## 4 Discussion  
Previous studies in Malaysia on the use of RT seed shells as a CA for concrete, after being processed by crushing to a specific fraction, were mainly aimed at studying the mechanical properties of this concrete. Strength features were determined, which directly reflected the ability of such concrete to absorb mechanical loads according to the criterion of compressive strength. However, this indicates that there is a serious scientific deficit in the study of the deformation features of concrete using RT seed shells; structural studies are needed at the micro level to confirm the effectiveness of the proposed method. Thus,  
Figure 14: Photos of the microstructure of hardened concrete samples with local replacement of CA by RSS at **(a)** 0%; **(b)** 2%; **(c)** 4%; **(d)** 6%; **(e)** 8%; **(f)** 10%; **(g)** 12%; **(h)** 14%; **(i)** 16%. this study fills this scientific gap and provides an empirical basis for subsequent research. However, the empirical basis alone is not enough to evaluate the influence. This can be explained in terms of microstructure, using SEM analysis. With the help of an electron microscope, it was possible to photograph fragments of concrete located near the interface between the cement-sand mortar and RSS phases. Due to the fact that the cement-sand mortar acts as a matrix in the resulting composite, and the shell of the RT seeds, unlike traditional stone aggregates, acts as a filler, but at the same time adds a damping, softening influence, we evaluated structural changes using a microscope. In terms of microcracking, it can be seen that the concrete structure is as homogeneous as possible. On average, there is no cracking on the studied fragments. There are no gaps between the cement-sand stone and the shell of the RT seeds due to the fact that the shell has some roughness and a good level of adhesion to the matrix. Thus, at the microstructural level, the expediency of introducing the RT seed shell as an aggregate for concrete is confirmed. The nature of structure formation, the planned strength gain of concrete, as well as the changed deformation features indicate that the resulting concrete is promising for use, for example, in those structures that demand not only compressive strength but also twisting strength (floor and road structures with low load). That is, such concrete has a number of advantages compared to its counterpart with simple stone aggregates. There is a damping phenomenon during its operation, the elastic features are improved in general, the deformability changes, and the nature of the \"stress-strain\" diagram changes. Thus, such concrete is promising for use in certain products and structures. The best values for the strength features and the densest structure of the hardened cement paste were established when replacing CA with 4% RSS by total volume. With regard to the maximum allowable ratio of replacement of aggregate with shells, this limit is fixed at around 8%. A further rise in the ratio of replacement of coarse filler leads to a significant decrease in strength features, of more than 10%. The same is true for the modulus of elasticity. At RSS dosages of 6% and 8%, the drop in strength features is not as critical, which makes it possible to further use these concrete compositions in practice. Thus, the most important parameter in the creation of new concretes including mineral and vegetable components is the percentage of these two parts. In particular, the nature of the effectiveness of the partial replacement of traditional filler with vegetable (RSS) has both an ascending branch and a descending branch. Reaching its optimum, the content of the plant component subsequently increases to a state of supersaturation, which not only stops the growth of the mechanical characteristics of the composite, but also leads to a systematic decrease. Thus, we experimentally determined and proved the rational range of values of this ratio.