Document:

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                                                                   EXHIBIT 10.15

                               AMENDMENT TO LEASE

         THIS AMENDMENT TO LEASE ("Amendment") is dated as of the _______ day of
April, 1998, by and between CENTERPOINT PROPERTIES TRUST, a Maryland real estate
investment trust ("Landlord") and WINCUP HOLDINGS, INC., a Delaware corporation
("Tenant").

                                    RECITALS

     A.   Tenant and CenterPoint Properties Corporation, a Maryland corporation
("Original Landlord") entered into that certain Industrial Building Lease dated
as of May 6, 1996 ("Lease") with respect to certain property commonly known as
1250 Carolina Drive, West Chicago, West Chicago, Illinois, as more particularly
described in the Lease.

     B.   Landlord is the successor to Original Landlord's interest in the
Lease.

     C.   Tenant has requested, and Landlord has agreed, to lease additional
space to Tenant in the Building as depicted in Exhibit A ("Expansion Premises")
consisting of approximately 59,100 square feet on terms and conditions herein
contained.

     D.   The Term of the Lease expires on April 30, 2000. Tenant has requested
and Landlord has agreed to extend the Term of the Lease through and including
June 30, 2003 on the terms and conditions herein contained.

          NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:

     1.   Recitals. The Recitals are incorporated into this Agreement as if
fully set forth in this Section 1.

     2.   Definitions. All terms used herein, unless otherwise specified, shall
have the meaning ascribed to them in the Lease.

     3.   Expansion Space. Tenant hereby leases the Expansion Premises from
Landlord and Landlord hereby leases the Expansion Premises as of May 1, 1998
("Effective Date"). Tenant shall lease the Expansion Premises on the terms and
conditions as contained in this Lease. Except for Landlord's Work as described
in Paragraph 7 below, Tenant hereby acknowledges and agrees the Expansion
Premises shall be tendered to Tenant by Landlord in its then "as-is" condition.
From and after the Effective Date, the term "Premises", as used in the Lease,
shall include the Expansion Premises.

     4.   Tenant's Proportion. From and after the Effective Date, Tenant's
Proportion shall be 100%.

     5.   Base Rent. Base Rent shall be paid in monthly installments on the
first day of each month, without offset or deduction, in accordance with the
following schedule:

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                                         Annual              Monthly
            Period                       Base Rent           Base Rent
            ------                       ---------           ---------
     May 1, 1998 - June 30, 2001         $514,500.00         $42,875.00
     July 1, 2001 - June 30, 2003        $552,000.00         $46,000.00

     6.   Rent Abatement. Notwithstanding anything to the contrary contained in
the Lease, so long as Tenant is not in default under the terms and conditions of
the Lease as of the date any monthly installment of Rent would otherwise be due
during the Abatement Period (as hereinafter defined), Tenant shall be entitled
to an abatement of Base Rent for the Expansion Premises in the amount of
$16,892.75 per month for the months of May and June, 1998 ("Abatement Period").

          In the event Tenant is in default (after any applicable grace or cure
periods) under the terms and conditions of the Lease, the rent abatements
attributable to Base Rent shall no longer be in effect and Tenant shall be
obligated, during the period of such uncured default, to pay the entire monthly
installment of Base Rent which would have been due and owing hereunder but for
the abatement. Tenant shall not be entitled to a proration of any amount so paid
whether or not Tenant cures the default. In no event shall Tenant be entitled to
any extension of the Abatement Period because of any payment of a full monthly
installment of Base Rent made due to defaults.

     7.   Termination Date. The Term of the Lease is hereby extended from April
30, 2000 through and including June 30, 2003 ("Extension Term") and all
references in the Lease to a Termination Date shall be deemed to mean June 30,
2003. All terms and conditions of the Lease (as amended hereby) shall remain in
full force and effect through the Extension Term. Tenant hereby acknowledges and
agrees that the Premises shall be occupied by Tenant during the Extension Term
in their then "as is" condition.

