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- Diutan gum (2)
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African cement inffastructure is quite complex. Apart from Northern Africa and South Africa in particular, cement plants are scarce resulting in highly unstable cement pricing. Clinker and cement are imported from overseas, e.g. from Portugal, Turkey, Pakistan, Indonesia, and China. Imports are typically determined by the lowest price, and as a result the countries of origin of products vaiy regularly yielding large scatter of properties. Quality control and a good quality infrastructure are thus of utmost importance for the safety of the popuiace, an issue, which is actually often neglected. With funding of the German Metrology Institute (PTB) and Support of the SPIN project, a proficiency testing scheme for cement testing according to EN 196 was set up for African laboratories. Proficiency testing schemes, also called round robins. are interlaboratory performance comparisons allowing participants to evaluate themselves against pre-established criteria. Thev are a powerful tool to help laboratories improve their performance as well as demonstrate their competences to accreditation bodies or Customers. 26 laboratories from 20 nations, 18 of which from Africa, participated. The BAM Federal Institute for Materials Research and Testing acted as coordinator and provider of the scheme. The aim of the round robin was to interpret the submitted data further beyond the pure statistic analyses. The data provided a positive picture of the performance of the participants in general, but it also exhibited a number of technical fields that need improvement. The paper provides the general results of the scheme and analyses identified strengths and weak points based on the submitted and non submitted data as well as on discrepancies from the EN 196 procedures during measurements. The application of EN Standards for material testing is critically discussed and since quality infrastructure is also always an issue between industrial and political stakeholders, suggestions for the mitigation of the identified shared problems are given.
Starches and its derivatives are known to exhibit viscosity modifying characteristics. In an ongoing work, the influence of com and cassava starches on some properties of concrete such as compressive strength, heat of hydration and creep are examined. Various percentages (0.0, 0.5, 1.0, 1.5 and 2 %) of starches by weight of cement were added to concrete mixes prepared in the laboratory. Preliminary results of compressive strengths showed that both starches have some positive impact (e.g. there was 5.3 % increase in strength due to a 1 % addition of com starch by weight of cement in comparison to the control while cassava starch of the same percentage gave 4.9 % increase in strength) at certain percentages of starch addition to concrete at 28 days. The creep and hydration results shows the starch additions compares well and in some instance performs better.
This report is based on a three-year experience as coordinator of the ACP-EU funded SPIN project. The project involved eight African and three European partners. Practical and unforeseeable problems are addressed that occurred during the project implementation and ways how they were successfully solved are reported. The major problems in many African institutions were administrations that are not used to work in multi-national consortia and a lack of institutional support for the African researchers. In Europe a misjudgement of the African boundary conditions as well as inflexible administrations caused problems. Finally the funding scheme did not always allow to easily overcome the high number of unexpected practical problems. A major deficit identified during the project was a general trend in Africa to underestimate the role of research for the development of the continent. Most universities focus on teaching applied sciences, which is without doubt important to cover the market need for qualified staff in the rapidly growing African industries. However, this makes it unattractive for highly qualified performers to conduct research on the continent. Furthermore this leads to the situation that the curricula can only contain second hand knowledge. In order to attract international high level researchers, it is suggested to install multi-national regional excellence research centres that only promote PhD and post-doc research on a level that can cope with highest international excellence. High level research is often perceived as not capable of focusing on immediate actual problems that many African economies have to cope with.. However, it is considered to be very sustainable in terms of autonomy and mastering future challenges.
African cement infrastructure is quite complex. Apart from Northern Africa and South Africa in particular, cement plants are scarce resulting in highly unstable cement pricing. Clinker and cement are imported from overseas, e.g. from Portugal, Turkey, Pakistan, Indonesia, and China. Imports are typically determined by the lowest price, and as a result the countries of origin of products vary regularly yielding large scatter of properties. Quality control and a good quality infrastructure are thus of utmost importance for the safety of the populace, an issue, which is actually often neglected. With funding of the German Metrology Institute (PTB) and support of the SPIN project, a proficiency testing scheme for cement testing according to EN 196 was set up for African laboratories. Proficiency testing schemes, also called round robins, are inter-laboratory performance comparisons allowing participants to evaluate themselves against pre-established criteria. They are a powerful tool to help laboratories improve their performance as well as demonstrate their competences to accreditation bodies or customers. 26 laboratories from 20 nations, 18 of which from Africa, participated. The BAM Federal Institute for Materials Research and Testing acted as coordinator and provider of the scheme. The aim of the round robin was to interpret the submitted data further beyond the pure statistic analyses. The data provided a positive picture of the performance of the participants in general, but it also exhibited a number of technical fields that need improvement. The paper provides the general results of the scheme and analyses identified strengths and weak points based on the submitted and non submitted data as well as on discrepancies from the EN 196 procedures during measurements. The application of EN standards for material testing is critically discussed and since quality infrastructure is also always an issue between industrial and political stakeholders, suggestions for the mitigation of the identified shared problems are given.