This week has been exciting and we have some great progress to share!

From having just the outline of the shelter prepped last Friday, with the help of the team at CIDO we managed to not only complete the shelter build but also our field compression testing and start on the brick making!

The shelter build was fantastic and involved a number of people and materials to take it to completion. We bought wood, borrowed spades and help from two different local farmers, bought sustainable roof materials made from local grass called “Tight” Roof and help from Sarin, Sokphea and Poeuch at CIDO.

On Monday we finished with the main structure in place, which consisted of eight strong wood logs dug 0.5m in the ground to outline the skeleton of the building.

On Tuesday we finished with further supporting and strengthening timber straights, walls made from thick waterproof plastic sheets (donated by a local shop) and our testing rig firmly in place within the shelter.

On Wednesday, the roof was finished and we started Round 1 of the field compression tests…

The test rig is built up of a single metal rod 1.5m in length with a metal “pin” 2cm in diameter welded on at 0.5m. This rod is then hinged on a bolt and metal blacking plate to allow 180 degrees movement. A thick wall piece of wood is used to bolt the backing plate into, so that it can be dug into the ground and hold its place when carrying out the testing.

Before we could begin testing, a testing criteria and strategy was established. The recommended strength for bricks in a single story building is approximately 2Mpa and double story 4Mpa.

The final earth bricks in the construction of the Agri Tech Centre will only be used as single story loading however to account for any future work or developments we tested to 4Mpa also. There is also the factor of the bricks getting wet and the subsequently the remaining strength after. After a bit of discussion with the engineers at Burro Happold and Ed at SAWA, our final testing plan was as follows:

Round 1 Testing

-Dry Compression Test upto 2Mpa

-Bucket (soak) test for 12 hrs or more

Round 2 Testing

-Wet Compression Test at 2Mpa and 4Mpa

-Make test walls and carry out drop tests and bridge tests

We calculated that approximately 19.3kg weight hung onto the end of the metal rod would result in a 2Mpa force being applied through the 2cm diameter metal pin onto the sample earth blocks. And double the weight equaled double the force of 4Mpa.

On Thursday, we finished all the compression testing and collated our results to share with our international team (via whatsapp). The key highlights from the testing were:

-The earth-only samples passed the dry testing but immediately fell apart in the water during the bucket test!

-There was measurable variance in the earth samples from the three different locations with earth sample from location 3 being generally the weakest.

-Cement mix ratios of 8, 11 and 15% tested the best with all the earth samples which meant that it didn’t matter where the earth came from, the samples were all strong enough for both 2MPa and 4Mpa.

Having the test results allowed us to narrow down the range of viable cement/earth ratios we could use to begin making the full size earth bricks.

On Friday we began mixing up the first batch of test bricks (a mix of earth with 8% cement). After a full day of trialing different mixing and molding methods we successfully produced 32 bricks. These we now have to leave in the shelter (protected from the weather) to cure and reach their full strength.

Next week we need to aim to complete round 2 of testing which means building some test walls and carrying out some drop tests and bridge tests. This will hopefully help us in narrowing down the choices a bit further and finish with the best earth brick mix possible for the Agri-tech centre construction!

Tom & Sakshi

You can still contribute towards this project via this link: https://mydonate.bt.com/events/greenshoots10nov

Focusing on our first task, the earth blocks, here is a quick run through of what we achieved so far.

With the office closed on Monday and Tuesday for the public holidays celebrating King Norodom Sihamoni’s Birthday, we picked up where we left off last week on Wednesday.

The big focus for us this week was to finalise everything we were going to need to complete field-testing on the earth blocks samples, as well as beginning to source equipment to create the full size earth block bricks.

Due to the lengthy waiting times for lab testing in Phnom Penh we have designed a rig (drawing) that will allow us to quickly perform fairly accurate impression/compression tests on the existing cement samples prepared by Ed Dale-Harris on a previous trip. (lab testing to act as a final confirmation at a later date. This will allow us to shortlist 3-4 final cement mixtures that we can make up into small batches (~100 total) of full sized bricks.

