Fiber cement products and methods for the production thereof

A method for producing a fiber cement product comprising an inner core covered by at least one outer surface layer,

• wherein said inner core has a density of between about 0.4 and about 0.9 g/cm3 inclusive, and
• wherein said at least one outer surface layer has a density of between about 0.9 and about 1.4 g/cm3 inclusive, wherein said method comprises the steps of:
• i) providing a first cementitious material comprising cement and between 1 wt % and 70 wt % with respect to a total dry weight of said inner core of a lightweight filler,
• ii) providing a second fiber cement material comprising fibers and cement,
• iii) assembling said first cementitious material and said second fiber cement material to obtain a fiber cement product comprising an inner core made of said first cementitious material, which inner core is covered by at least one outer surface layer made of said second fiber cement material, and
• iv) curing said fiber cement product,
• wherein in steps (i) and (ii), a fiber cement slurry is prepared followed by forming one or more uncured fiber cement layers from said fiber cement slurry according to a Hatschek formation process and/or a flow-on process,
• wherein the at least one outer surface layer is formed according to the Hatschek formation process and is a Hatschek layer,
• wherein the inner core is formed according to a flow-on process comprising a fiber cement distribution step of discharging a fiber cement slurry composition onto a forming surface, resulting in an uncured non-Hatschek layer, and
• wherein in step (iii), the first cementitious material and second fiber cement material are assembled by superimposing an uncured non-Hatschek layer onto another layer during the fiber cement distribution step.