---
title: "ASTM C25"
url: "https://mat-cs.com/astm-c25/"
description: "These test methods cover the chemical analysis of high-calcium and dolomitic limestone, quicklime, and hydrated lime. These test methods are classified as either standard (preferred) or alternative (optional)."
---

ASTM Standard

# ASTM C25

Standard Test Methods for Chemical Analysis of Limestone, Quicklime, and Hydrated Lime

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## Significance and Use

4.1 These test methods provide accurate and reliable analytical procedures to determine the chemical constituents of limestone, quicklime, and hydrated lime (see Note 1). The percentages of specific constituents which determine a material’s quality or fitness for use are of significance depending upon the purpose or end use of the material. Results obtained may be used in relation to specification requirements.

4.2 Because quicklime and hydrated lime quickly absorb water and carbon dioxide from the air, precision and bias are extremely dependent upon precautions taken during sample preparation and analysis to minimize excessive exposure to ambient conditions.

NOTE 1: These test methods can be applied to other calcareous materials if provisions are made to compensate for known interferences.

## Scope

1.1 These test methods cover the chemical analysis of high-calcium and dolomitic limestone, quicklime, and hydrated lime. These test methods are classified as either standard (preferred) or alternative (optional).

1.2 The standard test methods are those that employ classical gravimetric or volumetric analytical procedures and are typically those required for referee analyses where chemical specification requirements are an essential part of contractual agreement between buyer and seller.

1.3 Alternative or optional test methods are provided for those who wish to use procedures shorter or more convenient than the standard methods for the routine determinations of certain constituents. Optional test methods may sometimes be preferred to the standard test methods, but frequently the use of modern and expensive instrumentation is indicated which may not be accessible to everyone. Therefore, the use of these test methods must be left to the discretion of each laboratory.

1.4 The analytical procedures appear in the following order:

Section

Aluminum Oxide

15

Available Lime Index

28

Calcium and Magnesium Oxide:

Alternative EDTA Titration Method

31

Calcium Carbonate Equivalent

33

Calcium Oxide:

Gravimetric Method

16

Volumetric Method

17

Carbon Dioxide by Standard Method

22

Combined Oxides of Iron and Aluminum

12

Ferrous Iron

Appendix X5

Free Calcium Oxide

Appendix X6

Free Moisture in Hydrated Lime

21

Free Moisture in Limestone

20

Free Silica

29

Insoluble Matter Including Silicon Dioxide:

Standard Method

8

Optional Perchloric Acid Method

9

Insoluble Matter Other Than Silicon Dioxide

11

Loss on Ignition

19

Magnesium Oxide

18

Manganese:

Bismuthate Method

Appendix X4

Periodate (Photometric) Method

27

pH Determination of Alkaline Earth Solutions

34

Phosphorus:

Titrimetric Method

Appendix X3

Molybdovanadate Method

26

Silicon Dioxide

10

Strontium Oxide

Appendix X2

Sulfur Trioxide

23

Total Carbon:

Direct Combustion-Thermal Conductivity Cell

```
  Method | 32 |
```

| Total Carbon and Sulfur: | | Combustion/Infrared Detection Method | 35 | | Total Iron: | | Standard Method, Potassium Dichromate Titration | 13 | | Potassium Permanganate Titration Method | Appendix X1 | | Ortho-Phenanthroline, Photometric Method | 14 | | Total Sulfur: | | Sodium Carbonate Fusion | 24 | | Combustion-Iodate Titration Method | 25 | | Unhydrated Oxides | 30 |