ICS 65.080  
 
Reference number
DRS 280: 2020
© RSB 2020
  
 RWANDA 
STANDARD  DRS
280
Second  edition
2020 -mm-dd
Agricultural liming materials  — 
Specification   
   
DRS 280 : 2020  
©RSB 2020  - All rights reserved                  ii 
 In order to match with technological development and to keep continuous progress in industries, 
standards are subject to periodic review. Users shall ascertain that they are in possession of the latest 
edition  
 
 
 
 
 
 
 
 
© RSB 2020  
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized 
in any form or by any means, electronic or mechanical, including photocopying and microfilm, without  
prior written permission from R SB. 
Requests for permission to reprodu ce this document should be addressed to : 
Rwanda Standards  Board  
P.O Box 7099 Kigali -Rwanda  
KK 15 Rd, 49  
Tel. +250 788303492  
Toll Free: 3250  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw   DRS 280: 2020  
iii                ©RSB 2020  - All rights reserved  
 Contents  Page 
1 Scope  ................................ ................................ ................................ ................................ ................ 1 
2 Normative references  ................................ ................................ ................................ ....................... 1 
3 Terms and defi nitions  ................................ ................................ ................................ ...................... 1 
4 Requirements  ................................ ................................ ................................ ................................ ...3 
4.1 Chemical composition  ................................ ................................ ................................ ..................... 3 
4.2 Requirements for agricultural limestone  ................................ ................................ ......................... 3 
4.2.1  Sieve analysis classifications for agricultural  ................................ ................................ ................ 3 
4.2.2  Neutralizing requirements for calcitic limestone  ................................ ................................ ............ 4 
4.3 Sieve analysis classifications for agricultural slag  ................................ ................................ ........ 4 
4.3.1  Air-cooled blast -furnace slag  ................................ ................................ ................................ ........... 4 
4.3.2  Granulated blast -furnace slag  ................................ ................................ ................................ ......... 5 
4.4 Requirements for hydrated lime and burnt lime  ................................ ................................ ............. 5 
4.4.1  Fineness  ................................ ................................ ................................ ................................ ........... 5 
4.4.2  Neutralizing requi rements of hydrated lime and quicklime  ................................ ............................ 5 
4.4.3  Neutralizing requirements for dolomite  ................................ ................................ ........................... 5 
4.5 Heavy metal contaminants  ................................ ................................ ................................ ............... 6 
5 Packagin g and labelling  ................................ ................................ ................................ ................... 6 
5.1 Packaging  ................................ ................................ ................................ ................................ ......... 6 
5.2 Labelling  ................................ ................................ ................................ ................................ ........... 6 
6 Sampling  ................................ ................................ ................................ ................................ ........... 7 
Annex  A (normative)  Determination of calcium carbonate equivalent (neutralizing value)  ..................... 8 
A.1 Coverage  ................................ ................................ ................................ ................................ ........... 8 
A.2 Significance and use  ................................ ................................ ................................ ........................ 8 
A.3 Apparatus  ................................ ................................ ................................ ................................ ......... 8 
A.4 Reagents  ................................ ................................ ................................ ................................ ........... 8 
A.5 Procedure  ................................ ................................ ................................ ................................ ......... 8 
A.6 Calculation  ................................ ................................ ................................ ................................ ........ 9 
Annex  B (normative)  D etermination of moisture content  ................................ ................................ ........  10 
B.1 Procedure  ................................ ................................ ................................ ................................ ....... 10 
B.2 Calculation  ................................ ................................ ................................ ................................ ...... 10 
Annex  C (normative)  Determination of available lime index  ................................ ................................ .... 11 
C.1 Scope  ................................ ................................ ................................ ................................ ..............  11 
C.2 Summary of test method  ................................ ................................ ................................ ................  11 
C.3 Reagents  ................................ ................................ ................................ ................................ .........  11 
C.4 Procedure  ................................ ................................ ................................ ................................ ....... 11 
C.5 Calculation  ................................ ................................ ................................ ................................ ...... 12 
Annex  D (normative)  Determination of magnesium oxide content  ................................ ..........................  14 
D.1 Scope  ................................ ................................ ................................ ................................ ..............  14 
D.2 Summary of test method  ................................ ................................ ................................ ................  14 
D.3 Reagents  ................................ ................................ ................................ ................................ .........  14 
D.4 Procedure  ................................ ................................ ................................ ................................ ....... 14 
D.5 Calculation  ................................ ................................ ................................ ................................ ...... 15 
 DRS 280 : 2020  
©RSB 2020  - All rights reserved                  iv 
 Foreword   
Rwanda Standard s are prepared  by Technical Committees and approved by Rwanda Standards Board (RSB) 
Board  of Directors in  accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT 
agreement on the preparation, adoption and application of standards.  
The main task of technical committees is to prepare national standards.  Final Draft Rwanda S tandards 
adopted by Technical committ ees are ratified by me mbers of RSB Board of Director s for publication and 
gazettment as Rwanda Standards.  
DRS 280 was prepared by Technical Committee RSB/TC 007, Agrochemicals . 
In the preparation of this standard, reference was made to the following standard:  
FDARS 1492 : Agricultural liming materials — Specification   
The assistance de rived from the above source is hereby acknowledged with thanks.  
This second edition cancels and replaces the first edition (RS  280: 2016 ), of which has been technically 
revised.  
 
