Problem: 50 feet of reinforced concrete curb where we wanted to build our community workshop. Plan A: Rented two pneumatic jack hammers. After a long afternoon, we had made progress, but only broken up about 10 feet. Plan B: My co-housing neighbor came across the previously-untried Dexpan. A non-explosive demolition agent, Dexpan is a mortar-like powder you mix with water and apply to rock, concrete and even reinforced concrete in order to break the material apart. As it dries, the powder expands a slight bit, but with a tremendous force. It’s easy to use. We followed the guidelines for the most part. With a 1.5″ carbide bit in a hammer drill, we made a series of strategically-placed holes holes on 12-16″ centers, mixed up the mortar, and poured. It takes 24 hours or longer for maximum effect. As I recall, some holes didn’t crack at first, but did after I added additional water and gave it more time. We did end up using a 20-pound sledge hammer and a 5-foot long solid steel pry bar when necessary to open up cracks so we could use an angle grinder to cut the rebar. The pry bar also was crucial in moving the chunks, which tended to be very heavy. Nevertheless, the Dexpan was responsible for breaking up the concrete into reasonably-sized pieces. The rebar had to be cut and required a lot of prying, but there’s no way we could have broken all this up using a sledge hammer in any reasonable amount of time. There are other non-explosive demolition agents out there, but my recollection is that Dexpan was by far the easiest to buy in small quantities. They say their 44-pound box will cover 34-36 linear feet.You must order one of three mixes depending on the temperature you will use it at. As I recall, it was probably the low 60′s on average when we used it so we got the middle mixture. If we had to do it over again, we’d probably price out having a professional remove the curb — it really was a lot more work than we thought. But if you’re going to do it yourself, this makes it a lot easier than just relying on a jackhammer.
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