Effect of hybrid fibers, calcium carbonate whisker and coarse sand on mechanical properties of cement-based composites

Abstract

Nowadays researchers are developing a new hybrid fiber reinforced cement-based composites (HyFRCC). The new HyFRCC can restrain micro-cracking, improves compressive and flexural performance of beams by addition of calcium carbonate (CaCO 3 ) whisker, polyvinyl alcohol (PVA) fiber and steel fiber. In this work, a mix optimization procedure is shown for multi-scale HyFRCC, with steel, PVA fiber and CaCO 3 whisker. The new HyFRCC is explored with addition of coarse sand to further improve its mechanical properties. Additionally, the flexural performance of beam and slabs has been investigated to optimize sand gradation and fiber combination in new HyFRCC. The compressive strength, flexural strength, flexural behavior, flexural toughness, equivalent flexural strength and deflection-hardening behavior of beams and slabs are improved with optimized content of sand gradation, fibers and CaCO 3 whisker. The HyFRCC slab with 1.5% steel fiber, 0.4% PVA fiber, 1% CaCO 3 whisker and optimized coarse sand showed overall best properties. Citation/Citar como: Cao, M.; Li, L.; Khan, M. (2018) Effect of hybrid fibers, calcium carbonate whisker and coarse sand on mechanical properties of cement-based composites. Mater. Construcc. 68 [330], e156 https://doi.org/10.3989/ mc.2018.01717 RESUMEN:Effecto de fibras híbridas, filamentos de carbonato cálcico y arena gruesa en las propiedades mecánicas de cementos compuestos. En la actualidad se están desarrollando nuevos cementos compuestos reforzados con fibras híbridas (HyFRCC, por sus siglas en inglés). Estos nuevos cementos HyFRCC pueden impedir la microfisuración y aumentar la resistencia a compresión y flexotracción de las vigas, mediante la incorporación de filamentos de carbonato cálcico (CaCO 3 ), fibras de alcohol polivinílico (PVA) y fibras de acero. En este trabajo se plantea un procedimiento para optimizar la proporción de fibras (de acero y de PVA) y filamentos (de CaCO 3 ) en un nuevo HyFRCC. Se investiga la influencia de la arena gruesa en sus propiedades mecánicas, además de la resistencia a flexotracción de vigas y forjados a fin de adecuar la granulometría de la arena y la combinación de fibras en el nuevo material. Un buen ajuste entre el contenido y la granulometría de la arena y la proporción de las fibras y de los filamentos de CaCO 3 permite: incrementar la resistencia tanto a compresión como a flexotracción, la tenacidad a flexotracción y la resistencia a flexotracción equivalente; perfeccionar el comportamiento a flexión; y reducir la flecha de vigas y forjados endurecidos. La mezcla que mejores resultados arroja en conjunto contiene 1,5 % de fibras de acero, 0,4 % de fibras de PVA, 1 % de filamentos de CaCO 3 y arena gruesa optimizada. PALABRAS CLAVE: Composite; Microfisuras; Carbonato cálcico; Resistencias a compresión; Resistencias a flexión ORCID ID: M. Cao

Effectiveness of multiscale hybrid fiber reinforced cementitious composites under single degree of freedom hydraulic shaking table

“…The behavior of FRCC depends on many factors, such as composite mixture characteristics, fiber characteristics, and base matrix characteristics 30,34 . From the existing literature, a significant work had been done on static properties of multiscale hybrid fiber reinforced cementitious composite (MSHFRCC) using steel fiber, PVA fiber, and CaCO 3 whisker 26,27,35–43 . However, material properties of steel fiber, PVA fiber, and CaCO 3 whisker FRCC under dynamic load are not studied yet.…”

“…The improved performance of PVA fiber is also observed in Engineered Cementitious Composite (ECC) 24,25 . Calcium carbonate (CaCO 3 ) whisker is new types of micron fiber with low production cost which resists cracking at the micro level 26–29 . The FRCC material must be designed for resisting the dynamic loading by enhancing its energy absorption capability 30 .…”

Effect of Macro-, Micro- and Nano-Calcium Carbonate on Properties of Cementitious Composites—A Review

“…It is different from limestone powder with a bulk shape [ 35 ] or granular shape (see in Figure 6 ), but is needle-like [ 56 ] (see in Figure 7 ). Because of its shape, CW not only fills the voids to make the matrix dense [ 14 ] but also plays a role in resisting the development of micro-cracks, especially with incorporated steel fiber [ 16 , 20 , 59 ], PVA fiber [ 15 ] and carbon fiber [ 60 ]. Moreover, a positive synergic effect can be demonstrated when incorporated of a hybrid fiber system [ 61 , 62 ].…”

“…Incorporation of SCMs and mineral admixtures such as fly ash, slag, silica fume and limestone is not only an effective way to reduce the carbon dioxide emissions and sources consumption, but also an economic and environmentally friendly way to produce cement or concrete, because most SCMs and mineral admixtures are industrial waste products [ 4 ]. Among these SCMs and mineral admixtures, limestone is widely used as a kind of filler material [ 5 , 6 , 7 , 8 , 9 ], aggregate [ 10 , 11 , 12 , 13 ], micro-fiber [ 14 , 15 , 16 , 17 , 18 , 19 , 20 ] and early strength agent [ 21 ] because of its various scales (macro-, micro- and nano-scale) [ 2 , 22 ], morphologies (bulk, granular and fibrous shape), crystal systems (calcite, aragonite, vaterite and amorphous calcium carbonate) [ 2 ].…”

Effect of different PVA and steel fiber length and content on mechanical properties of CaCO₃ whisker reinforced cementitious composites

“…25SP0.75, SS1.5LP0.5, SS1.25LP0.75, LS1.5SP0.5, LS1.5LP0.5 and LS1.25LP0.75, respectively. This indicated that addition of CW into PVAsteel fiber specimens could increase compressive strength because micro-sized CW filled pores of matrix and improve the compactibility of cubes(12,17). However, compared with LS1.25SP0.75, the compressive strength of LS1.25SP0.55CW2.0 was decreased by 16.4%which is probably related…”