     8.   Landlord's Work. Subject to the terms and conditions of this Paragraph
8, Landlord shall, at is sole cost and expense, construct or cause to be
construed in the Premises the improvements ("Landlord's Work") described on
Exhibit "B". Landlord agrees that all work performed in connection with the
Landlord's Work shall be done in a good and workmanlike manner and in
substantial compliance with applicable building codes and ordinances. Landlord
shall proceed with Landlord's Work upon approval of the City of West Chicago,
Illinois. Tenant acknowledges that Landlord's Work may not be complete on the
Effective Date and Tenant shall provide access to the Expansion Premises and, as
necessary, the Premises, to Landlord, its employees, agents and contractors for
purposes of completing Landlord's Work and for the repair and correction of any
punchlist items (as hereinafter set forth).

          Within five (5) business days after substantial completion of
Landlord's Work, Landlord and Tenant shall conduct an inspection of the
Expansion Premises, and work in good faith to jointly prepare a punchlist. Any
items not on such punchlist shall be deemed accepted by Tenant. Landlord shall
complete all punchlist items as soon as is reasonably practicable, subject to
extension due to any matters beyond Landlord's control.

     9.   No Other Modification. The Lease is only modified as set forth herein
and in all other respects remains in full force and effect.

     10.  No Default. Tenant and Landlord acknowledge that the Lease is in full
force and effect and that there are no defaults thereunder or any conditions
which with only the passage of time or giving of notice or both would become a
default thereunder.

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     11. Successors and Assigns. This Amendment shall be binding upon and shall
inure to the benefit of the parties and their respective successors and assigns.

     12. Modification. This Amendment may not be modified or amended except by
written agreement executed by the parties hereto.

     13. Governing Law. The validity, meaning and effect of this Amendment shall
be determined in accordance with the laws of the State of Illinois.

     14. Counterparts. This Amendment may be executed in two counterparts, each
of which shall be deemed an original, but all of which together shall constitute
one and the same instrument.

     15. Severability. The parties hereto intend and believe that each provision
in this Amendment comports with all applicable local, state and federal laws and
judicial decisions. However, if any provision in this Amendment is found by a
court of law to be in violation of any applicable ordinance, statute, law,
administrative or judicial decision, or public policy, and if such court should
declare such provision to be illegal, void or unenforceable as written, then
such provision shall be given force to the fullest possible extent that the same
is legal, valid and enforceable and the remainder of this Amendment shall be
construed as if such provision was not contained therein.

     16. Construction. The headings of this Amendment are for convenience only
and shall not define or limit the provisions hereof. Where the context so
requires, words used in singular shall include the plural and vice versa, and
words of one gender shall include all other genders. In the event of a conflict
between the terms and conditions of the Lease and the terms and conditions of
this Amendment, the terms and conditions of this Amendment shall prevail.

     17. No Third Party Beneficiaries. This Amendment shall inure to the sole
benefit of the parties hereto. Nothing contained herein shall create, or be
construed to create, any right in any person not a party to this Amendment.

     18. Legal Review. The parties hereto acknowledge that they have been
advised by legal counsel of their choice in connection with the interpretation,
negotiation, drafting and effect of this Amendment and they are satisfied with
such legal counsel and the advice which they have received.

     19. Facsimile Signatures. The parties hereto agree that the use of
facsimile signatures for the negotiation and execution of this Amendment shall
be legal and binding and shall have the same full force and effect as if
originally signed.

     20. No Commissions. The parties hereto acknowledge and agree that no real
estate brokerage commission or finder's fee shall be payable by either party in
connection with this Amendment.

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     IN WITNESS WHEREOF, the parties have executed this Amendment as of the date
set forth above.

LANDLORD: CENTERPOINT PROPERTIES TRUST,    TENANT: WINCUP HOLDINGS, INC., a
a Maryland real estate investment trust    Delaware limited partnership [SIC]

By:    /s/ [Signature Illegible]           By:    /s/ Don Rogalski
   ----------------------------------         ----------------------------------
Its:   Chief Operating Officer             Its:   Sr. V.P. Admin.
    ---------------------------------          ---------------------------------
Name:  Michael M. [Illegible]              Name:  Don Rogalski
     --------------------------------           --------------------------------

By:    /s/ Brian M. Sheehan
   ----------------------------------      By:    /s/ Angela S. Riddle
Its:   Asst. Secretary                        ----------------------------------
    ---------------------------------      Its:   Admin. Asst.
Name:  Brian M. Sheehan                        ---------------------------------
     --------------------------------      Name:  Angela S. Riddle
                                                --------------------------------

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                               [Exhibits Omitted]<PAGE>

                                                                   EXHIBIT 10.16

                            SECOND AMENDMENT TO LEASE

     THIS SECOND AMENDMENT TO LEASE ("Amendment") is dated as of the 4 day of
February, 2003, by and between CENTERPOINT PROPERTIES TRUST, a Maryland real
estate investment trust ("Landlord") and WINCUP HOLDINGS, INC., a Delaware
corporation ("Tenant").

