Display omitted •Sustainable bricks can be manufactured using MSS, BFS and kaolin.•The use of BFS as a flux improved the physicochemical properties of bricks.•Elevated temperature and BFS dose both enhanced the vitrification and densification mechanisms.•The fired bricks had excellent compressive strength, with a maximum value of up to 70 MPa.•Providing an effective method to valorize MSS and BFS wastes. In recent years, the contradiction between the huge production of municipal sludge and industrial residue and the shortage of landfill space has driven the exploration of novel effective methods to valorize these solid wastes. In this research, blast furnace slag (BFS), municipal sewage sludge (MSS) and kaolin are combined innovatively as precursor materials to manufacture self-foaming porous bricks, and the sintering behavior of bricks under different BFS doses and sintering temperatures is deeply studied to reveal the development mechanism. The results indicate that the formation of Fe2O3-hematite during sintering leads to a reddish-brown appearance of the bricks, while the generation of CaAl2Si2O8-anorthite with lower melting points helps to enhance the vitrification process. Besides, the increase in BFS dose or sintering temperature has significant impacts on the evolution of the brick physicochemical properties. This occurs because changing the dose of BFS or sintering temperature can obviously regulate the internal morphological characteristics of bricks, such as particle consolidation, pore size and structural compactness. Among them, large-sized pores are considered as the weak areas of mechanical strength, which is also the responsibility for the worst compressive strength of bricks sintered at 1300 °C. Finally, under the optimal sintering conditions of 15 % BFS dose and 1250 °C sintering temperature, the compressive strength, water absorption, apparent porosity, bulk density and linear shrinkage of the resulting brick are 65 MPa, 0.45 %, 2.50 %, 2.34 g/cm3 and 19.56 %, respectively. Overall results demonstrate that using recycled sludge and waste slag in brick manufacturing can produce products with desired performance, providing preferable solutions for solid waste valorization and sustainable brick production.