In article ,
"stuart noble" writes:

Andrew Gabriel wrote in message ...
However, I recall reading somewhere a few years ago (possibly
in this newsgroup) that the BRE had experimented with various
cement/lime mixtures, and the 1:1 was quite good. Any less lime
and the mortar loses all the movement and self-repair qualities
of lime,
Movement and self repair in regard to pointing amounts to something that
will wash away with the first rainfall. If the mortar *and* the pointing
were the same, maybe....

Long before portland cement, lime mortar brickwork usually had
some cement in the exterior pointing (exterior pointing was not
done as the bricks were layed, but later). Most of mine has lasted
100 years without any trouble, and where it hasn't, it's due to
some unreasonable influence happening subsequently like bridging
the damp poof course or failing to repair leaking gutter downpipes
(not me -- previous owners;-). There were also a couple of small
places where someone had repointed wrongly (in one of them, using
pure cement and no sand -- a bugger to get out).

--
Andrew Gabriel