Study of hygral behavior of non-asbestos fiber cement made by similar hatschek process

Abstract

Fiber cement, similarly to all cementitious materials, undergoes dimensional and volumetric changes when it is exposed to dry and wet environments. When exposed to natural weathering, cement-based materials absorbs and may also release water to their surroundings via a very complex inherent pore structure. In this work initialized a few years ago, some properties of asbestos-free fiber cement composites were studied, such as density, porosity and loss or absorption of water. For the understanding of the behavior of this material, modifiers were employed in the cement matrix such as styrene-acrylic, styrene-butadiene and vinyl acetate-versatic vinylester copolymers to verify their influence on the variables described above. All composites were analyzed by mercury intrusion porosimetry (MIP). For monitoring the expansion/shrinkage movements, the specimens were exposed inside a controlled environmental chamber with constant temperature and relative humidity (RH) during the test time. The results showed no interference on hygral behavior because particular casting process of these composites but, as showed by literature, increase of toughness. Also, it was possible to verify that moisture movement within the asbestos-free fiber cement can be very complex and the variables density and porosity (pore structure) play a very important role in the expansion/shrinkage properties of these composites.

Microstructural Assessment of Pozzolanic Activity of Ilmenite Mud Waste Compared to Fly Ash in Cement Composites

“…Each type of mortar, after each period of curing, was analysed using three samples, calculating the average values. According to the derived data, pore sizes were divided into the following groups depending on their diameter [ 39 ]: macropores: above 10 μm large capillary pores: 0.05–10 μm small capillary pores: 0.01–0.05 μm gel pores: under 0.01 μm …”

“…Each type of mortar, after each period of curing, was analysed using three samples, calculating the average values. According to the derived data, pore sizes were divided into the following groups depending on their diameter [39]:  macropores: above 10 µm  large capillary pores: 0.05-10 µm  small capillary pores: 0.01-0.05 µm  gel pores: under 0.01 µm Also, other parameters were studied such as total porosity, pore size range, average pore volume and diameter, and median pore volume, and diameter.…”

Effect of aluminum hybrid additive on water absorption of fiber-cement composites

“…The differential pore size distribution and cumulative intrusion of the samples cured for 28 days are plotted in Figure 9. The pores are classified into 4 groups including gel pores (<0.01µm), medium capillary pores (0.01-0.1 µm), large capillary (0.1-10 µm) and air voids (>10 µm) (Gomes and Savastano, 2014;Zhao et al, 2022;Long et al, 2021). From the MIP results, the volume of large pores (void pores), capillary pores, and gel pores decreases in the AHA sample.…”