Modification of properties of fresh mixture for 3D printing using cement-based mortar

Currently, 3D printing technology in construction is becoming more popular every day in many countries and regions in the world. In parallel with the development of 3D printers, the research, design and application of materials as "ink" for this technology is also an urgent direction in materials science. Improvement of 3D printing technology with the use of concrete mixtures based on Portland cement largely depends on the sustainable solution of the problem of ensuring normal hardening of extruded concrete layers. A violation of hardening has known negative consequences and entails significant economic losses. It has been suggested to use polyacrylate solutions, preparation of which before application in concrete mixture allows controlling the process of their polymerization, postponing the sorption function of the additive in time to ensure the required rheology. Influence of super absorbent polymer (SAP) solution on structural formation processes and properties of cement materials is studied. Assessment of the degree of hydration was carried out by the calorimetric method for total thermal power using the isothermal calorimeter TAM AIR. Identification of main phases of cement stone (CS) by X-ray phase analysis was performed on XRD-6000 diffractometer. It is established that the use of SAP solutions has a positive effect on the mobility of cement mixtures due to the delayed polymerization and the corresponding water absorption by the polymer. The flexural strength range is 6.7–7.2 Mpa and the compression strength range is 68.5–71.7 MPa. It is established that the range of concentrations of SAP less than 1.5 % provides close to the reference composition (without SAP) the total hydration heat power of Portland cement at the age of 86 hours. The dependences of rheological and mechanical properties of cement materials on SAP concentration have been established. It has been proved that the use of SAP solutions is an effective engineering solution to ensure the hardening of concrete in adverse conditions. Further development of the topic may be aimed at studying the effect of SAP solutions on the properties of concrete mixtures of different compositions for 3D printing.

In this study the following mineral additions were used as 10% by weight cement replacement: silica fume SF, two types of metakaolin MK1 and MK2, and limestone powder LP. One type of cement CEM I 42.5R and one high range water reducing (HRWR) admixture were used in all mixes. Fresh properties of mortars with natural postglacial sand 0/4 mm were examined by mini-cone test and rotational viscometer Viskomat XL. In this instrument, when the cylindrical sample container rotates, the mortar flows through the blades of the impeller and exerts a torque which is measured by a transducer. As a result of the measurement, a set of data expressing the resistance of the mix subjected to the stresses induced by the rotation of the impeller was obtained. By linear approximation of the obtained results from the down-curve, the flow line of the mixture was obtained and compared with the modified Bingham Equation, which allowed to determine the rheological parameters of the tested mortars. All additions except for LP decreased rheological properties of the tested pastes and mortars. Not only particle size distributions (PSD), cumulative percentages and specific surfaces of the powders influence water and admixture demand of cement-based composites. Also shape and texture of the individual particles have an effect on the rheological properties.

Recently, a 3D printing process, also known as additive manufacturing, has been introduced in the construction industry as a means of increasing productivity. To apply this technology to construction, concrete, one of the most representative construction materials, must be used as the 3D printing material. Concrete is one of the key elements associated with 3D printing in construction. However, the research on concrete that considers the unique characteristics of 3D printing technology is currently insufficient. There are few studies that address the use of polymer-modified cement composite as a 3D concrete printing material. Thus, this research used preliminary tests to evaluate the feasibility of using a polymer-modified cement composite as a 3D concrete printing material. The polymer-modified cement composite was prepared using not only Portland cement, fly ash, blast furnace (BF) slag, and silica fume, but also a water-soluble polymer. Four fresh properties – flowability, extrudability, open time, and buildability – were evaluated, and it was determined that the addition of the polymer effectively improved the performance of 3D concrete printing materials.

Effect of superabsorbent polymers (SAPs) on rheological properties of fresh cement-based mortars — Development of yield stress and plastic viscosity over time

Assessment of dimensional accuracy of 3D printed part using resin 3D printing technique

Additive manufacturing of cementitious composites: Materials, methods, potentials, and challenges

Recent advances in 3D printing technologies for wearable (bio)sensors

Is This the Future of Medical Technology?

Effect of printing patterns on pore-related microstructural characteristics and properties of materials for 3D concrete printing using in situ and ex situ imaging techniques

To assure the quality and required workability of mortar or concrete, various types of superplasticizers are used. There are many factors affecting the performance of superplasticizers explicitly, type and dosage of the superplasticizers, type of cement, temperature and mixing procedure, as well as the addition times of the superplasticizers. Some researchers investigated the effect of delaying the addition time of superplasticizer to mortar or concrete, but there is not enough data about the effect of external temperature on performance of superplasticizers and consequent influences on fresh properties of mortar or concrete. In this research the effect of delaying the addition time of superplasticizers and influence of external temperature, namely, heat stimulation of superplasticizers, on fluidity, fresh density and air content of fresh cement mortar was investigated. Two types of Precast and Ready-Mix of Polycarboxylic acid-based ether superplasticizers with Ordinary Portland Cement was used. Delaying the addition time of superplasticizers enhanced the fluidity, slightly decreased the fresh density and increased the air content of mortar in comparison with simultaneous addition time with both heated and non-heated Superplasticizers.

Emerging 3D printing technologies for solid oral dosage forms: Processes, materials and analytical tools for real-time assessment.

