African Brickmaking : Part 3 – Theoretical Solutions

A Brick Making Factory and Dairy in Morogoro, Tanzania

 

The Problem – restated

Morogoro is city of nearly 300,000 about two hours west along the main highway from Dar es Salaam, sitting in the southern Tanzania highlands at the base of the  Uluguru mountain range. The Ngerengere river flows over the northwest quadrant with tributaries coursing throughout both the formal and informal communities within the boundary of the Morogoro Municipality. Formal communities are areas of land which have been platted by the municipal authority. These communities are sanctioned and controlled by the local government.

In contrast, the informal communities were never platted. They simply emerged as people moved in from the countryside to find employment in the city. Individuals simply squatted on a piece of land and began to build. These communities are mostly self sufficient, consisting of both housing and small scale businesses. There are schools, markets, restaurants, building supplies, unlicensed contractors (fundis), and some basic services. In an effort to control and manage the growth of the city, however, the local municipality is trying to restrict the unregulated growth of these communities as well as retrofitting some basic measure of infrastructure and city governance into the communities which are already well established.

The effect on the brick makers

All brickmaking with the municipality occurs in the informal sector, and is therefore unsanctioned and unregulated. In order to curb both the health and environmental concerns raised by current brickmaking techniques, the municipal authority has declared all brickmaking within the municipality illegal. They have identified a new site for legal brickmaking some 30 kilometers outside of town. The distance, however, greatly affects the sustainability of brick as a viable industry in Morogoro and would drive the price up near the cost of concrete. Currently, the brickmakers work within their own communities, they live within walking distance, and the bricks themselves are often transported by the use of a hand, or oxen drawn cart.

The Challange

The challenge is to address both the health and environmental concerns of the municipal authority while letting the industry remain within the interwoven context of the informal community, thereby avoiding the loss of jobs and low-cost building materials.

 

This ceramic map illustrates the solution described on the following pages.  After a primary brick making factory has run its course and helped to generate a portion of the city, its function as a brick making factory would cease and it would be absorbed into the community it created as an adaptive reuse project. Simultaneous to this occurrence another second generation brick factory would form to start generating the next neighborhood.

 

Solution – Part One

The municipal authorities main concern is the spoils area left in the wake of current brick making techniques when brick making operations have concluded.  In any one site, brick making can only occur for so long before the area is sufficiently mined. Once this occurs the pits left behind pose multiple complications for development in the area.

The proposed solution would alter the method which clay is extracted from  the soil. Rather than digging into the edge of the river banks, a series of shallow mud dams would be employed to catch alluvial drift during the wet season. These dams would be placed in areas where they would not disturb or further degrade the river banks.  By moving the extraction points into the alluvial flood plain and spreading them out over a large area, the borrowed areas would not have time to deepen before the next years flood recharged them again.

These mud dams will control the areas where the alluvial material for brick making is removed. Similarly to how some of the brick makers are rotating the areas where they dig for mud from year to year to let depleted areas recharge during the rainy season, these shallow dams will only be mined once every several years. The placement of these dams, will also keep brick makers away from the shallow banks of the river and allow them access to the middle regions of the alluvial plain. The loss of the banks can had a devastating effect on both the stability of the rivers course and the water quality down stream.

The other concern of the municipality is to avoid the complications that plagued the former brick factory in Morogoro.  This factory suffered as a result of the extracted material being too far away as well as the distance to transport the bricks to the area where they were needed expanding further and further away.
Current sisal plantations in Morogoro often use small tracks and carts to move cut sisal leaves from the fields to the processing sheds. The proposal here is to connect these dams with a similar track system which would carry the mud back to factory.

 

City Generator

As the municipality grows it may be more economical to move brick making activities closer to the source of the main construction. Any brick making factory would act as a city generator, existing in a certain location long enough to build out the surrounding zone. Once this occurred and the distance becomes too great between the factory and new construction a second generation factory would be built in the new construction zone.

 

the Site

 

The factory site is situated in an area currently surrounded by brick making, the idea being that the brick makers can construct the factory of bricks made with their current techniques. Once the factory is built they can continue making bricks with the new method.

