Blocos de concreto para pavimentação intertravada com adição de sílica ativa

Abstract

The addition of silica fume in high performance concrete for structural purposes has been widely studied over the last years, in order to reduce the cross section dimensions of the columns. Regarding to the precast concrete blocks for paving, known as pavers, with added silica fume in the concrete mix ratio, the number of references which were available for study was limited, thus this paper was mainly based on the high performance concrete studies. The concrete used to manufacture products for paving purposes is denominated Zero-slump concrete, which the principal method of casting uses a vibro press block machine. Due to the growth of the informal sector that produces concrete blocks, a considerable amount of products which are not in accordance to the technical standards can be observed. The NBR 9781 was recently revised in 2013 and the concrete block for paving minimum compression resistance was changed to 35 MPa. Thus, several methods to improve the concrete resistance are necessary to be studied, and this paper aims to investigate the addition of silica fume, with a ratio of 5 and 8% of the cement mass present in a standard concrete mix ratio of an industry located in Campo Mourao – PR, verifying the changes in the resistance and water absorption of the blocks and the concrete used to produce the blocks. After the manufacture procedure, the specimens were submitted to compression resistance and water absorption tests. The results show that with the addition of silica fume to the concrete block, the compression resistance increased significantly, while the water absorption did not present a considerable change. However, the water penetration inside the specimens with 8% of silica fume during the water absorption by capillarity test was less distributed.