Exhibit 4.31.8

Translation into English for

the benefit of Wilmington Trust

Monterrey, Nuevo León, July 11, 2011

Banco Nacional de México, S.A.,

Integrante del Grupo Financiero Banamex,

División Fiduciaria

Calzada del Valle
No. 350 Oriente

1er. Piso

Col.
Del Valle

San Pedro Garza García, Nuevo León 66220

Mexico

Attention: Nelly Wing

Wilmington Trust (London) Limited

6 Broad
Street Place

Fifth Floor

London
EC2M 7JH

United Kingdom

Attention: Elaine K. Lockhart

Reference is made to the Irrevocable Security
Trust Agreement in Respect of Stock No. F/111388-5, dated September 3, 2009, as amended from time to time (the Agreement), entered into among CEMEX, S.A.B. de C.V. (CEMEX SAB), Empresas Tolteca de
México, S.A. de C.V. (Tolteca), Impra Café, S.A. de C.V. (Impra Café), Interamerican Investments, Inc. (Interamerican), CEMEX México, S.A. de C.V. (CEMEX
México), and Centro Distribuidor de Cemento, S.A. de C.V. (Cedice), as settlors (CEMEX SAB, Tolteca, Impra Café, Interamerican, CEMEX México and Cedice, together, the Settlors);
CEMEX México, Cedice, Mexcement Holdings, S.A. de C.V. (Mexcement) and Corporación Gouda, S.A. de C.V. (Gouda), as issuers (CEMEX México, Cedice, Mexcement and Gouda, together, the
Issuers); Banco Nacional de México, S.A., Integrante del Grupo Financiero Banamex, División Fiduciaria, in its capacity as trustee (the Trustee); and Wilmington Trust (London) Limited, on its own
behalf and in its capacity as Security Agent, for the benefit of the Participating Creditors, the Refinancing Creditors (and their respective successors and assigns) and the other Secured Parties (the Beneficiary). Unless
otherwise defined herein, capitalized terms defined in the Agreement, are used herein as therein defined.

On July 11,
2011, CEMEX, S.A.B. de C.V. issued U.S.$ 650,000,000 of 9.000% senior secured notes due 2018, guaranteed by CEMEX México, CEMEX España, S.A. and New Sunward Holding B.V. (together, the Additional Notes). Because the
purpose of the Additional Notes is to refinance existing indebtedness and, as a consequence thereof, the Additional Notes will be part of the Refinancing Debt and the holders of the Additional Notes will be a Refinancing Party, in both cases
pursuant to the Agreement, by means of this letter the Settlors and the Issuers hereby inform the Trustee and the Beneficiary, and confirm, that the Additional Notes are secured in accordance with the terms provided in the Agreement, and are part of
the Secured Obligations and the holders of the Additional Notes are Secured Parties.



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We appreciate you acknowledging receipt of this letter, by signing in the space provided
below.



|                                             |  |                   |  |                 
|-------------------------------------------- |  | ----------------- |  | ----------------
|CEMEX, S.A.B. de C.V.                       
|                                             | 
|By                                           |  | /s/ Roger Saldaña
|                                             |  | Name:             |  | Roger Saldaña   
|                                             |  | Title:            |  | Attorney-in-Fact
|                                            
|Empresas Tolteca de México, S.A. de C.V.    
|                                             | 
|By                                           |  | /s/ Roger Saldaña
|                                             |  | Name:             |  | Roger Saldaña   
|                                             |  | Title:            |  | Attorney-in-Fact
|                                            
|Impra Café, S.A. de C.V.                    
|                                             | 
|By                                           |  | /s/ Roger Saldaña
|                                             |  | Name:             |  | Roger Saldaña   
|                                             |  | Title:            |  | Attorney-in-Fact
|                                            
|Interamerican Investments, Inc.             
|                                             | 
|By                                           |  | /s/ Roger Saldaña
|                                             |  | Name:             |  | Roger Saldaña   
|                                             |  | Title:            |  | Attorney-in-Fact
|                                            
|Cemex México, S.A. de C.V.                  
|                                             | 
|By                                           |  | /s/ Roger Saldaña
|                                             |  | Name:             |  | Roger Saldaña   
|                                             |  | Title:            |  | Attorney-in-Fact
|                                            
|Centro Distribuidor de Cemento, S.A. de C.V.
|                                             | 
|By                                           |  | /s/ Roger Saldaña
|                                             |  | Name:             |  | Roger Saldaña   
|                                             |  | Title:            |  | Attorney-in-Fact
|                                            
|Mexcement Holdings, S.A. de C.V.            
|                                             | 
|By                                           |  | /s/ Roger Saldaña
|                                             |  | Name:             |  | Roger Saldaña   
|                                             |  | Title:            |  | Attorney-in-Fact



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|                                                                                           |  |                     |  |                 
|------------------------------------------------------------------------------------------ |  | ------------------- |  | ----------------
|Corporación Gouda, S.A. de C.V.                                                           
|                                                                                           | 
|By                                                                                         |  | /s/ Roger Saldaña  
|                                                                                           |  | Name:               |  | Roger Saldaña   
|                                                                                           |  | Title:              |  | Attorney-in-Fact
|                                                                                          
|Acknowledgment of receipt:                                                                
|                                                                                          
|Banco Nacional de México, S.A.,Integrante del Grupo Financiero Banamex,División
Fiduciaria
|                                                                                           | 
|By                                                                                         |  | /s/ Elba Nelly Wing
|                                                                                           |  | Name:               |  | Elba Nelly Wing 
|                                                                                           |  | Title:              |  | Trust Delegate  
|                                                                                           |  | Date:               |  | July 11, 2011   
|                                                                                          
|Wilmington Trust (London) Limited                                                         
|                                                                                           | 
|By                                                                                         |  | /s/ Elaine Lockhart
|                                                                                           |  | Name:               |  | Elaine Lockhart 
|                                                                                           |  | Title:              |  | Director        
|                                                                                           |  | Date:               |  | July 11, 2011   



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