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!