Screed rail system

A system for leveling concrete to provide a flat, planar upper surface. The system involves the use of elongated screed rails including upper and lower edges. The lower edge of each screen rail includes an elongated slot in each end portion. Each screed rail can be positioned over upright grade pins which extend into the slots and rest against the underside of the top edge of the screed rail. A leveling or strikeoff rod having a straight lower edge is supported on the upper edges of the screed rails. When the leveling rod is drawn along the screed rails it levels the poured concrete and provides a planar concrete surface.

FIELD OF THE INVENTION 
This invention relates to techniques and apparatus for leveling concrete 
(e.g., in the pouring of concrete floors, parking lots, etc.). More 
particularly, this invention relates to screed rails used for leveling 
concrete. 
BACKGROUND OF THE INVENTION 
Concrete is a very commonly used construction material for floors in 
buildings, for parking lots, driveways and the like. Typically the 
concrete is poured onto the ground or other support surface and then is 
leveled to the desired grade level or shape so that it will cure in place. 
Conventionally, a mud screed method or a pipe screed method is used to 
shape concrete to the desired level or shape. Using the mud screed method, 
metal stakes (called grade pins) are driven into the ground in a manner 
such that the top of each pin will be level with the top of the slab that 
is being poured or cast. The grade pins are typically spaced about ten 
feet apart throughout the entire area in which the concrete is to be 
poured. Then, after an amount of concrete has been delivered to the site 
and poured onto the ground around the grade pins, the concrete is leveled 
manually with a strikeoff rod (sometimes referred to herein as a leveling 
board or rod) between the grade pins to form a mud screed. "Mud" is a 
conventional slang term for concrete. 
The mud screed is used as a guide or leveling screed guide to strikeoff the 
mud or concrete to the desired level or shape. 
When an experienced workman uses the mud screed method, he is relying upon 
his eyes, hands and arms to keep the strikeoff rod from going above or 
below the proper mud screed level. Unfortunately, the end result is never 
very accurate because even an experienced workman is not able to 
consistently maintain the mud screed level at all points between the grade 
pins. Also, a significant amount of time is required to form and work with 
the mud screed in this manner. It is a tedious job. 
Consequently, it is common for a finished concrete surface to have high 
areas and low areas (i.e., areas where the concrete surface is more than 
1/4 inch off, high or low, from where it is supposed to be). Thus, the 
concrete surface is wavy. This is very undesirable. Often a poured 
concrete floor does not meet the required specification and has to be 
patch-leveled or ground down afterwards, and these procedures are very 
time consuming and costly. 
One alternative to the use of the mud screed method of pouring, casting, or 
placing concrete is the pipe screed method. It involves the placement of a 
number of special stakes in the ground in a straight line. The top of each 
stake includes a holder for supporting a pipe in a horizontal plane. 
Several such stakes support a single pipe. 
Then a leveling board or strikeoff rod is supported on two of such pipes 
and drawn along the pipes to level or strikeoff the concrete. However, 
this technique requires the use of special stakes with either nails or 
rocker chairs on top of the stakes so that the pipe does not roll off of 
the stakes. Also, the pipes must be supported along their length by three 
or more stakes. This requires that the stakes be in perfect alignment. 
This system is also very time consuming to set up and consequently is more 
costly. Therefore, the pipe screed method is used on only a small number 
of jobs compared to the mud screed method of casting concrete. 
There has not heretofore been provided a screed rail and a leveling system 
of the type provided by the present invention. 
SUMMARY OF THE INVENTION 
In accordance with the present invention there is provided a unique screed 
rail and a simple and efficient system for leveling concrete at a job 
site. The present invention exhibits the advantages of both the mud screed 
method and the pipe screed method but does not include the disadvantages 
of those two prior methods. 
The screed rail of the invention comprises an elongated, preferably 
tubular, rectangular rail having an opening or slot in the lower edge near 
each end thereof. The screed rail is rigid and stiff so that it can 
support a leveling board or rod without sagging. It is preferably hollow 
so that it is easy to carry and handle, yet it is sufficiently heavy to 
remain resting on the tops of two adjacent grade pins when concrete is 
poured. 
The leveling system of the invention involves use of two of the novel 
screed rails. Each screed rail is adapted to be supported on the tops of 
two adjacent grade pins. Then a conventional leveling board or strikeoff 
rod is used to strikeoff the concrete to the grade or plane desired. In 
order to level the concrete the leveling board or strikeoff rod is simply 
pulled or drawn along the screed rails. Any concrete which projects above 
the level of the top of the screed rails is accordingly pushed ahead of 
the strikeoff rod and displaced until all the concrete is at the screed 
rail level or plane. 
This strikeoff operation is performed quickly and efficiently to provide a 
desired flat, planar surface, without the need for highly skilled labor. 
Also, since only two grade pins are required for supporting each screed 
rail, exact placement or alignment of the grade pins is not required. The 
same grade pins as used in the mud screed method can be used effectively 
and efficiently in the present invention. This is a very distinct 
advantage because no other screed rail support system is required for this 
invention, many hours of labor are saved. Also, the screed rail of this 
invention will not roll off of the grade support pins because the 
depending flanges or sides of the rectangular tubular member fit closely 
to the sides of the grade pins. Using the screed rail system of this 
invention, a concrete slab can be cast or poured in approximately one-half 
the time required when using the conventional mud screed method. Another 
advantage of using the screed rail system of this invention is that it 
allows the use of the more preferred low slump concrete which has superior 
qualities.

