– all activities  backed up by sound literature, patent, and state of the art reviews
PLEASE permit me space in your publication to address a concern raised by Mr. or Ms. L. Ferreira in the Chronicle’s February 14th edition. The writer suggests that the Institute of Applied Science and Technology (IAST) project of some years ago to produce clay-based building and construction materials is retrograde, and that as such, this should be cause for concern to our general public. We have a policy of not responding to technical questions in the media, because of the obviously inefficient use of space and time, and we encourage members of the public to get in touch with us if they have questions of a technical nature (tel. 222-4214, email: csec_iast@yahoo.com).
However, the writer is correct that it should be of importance to taxpayers in Guyana whether or not their dollars are being spent on frivolous projects, and therefore the questions posed command a respectful response from the institute. I hope that the explanations below will serve as general interest to the public on the evolution of building materials, and as information to Mr/Ms Ferreira in particular.
Quite to the contrary than what has been suggested, technologies related to the use of improved clay amalgams for construction purposes are most decidedly modern, has been currently engaging the attention of scientists, civil engineers and economists in both the developing and developed world, and represent a movement towards materials which are not only durable, aesthetically pleasing, and easier to work with, but also are more sustainable in terms of energy requirements for production, environmentally friendly in terms of greenhouse gas emissions, and accessible to broader ranges of incomes.
A review article published in 2011 provides a very clear trajectory of the evolution of clay-based building materials within a steel and concrete context: its recent publication date and the recent publication date of the many articles it cites serves to underscore the currency and relevance of this research focus. This article is freely available to the general public at http://www.academicjournals.org/SRE and is written in plain language, understandable to a lay audience.
Of course, it becomes a matter of marketing and personal choice whether or not such materials will become commercially adopted in Guyana. Certainly, across Europe and North America, this is a growth sector in terms of sustainable and environmentally responsible building materials.
As a matter of historical context, some of the earliest and most durable structures still standing from antiquity are made of different amalgams of compressed clay-based materials – ranging from the awe-inspiring Great Wall of China, to such majestic and architecturally astounding buildings as the Sultan Abdul Samad building in Kuala Lumpur. These are but two of a long list of impressive clay structures – but of course, we have all also seen clay structures that fit the description of “mud huts” which are poorly constructed, weak, and aesthetically unappealing.
So, what is the difference? Lack of sound and  available technology, lack of building codes and regulations, and inaccessible cost structures by the most vulnerable sections of society. The public can rest assured that what we are attempting to enable are not “mud huts” in the sense that this miss-used phrase conjures to the general public.
Indeed, our efforts, and those of the scientists and engineers in this very active field of research worldwide are directed at developing technology that allows these materials to be competitive in terms of price, functionality and aesthetics.
I am quite sure that the compressed blocks produced by the IAST are not the best in this growing industry worldwide, but they certainly are among the best, and they are certainly more affordable than cement blocks.  I am also equally sure that they can be improved upon – this is the iterative nature of research and development.
Due to the changing compositions of available clay around the world, different geographies will have different compositions for the best-performing amalgams, and this is why it was important for IAST to use existing approaches to optimise the behaviour of our clay deposits on the coast.
Although we have been unable to determine what are the local regulations for blocks used in load-bearing walls, a conversation with VIKAB Engineering and Consultants Inc., a company which is the design consultant for many buildings in Guyana, indicated that the compressive strength required for a cement block which is intended to be load bearing is 1015 psi (~7 N/mm2).
Information obtained from the University of Guyana materials-testing laboratory suggests that the standard required for non-load bearing blocks is 750 psi (~5 N/mm2). Singaporean standards (Standard SS 103 (1974)) defines three grades of blocks – First, Second and Third. The required compressive strengths are, respectively, 35, 20, and 5.2 N/mm2.
British standards (BS, 3921, 1985) defines two classes of blocks – Engineering A and Engineering B, with required compressive strengths of greater than or equal to 70 N/mm2 and 50 N/mm2, respectively. The IAST conducted random surveys of cement blocks (note that there is no designation of blocks sold in Guyana as either load bearing or non-load bearing) available on the local market and found that, excepting for one particular producer (whose blocks ranged from 900 – 1000 psi (6.2 N/mm2 – 7 N/mm2)), the average strength of blocks ranged from 300 psi – 500 psi (2 N/mm2 – 3.4 N/mm2).
I hasten to add that this was not an exhaustive test of blocks across the country – simply a randomised evaluation of blocks available around Georgetown in a 10-mile radius.
There are very likely, producers whose blocks are much higher in compressive strengths, and whose products were simply not tested. Compressive tests were conducted by the IAST in collaboration with the University of Guyana, at the University of Guyana.
