ABSTRACT
This work presents the design, fabrication and performance evaluation of a multiple sandcrete blocks moulding machine (MSBMM) for simultaneously moulding three of 6 inches sandcrete blocks of size 450 x 150 x 225mm. The machine was designed to operate at speed of 151.8 rad/s, and provided the vibration right through compactor drive shaft (CDS)-eccentric system that compressed the three sandcrete blocks with 1.26 X 10-6 N/mm2 with the aid of automatically controlled ram. Machine parts like frame, chassis, lever, vibration compaction chamber, ram, mould, handle as well as rack and pinion were designed while standard parts like electric motors and wheel were simply chosen after calculation during the fabrication of MSBMM. The performance of the machine was compared to that of a conventional sandcrete block moulding machine (CSBMM) by using them to mould blocks from same concrete mix sample. MSBMM was able to produce 90 sandcrete blocks per hour by two (2) workers while CSBMM can produce 125 blocks by minimum of five (5) workers. Average compressive strength produced by these machines were determined then blocks produced from these machines were subjected to water absorption test. Results obtained showed that the average compressive strength test for MSBMM was found to be 1.78 N/mm2 while blocks produced from it have average water absorption of 10.35%. However, CSBMM has average compressive strength of 0.62 N/mm2 while blocks produced from it has average water absorption of 9.29%. The cost of fabricating the machine was one hundred and five thousand, six hundred naira (N 105, 600:00) only, whereas, CSBMM in Nigeria cost about two hundred fifty thousand naira (N 250, 000.00) only based on current market price. This is about 57.76% reduction in price of commercial machine available in market. Thus, the machine is very affordable for small and medium enterprise (SME) based on the price difference.