Roads Department - Government of Botswana

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FOREWORD Roads Department The prevention of soluble salt damage to bituminous roads and runways plays a vital role in reducing the cost of both construction and maintenance of roads in Botswana. Without adequate prevention measures and monitoring of soluble salt during construction, the road may deteriorate and will often result in extensive rehabilitation. There is, therefore, a need to draw the attention of designers and engineers to the dangers of soluble salts in the early stages of road construction. Because of Botswana’s environment, construction materials and construction water contain soluble salts which when used in construction has resulted in severe damage to roads and runway surfaces. These problems have been encountered in several projects including Sua Pan airstrip, Nata-Gweta road, Orapa-Mopipi-Rakops road, Selibe-Phikwe runway, the trans-Kgalagadi road and many others. It is exorbitantly expensive to avoid the use of saline materials and water by importing non-saline alternatives. By providing guidelines for the use of available saline materials and water where technically feasible, significant cost savings can be achieved. The guidelines discuss the occurrences of salt damage in Botswana and elsewhere worldwide, detailed design and construction procedures are provided for the prevention of salt damage. Methods of testing and measurement of salts are also given together with repair methods where damage has already occurred. The user, whether a technician or an experienced engineer will find the guideline useful in identifying whether there is likelihood of damage occurring and in determining the design and construction measures required to prevent damage. The guideline will also be useful to those working in other semi-aid environments of the SADC region where much of the available materials and contain soluble salts. Gaborone July 2001 A. Nkaro Director of Roads Roads Department Ministry of Works, Transport and Communications Guide to the Prevention and Repair of Salt Damage to Roads and Runways 7
Roads Department ACKNOWLEDGEMENTS This Guideline is one of a series that has been produced by Botswana Roads Department under the Institutional Cooperation with the Norwegian Public Roads Administration (NPRA). This agreement falls under a NORAD Technical Assistance Programme to Roads Department, which is co-funded by the Government of the Republic of Botswana and the Kingdom of Norway. The guideline was written by Dr. Bernard Obika. Significant contributions and comments on various drafts of the guideline were made by the following: Mr. Barry Kemsley, Roads Department Mr. Charles Overby, NPRA Mr. B. Sharma, Roads Department Mr. B. Kowa, Roads Department Mr. E. Maswikiti, Roads Department Mr. M. Segokgo Mr. Charles Overby co-ordinated production of the guideline including final editing and formatting. The photographs were provided by: Dr. Bernard Obika, Ms. M.T. Keganne, Diwi Consult Mr. Charles Overby, NPRA 8 Guide to the Prevention and Repair of Salt Damage to Roads and Runways
Page 2 and 3: Roads Department The Prevention and
Page 4 and 5: Roads Department ROADS DEPARTMENT U
Page 6 and 7: Roads Department 3.3.3 Field Determ
Page 10 and 11: Roads Department 1. INTRODUCTION 1.
Page 12 and 13: Roads Department 2. OCCURRENCE AND
Page 14 and 15: Roads Department Preliminary field
Page 16 and 17: Roads Department tained up to 0.5%
Page 18 and 19: Roads Department In addition to the
Page 20 and 21: Roads Department The various salt t
Page 22 and 23: Roads Department 2.5.4 Pavement Sur
Page 24 and 25: Roads Department to temperature. Th
Page 26 and 27: Roads Department 3. LABORATORY AND
Page 28 and 29: Roads Department E.C can also be co
Page 30 and 31: Roads Department 4. RISK EVALUATION
Page 32 and 33: Roads Department The salt content v
Page 34 and 35: Roads Department 5. PREVENTATIVE DE
Page 36 and 37: Roads Department 20 19 12 11 10 9 8
Page 38 and 39: Roads Department 6. REPAIR OF DAMAG
Page 40 and 41: Roads Department 8. REFERENCES Refe
Page 42 and 43: 41 Guide to the Prevention and Repa
Page 44 and 45: Roads Department APPENDIX B Appendi
Page 46 and 47: Roads Department Appendices Stage 3
Page 48 and 49: Roads Department APPENDIX E - ABBRE

Roads Department - Government of Botswana

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