when we carried out experiments on the machine cut stones last year a good proportion was very weak with a crushing strength of less than 5 N/mm2..

this essentially placed them below the crushing strength of matofali.. stabilised earth blocks etc..

The machine cut stones are only good for the infill for reinforced structural systems.

I concur with the above in terms of their strength and porosity and as sed they are not suitable for foundations. In terms of wastage, they can also cost u a lot as they are brittle and usually break at the slightest impact while handling them. But if u manage to get the stones which are cut deeper from the ground surface u are likely to get stronger ones

However, due to their uniformity, machine cut stones have advantages in terms of labour i.e. u wunt need fundis to chonga them to make them regular. In addition, u get savings in the mortar for bedding and jointing them.

If u use machine cut, you also save on the plaster as u will not require to do a thick plaster because of their uniformity. If done neatly, they also form walls which are aesthetically appealing.

So is it recommended that they are not used at all, or can one use the regular quarry stones for the foundation and perimeter walls and use these for the internal walls ?

i think people got it wrong here, machine cut stones are used cause they are cheap...period...nothing to do porosity, crushing strength aesthetics..just the cost, its cheaper to chonga mawe with machines than with human labour..thus they are cheaper than the manually cut stones

For porosity & strength, its the type of stone used
For aesthetics, i have seen stones chongwad by a fundi using some axe and i could have sworn it was machine cut..

And by the way, machine cut stones are still quarry stones, but now cut with a machine.

For strenth one can used precast concrete blocks...

elaborate further for building amateurs.
superstructure is ....Masterhouse ????

Substructure is.....sewer/septic tank /servant quarter?????
Please guka ingilia katikati

Can the machine cut those hard blueish quarry stones ? Zile zikigongwa na chisel zinatoa fireworks ?

Njunge - kudos on your ability to know this stone costs.. hio ni mjengo proper...

i hear the stone prices have risen thin the last 3 months. something to do with mobile axle weighing machines.

the issue on using machine cut stones for the foundation is not right. you are better of having no foundation at all.