Grand Housing Development Program Volume III - Gtz

HOLLOW CONCRETE BLOCK (HCB) PRODUCTIONat a time. The HCB is transportedby two people on a wooden pallet.The HCB remains on the woodenpallet for 24 hrs. Then it is becured covered by a plastic sheetto enhance the curing process andpreventing the water from evaporation.The materials required for the productionof HCBs and their mixingratio differs from site to site dependingon the availability of thebuilding materials and the ratiothat fulfils the required strength.This holds true for all types ofHCBs production.The machine used for the productionof HCBsThe machines used to produceHCBs are electrical vibrating machineswhich have 1.5 HP motorto make sure, that the vibration isstrong enough to compact the concretesufficiently in the moulds andto achieve the required strength.Curing-time is at least 10 days beforeusing the HCBs for construction.It is important to write the date ofproduction on the HCB so thatthe mason can easily identify theHCBs, ready for construction.The average overall production is1200 HCBs per day per machine.The pictures show machines, usedby LCH-Project.Before starting production the differentmaterials used to producethe HCB will be dry-mixed thoroughlyon a clean and dry groundby hand. Then the mixture will beput in the mixer with the appropriateamount of water required (water tocement ratio of 0.49 – 0.55). Themixture is inserted into the mouldand vibrated for about 60 secondsbefore extruded as HCBs.Filling in concrete while the machine isalready vibratingConcrete is filled up during compactinguntil the mould is filledExcept for the slab-HCB, the machinescan produce three piecesThe mould viewed from the topClearing the topRemoving the mould upwards14Addis AbabaCity Government