Expert: Dan Griffin - 10/14/2008

Question
1.Would do you give me appropriate type of reinforcement  bars need to construct ground zero L-shape house?
2. I need to produce hollow blocks manually but I have no clean information the ratio of sand :Cement:Water,would do you mind giving me?
3.Please give me the ratio of cement to sand and water to plaster and touch of fills between hollow blocks?

Answer
Diriba, lots of questions and so many answers.

1.  House footings for single story here require a minimum of 2 #5 (5/8") rebars in the footing that must be poured below frost line.  The more correct answer would need to know the bearing capacity of the soil, the frost depth, the loads that will be imposed.  Your mention of hollow block sounds like our CMU, concrete masonry units, which are usually purchased from a block supplier.  They come in many dimensions, but normally are 8"x8"x16" and these require a typical footing 16" wide.

2.  CMU are cement product usually made with light weight aggregate.  Commercial cemnt block 8/8/16 run over 65 pounds per unit.  The same block made with Haydite or similar light weight run 40 pounds.  A ratio of 1 part cement, 3 parts washed sand, 5 parts aggregrate should give serviceable blocks, but you should make a sample and test.

3.  I'm sure you're asking about the mortar to lay the block.  A typical mix would be 1 part cemenet, 1 part lime, 5 parts sand.  The lime is important to make the mortar sticky, a requirement to make the mortar useable.