“by Roberto Lou Ma, Civil Engineer, Centro de Experimentación enTecnología Apropiada, Guatemala
The CETA-RAM is a manually operated block press, developed by the author just after the February 1976 Guatemalan Earthquake, specifically for the production of hollow soil-cement building blocks. The hollow blocks are intended for use in reinforced masonry for low cost earthquake resistant housing.The CETA-RAM is a modified version of the well known CINVA-RAM.The name CETA-RAM honors the Centro Experimental de Tecnología Apropiada (CETA), where it was developed, and the Chilean engineer Raúl Ramírez, creator of the CINVA-RAM.
The CETA-RAM is a compact and lightweight machine, mechanically simple, low in cost, and easily operated and maintained. Nevertheless, it is capable of molding at high pressure, dense and neatly finished blocks ofhigh structural quality, at the rate of 300 to 500 units per eight hour shift,when operated by two persons. Built entirely of steel, it is composed of three main assemblies (see drawings): – MOULD (1) with COVER PLATE (2)- PISTON (3)- YOKE (4) and LEVER DEVICE (5).
The dimensions of the CETA-RAM block are 32.3 x 15.7 x 11.5 cm. Two 6cm diameter holes run through its full thickness. The holes simplify the placement of vertical reinforcement in earthquake resistant wall constructions: the steel reinforcing rods running through the holes in the laid blocks, at the required spacing, are set in cement mortar or grout. The length of three blocks, included the respective joints, add exactly one meter. This comes out to be convenient in the planning and execution of low cost housing projects, as it allows a modular coordination on the basis of 50 and 100 centimeters, in both architectural and structural aspects. Twenty four blocks lay up one square meter of wall.
The CETA-RAM design has already been fully field proven. To date, CETA has built more than 50 units, used in various rural habitational projects throughout the country and abroad. Some of these machines have produced more than 60,000 blocks apiece, without operational problems and without undue wear. It would appear that with proper care and maintenance, the life span of CETA-RAM, expressed in terms of production, could conservatively be estimated at 100,000 blocks.”