Unit 26

Sizes7-5/8” high15-5/8” longCommon depths – 8”, 10”,12”3/8” mortar jointsWalls usually stand 7’-4”

Block WallsSeries of blocks one layer over another is

called a courseConcrete blocks do not use formsConcrete block may be reinforced by

pilastersStack bond pattern is when one block is laid

directly over another to produce a continuous vertical jointStack bond requires reinforcement

MortarFreezing weather affects mortar

Low adhesionLess strengthFailure in joints

Coat of asphalt over mortar will ensure a dry basement

Applying roofing felt over first coat will provide extra water-proofing

Mortar (continued)Mortar strength depends upon

The rate which block absorbs moisture from mortarPlasticity or workability of mortarHow much water the mortar retainsQuality of workmanship by the mason

Mortar will be usable for 2-1/2 hours at 80 degrees or higher

Do not water down block before adding mortarPosition the first blocks before applying mortar

Construction of concrete block wallsAlignment of the first course is the most criticalLay the smaller holes of the block up to provide

a larger mortar bedCheck the blocks with a level or a straight edgeUse a story pole to check if one course is 8”

above the nextFinal gap in the wall is filled with a closure block“Thumbprint” hard will not leave an indentation

and the mortar should be tooledTooling should be done when the mortar has set

Control JointControls cracking due to stressPermits slight movement in a wallGives the wall longer lifeBuilt vertically into a wallShould be plumbShould be caulked if it shows

FinishingRemove excess mortar from walls after it has

driedIntersecting walls must be anchoredTops of windows and doors require lintelsTotal mixing time of fiberglass reinforced

mortar should not exceed 5 minutesUse a joint guide when fiberglass mortar

application is interrupted for more than 1 hour

Finishing (continued)Wet the wall prior to fiberglass mortar

applicationSlope the finish grade away from the

foundation for good surface drainageBackfill material should be expected to settle

Foundation informationThe same block is needed for reinforced

mortar as is conventional mortarSplit face block has one rough face that looks

like stoneThere are many specialty blocks for specific

purposes