Committ ee membership  
The following organizations were represented on the Technical Committee on Agrochemicals  (RSB/TC 007) in 
the preparation of this standard.  
One Acre Fund - TUBURA  
Ministry of Environment (MoE)  
University of Rwanda/College of Agriculture and Veterinary Medicine (UR/CAVM)  
University of Rwanda/College of Sciences and Technology (UR/CST)  
Rwanda Inspectorate, Competition and Consumer Protection Authority (RICA)  
Star Construction and Consultancy (SCC) Ltd  
Rwanda  Standards Board  (RSB) – Secretariat  DRS 280: 2020  
v                ©RSB 2020  - All rights reserved  
 Introduction   
At a global scale , soils are increasingly being degraded and becoming  marginal for agricultural production 
driven by e.g. salinization, erosionand acidification (FAO , 2015) .Soil acidi fication  is one of the most prevalent 
problems in production of food and fibre because at least 40%, and by some estimates as much as 70%,  of 
the world’s arable land is affected (Rengel, 2003) .With increased pressure to produce more food for the 
expanding population of this planet and with urbanization claiming large chunks of arable land, agri culture is 
pushed more and more into marginal land plagued with edaphic and other stresses, including ac idity. The 
major processes leading to soil acidification include (1) net Hାexcretion by plant roots due to excess uptake of 
cations over anions; (2) removal of alkalinity in farm  biomass  products such as grain, hay, meat, and wool  
which increases as yields  increase ; (3) accumulation of organic anions in the form of soil organic matter; (4) 
mineralization of organic matter, nitrification of ammonium, and subsequent leaching of nitrate, and  (5) input of 
acidifying substances such as NHସା-based fertilizers  and urea, elemental S fertilizer and the growth of legumes  
(Rengel, 2003; Goulding, 2016; Holland et al., 2019) . 
Crop growth is often limited in tropical acid soils through a number of factors, including low pH  per se, 
toxicities of aluminium (Al) and manganese (Mn), and deficiencies of phosphorus (P), calcium (Ca), 
magnesium (Mg) or molybdenum (Mo) (Blamey et al., 1989) . At 8.1 %, a luminium is the most abundant metal 
and the third most common element in the earth's crust after oxygen  (46.6 %)  and silicon  (27.7 %) . At mildly 
acidic or neutral soil pH values, Al is primarily in the form of insoluble aluminosilicates or oxide s.The princ ipal 
adverse effects of acidity on soil fertility occur at soil pH values below 5.5 due to acid dissoluti on of aluminium 
(Al) and the onset of Al phytotoxicity that affect root (and plant) growth (Wong et al., 2003) . Thus, Al toxicity is 
the major growth -limiting factor for crop cultivation on acid soils. The initial and most dramatic symptom of Al 
toxicity is inhibition of root elongation, which can occur within 1 -2 hrs after exposure to Al.  This results in 
reduced volume of soil explored by the root system and direct interference with uptake of ions such as calcium 
and phosphate across the cell membrane  of damaged roots  (Kochian, 1995) . These phytotoxic ef fects are 
unimportant in moderately acidic soils with pH values of 5.5 to 6.5 when the concentration of toxic forms of Al 
is normally negligible. Manganese toxicity and deficiencies of phosphorus, calcium, and magnesium ar e 
common in acidic soils. Soil nut rient deficiencies exacerbate the problem of inefficient nutrient uptake due to 
restricted root growth and root damage (Sumner et al., 1991) . In drier  environments, poor water use due to 
poor root development is considered to be another adverse effect of Al phytotoxicity.  