                                    RECITALS

     A.   Tenant and CenterPoint Properties Corporation, a Maryland corporation
("Original Landlord") entered into that certain Industrial Building Lease dated
as of May 6, 1996 (as amended by that certain Amendment to Lease dated April __,
1998, the "Lease") with respect to certain property commonly known as 1250
Carolina Drive, West Chicago, Illinois, as more particularly described in the
Lease.

     B.   Landlord is the successor to Original Landlord's interest in the
Lease.

     C.   The Term of the Lease expires on June 30, 2003. Tenant has requested
and Landlord has agreed to extend the Term of the Lease through and including
June 30, 2013 on the terms and conditions herein contained.

          NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:

     1.   Recitals. The Recitals are incorporated into this Amendment as if
fully set forth in this Section 1.

     2.   Definitions. All terms used herein, unless otherwise specified, shall
have the meaning ascribed to them in the Lease.

     3.   Extension of Term. The Term of the Lease is hereby extended for an
additional one hundred twenty (120) month period commencing on July 1, 2003 and
continuing through and including June 30, 2013 ("Extension Term"). All terms and
conditions of the Lease, as amended hereby, shall remain in full force and
effect through the Extension Term, except that Base Rent, commencing on July 1,
2003 and continuing through June 30, 2004 shall be $465,000.00, payable in
monthly installments of $38,750.00. Base Rent shall increase two percent (2%)
each July 1 thereafter during the Extension Term. On or before the commencement
of the Extension Term, Landlord shall return to Tenant any existing security
deposit currently held by Landlord.

     4.   Extension Options. Tenant shall have two options (each, an "Extension
Option") to extend further the Extension Term for all of the Premises as of the
then expiration date of the Extension Term, for

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two (2) additional periods of five (5) years each (each, an "Option Term") upon
the following terms and conditions:

          A.   Tenant gives Landlord written notice of its exercise of said
     Extension Option at least nine (9) months prior to the then expiration of
     the Extension Term.

          B.   No Event of Default is then continuing either on the date Tenant
     delivers the notice required under Section 4A above or at any time
     thereafter prior to the commencement of the Option Term.

          C.   All of the terms and provisions of the Lease (except this Section
     4) shall be applicable to the Option Term, except that Base Rent for the
     Option Term shall be determined as follows: Base Rent for the Option Term
     shall be equal to Landlord's determination of the Fair Value (as
     hereinafter defined). For purposes of this Amendment, "Fair Value" shall
     mean Landlord's determination, utilizing its reasonable judgment, of an
     annual amount per rentable square foot for a term equivalent to the period
     for which Fair Value is being determined beginning with the first (1/st/)
     day of the subject period that a willing, creditworthy, new non-equity
     tenant leasing comparable space to Tenant's would pay and a willing,
     comparable landlord of an industrial building comparable to the Building in
     the Chicago metropolitan area (hereinafter referred to as the "Market")
     would accept at arm's length, giving appropriate consideration to terms of
     the Lease, as amended hereby, annual rental rate per rentable square foot,
     rental escalations (including type, base year and stops), length of lease
     term, size and location of the premises being leased, and other generally
     applicable terms and conditions prevailing for comparable space in
     comparable buildings located in the Market. In the event that Tenant does
     not agree in writing to Landlord's determination of Fair Value prior to the
     date which is seven (7) months prior to the then expiration of the
     Extension Term ("Option Expiration Date"), then Tenant's exercise of the
     Extension Option shall be deemed null and void and this Section 4 shall be
     deemed null and void unless Tenant, prior to the Option Expiration Date,
     notifies Landlord in writing that Tenant will agree that Base Rent for the
     Option Term shall be One Hundred Two percent (102%) of the Base Rent for
     the last year of the then Extension Term and shall increase by two percent
     (2%) each July 1 thereafter during the Option Term.

