[papercreters] Cement, papercrete and hypertufa

One reason "old concrete guys " might look askance at papercrete is it violates some basic guidelines. Concrete is a crystalline sturucture. making crystals means a holding concrete insolution long enough for it to develope big crystals. In concrete slabs they might be covered with burlap, or plastic or sprayed with a sealer like gum arabic. This serves to keep the water from escaping too quickly. {experience Arcosanti in central Arizona}
While reading an article on hypertufa ( a mix of peatmoss, sand and Portland cement) used to make planters and planting troughs of all sizes; the author advocated removing the troughs from their molds asap and covering with plastic for two weeks (normal concrete is said to gain 70 % of its "strength" in the first two weeks. One of y'al making blocks might want to try this technique and see if affects the strenght of the finished product. Hypertufa is preferred for garden troughs as you can leave it out thru the winter and not have the frost crack it.

Dan



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