A honeycomb structure includes honeycomb segments each having a porous partition wall defining a plurality of cells, and includes a porous bonding layer containing a crystalline anisotropic ceramic and disposed so as to bond side surfaces of the honeycomb segments to each other. A ratio of a pore volume (cc/g) of a fine pore defined as a pore in the bonding layer having a pore diameter of 10 m or more and less than 50 m with respect to a pore volume (cc/g) of a coarse pore defined as a pore in the bonding layer having a pore diameter of 50 m or more and 300 m or less is from 2.0 to 3.5, the pore volume of the fine pore is from 0.15 to 0.4 cc/g, and the pore volume of the coarse pore is from 0.05 to 0.25 cc/g.

A plugged honeycomb structure, including: a plurality of honeycomb segments, a bonding layer and a circumferential wall disposed to surround circumference of a honeycomb segment bonded body where the plurality of honeycomb segments are bonded, wherein in the bonding layer, the bonding layer at a part that bonds the honeycomb segments disposed in contact with the circumferential wall is a circumferential bonding layer, and the bonding layer at a part that bonds the honeycomb segment including a center of gravity in a cross section orthogonal to the extending direction of cells of the honeycomb segment bonded body or at a position closest to the center of gravity and another honeycomb segment adjacent to the honeycomb segment is a center bonding layer, and a bonding strength A1 of the circumferential bonding layer is larger than a bonding strength A2 of the center bonding layer.

A ceramic honeycomb structure comprising pluralities of honeycomb segments each having pluralities of longitudinally penetrating flow paths partitioned by porous cell walls and plugs formed in the end portions of the flow paths, and a bonding material layer boding the peripheral walls of the honeycomb segments, the bonding material layer comprising silicon carbide particles as aggregate and a bonding phase bonding the silicon carbide particles, the bonding phase comprising at least a cordierite phase and a spinel phase, the molar ratio M1 of the cordierite phase [=cordierite phase/(cordierite phase+spinel phase)] being 0.50 or more and less than 1.0, and the content of (cordierite phase+spinel phase) in the bonding phase being 50% or more by mass.

A porous honeycomb structure including cell channels passing through an interior of the porous honeycomb structure and partitioned by porous partition walls, wherein the porous partition walls include skeleton portions containing an aggregate and a bonding material, and pore portions formed among the skeleton portions and through which a fluid can flow; and the porous partition walls have a porosity of 40 to 48% as measured by a mercury intrusion method, and a cumulative 50% pore diameter (D50) from a large pore side of 6 to 10 m in a volume-based cumulative distribution of pore diameters measured by the mercury intrusion method, and a maximum pore diameter observed with a scanning electron microscope of 40 m or less, and a ratio of a contact area between the aggregate and the bonding material to a surface area of the bonding material observed with the scanning electron microscope of 61 to 80%.

There is provided a honeycomb structure where a crack at honeycomb segments, which constitute a honeycomb bonded assembly, is reduced. A honeycomb structure has a pillar-shaped honeycomb bonded assembly that has a plurality of pillar-shaped honeycomb segments having a porous partition wall defining a plurality of cells extending from an inflow end face as one end face to an outflow end face as another end face and becoming channels for a fluid, and a bonding layer bonding side surfaces of the plurality of honeycomb segments, and in the honeycomb bonded assembly, at 25 to 800 C., a thermal expansion coefficient of the bonding layer is larger than a thermal expansion coefficient of the honeycomb segment.

A ceramic honeycomb structure comprising pluralities of honeycomb segments each having pluralities of longitudinally penetrating flow paths partitioned by porous cell walls and plugs formed in the end portions of the flow paths, and a bonding material layer boding the peripheral walls of the honeycomb segments, the bonding material layer comprising silicon carbide particles as aggregate and a bonding phase bonding the silicon carbide particles, the bonding phase comprising at least a cordierite phase and a spinel phase, the molar ratio M1 of the cordierite phase [=cordierite phase/(cordierite phase+spinel phase)] being 0.50 or more and less than 1.0, and the content of (cordierite phase+spinel phase) in the bonding phase being 50% or more by mass.