 

 

Solution – Part Two: Combining the Brick Making Factory with a Large Scale Dairy

The second part is to implement solutions to the health and environmental concerns by changing the firing process from a wood fuel based kiln system to a methane gas based kiln system. The methane fuel source is achieved by merging the programs of brick making and dairy operations. Large scale dairy operations have been used in other parts of the world to generate electricity by capturing methane. Manure is fed into an anaerobic digester, which in turn produces the gas. As agricultural waste can also be tapped as a bio-fuel, waste from the nearby sisal plantations may also be used to generate fuel for firing.

 

The Building

The Elegant Roof

Roofs are especially problematic in the informal sector. The main issue here being a balance between cost and safety. In an interview with Dr. Amon Makenya, a lecturer in the School of Construction Economics and Management, he claimed that a majority of the building expense in the informal sector is in the roofing, on corrugated metal.

The only other viable and cheaper solution used with any prevalence is traditional makuti, a roofing made from either reeds or palm fronds.  Although this alternative is indeed cheaper. It must be continuously maintained and is susceptible to fire.

Brick has been used as a roofing material for centuries. It requires two conditions to be used today, however, one is a low labor cost and the second is a highly skilled workforce. The context of Morogoro succeeds in the first requirement, and the second can be learned and spread, perhaps helping to create a new sector of skilled labor in the work force.

In researching precedents for brick roofing, I became interested in the use of brick in the construction of shells in the  visitors’ center at the Mapungubwe National Park in South Africa , a project by the architect  Peter Rich.  Although the project used stabilized earth blocks as opposed to burned bricks, the method of construction consisting of laminating several layers of block together to create the shell is applicable to burned brick as well as stabilized earth blocks.

 

Perhaps the most elegant use of the technique as it pertained specifically to burned brick is found in the work of Eladio Dieste, the Uruguayan engineer.  In his book Eladio Dieste: Innovation in Structural Art, Stanford Anderson states:

Today, the increasing emphasis on sustainability in architecture gives cause to continue the consideration of reinforced masonry. This building technology employs a material that is local under most circumstances and is remarkably efficient in the use of that material. It has excellent thermal properties. That it is labor intensive may be altered through innovation, but there are still large parts of the world in which this trait remains an economic and social good.

That a large part of Dieste’s work was devoted to humble spaces, grain storage, warehouses, basket ball courts, is a testimate to the economics of this building technique in the right context. I believe Morogoro is such a context for its low cost of labor, the availability of material, and rapidly expanding municipality which will need building of increasingly larger scales.

Dieste’s work is also unique in the way he opens of the roof forms to allow daylighting and ventilation. These roofs have a light and airy feel, much different then the often heavy and dark nature of a traditional brick vault.

 

Shells and Ceramics
Shell construction finds its fundamental twin in ceramics. Both are based on the principle of arches moving in multiple directions, supporting themselves. Their forces are self contained, transmitting directly downward. The traditional roof vault requires either buttressed end walls to absorb lateral forces or a tie rod to mitigate the effect of that force with tension.  This self contained nature allows much more freedom to the form.

The examples below are small clay studies for a simple shell form. The first is a concave arch, the second convex. Structurally, as mentioned before, these forms would operate more like a beam than an arch, supporting their own weight and delivering the forces straight down. The forms, however, are not purely derived for their structural characteristics, but also for their environmental and passive design attributes. When used in tandem as in the photos to the right, these forms can both shed and collect and channel water, as well as providing a separation adequate both to let in light and ventilate the roof system.

 

 

Formwork and Function

These models break the form down into segments to study the method of constructing formwork . One of the major benefits of reinventing the firing process and using brick roofs is to eliminate the need to cut timbers from the rain forests. If those same timbers are being used to create formwork to construct the shell, nothing is gained. The two forms to the extreme upper and lower left are the smallest repeating componants of the shell. The segments to the immediate right and the roof model on the right are constructed soley from these two parts. The idea is to make a set of these forms which could move beneath during the course of construction . Once a shell became self supporting the form would be moved to the  next one over.

The study models on the following pages investigate a series of connical shells which connect to cover the dairy portion of the factory. These forms would be supported at the narrow end by a column or vertical arch form.

 

 

  

 

Roofscape

 

The factory mediates an elevation shift between the high ground of the cities future development and a low area near the alluvial plan.  The roof of the dairy lays even with the ground plain on the high side. Nearest the center of the factory a worker, or a child could move from the ground directly onto the roof,  and observe through different parts of the milking process peering down through the skylights.  This “roofscape” is also the access point for the granary.