This question was previously asked in

MP Sub Engg Official Civil Paper Held on 9th July 2017 - Shift 1

Option 1 : independent and dependent

ST 1: Building Material and Concrete Technology

18425

20 Questions
20 Marks
12 Mins

**Explanation:**

**Gel/space ratio**

- The
**ratio of the volume occupied by hydrated cement paste**to the**aggregated volume of capillary pores and hydrated cement paste**is known as the gel/space ratio. - It is denoted by
**r.** - Powers (1958) found that
**no influence of the mix proportion of concrete and age**of it on**strength prediction.**

**Water / cement ratio**

- Water/cement ratio can be expressed in terms of weight and volume too.
- For a
**fully compacted concrete**, its**strength**is taken to be**inversely proportional water/cement ratio.** **Abram’s s water/cement ratio law**states that the strength of concrete is only dependent on the water/cement ratio provided the mix is workable.- According to Abram ' s law, \({f_c} = \frac{{{K_1}}}{{{{\left( {{K_2}} \right)}^x}}}\),
where, f

_{c}= concrete cylinder (15 x 30 cm) strength at 28 days after proper curing, K1 & K2 = constants, x = water / cement ratio. - The numerical values for
**K****1 and K2****vary**with the**age of concrete,**mode of testing at which strength is desired.

Hence, from the explanation above, it is clear that strength calculated on the basis of** gel/space ratio is independent of the age** of concrete and** water/cement ratio dependent on age**.