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close this book BASIN - News No 3 - January 1992 - Building Advisory Service
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Basin enquiries statistics

Statistics of Enquiries dealt with by all BASIN-network partners between January and September 1991

Since the network began operating three years ago, we have noted a steady increase in the number of written enquiries received. Whereas at the beginning of the functioning of BASIN quite a large number of enquiries were of a more general kind, of late the contents of questions received are more specific and require professional experience for their reply. As we already explained in the editorial of BASIN-News No. 2 ("Help us to help you") our aim is to establish a dialogue with the enquirer(s) in order to offer the best and most appropriate advice as possible. This, of course, canonry be done if the enquiries we receive are precise and explain as detailed as possible the problem(s) for which a solution is sought.

From the statistics it can also be seen that most of the enquiries reach us from Africa. The reason for this is most probably the fact that our advisory service operates in English and French. We would, however, like to assure Spanish-speaking enquirers, that -whenever possible -efforts will be made to reply in Spanish to letters that we recieve in Spanish.

BASIN's objective is to collaborate with local resource-centres, persons, or institutions. We aim at involving these increasingly in our technical enquiry service in the future. If you have any suggestions in this context, kindly contact the undersigned.

1. Total number of enquiries received

732

- WAS (Wall Building Materials)

214

- CAS (Cementitious Binders)

134

- RAS (Roofing Materials)

74

- EAS (Earth Building Materials)

310

2. By region of enquiry (BASIN total)

Africa total

46 %

West Africa

17 %

East Africa

12 %

North Africa

1 %

South Africa

7 %

Central Africa

9 %

Asia total

17 %W

Est Asia

13 %

South East Asia

4 %

Pacific

2 %

Caribbean

2 %

North America

4 %

Central America

2 %

South America

8 %

Europe

19 %

3. By categories of enquirer

Individual

34 %

Student

3 %

Research Institute

4 %

University

5 %

Private Company

24 %

Government Organisation

4 %

Non-governmental Organisation

19 %

Co-operative

1.5 %

Corporation

0.3 %

Credit Institution

0.4%

Foundation

0.8 %

Donor Agency

2 %

UN-Organisation

1 %

Training-Institution

1 %

4. General and specific enquiries

General (e.g. Low-cost-housing)

20 %

Specific

64 %

Literature requests

16 %

5. By main subjects of enquiry

Construction and architecture

14 %

Building materials / equipment (general)

15 %

Information on BASIN

15 %

Wall building (burnt bricks, compressed earth blocks and other materials)

30 %

Roofing (FCR/MCR, vaults, domes and other materials)

14 %

Binders (cements, lime, pozzolanas)

7 %

Training

5 %

6. Dialogue established with enquirers

With 31 % of the enquirers a dialogue was established, involving up to about 4 letter exchanges together with accompanying information material each time.

7. Some typical enquiries which were received and answered

-Enquiry No. I

"At present in Zambia there are no reasonable quality bricks (or blocks) available for the building industry. Various small companies produce cement/sand bricks and blocks which are usually of poor shape and strength; others make clay bricks, burnt in the open during the dry season, which are of very poor quality (cracked and badly chipped after handling).

There are abundant supplies of clay, talc, limestone, cement (cement factories in Ndola and Lusaka) and sand.

ln the past we have written to UK brick manufactures about advice on making sand-lime bricks, which, with various colours, would enrich the options available for cladding buildings; but we have had no response.

If you are able to assist with advice on a sand-lime brickmaking process that would be reasonably simple to implement and to operate in Zambia, we shall be most interested (Mr. R., Zambia)"

+ Answer

The production of sand-lime (or calcium-silicate) bricks requires a rather sophisticated technology and is a process which is definitely not on "small-scale". On the enclosed extract from a publication entitled "Advances in Building Materials and Construction", by the Central Building Research Institute (Roorkee 247 667, India), you will find a short description of the production of autoclaved calcium-silicate bricks. We would advise you to contact the CBRI in India. We have heard that they are in fact producing a medium level plant, but we are not sure whether on a commercial basis already.

