Page 152 - Masonry and Concrete

Masonry Construction Techniques
151
MASONRY CONSTRUCTION TECHNIQUES

sories. Grout consistency at the time of QUICK>>>TIP
placement should produce a slump of 8 to Masonry mortar should
11 in. (Figure 5-14). be the consistency of soft mud. To check
for proper consistency, make a series of
The amount of moisture in the sand will
sharp ridges in the mortar with a hoe or
influence how much water is needed in a
trowel. If the ridges appear dry and
mortar mix to get the right consistency.
crumbly, more water is needed. If the
Sand bought in bags for small projects will
ridges stay sharp without slumping, the
usually be very dry. Sand bought in bulk by
mortar is the right consistency. If you get
the ton for larger projects will probably be
too much water, add proportional
damp or wet. Keeping sand piles covered amounts of each dry ingredient to bring
with water-repellent tarps or plastic covers it back to the proper consistency.
assures that the moisture content will not
change drastically because of rain or evap-
oration.
To avoid excessive drying and stiffening, mortar batches should be
sized according to the rate of use. With a big crew, large mortar batches
will be used quickly, but with a small crew, large batches may dry out
too much before they can be used. Loss of water by absorption and evap-
oration can be minimized on hot days by wetting the mortar boards and
1
1
covering the mix in the mortar box. Within the first 1- 2 to 2- 2 hours of
initial mixing, the mason may add water to replace evaporated mois-
ture. This is called retempering and is accomplished by adding a little
water to the mortar and thoroughly remixing. Mortars containing added
color pigment should not be retempered because the increased water
will lighten the color and cause variation from batch to batch.

2" TO 6"
5" TO 8"
12" 8" TO 10"

CONE CONCRETE MASONRY MASONRY
MORTAR GROUT
FIGURE 5-14
Masonry grout slump compared to typical concrete slump. (from Beall, Christine, Masonry Design and Detail-
ing, 4th edition, McGraw-Hill, New York).

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