     5.   Brokerage Commission. Landlord agrees to pay Equis Corporation
("Broker") a fee of $170,069.20 ("Commission") for the Extension Term, payable
in two equal installments due (i) seven (7) days after execution of this
Amendment, subject to presentation by Broker to Landlord of an invoice and a
partial lien waiver, and (ii) July 1, 2003, again subject to presentation by
Broker to Landlord of an invoice and a final lien waiver. If Landlord fails to
pay any portion of the Commission due Broker when due, then Tenant shall have
the option, exercisable upon five (5) days' prior written notice to Landlord, to
pay that portion of the Commission due Broker and shall have the right to offset
the amount paid to Broker by Tenant against Rent next coming due.

     6.   Rent Abatement. Notwithstanding anything to the contrary contained in
Section 3 above, so long as no Event of Default then exists as of the date any
monthly installment of Rent would otherwise be due during the Abatement Period
(as hereinafter defined), Tenant shall be entitled to an abatement of Base Rent
and Rent Adjustment for the Premises for the period from July 1, 2003 until
December 31, 2003 ("Abatement Period").

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          If an Event of Default occurs, the rent abatements attributable to
Base Rent and Rent Adjustments shall no longer be in effect and Tenant shall be
obligated, during the period of such uncured Event of Default, to pay the entire
monthly installments of Base Rent and Rent Adjustments which would have been due
and owing hereunder but for the abatement. Tenant shall not be entitled to a
proration of any amount so paid whether or not Tenant cures the Event of
Default. In no event shall Tenant be entitled to any extension of the Abatement
Period because of any payment of a full monthly installment of Base Rent and
Rent Adjustments made due to Events of Default. However, if Tenant cures the
Event of Default during the Abatement Period, the abatement shall become
effective on the first day of the following calendar month and shall continue to
the end of the remainder of the Abatement Period or, if earlier, the occurrence
of another Event of Default. By way of example, if an Event of Default occurs on
August 15, 2003 and is thereafter cured by Tenant on September 15, 2003, Tenant
shall be obligated to pay the installments of Base Rent and Rent Adjustment for
the months of August and September, 2003, and the abatement shall continue in
effect commencing October 1, 2003 until the earlier of the expiration of the
Abatement Period or the occurrence of a further Event of Default.

     7.   Termination Option. Provided no Event of Default is then continuing
either on the date Tenant delivers the notice described in Section 7A below or
at any time prior to the effective date of such termination, Tenant shall have
the option to terminate this Lease ("Termination Option") upon the following
terms and provisions:

          A.   Tenant shall have the option to terminate the Lease effective as
     of June 30, 2008 ("Termination Option"), provided Tenant gives Landlord at
     least six (6) months prior written notice of Tenant's exercise of the
     Termination Option, which notice, to be effective, must contain the payment
     to Landlord of a termination fee equal to six (6) months Base Rent and
     Adjustment Deposits (at the then current rate) plus the amount of
     unamortized brokerage commissions paid by Landlord pursuant to this
     Amendment.

          B.   The Termination Option herein granted shall automatically
     terminate upon the earliest to occur of (i) the expiration or termination
     of the Lease, (ii) the termination of Tenant's right to possession of the
     Premises, (iii) any assignment or subletting by Tenant (other than
     assignments for which Landlord's consent is not required under the terms of
     the Lease or sublettings of less than 20% of the Premises), or (iv) the
     failure of Tenant to timely or properly exercise the Termination Option.

          C.   Tenant shall remain obligated to perform each and every term,
     covenant, condition and agreement to be performed by Tenant under the
     Lease, including, without limitation, the obligation of the Tenant to pay
     all fixed rent and other payments which are the obligation of the Tenant
     under this Lease, through and including the effective date of such
     termination.

     8.   Landlord's Work. Subject to the terms and conditions of this Section
8, Landlord shall, at its sole cost and expense, repair the parking lot and
demolish the office section in the northeast area of the Premises and return
such section to warehouse space (similar to existing warehouse space in the
Premises) ("Landlord's Work"). Landlord agrees that all work performed in
connection with the Landlord's Work shall be done in a good and workmanlike
manner and in

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substantial compliance with applicable building codes and ordinances. Landlord
shall proceed with Landlord's Work upon approval of the City of West Chicago,
Illinois. Tenant acknowledges that Landlord's Work may not be complete on the
commencement of the Extension Term and Tenant shall provide access to the
Premises to Landlord, its employees, agents and contractors for purposes of
completing Landlord's Work. Landlord also agrees to pay to Tenant, within five
(5) days after execution of this Amendment, the amount of $7,500.00 for Tenant
to use to pay a portion of Tenant's costs in painting and carpeting the offices.
Landlord shall use reasonable efforts in performing the Landlord's Work to
minimize the interference with Tenant's conducting its business at the Premises.

