The photograph presents two methods of calculating the weight of sugarcane bagasse ash (SCBA) as a replacement for cement in a (1:2:4) concrete mix at 5% replacement.

Clarification of the Design Mix:

1. (1:2:4) Mix Ratio: This ratio represents the proportions of cement, sand, and gravel, respectively. In this case, for every 1 part cement, there are 2 parts sand and 4 parts gravel.

2. Replacement Calculation: The SCBA is used as a 5% replacement for the mass of cement.

Comparison of the Methods:

• Method A calculates the weight of SCBA as a direct percentage of the mass of cement:

• Cement mass =

• 5% of cement replaced by SCBA =

• Method B attempts to calculate the SCBA weight by including its specific gravity (2.8):

• Cement mass remains

• SCBA weight =

Clarification:

• Method A directly computes the 5% of the cement weight, which aligns with the approach typically used for partial material replacements.

• Method B uses specific gravity to adjust the weight based on volume, which leads to a slightly different result (20.02 kg). However, this method introduces a volume-based replacement approach, which might not be necessary unless the replacement is meant to be volumetric rather than weight-based.

In most practical concrete mix designs, Method A (calculating the replacement as a percentage of the cement mass) is the standard and more straightforward approach unless specifically instructed to account for volumetric differences.

Thus, Method A is likely the correct and more widely accepted approach for this calculation.

The mix design method that we use is the SNI method (Indonesian National Standard)

Sir, We used Methode A.

Method A:

- Total volume: 1m³

- Volume of cement: 1/7 = 0.143

- Mass of cement: \( 3.1 \times 0.143 \times 1000 \) = 443 kg

- Weight of 5% SCBA: \( 0.05 \times 443 \) = 22.15 kg

Method B:

- Total volume: 1m³

- Volume of cement: 1/7 = 0.143

- Mass of cement: \( 3.1 \times 0.143 \times 1000 \) = 443 kg

- Weight of 5% SCBA: \( 0.05 \times 0.143 \times 2.8 \times 1000 \) = 20.02 kg

Correct Method:

Method A is correct because it straightforwardly calculates the 5% replacement of cement by weight. Here’s why:

- The 5% replacement is directly related to the weight of the cement, not to the volume.

- \( 5\% \) of the 443 kg of cement is indeed 22.15 kg.

In Method B, multiplying by the specific gravity of SCBA (2.8) along with the volume doesn’t align with the standard practice of calculating the replacement material by its weight proportion.

So, Method A: is the accurate approach to determine the weight of SCBA for a 5% replacement of cement in a (1:2:4) mix ratio.

The research method we carried out is in accordance with method a that you explained.

Yes Sir

Thanks you for your attention

Dear sir,

we use method A

Thanks for your attention and cooperation

We used methode a