In Germany there are two manufacturers of calcium-silicate brick plants and equipment. They are:

1. Krupp Polysius AG Bereich Atlas Baustofftechnik (Abtlg. 773) Graf-Galen-Str. 17 D -4720 Beckum-Neubeckum2. Dorstener Maschinenfabrik AG Vertriebsabteilung Postfach 21 01 63 D -4270 Dorsten 21.

It is, however, very likely that these German plants are of a standard that exceeds your requirements. Apart from several technical advantages of calcium-silicate bricks, it appears doubtful that they are suitable for low-cost construction. A comparison with other more economic building materials is recommended."

-Enquiry No.2

"I would ask if you could forward me additional information, design data, costing and practical details on the office building in India (BASIN-NEWS -July 1991, page 7 & 8) together with details of the brick making technique, quality controls, material requirement and mortar details plus of course anything else you think relevant (Mr. S., Namibia)."

+ Answer

The domes of the experimental earth building, which was described in our BASIN-News No. 2, was built with rectangular bricks which were produced with the manually operated Indian TARABALRAM block press, a similar press as the Cinva Ram. The tapered bricks mentioned in the article were used for constructing the vaults. These bricks, 20 cm long and 6 cm thick with a width tapering from 20 cm to 18 cm, were hand-made in wooden forms (like adobe blocks) and not pressed in a block press.

The shape and construction of the rotating jig for building the dome is still in a developing stage and each one made so far is a modification of the previous one. The first one was made of steel, later aluminium profiles were used and the template was divided into three parts. The design of the jig, which so far has not been drawn on paper but was developed in the workshop, largely depended on the building design. As regards the shape of the dome, it has been found that the ideal curve of the template lies between a catenary curve and an ellipse, and was first determined by empirical methods, but for which a computer programme has now been developed. An important structural design criterium of the dome is to avoid tensile forces acting around its base, which has often been the main cause of conventional, hemispherical domes collapsing, as a result of which, some have had to be built with steel or reinforced concrete ring beams. Another design aspect is that the bricks in the top portion are not laid at too step an angle, or else they cannot be laid without a supporting form work to prevent them from slipping down during construction.

Unfortunately no printed material about the experimental building at the IIT in New-Delhi exists yet, or we would have gladly sent you some. But when the jig design has been optimized and costing of the construction and especially of the energy saving (tests about this are still being conducted) are available, we may be able to prepare a kind of construction manual for people who are interested."

-Enquiry No. 3

"Can you give directions for making durable low-cost paints suitable for a variety of wall surfaces, for use in Zambia? (Mr. D., Zambia)"

+ Answer

(a) For the emulsion use 0.75 litres vegetable oil, 0.4 litres washing powder detergent and 1.5 litres boiling water. Stir together well in a can, then add in more water to make up to 5 litres in total.

(b) Take 0.75 litres of the emulsion and mix in 6.5 litres of slaked lime powder until all the lime is wetted and the mixture takes on the consistency of a crumbly powder rather than a paste. Then add water to this mixture to make the mixture up to 5 litres in total. The paint should have the consistency of a fairly thick soup.

(c) Paint in the normal way, but also pressing the paint firmly into cracks and mortar joints. The thickness should be between 0.5 and 1 millimetre, any thicker and the paint may come loose.

(d) Avoid allowing the paint to dry too quickly, and rubbing the paint for about six weeks. Eventually it will become as hard as commercial paint.

The cost of this paint is estimated to be 10 % of that of commercial exterior wall paint."

(Advice courtesy of G.E. Westwood Esq. FRIC, Bergers Paints Ltd.)

