Civil and Environmental Research www.iiste.org ISSN 2224-5790 (Paper) ISSN 2225-0514 (Online) Vol.9, No.10, 2017 25 Environmental Water Related Deterioration of Compressed Stabilized Earth Block Structures in Uganda Anthony G Kerali 1 * Ronald Ekyalimpa 2 1.Associate Professor, College of Engineering Design Art and Technology, Makerere University, P. O Box 11550; Kampala, Uganda 2.Lecturer, College of Engineering Design Art and Technology, Makerere University; P. O Box 7062, Kampala, Uganda Abstract The provision of shelter for all has not yet been realised. The main challenge is the high cost of building materials. Compressed and stabilised earth blocks (CSEB) are now recognised as low cost materials. While their green properties are well understood, the durability of these materials remain enigmatic. The objective of this research was to investigate the durability of CSEBs as used in the humid tropics. The interplay between the block and the effects of natural exposure conditions, especially the dynamics of rainfall, are examined. Through a methodology involving literature reviews, physical inspections, and exposure condition survey, block behaviour and defects over time are rigorously investigated. Water deterioration modes and their mechanisms of progression are discussed. The sources of water, agents, actions, effects, affected properties, and rate of deterioration are described. Defects were exhibited mainly as surface erosion, and cracking. However, it is still possible to improve the durability and wear resistance of CSEBs for use in the humid tropics. The improvement is achieved via lowered water absorption, and improved design codes, tests and standards. The findings are likely to contribute to the future widespread use of CSEBs. The findings raise a number of questions for further studies. Keywords: Compressed Earth Blocks, Deterioration, Durability, Rainfall, Soil-Cement, Stabilization, Water 1. Introduction Cement based building materials like compressed stabilized earth blocks (CSEB's) and concrete were for decades promoted as having an indefinitely long service life. That they would require only minimal maintenance or none at all over time. However, as these structures continue to be left exposed, it is becoming evident over time that even normal exposure conditions are actually more deleterious than originally thought. Occurrences of undesirable, unpredicted premature deterioration where defects are clearly visible even to the casual observer are becoming common. The main cause of deterioration is associated with the action of water on the surface and bulk of the block. The sources of water as an agent of deterioration were: liquid rain, hailstorms, rising damp, condensation and humidity from water vapour. The types of action include; abrasion, wetting, penetration, solvent, and catalytic. The effects include; erosive wear and tear, dampness, swelling, softening, dissolution, and initiation of chemical activity. Both surface and bulk properties are affected, with the former progressing at a higher rate than the latter. Defects in CSEB structures are mainly presented as surface erosion, volume reduction, volumetric changes, mass loss, cracking and crazing, surface pitting and roughening, detachment of render, exposure of mortar, and moulding. These deterioration phenomena have been predominantly witnessed in the wetter humid tropical regions of the world. No similar adverse reports have been documented from the hotter and drier regions. In this paper, it is noted that while much research has been undertaken in the recent past on initial properties of CSEBs, very little similar research has been done on its durability. Recent advances have however been made in the durability research of comparable materials such as concrete. These are now well documented, and moves to redress identified shortcomings are following. A similar treatment is required in the case of CSEBs. The urgency is more acute. Interest in the durability of CSEBs is likely to become a major concern in the foreseeable future given the potential of the material in alleviating shelter backlogs in developing countries. Durability research is a complex undertaking. This is because in practice several causes of deterioration will occur simultaneously. These are compounded by cumulative as well as synergistic actions (Sjostrom, et al, 1996). This paper is presented in six sections. After this introductory section, the rest of the paper covers the background, research objectives, methodology, findings and discussions, and conclusion. 2. Background 2.1 Brief The majority of developing countries are today faced with an ever increasing problem of providing adequate yet affordable housing in sufficient numbers. In the last few decades, shelter conditions have been worsening yet resources remain scarce. Adequate shelter is one of the most important basic human needs, yet 25% of the world's population does not have any fixed abode, while 50% of the urban population live in slums. With the population in developing countries growing at rates of between 2% and 4% per year and the population in their