     9.   Indemnification. The parties hereto acknowledge that Tenant and/or its
affiliates were negotiating with USAA or an affiliate of USAA ("Other Landlord")
for other leased premises located at 1801 Hawthorne Lane, West Chicago, Illinois
("Other Premises") instead of entering into this Amendment. Provided that Tenant
has not entered into any written binding lease agreements (i.e. agreements other
than non-binding letters of intent or communications regarding negotiations)
with Other Landlord for the Other Premises, Landlord agrees to indemnify, defend
and hold Tenant and its affiliates harmless from any monetary claims, damages,
losses, costs or expenses (including reasonable attorneys' fees) which Tenant or
its affiliates suffer or incur as a result of Tenant not entering into a lease
with Other Landlord for the Other Premises; provided, however, Landlord's
liability hereunder shall not exceed $50,000.

     10.  No Other Modification. The Lease is only modified as set forth herein
and in all other respects remains in full force and effect.

     11.  No Default. Tenant acknowledges that the Lease is in full force and
effect and that there are no defaults thereunder or any conditions which with
only the passage of time or giving of notice or both would become a default
thereunder.

     12.  Successors and Assigns. This Amendment shall be binding upon and shall
inure to the benefit of the parties hereto and their respective successors and
assigns.

     13.  Modification. This Amendment may not be modified or amended except by
written agreement executed by the parties hereto.

     14.  Governing Law. The validity, meaning and effect of this Amendment
shall be determined in accordance with the laws of the State of Illinois.

     15.  Counterparts. This Amendment may be executed in two counterparts, each
of which shall be deemed an original, but all of which together shall constitute
one and the same instrument.

     16.  Severability. The parties hereto intend and believe that each
provision in this Amendment comports with all applicable local, state and
federal laws and judicial decisions. However, if any provision in this Amendment
is found by a court of law to be in violation of any applicable ordinance,
statute, law, administrative or judicial decision, or public policy, and if such
court should declare such provision to be illegal, void or unenforceable as
written, then such

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<PAGE>

provision shall be given force to the fullest possible extent that the same is
legal, valid and enforceable and the remainder of this Amendment shall be
construed as if such provision was not contained therein.

     17.  Construction. The headings of this Amendment are for convenience only
and shall not define or limit the provisions hereof. Where the context so
requires, words used in singular shall include the plural and vice versa, and
words of one gender shall include all other genders. In the event of a conflict
between the terms and conditions of the Lease and the terms and conditions of
this Amendment, the terms and conditions of this Amendment shall prevail.

     18.  No Third Party Beneficiaries. This Amendment shall inure to the sole
benefit of the parties hereto. Nothing contained herein shall create, or be
construed to create, any right in any person not a party to this Amendment
(other than Tenant's affiliates under Section 9 above).

     19.  Legal Review. The parties hereto acknowledge that they have been
advised by legal counsel of their choice in connection with the interpretation,
negotiation, drafting and effect of this Amendment and they are satisfied with
such legal counsel and the advice which they have received.

     20.  Facsimile Signatures. The parties hereto agree that the use of
facsimile signatures for the negotiation and execution of this Amendment shall
be legal and binding and shall have the same full force and effect as if
originally signed.

     IN WITNESS WHEREOF, the parties hereto have executed this Amendment as of
the date set forth above.

LANDLORD: CENTERPOINT PROPERTIES        TENANT: WINCUP HOLDINGS, INC.,
TRUST, a Maryland real estate              Delaware corporation
investment trust

By:    /s/ Paul T. Ahern                By:    /s/ Michael V. Valenza
   ---------------------------------       -----------------------------------
Its:   Chief Investment Officer        Its:    Sr. V. P. Finance/CFO
    --------------------------------        ----------------------------------
Name:      Paul T. Ahern                Name:      Michael V. Valenza
     -------------------------------         ---------------------------------

By:     /s/ Michael A. Tortorici
   ---------------------------------
Its:    Vice President Controller
    --------------------------------
Name:       Michael A. Tortorici
     -------------------------------

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