hello out there...just finished my first test batch of reef rocks using crushed oyster shells & type I portand cement, it took me awhile to find oyster shells but i got it(dont ask me how a chicken is able to eat and digest this stuff), in fact the store was right under my nose,past it on my way home from work...here in new jersey theres not alot of chicken farms
, if all turns out well my cost will be no where near the $8.99lb. they charge for rocks around here...ive read several articles on this subject and found that some folks are placing the rocks in the oven after forming...this is not good, ive been aound concrete for the last 6 years in my work...concrete needs water to hydrate(chemical reaction between portland cement and water)or it will never reach full strength, by placing the concrete in the oven one one will end up with weak rocks because the water cement ratio is not in proportion...when we take test cylinders for compressive strength testing immediately after forming the molds they are covered with a plastic cap or burlap(to hold the moisture in) til they set(24hrs.) then they are tranported to the lab and placed in either a cure room(where humidity and temp are constant) or placed in large troughs covered completely with water @ 60F to 80F temp til they are broken @ 28days(ulitmate strength).Even though the concrete seems strong after initial set 3-6 hrs.,the chemical reaction is still taking place between the cement& water...so toss out the oven and place in water...also make sure the mold sand is moist or it will absorb moisture from the prepared concrete once again altering the water cement ratio... hope this will help !:eek3:



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, in fact the store was right under my nose,past it on my way home from work...here in new jersey theres not alot of chicken farms
, if all turns out well my cost will be no where near the $8.99lb. they charge for rocks around here...ive read several articles on this subject and found that some folks are placing the rocks in the oven after forming...this is not good, ive been aound concrete for the last 6 years in my work...concrete needs water to hydrate(chemical reaction between portland cement and water)or it will never reach full strength, by placing the concrete in the oven one one will end up with weak rocks because the water cement ratio is not in proportion...when we take test cylinders for compressive strength testing immediately after forming the molds they are covered with a plastic cap or burlap(to hold the moisture in) til they set(24hrs.) then they are tranported to the lab and placed in either a cure room(where humidity and temp are constant) or placed in large troughs covered completely with water @ 60F to 80F temp til they are broken @ 28days(ulitmate strength).Even though the concrete seems strong after initial set 3-6 hrs.,the chemical reaction is still taking place between the cement& water...so toss out the oven and place in water...also make sure the mold sand is moist or it will absorb moisture from the prepared concrete once again altering the water cement ratio... hope this will help !:eek3:
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