A modular nuclear shield wall construction block /1, 40 )comprising a framework (30) formed from a basalt fibre reinforced polymer composite and concrete interspersed within the framework, wherein the block is configured to interlock with a corresponding block in one or more dimensions. A method (500) of forming a modular construction block (1, 40); and a method (600) of forming a modular structure are also disclosed.

A modular nuclear shield wall construction block /1, 40 )comprising a framework (30) formed from a basalt fibre reinforced polymer composite and concrete interspersed within the framework, wherein the block is configured to interlock with a corresponding block in one or more dimensions. A method (500) of forming a modular construction block (1, 40); and a method (600) of forming a modular structure are also disclosed.