Why Roman concrete was so durable - photo

[olderdan]

Yes, bring back lime mortar. But how would you find labourers to mix quicklime?

Agreed Philip, perhaps the answer is pay them enough?. I worked for an old building firm in Budleigh Salterton and had to mix lump quicklime in troughs for lime mortar, also used for lime wash for cob buildings. Not a pleasant job but we just got on with it, no mobile phones to play with then.