such as pipe bursting, close-fit lining and sliplining. Close-fit compact pipe manufactured by Wavin Overseas B.V. was newly introduced in South Africa in 2010 for the rehabilitation of deteriorated pipelines. These trenchless methods require further research into their technical application merits, drawbacks and costs in relation to the traditional open trenching method in order to determine which method is more expensive and also least suitable. Traditionally, the ‘total cost’ associated with pipe rehabilitation or replacement projects consisted only of the direct costs. The indirect and socio-economic inconvenience costs were often ignored and resulted in costly expenses to the municipalities. However, this research will show that these indirect and socio-economic inconvenience costs must form part of the total cost of a project as it assists with the successful completion of the project without expensive unforeseen costs to the municipalities. In addition, this research will provide insight as to which indirect and socio-economic inconveniences are dominantly experienced by the public. To achieve this, a quantitative socio-economic survey questionnaire was developed. This questionnaire was aimed at residents and business owners who were affected during a project of this nature. This research study will serve as a support tool to municipalities of South Africa when selecting a pipe rehabilitation or replacement method. This support tool will provide key technical merits and drawbacks of the traditional open trenching method, pipe bursting method, close-fit compact pipe method and sliplining method. In addition, this research study will compare the ‘total cost’ of the traditional open trenching method against the trenchless pipe bursting method. The decision making process lies in the hands of the municipal technical managers. Therefore, their knowledge and experience of up to date information on trenchless methods (as well as the traditional open trenching method) is vitally important. This research provides insight as to the knowledge and experience of technical municipal staff on trenchless methods, its application and use in South Africa. A quantitative survey questionnaire was developed by the researcher. This questionnaire was aimed at technical staff in the water departments of district and local municipalities of South Africa. The results of the above questionnaire surveys formed part of the eThekwini Water and Sanitation (EWS) Feasibility study funded by the Dutch Government. When comparing the costs of the trenchless pipe bursting method against the traditional open trenching method, the results revealed that trenchless methods are undoubtedly cheaper and far less disruptive to the public. The results of the socio-economic survey revealed that trenchless methods were preferred by the public since it was less disturbing and the hindrances experienced were also far less than the traditional open trenching method. The results of the technical municipal survey questionnaire revealed that at least 50% of municipal technical staff of South Africa are not adequately informed about trenchless methods, its application and technical merits and drawbacks respectively. This survey questionnaire revealed that South Africa may be advancing over the years on the use of trenchless methods, however, more educating in the form of training, seminars and other methods of marketing must be undertaken starting at a municipal level.

Effect of a Calcium Carbonate-Based Dentifrice on in situ Enamel Remineralization

2005 ◽  
Vol 39 (3) ◽  
pp. 255-257 ◽  
Author(s):  
J.A. Cury ◽  
G.S. Simões ◽  
A.A. Del Bel Cury ◽  
N.C. Gonçalves ◽  
C.P.M. Tabchoury
Keyword(s):  
Calcium Carbonate

Crystallization of Calcium Carbonate Observed In-situ by Combined Small- and Wide-angle X-ray Scattering

2003 ◽  
Vol 107 (22) ◽  
pp. 5123-5125 ◽  
Author(s):  
Diego Pontoni ◽  
Joerg Bolze ◽  
Nico Dingenouts ◽  
Theyencheri Narayanan ◽  
Matthias Ballauff
Keyword(s):  
Calcium Carbonate ◽  
Wide Angle ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering
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