Question

highway materials soils and concretes

7-23 Using the water/cement ratio method, select quantities for a trial mix consisting of two strength cylinders to meet the following criteria: non-air entrained; W/C ratio, 0.55; maximum aggregate size, 37.5 mm (1 1/2 in); slump, 80mm (3 in)

Answer 1

Solution:- the values given in the question are as follows:

water cement ratio(w/c)=0.55

maximum size of aggregate=37.5 mm (1.476 in)

slump of concrete= 80 mm (3 in)

According to abram's law water cement ratio how effect strength of concrete:

according to this low the strenth of concrete is inversely proportional to water cement ratio.if water cement ratio increase so the strenth of concrete is decrease and vice-versa.

According to slum effect on workability:

slump type of workability

0-25 very low

25-50 low

50-100 medium

100-175 high

>175 very high

slump is given in question is 80 mm so workability is high.

Find quantities of material according to trial mix:

maximum size of aggregate given in question is 37.5 mm

water cement ratio 0.55 is used for mild exposer and M20 grade of concrete is used for mild exposer.

M20 concrete grade=1(cement) : 1.5(fine aggregate) : 3(coarse aggregate)

for design trial mix is based on minimum quantity of cement(Kg) used in 1 m^3

minimum quantity of cement in 1 m^3 =300 Kg

but we used the cement 383.2 Kg/m^3

according to M20, find quantity of material

quantity of cement=383.2 Kg

quantity of fine aggregate=1.5*383.2=574.8 Kg

quantity of coarse aggregate=3*383.2=1149.6 Kg   [this quantities of material for 1 m^3 of concrete ] [Ans]