A novel 3D printing material based on hydroxypropyl methylcellulose (HPMC)—improved sulphoaluminate cement (SAC) for rapid 3D construction printing application is reported. The hydration heat, setting time, fluidity of paste and mortar, shape retainability, and compressive strength of extruded SAC mortar were investigated. HPMC dosage, water-to-cement (W/C) ratio, and sand-to-cement (S/C) ratio were studied as the experimental parameters. Hydration heat results reveal HPMC could delay the hydration of SAC. The initial and final setting time measured using Vicat needle would be shortened in the case of W/C ratio of 0.3 and 0.35 with HPMC dosage from 0.5% to 1.5%, W/C ratio of 0.40 with HPMC dosage of 0.5%, 0.75%, and 1.5%, and W/C ratio of 0.45 with HPMC dosage of 0.45, or be extended in the case of W/C ratio of 0.4 with HPMC dosage of 1.0% and W/C ratio of 0.45 with HPMC dosage from 0.75% to 1.5%. Fluidity measurement shows HPMC significantly improves the shape retainability. Furthermore, the addition of HPMC remarkably increased the compressive strength of extruded mortar. The results showed that HPMC could be used to prepare 3D printing SAC having satisfactory shape retainability,
setting time and compressive strength.
Representative pictures during measuring fluidity of paste: (a) a mold filled with paste; (b) control paste with W/C of 0.3 after removing a mold.
The lower mouth diameter of the truncated conical mold used for the fluidity test was 60 mm (Figure 7a). Thus, the test results of 60 mm fluidity showed that the pastes did not flow away after removing the mold (Figure 7b). Lower W/C ratio could result in lower paste fluidity, irrespective of the presence or absence of HPMC, because lower W/C ratio indicates smaller space and shorter distance between particles in fresh paste (Figure 4), forming greater interparticle friction. The friction is the key factor that affects fluidity. As a result, the lower the W/C ratio, the lower the fluidity. When the W/C ratio of the control paste is 0.30, the friction between the particles is high enough to withstand the flow of paste.
Cellulose ethers such as hydroxyethylmethyl cellulose (HEMC) and hydroxypropylmethyl cellulose (HPMC) are common admixtures in factory made mortars. Nevertheless, their use principally ...
Polished section analysis was employed to study the pore structure of model tile adhesive mortars containing different types of cellulose ethers (CE, ...
Cellulose ethers (CEs) are used to improve the workability of cement mortars while maintaining the water holding capacity and fluidity [1,2]. HPMC ...
A novel 3D printing material based on hydroxypropyl methylcellulose (HPMC)—improved sulphoaluminate cement (SAC) for rapid 3D construction printing application is reported. The ...
