3D-Admix With Neat Cement and Regular Concrete for 3D Printing

https://spacecrete.com/ A few people requested a video of the demo made at World of Concrete 2019, so here it is. To see the thickened concrete vibrated into place, please see a test project:    • SpaceCrete Concentrate:  pumpable-zero-slu...   The Water Reducer (Super Plasticizer) used here is SIKA Viscocrete 1000, a polycarboxylate either that is slightly more compatible with the shear thinning rheology we are after. All the PCEs (I know of) are self-leveling +/- and really very similar to each other in this application, where their effect must be cancelled to get 3D printability. All types of water reducers tested here have that effect. The PCEs can make a stronger concrete. The retarder/stabilizer used, Delvo, is similar to those made by the other admix marketers - it is the most well-known where I live. Citric-based retarders will behave really the same, in that the thickening action is not affected much unless the retarder dose is quite high. The concrete as it was mixed here, with grams substituting pounds - to make the math easy, making this test batch about 1/454 of a cubic yard of concrete: 3/8" Rock 1100 Conc Sand 1600 Fine Sand 230 (typical of the local batch plant) Cement 611 Fly Ash 200 Water 260 SIKA 1000 4.5 Delvo 6 3D Admix 15 (can vary, 10 lb per yard is more typical, per w/c)