Question
Hi Sean
I was reading through some of your answers and appreciate your help.

Question 1: I have a brick patio that was installed over concrete several years ago and we have a lot of moss issues (n. Florida).  When the pressure washing was done it eroded the mortar? (I don't know if that is the right term) between the bricks. I'd rather have mortar than sand - what can I do?  When they installed the front path they spread something down from a bag and wet it down and it hardened like the mortar?

Question 2: in the front where they installed the path there was not a concrete base and some of the brick have sunk down... very sandy soil  They have the mortar between them though - Is there an easy way to repair this?

Thanks so much for your help - I really appreciate your time and expertise!~ TD

Answer
In order the answers to your questions are:
The best thing to do would be to re-grout the joints with new mortar.
You'll have to first be sure to remove about 1/2inch minimum of the existing mortar to acheave a space suitable to hold the new mortar.

The "Stuff" they spread was most likely mortar or Portland cement that may have been mixed with some sand (which is essentially mortar.

Other than mortar or sand you could also use 'permatil'. It is a fine gravel like substance which is actually expanded shale. It won't splash like sand and is too big generally, to stick to your shoes. Google "permatil" to learn more.

No there is not an easy way to repair the sunken pavers, this is a common problem often due to lack of proper base preparation.

To repair the sunken pavers you need to remove them first and chizzle away the mortar by hand.  Then re-set them as you like and re-grout the joints. However, before re-setting them you need to make sure their is a good sub-base to set them on which is level and will not fail. Consider adding a 3-4" deep sub-base of compacted granite dust/gravel or 3" min slab of concrete to lay the pavers on. Unless cars will drive on it this will be all you need.
You must ensure the sub-base can not "flare out" under pressure and sink or spread into the surrounding soil. If your soil is very dry and sandy you may need an edge restraint for your sub-base. Concrete would be the best option to stop sinking.

Best of Luck
Sean J Murphy, LA,ISA, LEED AP
Please check out my blogs and articles on landscape topics like this on my websites.
http://www.seanjmurphy.com
http://amenityarchitects.com