-Enquiry No. 4

"We have substantial deposits of recent volcanic ash in our area. Would these be suitable for use in pozzolanic cements? (Mr. M., Mexico)"

+ Answer

" It is not possible to tell without doing some tests on the material. For the tests you should ideally take samples from the whole area of the deposit, since ash properties are likely to be quite variable, even over a small area.

The main reactive components of a pozzolana are aluminium and silicon oxides. Silicon oxide usually forms the largest part of a pozzolana, and should be in an amorphous rather than a crystalline form. Materials containing substantial quantities of silicon oxide in the form of quartz grains do not make good pozzolanas. Chemical and mineralogical tests can be used to identify and indicate the quantities of constituent minerals in the pozzolana.

A vital requirement for an effective pozzolana is that it is very finely powdered: in fact, much of the material should pass through a 45 ym sieve. If this is not the case then either the material should be pulverized in a ball mill, or the fine fraction of it separated off. The coarser particles can be used as aggregate but, by themselves, they have no cementing roperties.

A chemical test can be done to assess the activity of a pozzolana, but, possibly, a more reliable test is to actually make up cubes of concrete containing the pozzolanic cement and test them for compressive strength after 28 days. If a mixture of three parts ash to one part hydrated lime is used as the cement, then a reasonably reactive pozzolanic material should be capable of giving a cube strength of at least 2 MPa (or 2 N/mm_)."

Hannah Schreckenbach CTZ/Section 413

 

OBITUARY: Tom Moncrieff

by Dr. David Payne

Tom Moncrieff who died at the age of 37 in a tragic car accident in Australia, was at the forefront of Micro Concrete Roofing (MCR) Technology in Nepal. As the Roofing Tile Programme Leader at the United Mission to Nepal's Development and Consulting Services he directed the development of a researched product into an appropriate technology that is currently providing low cost roofing and income generation to many people throughout Nepal.

Born in Adelaide, Australia and completing his civil Engineering Degree at Adelaide University, he worked for The Electricity Trust of South Australia over a period of 6 years.

In 1985 Tom, together with his wife and (then) 3 children, began his service with the United Mission to Nepal. A man of courage and strong conviction, this step was a result of Tom's personal faith and commitment to Jesus Christ which led Tom to service and love for others through his professional skills. After initially working in the hospital building programme at Tansen, they moved to the Development and Consulting Services (DCS), Butwal at the end of 1985.

At DCS, Tom was assigned as Senior Civil Engineer with particular responsibility for developping the then 2 year-old Roofing Tile Programme. The moment he became involved in the programme, it was clear Tom was a man of action: within a relatively short space of time he had implemented a new design of concrete tile and new tile making equipment that was both original and appropriate to the remote and undeveloped land of Nepal.

The specific technical developments that have been introduced under Tom's direction included: Nylon rope nib tiles, the workability test, the lower nib tile, the concrete tile mould and the DCS's foot-powered vibrating table.

It is largely due to his personal concern for the basic needs of Nepali people for housing and income generation, that this technology has been disseminated. Through training, equipment supply and follow-up to small tile industries, there are now over 75 independent entrepreneurs in Nepal who can look back to Tom with deep regard.

The significance of this work was soon appreciated by organisations inside and outside of Nepal and Tom made contributions in the International area of appropriate building materials development. Through both his attendance at annual FAS seminars and his contributions to the ILO published FCR/MCR Quality Control Guidelines, Tom has shared the benefits of his experience with a wide audience.

Tom's values of truth, self discipline and high standards of workmanship placed high expectations on the staff he worked with in DCS. These, together with his determination and energy have inspired a small but dedicated team to continue this work of service in the field of appropriate technology.

To his wife Liz and children James, Emily, Peter and Suzanne we extend our deepest sympathies and prayers -particularly as their planned return to life and service in Nepal has now so suddenly been changed. Tom died as he lived -confident in his faith and convictions and loving to his neighbours -surely an example to us all.

(Thomas Andrew Moncrieff, born 19 June 1954, died 10 October 1991).