Three dimensional (3D) printing as an advanced manufacturing technology is progressing to be established in the pharmaceutical industry to overcome the traditional manufacturing regime of 'one size fits for all'. Using 3D printing, it is possible to design and develop complex dosage forms that can be suitable for tuning drug release. Polymers are the key materials that are necessary for 3D printing. Among all 3D printing processes, extrusion-based (both fused deposition modeling (FDM) and pressure-assisted microsyringe (PAM)) 3D printing is well researched for pharmaceutical manufacturing. It is important to understand which polymers are suitable for extrusion-based 3D printing of pharmaceuticals and how their properties, as well as the behavior of polymer–active pharmaceutical ingredient (API) combinations, impact the printing process. Especially, understanding the rheology of the polymer and API–polymer mixtures is necessary for successful 3D printing of dosage forms or printed structures. This review has summarized a holistic materials–process perspective for polymers on extrusion-based 3D printing. The main focus herein will be both FDM and PAM 3D printing processes. It elaborates the discussion on the comparison of 3D printing with the traditional direct compression process, the necessity of rheology, and the characterization techniques required for the printed structure, drug, and excipients. The current technological challenges, regulatory aspects, and the direction toward which the technology is moving, especially for personalized pharmaceuticals and multi-drug printing, are also briefly discussed.

In recent years additive manufacturing, or three-dimensional (3D) printing, it is becoming increasingly widespread and used also in the medical and biomedical field [1]. 3D printing is a technology that allows to print, in plastic or other material, solid objects of any shape from its digital model. The printing process takes place by overlapping layers of material corresponding to cross sections of the final product. The 3D models can be created de novo, with a 3D modeling software, or it is possible to replicate an existing object with the use of a 3D scanner. In the past years, the development of appropriate software packages allowed to generate 3D printable anatomical models from computerized tomography, magnetic resonance imaging and ultrasound scans [2,3]. Up to now there have been 3D printed objects of nearly any size (from nanostructures to buildings) and material. Plastics, metals, ceramics, graphene and even derivatives of human tissues. The so-called “bio-printers”, in fact, allow to print one above the other thin layers of cells immersed in a gelatinous matrix. Recent advances of 3D bioprinting enabled researchers to print biocompatible scaffolds and human tissues such as skin, bone, cartilage, vessels and are driving to the design and 3D printing of artificial organs like liver and kidney [4]. Dentistry, prosthetics, craniofacial reconstructive surgery, neurosurgery and orthopedic surgery are among the disciplines that have already shown versatility and possible applications of 3D printing in adults and children [2,5]. Only a few experiences have instead been reported in newborn and infants. 3D printed individualized bioresorbable airway splints have been used for the treatment of three infants with severe tracheobronchomalacia, ensuring resolution of pulmonary and extrapulmonary symptoms [6,7]. A 3D model of a complex congenital heart defects have been used for preoperative planning of intraoperative procedures, allowing surgeons to repair a complex defect in a single intervention [8]. As already shown for children with obstructive sleep apnea and craniofacial anomalies [9]. personalized 3D printed masks could improve CPAP effectiveness and comfort also in term and preterm neonates. Neonatal emergency transport services and rural hospitals could also benefit from this technology, making possible to print medical devices spare parts, surgical and medical instruments wherever not readily available. It is envisaged that 3D printing, in the next future, will give its contribute toward the individualization of neonatal care, although further multidisciplinary studies are still needed to evaluate safety, possible applications and realize its full potential.

The rapid development in 3D printing applications requires exploring a sustainable printable mixture to decrease the environmental impact induced by the existing Ordinary Portland Cement (OPC) mixtures and enable 3D printing technology to reach its peak efficiency. The high-volume substitution of OPC with supplementary cementitious materials (SCMs) is of significant interest as a promising solution for developing low-carbon feedstock for 3D printing. Yet, those materials share the problem of limited availability. The combination of limestone and calcined clay could be a promising alternative, offering various benefits, including replacing OPC in high ratios. This paper reviews 3D printable limestone calcined clay cement (LC3) mixtures, compositions, and chemical behaviour. The effect of different sand-to-binder ratios, additives content, OPC replacement levels, clay grade and calcination, and admixtures on the fresh, hardened and printing properties of the 3D printed mixtures are critically discussed. The environmental impact and production cost of the LC3 system compared to OPC and other systems are also critically evaluated along with the applications, future directions and research gaps in this field. The findings of this review show that 3D printed LC3 has a similar hardened performance and better microstructure than OPC system. Moreover, cast LC3 system has 30–50% lower environmental impacts depending on the replacement level and better economic feasibility than OPC. Therefore, making it a suitable feedstock for the innovative manufacturing technology of 3D printing.

- This paper presents the design and development of a low-cost, modular 3D printer utilizing polyvinyl chloride (PVC) pipes as the primary structural framework. The use of PVC pipes, selected for their affordability, ease of procurement, and mechanical stability, enables a customizable and scalable printer architecture suitable for various build volumes. The mechanical structure is integrated with standard additive manufacturing components, including NEMA 17 stepper motors, lead screw or belt-driven linear motion systems, a hot end with thermistor and heating element, and open-source control electronics such as the RAMPS 1.4 board coupled with Marlin firmware. The PVC-based frame provides adequate rigidity for low- to medium-precision fused deposition modeling (FDM), while significantly reducing material costs compared to conventional metal or aluminum extrusion frames. This work demonstrates that PVC can serve as a viable structural material in entry-level 3D printer designs, offering an accessible platform for technical education, rapid prototyping, and experimental research in digital fabrication. The system's performance, limitations, and potential improvements are discussed, with a focus on its application in resource-constrained environments and STEM education. Key Words: 3D printing, PVC frame, additive manufacturing, low-cost 3D printer, modular design, DIY 3D printer, FDM, mechanical stability, open-source electronics, RAMPS, Marlin firmware, stepper motors