To make the full sized bricks we also designed some moulds that can be used both for testing and during larger scale production later in the year.

With rough sketches for each in hand we headed to various machine shops and welders around Samroang. One of the local staff at CIDO, Sarin, helped significantly with translating the sketches and explaining the purpose of the moulds. Eventually we were able find a shop that could produce both of our designs in just a few days.

We visited the workshop the next morning for a check up, and they had already constructed the earth block moulds! Our initial impressions are that they will be durable enough to produce blocks for the entire building project, and that they are lightweight enough to be easily handled onsite.

All of our testing and trial block making will be conducted on the same site as the future Agritech centre. We have started preparing a test site and shelter that will house our testing rig, small scale earth block production, and should provide a useful shelter throughout the build of the Centre.

On Friday morning we visited the site to confirm a suitable location for the shelter, and begun clearing the proposed site with help from CIDO members Sarin, Sokphea and Poeuch.

Once completed this will provide a flat surface for creating the cement blocks, cover from the rain that that could erode the blocks while curing and, thankfully, shelter from the sun!

It has been great this week to get our hands dirty and see some tangible results, we are very excited to continue working on the project and are looking forward to sharing test results and producing some earth blocks in the next week!

Tom & Sakshi

You can still contribute towards this project via this link: https://mydonate.bt.com/events/greenshoots10nov

Hi our names are Sakshi Sircar and Tom McIntyre, and we have come from chilly Scotland all the way to sunny Samrong to work with CIDO and Green Shoots for the next four weeks.

CIDO and Green Shoots are embarking on an exciting project to build an Agri-Tech center to help them better facilitate the training that they have been rolling out around the schools in Odtar Meanchey Province. They are currently in the stages of researching and testing brick materials and setting up local contracts, ahead of the building works later this year.

With our engineering backgrounds, we plan to be able to progress some of these tasks in the time that we are here.

The sun was beating in the sky when we arrived here and one of the first things we did was to visit some local schools to see how the children were learning about farming and agriculture. It was really fun to the see the enthusiasm between all the kids which only makes it more important for the training centre to be built and come of use.

The building design is focused on the use of rammed earth bricks. Rammed earth bricks are more environmentally friendly, use local soils, simple to construct and can be strong and durable once adequately protected. The design also uses locally sourced materials to help local businesses and trade.

One of our first tasks here is to determine which composition of ingredients to make the earth bricks is optimum for the main building construction. This requires us to consider the environment that the bricks will be subject to, such as the high rainfall and sunshine and make sure that the bricks will be strong enough to survive this as well as bear loads such as the roof, windows and guttering, amongst other things. The composition of the bricks can vary in terms of how much cement or lime is mixed with local earth. It is likely that bricks comprising of only local earth will disintegrate under the loads or erode with the weather so we will probably have to include cement or lime as stabilizers. There were a range of samples created already (with different levels of cement and lime) so our job is to test these to determine which one best suits our needs, i.e. meets the required strength criteria for the lowest price. The tests we plan to do are compression tests (force applied on top of the brick) and ‘Bucket’ tests (repeat the compression tests after a period of soaking to establish the structural effects of saturation).

It is important that the building survives the test of time so it can be used for as long as it’s needed and allow CIDO and Green Shoots to spread their knowledge!

Our first few days have been a great experience and we are looking forward to settling in and continuing to work with the local CIDO staff and businesses.

Until next week!

Sakshi & Tom

Architect, Edward Dale-Harris reports on making Compressed Earth Blocks- a more sustainable option to bricks. Not only do they keep the room cooler, the emissions from brick making are extremely high. Compressed Earth blocks also have a quicker drying time, making them more efficient and they use readily available materials- rather than costly cement which might have to be transported from elsewhere.

Will this be a worthwhile technique to apply in the Green Shoots Agritech Centre? Read more »