3D打印工程弃土挤出过程力学性能试验研究

Experimental Study of Mechanical Properties of 3D Printing Bricks with Construction Spoil During Extrusion

摘要:

通过13种不同配合比的工程弃土复配，研究了不同复配弃土在挤出过程中的可打印性，同时对掺入河砂和再生粉的土样分别进行无侧限抗压强度试验和直剪试验，探讨了河砂和再生粉作为工程弃土掺料的可行性。试验结果表明，黏质弃土的掺配比例会影响复配弃土的打印形态，当黏土掺配比例达50%时，打印效果良好。再生粉的掺入能够提高土体的无侧限抗压强度和弹性模量，超过这一范围后，再生粉的高吸水性会严重影响土体的黏聚性，进而导致强度降低，弹性变形阶段维持时间减少。在保证工程弃土强度改良和满足可挤出性的前提下，建议再生粉掺量为5%，此时土体无侧限抗压强度可提升22.5%，而河砂的掺入会整体降低弃土无侧限抗压强度和弹性模量，呈逆骨架效应。在减少环境污染和推进智能土制建筑方面，利用3D打印挤出成型技术，生产满足不同工况要求的工程弃土3D打印砖具有较高的应用价值和潜力。

Abstract:

In this paper， the printability of 13 kinds of engineering spoil with different mix proportion in extrusion process was studied. Meanwhile， unconfined compressive strength test and direct shear test were carried out for spoil samples mixed with river sand and recycled powder respectively， and the feasibility of river sand and recycled powder as engineering spoil admixture was discussed. The experimental results show that the mixing proportion of clayey spoil will affect the extrusion effect of composite spoil. When the mixing proportion of clay reaches 50%， the extrusion effect is good. The addition of recycled powder can improve the unconfined compressive strength and elastic modulus of spoil. Beyond this range， the super water absorption of recycled powder will seriously affect the cohesion of spoil， resulting in the decrease of strength and the maintenance time of elastic deformation stage. On the premise of ensuring the strength improvement and extrudability of engineering spoil， it is suggested that the content of recycled powder is 5%， and the unconfined compressive strength of spoil can be increased by 22.5%， while the incorporation of river sand will reduce the unconfined compressive strength and elastic modulus of spoil as a whole， showing an inverse skeleton effect. In terms of reducing environmental pollution and promoting intelligent earth building， 3D printing extrusion technology is used to produce engineering 3D printing bricks that meet different requirements， which has high application value and potential.