# Bricks Using Clay Mixed with Powder and Ashes from Lignocellulosic Biomass: A Review
## 8 Conclusions  
This study focuses on the use of lignocellulosic ash as a partial replacement for clay in the manufacture of fired and unfired clay bricks and their industrial integration. Indeed, the use of lignocellulosic ash in the manufacture of bricks is a promising way to decrease the need for non-renewable clay, as well as to reduce the environmental risks and high costs associated with the landfilling of this ash. Several conclusions can be drawn:  
* Ashes from lignocellulosic biomass are favored by high concentrations of melting oxides, which enable the reduction of the firing temperature of the fired clay bricks. However, a sizable amount of their use causes the bricks' compressive strength to decline. Considering the various results of the research made on fired clay bricks elaborated by lignocellulosic ashes, and to make a compromise between thermal and mechanical properties, it is advised that the rate of reinforcement within the clay matrix be lower than 10% for the ashes-rich in melting oxides and lower than 4% for the ashes rich in amorphous silica and gaseous materials to ensure a compromise between physical, thermal, and mechanical properties. According to the papers studied, ash of rice husk, sugar cane bagasse, and palm oil contains high levels of amorphous silica (more than 50%). These materials have low compressive strengths (7.5 MPa), except in [65] where high compressive strengths (35.9 MPa) were found due to the high pressure (54.5 MPa) used in molding the brick.  
* To decrease the energy required to fire bricks in conventional kilns, numerous studies have concentrated on the development of unfired bricks stabilized by lignocellulosic biomass ash and cementitious binders (lime/cement). The combination of cement and lignocellulosic ash offers a promising way to both cut down on cement usage and waste production. The addition of lignocellulosic ash at a lower cement content results in the gain of higher compressive strength. With cement percentages below 10%, this gain was no longer significant. Despite the effectiveness of adding these ashes to cement to improve mechanical properties, using lime with lignocellulosic ashes demonstrates greater efficiency than cement because of the pozzolanic reactions that occur and cause the clay matrix to gradually become denser.
* New research has been focused on the stabilization of bricks using chemical binders by alkaline activation or by a geopolymer mechanism to produce more environmentally friendly and sustainable building materials and to lessen the significant carbon footprint associated with the use of cementitious binders for the stabilization of unfired bricks. The use of lignocellulosic biomass ash rich in potassium oxide is a promising and affordable solution to reduce the high cost of chemical binders in the manufacture of geopolymer bricks. It has interesting mechanical and physical properties similar to those desired for fired bricks, which encourages brick factories that are a part of the sustainable development framework to carry out this research from the laboratory scale to the industrial scale.