What does it mean to Retemper?
Retempering, the practice of adding water to mortar to restore workability, is considered good practice because it keeps mortar in the right condition for laying brick, block, and stone. This replaces water lost by evaporation. It keeps the mortar plastic so that units can be laid and positioned in it.
How many times can you temper mortar?
American Society for Testing and Materials (ASTM) standards require that all mortar be used within 2 1/2 hours but permits retempering as frequently as needed within this time period. Tests have shown that the decrease in compressive strength due to additional water is minimal if retempering occurs within 2 1/2 hours.
What is the effect of slump on concrete strength?
It shows the flow and overall workability of freshly mixed concrete. Simply put, the higher the slump, the wetter the mix. Four-inch (4”) slump is very common with normal weight concrete and is a good for pumping. Slumps that are above average will cause reduced strength, durability, and permeability of the concrete.
How do you get mortar to stick to concrete?
The most effective way to ensure a really good bond is with a scratch coat. This is simply a very wet coat made up by mixing the repair product with water. Mix up a small amount of the repair material to a soupy consistency. You don’t need to measure the water-just turn the stuff into slop.
How long can you work with mortar?
Mortar is good for 90 minutes. After that time, discard the mortar because it starts to lose some of its characteristics. Also, weather can affect how mortar reacts and how manageable it can be, so plan accordingly. Successful mortar mixing relies on consistency.
Which mortar property is increased by re tempering?
Mortars that have stiffened may be re-tempered by mechanical agitation & adding water as needed to restore the original consistency. Although compressive strength of the mortar is reduced slightly by re-tempering, bond strength is usually increased.
Can fresh mortar get rained on?
Mortar should be kept moist for 36 hours to allow it to fully cure. However, a heavy rain may wash the lime out of the mortar, weakening the bond between the bricks and the mortar. If the weather is warm, dry and windy, the mortar may dry too rapidly, pulling away from the bricks and crumbling.
What is the strongest mortar mix?
Type M mortar mix has the highest amount of Portland cement and is recommended for heavy loads and below-grade applications, including foundations, retaining walls, and driveways.
Does mortar bond to old concrete?
Concrete, mortar or similar materials are not designed to stick or bond to old surfaces. You will not get any satisfactory results if you simply add new mortar to old. It just doesn’t work. Using a modified thinset mortar would be the preferred method for this type of installation.