Barriers and enablers for scaled-up adoption of compressed earth blocks:

Compressed earth blocks (CEBs) are a low-cost, low-carbon construction product, which is well suited for masonry infill in the Global South. A knowledge gap remains around the technical and socio-economic barriers to CEB adoption. A combined survey and interview study was carried out among architects, CEB manufacturers, and academics within Egypt: firstly, to explore technical and socio-economic barriers to greater adoption of CEBs for masonry infill, and secondly, to identify potential enablers. Many technical challenges still exist, despite the fact that building codes for CEB in Egypt were introduced in 2019.

The majority of respondents agreed that socio-economic barriers are more significant than technical barriers. These included CEBs being unfamiliar to most architects and builders, and that most clients perceive CEBs as ‘low-quality’ or ‘inaesthetic’. Most respondents believed that CEBs can achieve ≥25% market share for masonry in Egypt. However, CEB press supply is likely to be a major barrier to scale-up.

Suggested enablers included tailored marketing suggestions for low-/middle-income and high-income clients, and deciding at the earliest possible design stage whether to manufacture CEBs on-site or off-site. Mapping the enablers across stakeholders showed that more research is needed to understand the views of CEB press manufacturers and government officials.

Egypt, like other Global South countries, faces a challenge in meeting the forecasted housing demand by 2050 with low-cost solutions that do not exacerbate climate change. The current population of Egypt is 106 million; by 2050, the population is projected to grow to 160 million (Nabawy et al., 2021). The urban population is 40% (Marzouk et al., 2021), but this is concentrated within only 10% of the country’s area. To meet the forecasted increase in population between 2022 and 2050, an additional 13 million housing units will be required – 43% of these are expected to be urban and the remaining 57% to be rural (Appolloni & D’alessandro, 2021).

Historically, load-bearing walls in Egypt have typically been made of adobe bricks and natural stone. Adobe, a term referring to sun-dried mud bricks, has been used ever since the Ancient Egyptian era (Morgenstein & Redmount, 1998). Today, the majority of new housing projects in Egypt use reinforced concrete as a structural system and a wall infill of either fired clay bricks or concrete masonry blocks. Comparing these two masonry materials, the embodied carbon of hollow concrete blocks (971 MJ/m3 of masonry, for 10% cement blocks) is much lower than that of fired bricks (2141 MJ/m3 of masonry) (Reddy and Jagadish, 2003).

Whilst concrete blocks may seem preferable to fired bricks in terms of embodied energy and carbon, they have drawbacks in other aspects of sustainability. Concrete houses can have poor thermal comfort in Egypt (Gado et al., 2010); given trends of rising global surface temperatures, overheating of housing is an increasingly important public health concern (Hales et al., 2007; Mastrucci et al., 2019). Therefore, it is crucial for new housing to minimize the risk of overheating.

There is also concern that the use of conventional contemporary construction materials, including concrete, is eroding the cultural identity of oasis towns in Egypt by replacing traditional earth-based materials and construction techniques (Gado et al., 2010). These considerations drive the search for low-cost, low-carbon infill brick solutions to replace the use of fired clay bricks and concrete blocks in Egypt and other Global South countries.

Compressed earth blocks (CEB), made using manual or automated presses to form a standardized block, have been developed in recent decades. The compression process gives higher strength and durability compared to Adobe (Adam & Agib, 2001). Stabilizing agents, such as cement or lime, are often added to further improve strength and durability (Reddy et al., 2022).

The presence of unfired clay in CEB helps to regulate both indoor temperature and humidity, contributing to thermal comfort for occupants (Fahmy et al., 2022). CEB production does not require skilled labor, as the production process goes through three simple phases; soil preparation, compression, and curing (Riza et al., 2011).