Dear Louise,
On my trips to Thailand from 1988 until 2026 I often visited brick making companies. These varied in scale from single family brick makers to medium scale factories running several scove kilns.Mostly what I was were medium scale factories. In Nakorn Ratchasima they moved some. They had little infrastructure other than some open wall structures with metal roofs and sometimes some large cement vats the size of swimming pools.
Thai builders in general do not need the same thing from brick that we need in the United States. Brick are almost never used structurally. They are used as fill between reinforced concrete posts and beams on exterior walls. It also, for all intents and purposes, does not freeze in Thailand. This allows softer brick to be used that is fired lower, and is more porous. These brick have a lower tensile and compressive strength. They also require less fuel that denser brick.
Buildings in Thailand that use brick are generally stuccoed outside and often inside. Consequently the brick can be relatively crude.Per cubic foot installed they are cheaper than concrete or there would be no demand.

The brick are fired in scoves, loose stacks of brick with space for fuel between the brick. The first few layers on the ground are made of already fired brick, and an outside wall of fired brick is stacked around the raw brick being fired. In Thailand the fuel used is rice husks. They are agricultural waste. The compost very slowly and are low in nutrients. The burnt husks are almost 100% silica. Because of their composition and low soluble salt content they make an excellend addition to the clay as temper or grog. The temper reduces shrinkage and the resulting cracking and make the raw brick more porous. The porousity allows the brick to dry faster and because the pores allow steam to escape before pressure can build much, allows the brick to fired faster. It also gets rid of the ash. The ash is generally not burnt white and has some residual carbon. This adds a small amount of fuel to the fire. I suspect that it is not significant.
The clay mixing operations does vary some, but mostly what I have seen is a vat, really better described as a cement swimming pool filled with alternating layers of clay and ash that has water added as it is filled. After slaking and aging it is dug out and but into a brick extruding pug mill.

It was truly amazing for me to see working scove kilns in both the brick factories and the stove factories. I had always bee interested in scove kilns and about 5 years before going to Thailand I built a scove brick kiln. I was in graduate school and built this small kiln on a cart with wheels and rolled it into the galler for an exhibition.