repair of stonework

[laika]

Apart from replacing a damageed block what is the best molrtar to repair cracks and other damage to stonework.  In particular I have a fireplace which requires some work. Also some of the facing of exterior stone has crumbled.

Laika in 36 Indre 

[legs_akimbo]

When stone decay is present it is often an indication that impervious mortars have been used to repair and repoint, theese trap moisture behind the stone as there is no permeable route for the evaporation of moisture causing spalling of the stone. Always use materials that are sympathetic toward stone in hydraulic or lime putties, stone walls rely on the thickness of their make up and allow rain water to absorb naturally both into them and to evaporate through the joints, lime mortars allow this to happen freely. Any repointing therefor should be done in this manner, though on a larger scale it is adviseable to determine which lime mortars will compliment a particular type of stone. Internally if opc mortars (sand cement) are used on stonework such as a fire place an aesthetic way to repoint is the bag rubbed method. By taking a pointing trowell and filling out the joints, as the mortar stiffens take a strip of paper cement bag scrunched into a ball, and rub the mortar into the joint which will fill all the crevices around the stone and leave a finish that looks as if it has been there for ever...very pleasing to the eye.

[laika]

A French neighbour recommended using Parexlanko mortier pierre. Its lime based. Unfortunately it's  rather expensive at 65E for 40Kg, however having used it on my fireplace today it seems to do the job.  My neighbour  says that it will work on outside stonework.. . My local Tout Faire stockist had it in stock.  Best wishes to all