There is a predictive, correlated relationship between the compressive strength of blocks used, the amount of mortar used, and the compressive strength of a wall built with the blocks, so the stronger the blocks, the stronger the wall built of the blocks, within a certain range, beyond which an increase in block strength does not add any marginal utility in the strength of the wall.
Data published by E. A. Adam and reproduced by Deboucha and Hashim, cited below, shows that the typical wet compressive strength of compressed stabilised clay blocks are usually at or below 4 N/mm2, with the industry leading standard coming from a special soil found in the Sudan (the Sudanese black cotton soil), from which stabilised compressed clay blocks can be made with wet compressive strengths in the range of 6 – 8 N/mm2.
The cement-stabilised compressed clay blocks made by the IAST have compressive strengths of 5 – 6 N/mm2.
This compares very favourably with the industry-leading standard for stabilised compressed clay blocks, with the source of the clay being regular clay deposits found along the entire Guyana coast.
Better strengths were obtained from clay sourced from the clay mine in Canal #2. Furthermore, this compressive strength was much greater than a randomised set of cement blocks tested in Guyana, and equivalent to the compressive strength of the strongest cement block products we tested in Guyana.
Very importantly, this is at 40 – 50% of the cost of the cement blocks. Also, very importantly, these blocks require at maximum, 1/4 of the cement used in regular cement blocks (incidentally, this reduction is also within the best examples of what has been achieved in the industry).
The energy usage to produce 1 ton of Portland cement is approximately 5, 000 MJ, and this contributes approximately one ton of carbon dioxide to the atmosphere (cement production is cited as one of the most major contributors to introduction of the greenhouse gas, carbon dioxide, the atmosphere, leading to global warming and climate change).
Therefore, by simply reducing the cement used in these blocks by 75%, impressive reductions in greenhouse gases and energy consumption are realised.  Significant improvements can still be made – the blocks can benefit from a better shape-design, allowing a lock-and-key manner of laying them down, so as to reduce mortar requirements.
Currently, they need to be plastered to protect them from excessive moisture – a protective polyurethane coating or similar bio-based resin can be used to ensure better moisture-barrier properties.
The blocks at IAST were produced using antiquated hydraulic equipment, and staff had no access to earth-moving equipment, making the process laborious.  However, with relatively low capital investments, this process can be made industrially much more efficient.  An application has been made to the Office of the President by an investor interested in producing the blocks commercially.
I would be remiss for not pointing out some of the issues with this technology:
** a) because of the kind of views held by people with respect to clay, this can be a barrier to commercialisation. It is worth noting that all ceramics and fired blocks are also “mud”
**b) However, mining of clay does mean that landscapes are destroyed and stagnant waterways are created which can lead to mosquitoes and other pests breeding, etc.
**c) some exceedingly tall buildings with load-bearing walls would not be suitable to make with such blocks (although again it should be noted that many buildings are walled today with gypsum and glass combinations, and the structural strength is provided by a “skeleton” of steel or other high-tensile materials).  There may be other detractions, but these suffice for the discussion at hand.
I note that Mr/Ms Ferreira commented on the fact that the demonstration home built by the IAST is built flat on the ground – this is not a limitation of the technology itself.  One can choose to use the blocks in an elevated building with equal ease.
Indeed, the design we chose to utilise at the IAST is really just reflected by my own aesthetic approach – I happen to like buildings with thatched roofs and ecologically-friendly designs which are on mounds.  The demonstration building at the IAST is built on an earth mound, so it is protected from flooding.
Mr/Ms Ferreira provided an estimate of costs related to the production of cylindrical clay aggregates, which is significantly inflated from our own empirically determined costs.
May I offer my services to help Mr/Ms Ferreira with these calculations – we would certainly be happy to collaborate on further assessments of costs, in the event we are missing something elementary.
A suggestion was made by the writer of making the house off-grid. Mr/Ms Ferreira would be pleased to note that the demonstration house is indeed off the electrical grid, with all of its electricity provided by solar energy.
I have already used up significant space, so I will not continue to enumerate the numerous benefits of clay-based building materials. These are readily extolled on numerous sites on the internet. I have tried to present a balanced perspective and highlighted some of the more problematic issues with the technology, and to present facts rather than opinions.
I hope that the taxpaying and general public and Mr/Ms Ferreira in particular, will find my answers sufficient to conclude that at the IAST we do not engage in frivolous activities. All of our activities are backed up by sound literature, patent, and state-of-the art reviews.
In closing, let me hasten to add that this project is certainly not one which I would categorise as the most or even among the most technologically advanced projects that we conduct at the institute.
However, it is appropriate, relevant, and in this instance, was quite successful compared to the industry standards.
Anyone in the research and development sector will tell you that there are always many more failures than successes (I suppose this is why it is called RE-search). I also wish to thank Mr/Ms Ferreira for his/her interest in our work, and in the development of Guyana in particular.