Contribution to the rheological study of cementitious pastes with addition of residues from the processing of ornamental rocks

Abstract Brazil is one of the world's largest producers and exporters in the field of ornamental stones. On the other hand, the production and processing of ornamental stones result in a large volume of unused material in the form of sludge, usually discarded inappropriately in sedimentation ponds or landfills. Several researches have been carried out aiming the reuse of this material in cementitious matrixes. In the field of rheology, there are still incipient national studies that use the rheological parameters obtained experimentally to determine the behavior of cement matrix based on Portland cement. Thus, the objective of this work is to characterize rheologically the behavior of cementitious pastes with and without addition of ornamental rock processing residue (RBRO) in its natural condition. Cement pastes were prepared with three a/c ratios (0.45, 0.55, 0.65) and four residue addition contents (0%, 5%, 10%, 15%) and submitted to the flow test. In tests for characterization of the residue, the RBRO presented as a material of specific fineness and mass near the cement, having low reactive activity, indicating that the residue can be used as an inert mineral addition in the cementitious matrix. In the rheological characterization tests of the pulps studied, it was observed in the flow tests that the samples behaved as a non-Newtonian, pseudoplastic and thixotropic fluid.

摘要 巴西是全球观赏石材领域最大的生产国与出口国之一。与此同时，观赏石材的生产与加工会产生大量以污泥形式存在的废弃物料，这类物料常被不合理地堆放在沉淀池或垃圾填埋场中。已有多项研究致力于将这类物料应用于胶凝基料的再利用。在流变学领域，国内针对硅酸盐水泥基胶凝体系流变行为的实验研究仍处于起步阶段，此类研究多通过实验获取流变参数以表征体系行为。因此，本研究的目标是在天然状态下，从流变学角度表征添加与未添加观赏石材加工残渣（RBRO，ornamental rock processing residue）的水泥浆体的流变行为。本研究制备了三种水灰比（0.45、0.55、0.65）以及四种残渣掺量（0%、5%、10%、15%）的水泥浆体，并开展了流动度试验。在残渣表征试验中，该观赏石材加工残渣表现出与水泥相近的比表面积与质量特性，且反应活性较低，表明该残渣可作为惰性矿物掺合料应用于胶凝基料中。在所研究浆体的流变表征试验中，流动度试验结果显示，所有试样均表现出非牛顿、假塑性且触变性的流体特性。