DETAILED DESCRIPTION OF THE INVENTION 
The invention is illustrated by means of the accompanying drawings. FIG. 1 
is a side elevational view, partially cut-away, of a screed rail 10 of the 
invention which is shown supported on the top of grade pins 20. The lower 
ends 22 of the grade pins are driven into the ground 30 in a manner such 
that the pins are upright and are driven to solid footing so that they 
cannot move downwardly when pressure is applied to the top of such pins. 
The upper ends 24 of the pins are set at the top of the finished concrete 
slab grade. In other words, the upper ends of the pins define a plane or 
grade for the concrete slab to be poured. 
The grade pins 20 are typically spaced about 10 feet apart from each other 
in the ground, although normally this distance not determined exactly. 
FIG. 3 is a top view of a job site where the tops of a plurality of grade 
pins 20 are shown. As illustrated herein, the placement of the grade pins 
is not exact, i.e., they are not equally spaced from each other nor are 
they necessarily aligned in perfect rows. 
The screed rail of the invention may be provided in any desired length, 
although lengths in the range of about 4 to 12 feet are most convenient, 
depending upon the spacing between grade pins at the job site. The most 
common length for the screed rail will be 12 feet. The screed rail 
preferably comprises a hollow tubular steel member having a rectanguaar 
cross-section. The width of the rail is preferably in the range of about 
7/8 to 11/8 inches (preferably 1 inch), and the depth of the rail is 
preferably about 11/2 to 2 inches (most preferably 2 inches). 
Typically the grade pins have a diameter of about 0.5 inch. Thus, the 
openings in lower edge of the tubular member must be slightly wider than 
0.5 inch so that the screed rail can be easily and readily placed over the 
grade pins when desired. Thus, when the grade pins are 0.5 inch in 
diameter, it is preferred that the slotted openings in the screed rail be 
about 5/8 inch wide or 1/8 inch wider than the diameter of the grade pins 
used. Thus, if the grade pins are 3/8 inch in diameter then the slotted 
openings in the screed rail should be about 1/2 inch wide. 
The two slotted openings 12 in the lower edge of the tubular member are 
illustrated in FIG. 2. The slotted openings may vary in length. Preferably 
they are each about 12 to 24 inches (preferably 18 inches) in length. This 
allows the screed rail to be supported on grade pins having a variance in 
spacing. If desired, the slotted opening on the bottom edge of the screed 
rail could extend over the full length of the screed rail provided that 
the screed rail is composed of a rigid and strong material which is 
capable of maintaining its original shape during use. In other words, it 
is necessary for the slotted opening(s) to maintain its shape during use. 
The slotted opening(s) should have a width which is no more than 1/8 inch 
larger than the diameter of the grade pins used, and the width should not 
change during use of the screed rail. 
In the embodiment of screed rail illustrated in FIG. 2, the slotted 
openings 12 do not extend all the way to the end of the tubular member. 
For example, there is preferably a portion 11 at each end which is not 
removed, and preferably the central potion between the slots 12 is not 
removed. The portions of the lower edge which are not removed help to 
maintain the rigidity, shape and flexural strength of the tubular member. 
These portions also prevent the lower edge of the tubular member from 
spreading outwardly and creating too much play between the grade pin and 
the edges of the slotted opening. Preferably this amount of play should 
not exceed 1/8 inch at any time. 
Preferably the screed rail is made of steel which is rigid and will not sag 
during normal use. The wall thickness of the metal should be about 0.083 
inch (14 gauge) to 0.120 inch (11 gauge). Preferably the wall thickness of 
metal is 0.083 inch. Other types of metal could also be used, if desired, 
such as magnesium or aluminum provided it is sufficiently rigid to 
maintain its shape during use. Composite materials could also be used if 
sufficiently rigid. 
FIG. 4 is a perspective view illustrating the use of two screed rails 10 in 
supporting a conventional leveling board or strikeoff rod 40 for leveling 
concrete. Each screed rail is supported on only two spaced apart grade 
pins 20. Each grade pin is driven into the ground, and the upper end 
passes through a slotted opening 12 in one end of a screed rail and rests 
on the underside of the top edge of the tube (in the manner illustrated in 
FIG. 1). After concrete is poured onto the ground between the screed rails 
it can be quickly and accurately leveled to provide a planar upper surface 
by means of the leveling rod or strikeoff rod 40 being supported on and 
pulled along the upper edges of the two screed rails. The lower edge 42 of 
the leveling rod or strikeoff rod 40 is a straight edge so that a planar 
upper surface of the concrete results. 
After the concrete has been leveled in one area, the screed rails can be 
simply moved to adjacent grade pins where additional concrete is poured 
and the process repeated. Because only two grade pins are used to support 
each screed rail, there is no need to carefully align the grade pins when 
they are placed in the ground. When the screed rails are lifted from the 
grade pins, a small amount of concrete is used to fill in the narrow 
grooves left by the screed rails. The filler concrete is placed as soon as 
the screed rail is moved to adjacent grade pins. 
Then the slab that has been screeded or striked off can be finished in 
accordance with any desired conventional technique as specified by the 
architect or engineer in charge. 
Other variants are possible without departing from the scope of the present 
invention. For example, plugs could be included in the ends of the tubular 
member, as well as adjacent the ends of each slotted opening, to prevent 
concrete from entering into the tubular member. However, concrete can be 
easily flushed out of the tubular member with water, if desired.