Question $4-4(20$ points$)$

Design concrete mix with $fc=30$MPa for six beams with dimensions of $1\mathrm{.}60$ m long and cross section of $250200mm$ exposed to $1600$ ppm sulfate in water using $19$ mm nominal maximum size of crushed coarse aggregate, the course aggregate specific gravity $=2\mathrm{.}8,$ moisture content of $0\mathrm{.}24\%,$ fine ageregate spesific gravity $=2\mathrm{.}65,$ moisture content of $1\mathrm{.}3\%,$ the concrete density is $2400k\frac{g}{m^{\text{'}}}$ and the cement specific gravity is $3\mathrm{.}14.$ Calculate the concrete modulus of elasiticty and flexural strength $[$Assume any missing engineering data$).$