# Enhanced Performance of Concrete Dispersedly Reinforced with Sisal Fibers
## 2 Materials and Methods
### Methods  
Samples were made in laboratory conditions from normal weight concrete with a strength of 40-50 MPa with a workability grade of P1 (cone draft 1-4 cm), which was determined according to GOST 10181, \"Concrete mixtures. Methods of testing\". The parameters of the composition of \"the concrete mixture obtained as a result of the calculations\" are shown in Table 3.  
For the preparation and testing of concrete samples, the same equipment and measuring instruments were used as in [60; 61; 62; 63; 64; 65; 66; 67; 68; 69]. The study of the structure of the samples reinforced with sisal fiber was performed using an MBS-10 microscope (Izmeritelnaya Tekhnika OOO, Moscow, Russia). Heat and moisture treatment during the hardening of samples and the formation of the structure of the cement stone were carried out in the steaming chamber \"KUP-1\" (OOO \"RNPO RusPribor\", Chelyabinsk, Russia), with an isothermal holding temperature of 80 \({}^{\circ}\)C, according to the following mode:  
* Rise in temperature--3 h;
* Isothermal exposure--6 h;
* Cooling in a closed chamber--15 h.  
After heat and moisture treatment, the samples hardened in natural conditions for 14 days. Samples were prepared as follows:  
* Batching of concrete components was carried out on a \"VLTE-2100\" scale (\"NPP Gosmetr\", St. Petersburg, Russia) with an accuracy of 0.05 g;
* Then, the concrete components were loaded sequentially into the concrete mixer: first water, then Portland cement, sand and crushed stone, and then fiber;
* After loading the components into the concrete mixer, mixing was carried out until a homogenized mixture was obtained;
* After the preparation of the mixture, it was unloaded into metal molds of standard sizes (Figure 3) and then compacted on a laboratory vibration platform;
* Then, the samples in the molds for 1 day were placed in a chamber for heat and moisture treatment, after which they were removed from the molds and continued to gain strength in natural conditions for 14 days;
* Fifteen days after manufacture, the samples were destroyed on the \"IP-1000\" press (OOO \"NPK TEKHMASH\", Neftekamsk, Republic of Bashkortostan, Russia) and a tensile testing machine (\"IMASH LLC\", Arnavir, Russia) in accordance with the requirements of GOST 10180, \"Concretes. Methods for strength determination using reference specimens\" [70], and GOST 24452, \"Concretes. Methods of prismatic, compressive strength, modulus of elasticity and Poisson's ratio determination\" [71]. * Control and evaluation of the strength of concrete were carried out in accordance with GOST 18105-2018, \"Concretes. Rules for control and assessment of strength\" [72]. In total, 6 series of samples were made and tested with different values of the percentage of fiber reinforcement with sisal fiber. The experimental research program is shown in Figure 3. \begin{table}
\begin{tabular}{c c c c c c} \hline
**Parameter** & **PC, kg/m3** & **Water, L/m3** & **Crashed Stone, kg/m3** & **Sand, kg/m3** & \(\rho_{\text{cm}}\)**, kg/m3** \\ \hline Parameter value & 375 & 210 & 1028 & 701 & 2314 \\ \hline \end{tabular}
\end{table} 
Table 3: Dosages of concrete mix components. The axial tensile strength was determined as follows. The sample is fixed in a tensile machine according to one of the schemes given in Appendix K to GOST 10180 [70] and loaded to failure at a constant rate of load increase (0.05 \(\pm\) 0.01) MPa/s. The test result is not taken into account if the destruction of the sample did not occur in the working area or the plane of destruction of the sample is inclined to its horizontal axis by more than 15\({}^{\circ}\). The axial tensile strength of concrete \(R_{t}\) is calculated with an accuracy of 0.01 MPa according to the formula:  
\[R_{t}=\beta\frac{F}{A} \tag{1}\]  
where \(F\) is the breaking load, N; \(A\) is the area of the working section of the sample, mm\({}^{2}\); \(\beta\) is a scaling factor for converting the strength of concrete to the strength of concrete in samples of basic size and shape.