planning, laying out, and tooling concrete block
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Planning, Laying Out, and Tooling Concrete Block
Next Generation Science/Common Core Standards Addressed!
CCSS.ELA Literacy. RST.9‐10.3 Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks, attending to special cases or exceptions defined in the text.
CCSS.ELA Literacy. RST.9‐ 10.5Analyze the structure of the relationships among concepts in a text, including relationships among key terms (e.g., force, friction, reaction force, energy).
CCSS.ELA Literacy. RST.11‐ 12.3 Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks; analyze the specific results based on explanations in the text
CCSS.ELA Literacy. RST.11‐12.4 Determine the meaning of symbols, key terms, and other domain‐specific words and phrases as they are used in a specific scientific or technical context relevant to grades 11–12 texts and topics.
CCSS.Math.Content.HSGCO.D.12 Make formal geometric constructions with a variety of tools and methods (compass and straight edge, string, reflective devices, paper folding, dynamic geometric software, etc.). Copying a segment; copying an angle; bisecting a segment; bisecting an angle; constructing perpendicular lines, including the perpendicular bisector of a line segment; and constructing a line parallel to a given line through a point not on the line
Bell Work/Student Learning Objectives
Discuss how to plan and lay out a job.Explain how to mix mortar and lay
blocks.Explain how to tool joints, patch holes,
and clean smears.
Terminology
Batter boards Block chisel Block hammer Block trowel Closure block Concrete masonry units Corner block Face shell mortar bed Frost line Full mortar bed Jointer Lightweight blocks
Mason’s line Masonry cement Masonry sand Mortar Mortar hoe Raker joint Standard or heavyweight
blocks Story or course pole Stretcher block Tooling joints
Concrete masonry
Popular type of agricultural construction.
Concrete blocks are strong, durable, fireproof, rodent and termite proof, and do not rot
Concrete masonry units, also called concrete blocks, come in two types and several standard sizes
General Types
Two general types:hollow solid
Standard or heavyweight block: Made from Portland
cement, water, sand, gravel, and crushed stone
General Types
Lightweight blocks: Made from Portland cement,
water, and lightweight aggregates, such as cinders, slag, or shale.
Weighs half as much as a standard block
Easier to handle but have greater insulating value
Block Sizes
Even number widths4, 6, 8, 10, and 12 inches
Even number heights 4 and 8 inches
8 ×8 ×16 blockWidely used to build agricultural structures.Actual dimensions are: 7 5 /8 ×7 5 /8 ×15
5 /8Mortar completes the dimensions (3/8 layer)
Block Sizes
When the standard 3/8 mortar joint is added, the block with one mortar joint is 8 inches high and 16 inches long.
Block Types Building dimensions
Total length and width in inches should be divisible by eight so that full blocks and half blocks will be used
Blocks come in a variety of shapes Corner block and stretcher blocks
are the most common
Block Types
Stretcher block: has ribs on both ends
Usually with three cores or holes in the block
Used between the corners
Block Types
Corner block: Square across one end and has ribs on the other end
Used at the corner when laying blocks Use the dimensions to figure the
Use the dimensions to figure the number of blocks needed.
Other types of blocks!
Bonding Materials
Mortar: Bonding material made of sand and masonry cementMix one part cement to 2½ to
3 parts masonry sand. Masonry cement: Type of
cement used to make mortar while Portland cement is used to make concrete
Bonding Materials
Masonry sand is fine sand while the sand used in concrete is coarse sand
Use the following as a guide to calculate the amount of cement and sand to purchase: in a 1:3 mix, 1 bag of cement
and 250 pounds of sand will lay 100 eight inch blocks.
Laying out the Structure Building must be laid out
prior to digging the footing and pouring it
Surveying instruments Easiest, quickest,
most accurate way to lay out building’s corners
Generally laid out parallel to property lines or other buildings
Laying out the Structure
Surveying level and target rod:Helps to set square corners and the proper height of the foundation wallDimensions should always be doubled checkedMeasuring for equal diagonals is a way to check for square corners.
If no Surveying Equipment
Establish a base line and use the 3–4–5 right triangle method to establish square corners
Outer Supports Batter boards: Outside supports used to stretch
strings stretch strings: set up when corner stakes are in
place The batter board includes three stakes and two
horizontal 1 x 4 or 1 x 6’s The strings mark the outside of the foundation wall
and the top of the foundation
Outer Supports Plumb bobs can be helpful to insure
that the strings intersect over the corner stake
Use powdered lime or spray paint to mark the ground for digging the footing
Outer Supports
Remove strings while the digging is done.
The surveying level and the target rod are used to set the grade stakes or forms in the trench
Outer Supports
The footing trench should be dug down to firm soil below the frost line
Frost line: Deepest point in the soil where the ground freezes in a typical year
The bottom of the trench should be flat and level
Most New Mexico building codes require the footing to be a foot deep.
Outer Supports
Footing rules are: Set at or below the frost line, pour a minimum of 8 inches for 8
inch blocks, 10 inches for 10 inch blocks, etc., and
have the footing at least twice as wide as the foundation.
