slo-mo #video of #expanding-grout breaking up a boulder
on 02024-05-04#CC #paper #PDF “An Alternative to Conventional Rock Fragmentation Methods Using SCDA: A Review” on #expanding-grout, describing many different products from different manufacturers, DOI 10.3390/en9110958. Also contains the absurd error mentioned in an earlier paper that the cement contains SO₃.
on 02024-05-03#CC #paper describes various excavation methods (plasma, foam injection, etc.) including #expanding-grout, which it says works by hydrating lime under confinement and also producing ettringite, but lists four different types: type K (4CaO·3Al₂O₃·SO₃ + 8CaSO₄⋅H₂O + 6Ca(OH)₂ + 74H₂0 → 3(3CaO⋅Al₂O₃⋅3 CaSO₄⋅32H₂O, can be enhanced with silica fume and plasticizer), type M (CaO⋅Al₂O₃ + 3CaSO₄⋅H₂O + 2Ca(OH)₂ + 24H₂O → 3CaO⋅Al₂O₃⋅3CaSO₄⋅32H₂O), type S (3CaO⋅Al₂O₃ + 3CaSO₄⋅H₂O + 26H₂O → 3CaO⋅Al₂O₃⋅3CaSO₄⋅32H₂O), and class [sic] G (CaO + H₂O → Ca(OH)₂). Calls it “SCDA” and mentions ASTM C 845 “Standard Specification for Expansive Hydraulic Cement”. It says they work too slowly (12h) to replace explosives in the usual mining cycle, but I suspect that’s not true of class G, where the main problem is keeping it from reacting to completion before you can pour it into the hole.
on 02024-05-03#PDF #paper on #expanding-grout from 02009: “Expansive Cements and Soundless Chemical Demolition Agents: State-of-Technology Review” by Huynh and Laefer, using the term “soundless chemical demolition agents”, or “SCDAs”, which says ettringite formation is the main mechanism. Lists brands including Prostar, CrackAG, Chemshine, Buster, and Dexpan.
on 02024-05-03“The use of expansive chemical agents for concrete demolition: Example of practical design and application” says #expanding-grout is CaO, SiO₂, Al₂O₃, MgO, and SO₃, which last is obviously an error; it says, “They expand due to the exothermic reaction between CaO and H₂O. … Additional pressure can also be created by ettringite formation.” Ettringite (Ca₆Al₂(SO₄)₃(OH)₁₂·26H₂O) can form in portland cement from the reaction of alabaster with tricalcium aluminate, and a thin layer of ettringite is what makes portland cement have a usably long pot life #paper
on 02024-05-03#CodysLab #video on #expanding-grout. He uses quicklime (not slaked lime like “Dexpan”!) and, to delay the reaction, washing soda (200mg or 600mg per 10g of quicklime). Features a quicklime steam explosion in the kitchen. He sinters the quicklime to try to reduce its porosity, which I didn’t think will do much because his kiln was only set for 1200°, but apparently it did. The mix was successful in breaking a rock in a couple of hours and a test tube in a bit more. The higher-soda mix expanded more (possibly because it stayed wet longer) but more slowly.
on 02024-05-03#MSDS for “Dexpan” brand #expanding-grout #materials “for controlled demolition, reinforced concrete cutting, rock breaking”, etc. Causes serious eye damage because it’s 75–90% slaked lime, also containing vitreous silica, hematite (Fe₂O₃), and alumina. But that can’t be all Expando is or it wouldn’t cost AU$15 a kilo. Specific gravity 3.2.
on 02024-05-03“Expando” brand #expanding-grout costs AU$305 for 20kg. #materials #pricing
on 02024-05-03“Expando” brand #expanding-grout generates heat that can result in steam explosions (“Do not look directly into the filled holes for the next 2 – 6 hours”!), should be poured into holes of 28mm to 40mm diameter, takes 24–76 hours to expand mostly and 5 days to expand fully, has a 10-minute working time, comes in five different formulations for different temperature ranges, and produces 14000 “psi” of compressive stress (100MPa). #materials
on 02024-05-03breaking up basalt with #expanding-grout. #materials #video doesn’t seem to say anything about what the expanding grout is made of. “Expando” brand. They drilled 149 holes with a rotary hammer about 200mm apart along crisscrossing lines about 600mm apart and then poured the stuff into them from a bucket with a funnel. Two days later the giant rock had broken into small pieces. The grout had turned white, seems to be crumbly and dusty and chalky when the hydraulic digger picks the rock apart, and seems to have expanded by on the order of 10% of its diameter. The holes where the grout couldn’t split the rock, they split with a hydraulic wedge splitter. Lots of hydraulic bucket digger action if that’s what you’re into. Bleh.
on 02024-04-06