Cob: Costs: Lime versus cement

[Taylor Publishing-DirtCheapBuilder]

Yes cement has higher embodied energy costs...and may have higher 
production costs too. but you can't compare by the WEIGHT of the bag of 
lime vs cement.

Cement here is $7-8. a bag 94 pounds, and lime is $7.50-$8. for 50 
pounds, but you are getting  a higher VOLUME of material in use with 
lime..  Cement weighs more due to the high clay content. ( cement is 
limestone and clay and other chemicals processed together, lime is pure 
calcium carbonate with less than 5% impurities)

lime is added TO clay in building to make a stabilized mix from as 
little as 2% to dry up muddy worksites, to  as much as 20% or more to 
stabilize for bricks and plasters.  8% lime is used as a basic guide to 
stabilize.( I use a 1-3 or 1-4 lime to clay ratio for my experiments to 
make Roman Cement for  stabilized (cobwood) sawdust bricks and 
(paperclay-papercob)  stepping stones)

Now, for making plasters and mortars you are adding sand 1:3 or 1: 2. 
depending on need.

It pretty much evens out in cost, as you are soaking the lime in water 
to make putty
( expanded volume)  to use. but lime exceeds the cement in MANY other 
ways depending on use ( ie breathable/reapairable plasters, ease of use, 
durability, vapor permeability, water release, beauty, self annealing 
for cracks..on and on)


Ms. Charmaine  Taylor/ Taylor Publishing
PO Box 375, Cutten (Eureka) CA 95534 707-441-1632  
books at dirtcheapbuilder.com   
Please see  www.papercrete.com for Online newsletter and more web links.