How to make hollow blocks

CEMENTLESS SOIL BLOCKS 

 In view of the rising cost of cement, the Forest Products Research and Development Institute made an attempt to form building blocks out of soil and water alone or in combination with one or two other agri-forestry waste materials, such as rice hull, coconut coir dust and wood ash. Lime is used as a binder. Lime is found in large quantities in Rizal, Negros Occidental and Davao Oriental. Coconut coir and other materials are available almost nationwide. 

Materials: Lime Soil Coconut coir Sand Rice hull Wood ash Rice hull ash 

Equipment: 1/4 inch mesh screen mold shovel 

Procedure: 1. Pulverize the soil and remove larger pieces with the use of a 1/4 inch wire mesh screen. 2. Mix together soil and any one or two of the agri-forestry wastes. Suggested combinations (in parts by volume) are: a. 3 soil + 1 coconut coir b. 3 soil + 1 rice hull c. 5 soil + 1 lime d. 5 soil + 1/2 lime + 1/2 rice hull ash e. 5 soil + 1/2 lime + 1/2 wood ash f. 4 soil + 1 rice hull + 1 lime g. 21/2 soil + 21/2 sand + 1/2 lime + 1/2 wood ash

3. Form a hill out of the dry mixture (or of soil alone if a pure soil block is to be made) with a crater on top and add water. 4. Pour water slowly and with a shovel, mix the materials until a paste is formed. The paste should neither be too dry nor too wet so that during the molding process. The ingredients are wet enough to stay packed but not too wet to produce slump when the product is removed from the mold. The right mixture can be learned easily by experience. 5. Fill the mold with the mixture. Tamp very well and level off. Apply pressure using a manually-operated molding machine or a similar device. 6. Dry the block in the shade for a few days and then sun dry for another few days. 

Source: Forest Products Research and Development, Institute (DOST) College Laguna 

LIME-CLAY-SAND BLOCKS 

With the materials that are available all over the country, Industrial Technology and Development Institute fabricated blocks which need no firing. The block has a square face and grooved sides which allow adequate surface for bonding. It measures 8"x8"x6". The provinces of La Union, Bulacan, Batangas, Quezon, Bohol and Negros Occidental have reserves of all the 4 non-metallic ores herein used. Clay and limestone may be found in almost all the regions while sufficient amount of sand and gravel occur in Regions III, IV, VI and X. 

Materials: Clay Gravel Lime Water Sand 

Equipment: Pickax Wire mesh screen Shovel Wooden measuring box 

Procedure: 1. Crush the lumps of clay into smaller pieces with a pickaxe. With the use of a wire mesh screen, remove impurities, such as stones, roots, twigs, etc. 2. Sift the lime and the sand separately to remove the bigger particles. 3. Mix thoroughly five (5) boxes of clay, two (2) of lime and two (2) of sand. 4. Add water slowly until the right consistency is reached. The mixture should neither be too wet nor too dry so that when molded, the block will maintain its shape. 5. Press the mixture into a wooden mold until all spaces are filled up and scrape off the excess. 6. Remove the mold and allow the formed block to stand in the shade for 3 days. Then sun-dry for another 3 days. 

Source: Ceramics Research Division ITDI (DOST) 

HOLLOW BLOCKS FROM RICE HULLS 

Procedure: 1. Carbonize the rice hulls. 2. Pulverize the ash. 3. Mix the following:60 parts cement40 parts carbonized ashwater 4. Pour the mixture into wooden molds 5. Allow to dry. 

Source: Forest Products Research and Development , Institute (DOST) Los Baños, Laguna. 

HOLLOW BLOCKS FROM WASTE MATERIALS 

 A new type of hollow blocks can be fabricated out of wood wastes, agricultural wastes and soil mixed with minimum amount of cement. As far as strength and durability are concerned, results of test showed that this type of blocks is comparable to some of the commercial or traditional concrete hollow blocks. However, they are considered as strictly non-loading bearing. 

Materials: 1 part cement 3 parts sawdust, ordinary soil, rice hulls, abaca waste, sugarcane bagasse, coconut coir dust and coconut trunk. Procedure: 1. Pulverized soil is passed through a wire screen, 1/4 inch wire mesh to separate larger pieces. A mixture of 1 part cement to 3 parts agri-waste is formulated. 2. Mix all materials together, add water and pour into molds. 3. Let stand for several hours until dry. 4. After drying, remove from molds and let stand along one side for 10 days while sprinkling water at regular intervals to avoid cracking. 

Source: PCARRD Farmnews December 1988, Photo courtesy of www.hindu.com