"Green" ASP?

I'm an environmental engineer, but that doesn't necessarily make me feel like an environmentalist. What I'm about to tell you does.

Here at ASP, we care about our environment. That's why we're replacing unsafe concrete and block steps with new steps, using the old block as aggregate for the new concrete, which will hold the new posts in place. The design for this concrete was based on Minnesota DOT's numbers, found here. The numbers have been rounded a lot, since the new concrete will serve less of a structural purpose, and more of a filling or stabilizing purpose. Also, the volunteers probably won't be very precise in their measurements anyway.

For 6x6 post-holes, 1.85 cubic feet (cf) of concrete will be needed. With 4 6x6 posts, we will need about 7.5 cf of concrete. The amounts of each ingredient needed to make 7.5 cf of concrete are shown below. Nevermind the fact that it adds up to more than 7.5. Call it a safety factor. The same ratios are used for the 4x4 post holes, but in different amounts.

	cf	lb	Spec Gravity (pcf)
Cement	1.4	130	94
Water	1.1	70	62
Coarse Agg.	3.8	450	120
Fine Agg.	3.3	330	100

The volunteers are being instructed to "disassemble" the existing steps, and break up the concrete blocks into coarse and fine aggregate piles. We'll give them the cement and the rest is history. We'll see how it goes, and I'll try to check in with the family as to the concrete's performance some time later down the line.

All photos in this post were taken by Robyn Rosner.