# Nanmodified Concrete with Enhanced Characteristics Based on River Snail Shell Powder
###### Abstract
An overview of previous studies on the types, dosages and uses of aquaculture waste is presented in Table 1. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Destination of Aquaculture Waste** & **Source** & **Dosage and Effect of Aquaculture Waste** \\ \hline \multicolumn{3}{c}{**As an Additive to the Material**} \\ \hline \hline \multirow{6}{*}{Asphalt modifier} & \multirow{6}{*}{[17]} & The addition of seashell powder as an asphalt modifier was studied at 5, 10 and 15\%. “Seashell powder improves the consistency, hardness, and high temperature performance of the bituminous binder, but weakens its low temperature performance; shell powder increases elasticity, recovery characteristics and resistance to residual deformation of bituminous binders, improves rheological properties at high temperatures; shell powder has minimal effect on the crack resistance of bituminous binders at very low temperatures” \\ \hline \multirow{3}{*}{Additive in building materials} & \multirow{3}{*}{[18]} & Modification of the surface of particles of crushed oyster shell waste by grinding in a high-energy ball mill makes it possible to obtain fine materials that can be used in building materials and as aggregates for concrete \\ \hline \multirow{2}{*}{Cleaning of drains} & \multirow{2}{*}{[19]} & Pyrolysis of waste oyster shells under certain conditions removes phosphates from wastewater \\ \hline \multirow{3}{*}{Expansion additive in cement mortar} & \multirow{3}{*}{[20]} & The volumetric expansion of “the calcined oyster shell powder during hydration compensated for the autogenous shrinkage of the mortar at an early age”. Excessive introduction of such a powder led to a decrease in the rate of compressive strength development. \\ \hline \multicolumn{3}{c}{**As a replacement part of the material**} \\ \hline \multirow{3}{*}{Replacing a piece of plaster} & \multirow{3}{*}{[21]} & Replacement of 40 and 50\% gypsum for refractory materials. The strength was reduced to 80\% when exposed to sulfates and cyclic freeze–thaw. When exposed to acids, an increase in strength was observed during the first three weeks and its further decrease [17]. \\ \hline \multirow{3}{*}{As a substitute for limestone in cement clinker} & \multirow{3}{*}{[22]} & “Oyster and scallop shells are suitable substitutes for limestone as a raw material for cement” [23] \\ \hline \multirow{6}{*}{Fine aggregate replacement} & \multirow{6}{*}{[22]} & Effect of the particle size of oyster shell instead of 20\% river sand on compressive strength, flexural strength, and modulus of elasticity of mortar, as well as its workability. A finer powder contributes to obtaining the maximum characteristics of the solution [24]. \\ \cline{1-1}  & Replacing part of the aggregate (5, 10, 20\%) with oyster shell powder led to a decrease in the workability of concrete, left the compressive strength unchanged or increased it compared to conventional concrete, and the modulus of elasticity decreased to 10\%. The setting time remained unchanged when the fine aggregate was replaced with oyster shell powder up to 20\% [25; 26]. The use of mussel shells in cement coating mortars as a substitute for conventional sand at various proportions of 25, 50 and 75\% has been investigated. The most effective dosage is 25\% [27]. “The use of coarse-grained shell aggregate improves the workability of the concrete. Concrete containing up to 50% shell aggregate as a partial replacement for fine or coarse aggregate has a density greater than 2100 kg/m\({}^{3}\). Up to 20\% of natural fine aggregate and up to 50\% of coarse aggregate can be replaced with ground shells to obtain concrete of sufficient density and strength. The most effective dosage of shells is 5\%\({}^{\omega}\)[1]. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Purpose of shells in cement materials and their influence on properties.