Expanded Clay Foam Concrete (eC-FC) is a light-weight foam concrete with expanded clay aggregates, which is an important class of building materials, yet its tensile strength f(t) and fracture toughness K-IC cannot be easily measured using small test samples due to its highly heterogeneous microstructures. This study presents a simple closed-form model for quasi-brittle fracture of heterogeneous solids confirmed by comprehensive three-point-bend (3-p-b) test results from 168 notched eC-FC specimens with eight group sample designs. One tensile strength ft was determined from individual group or all from the model initially developed for normal concrete, proving both the trans-granular fracture in eC-FC and inter-granular fracture in normal concrete can be modeled by this fracture model. Unidirectional compressive tests of the eC-FC were also performed, and tensile strength f(t) estimated from the compressive strength f(c) is consistent with f(t) from 3-p-b tests. Fracture toughness K-IC was determined from the model using tensile strength f(t) and the average aggregate size G.