Outer Supports
After footing is poured and forms are removed:
Sweep off the footing and re-stretch the strings
The plumb bob can be used at the string intersection to help mark the corners on the footing
This provides you with a straight line for laying the block wall
Outer Supports
Snap a chalk line on the concrete footing to mark the location of the outside of the first row of concrete blocks
Beginning block layers sometimes lay out the first row of blocks without mortar to make sure the layout was planned properly
Mixing Mortar and Laying Blocks
Good mortar: Absolutely necessary for good workmanship and a good finished wall
Process of laying concrete blocks requires considerable know-how and skill
Concrete masonry work may be contracted to professionals
Concrete Masonry
You start by mixing mortar and carrying blocks Start with:
Clean, dry blocks
water
masonry sand
masonry cement
concrete blocks
quality tools
Mixing Mortar
Strength of a mortar joint is affected by: Quantity of cementing material, Portions and moisture content of the
mortar, and Quality of the workmanship.
Mixing Mortar
Mix one part masonry cement to 2½ to 3 parts masonry sand with enough to make a workable mix that is plastic enough to support blocks on a 3 /8 inch mortar joint until it has set If masonry cement is not available:
Use Combination of Portland cement and hydrated lime
Mixing Mortar
Mix mortar in:A leak proof box with shallow
sides,A wheelbarrow, or A mixing machine
Mixing Mortar To hand mix:
Use a mortar hoe (a hoe with two large holes in the blade) to dry mix the cement and sand until a uniform color exists.
Gradually add water and continue mixing with the mortar hoe until the mortar is plastic and workable
Mixing Mortar
If mortar is:Too stiff: Will not bond well
and results in a thick jointToo thin: Will be squeezed out
by the weight of the block resulting in narrow mortar joints
Concrete Layout Locate the corners and
lay out the first course, without mortar, to check the layout
Full mortar bed: Using mortar on both horizontal and vertical cross webs of the block
Face shell mortar bed: Using mortar on only the horizontal cross webs of the block
Concrete Layout Normally the first
course uses a full mortar bed and the other courses use a face shell mortar bed
Always lay the blocks with the thicker end of the face shell up This provides a
larger area on which to place the mortar
Laying first course of Blocks Mason’s line: Nylon string that is stretched
tight to mark the top and outside edge of a row of concrete blocks
Once the first course corner blocks are laid in position stretch it so that the first course will be straight
Buttering refers to putting mortar on the end of a block
Laying first course of Blocks Block layers often stand
several blocks on end and butter the ends
To get a better bond to the block: Flip mortar off trowel onto
block with snap of the wrist
To place the block in position: Pick it up with both hands
and use a swinging motion to lower it into position
Laying first course of Blocks To make sure a laid block is level plumb, and aligned: Use a level Level the blocks by tapping the block
with the handle of the trowel
Laying first course of Blocks Block trowel: Triangular shaped piece of
metal with a wooden handle
Block hammer: Can be used to tap blocks into place as well as cutting blocks
Laying first course of Blocks Block chisel: Three or four inch wide metal chisel that can be hit with the block hammer to mark and cut concrete blocks
After first course of blocks
Use face shell mortar beds and lay up 4 or 5 courses of blocks at the corners
Check for each block’s: Level, plumb, and alignment
Checking horizontal spacing: Use a straightedge or four foot
level
After first course of blocks
Since each course is back spaced a half block, the corner of each back stepped row should touch the diagonally positioned straightedge.
Story or course pole: Board with markings eight inches apart Use to ensure that
the horizontal mortar jointing are running 3 /8 inches thick.
After first course of blocks
Key to a straight true wall: Using the mason’s line between
the corners as a guide
Most difficult part of laying blocks: Usually laying the closure block
After first course of blocks
Closure block: Last block laid to complete the row
If vertical mortar joints have been 3/8 inches the opening for the last block should be 16 3/8 inches long (2 3/8 inch mortar joints and a 15 5/8 inch block)
After first course of blocks Closure block:
Must be buttered on both ends or
Previously laid block must be buttered
If mortar falls off the end of the block as swung into place, block should be removed and re-buttered
Tooling joints and removing smears
Completes job resulting in a professional appearance to the job
Tooling Joints Procedure that pushes the
mortar into the groove between the blocks
Creating an improved bond of the mortar to the block
Results in a weather-tight joint with a neat appearance
Jointer: Concave or V-shaped metal tool with a handle and turned up ends
Tooling Joints
Brick layers often use a raker joint.
Raker joint: Tool that moves the mortar from the joint to depth of approximately 3/8 inches
Removing mortar burrs
After joints have been tooled, trim off with face of the wall with the trowel
Crooked Blocks
Do not attempt to move or straighten the block once the mortar has stiffened or even partly stiffened
Mortar Dabs
On block: Should be allowed to dry
Use trowel to knock dab off Piece of a concrete block to rub out
remaining particles
Smears
When laying blocks, be careful not to smear mortar into the blocks
Once the smears are in the block it is impossible to remove them
A wire brush will help but is unable to remove mortar from pores in the block
Muriatic acid rinse will help clean the wall and make paint smears less noticeable
Review / Summary
Discuss how to plan and lay out a job.
Explain how to mix mortar and lay blocks.
Explain how to tool joints, patch holes, and clean smears.
The end!
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