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INTRODUCTION
The popularity of sandcrete blocks and their extensive application as walling material in Nigeria and other developing countries cannot be overemphasised. Sandcrete blocks, when properly produced, meet BS 2028 (1968) recommendations for density and compressive strength of structural masonry.
Sandcrete blockwalls are usually not designed to support loads other than their own weight. However, one of the earliest warning signs of failure is often manifested by the formation of serious critical structural cracks (Figure 1 - See PDF,) long before the actual event. Recent structural collapses in Nigeria and elsewhere have raised serious concerns for more in-depth and intensified study on the mechanism of resistance of all components of the structure, as reported by Wenapere (2008), Gajanan et al (1983), Adisa (1997) and Ogar (1997). However, while significant research effort has been devoted to steel and reinforced concrete, concrete framework, concrete masonry blocks and blockwalls, there have been few studies on sandcrete, and these have been limited to block units only. There are very few recorded tests on sandcrete blockwalls.
Structural cracks may be associated with differential foundation movement or other movements leading to the transfer of load from frame to blockwall, among others (Figure 2 - See PDF,). Thus, the blockwall may be expected to possess enough strength to support its own loads, the effects of additional environmental and accidental loads, and any loads transferred from the structural frame. In addition, the blockwall should provide some reasonable in-fill restraint to the structural frame.
Current views on the strength deformations and failure mechanism of concrete masonry under static and dynamic loads are presented in the recent studies by Abrams (1996, 1997), Andam (2002a, 2002b), Page (1981), Paulson et al (1990) and Stroven (2002), among others. The problems of frame-in-fill interaction are addressed in the investigative studies by Ephraim et al (1990), Liauw et al (1983) and Madan et al (1997), among others. The few important studies that have attempted to address the connection of mixed composition and compactive effort on the strength and economy of sandcrete masonry include those by Wenapere (2003), Andam (2002a, 2002b), Chandhari and Gumel (2000) and Uzomaka (1977), among others.
The laboratory investigation of blockwall is highly limited by the sheer size and the loading equipment requirements, and due...