Liming is a common agricultural practice worldwide, used for increasing productivity in acid agricul tural 
soils(Bolan et al., 2003; Fageria et al., 2011; Paradelo et al., 2015) . Lime requirements of crops grown on acid 
soils are determined by the quality of liming material, status of soil fertility, crop species and c ultivar within 
species, crop managem ent practices, and economic considerations. Soil pH, base saturation, and aluminium 
saturation are important acidity indices that are used to determine liming. Liming improves soil pH,  Ca, and 
Mg contents and reduces Al concentrations in the soil solution.  In addition, liming improves beneficial microbe 
populations in the soil. Furthermore, liming improves P concentration in the soil solution by reduci ng P 
immobilization by Fe and Al in acid soils  (Fageria et al., 2008) . All these beneficial effects of liming improve 
the root growth of crop plants. Liming has also been shown to increase the soil organic carbon (SOC)  with 
resultant increase in crop yields (Paradelo et al., 2015)  while at the same time immobilizing cadmium in the 
soil, thus reducing its uptake by crops and i mproving the safety and quality of food crops (Shi et al ., 
2019) .Liming enhances the physical, chemical and biological properties of soil through its direct effect o n the 
amelioration of s oil acidity and its indirect effect on the mobilization of plant nutrients, immobilization of toxic 
heavy metals, and improvements in soil structure and hydraulic conductivity ( Ks) (Bolan et al., 2003) . 
A range of liming materials are available, which vary in their ability to neutralize the acidity. Th ese include 
calcitic limestone (CaCO 3), burnt lime (quicklime) (CaO), slaked/hydrated lime (Ca(OH) 2), dolomi tic limestone 
(CaMg(CO 3)2), slag (CaSiO 3), marl/  marlstone , shells, magnesian limestone, marine limestone, chalk  and 
other materials (Bolan  et al., 2003) . The amount of liming material required to rectify soil acidity depends on 
the neutralizing value of the liming material and pH buffer ing capacity of the soil.  DRS 280: 2020  
1                ©RSB 2020  - All rights reserved  
 Agricultural liming materials  — Specification  
1 Scope  
This Draft Rwanda Standard specifies the requirements and methods of sampling and tests for agricultural 
liming materials.  
2 Normative references   
The following documents are referred to in the text in such a way that some or all of  their content constitutes 
requirements of this document.  For dated references, only the edition  cited applies. For undated references, 
the latest edition of the referenced document (including any amendments) applies.  
EN 12048,  Solid fertilizers and liming  materials — Determination of moisture content — Gravimetric method 
by drying at 105 2 C 
ISO 7409, Fertilizers — Marking — Presentation and declarations  
ISO 8157, Fertilizers and soil conditioners — Vocabulary  
ISO 8397, Solid fertilizers and soil conditio ners — Test sieving  
ISO 11047, Soil quality — Determination of cadmium, chromium, cobalt, copper, lead, manganese, nickel and 
zinc — Flame and electrothermal atomic absorption spectrometric methods  
ISO 11465 , Soil quality — Determination of dry matter and water content on a mass basis — Gravimetric 
method  
ISO 14820 -1, Fertilizers and liming materials — Samp ling and sample preparation — Part 1: Sampling  
ISO 14820 -2, Fertilizers and liming materials — Sampling and sample preparation — Part 2: Sample 
preparation  
ISO 17318, Fertilizers and soil conditioners — Determination of arsenic, cadmium, chromium, lead and  
mercury contents  
3 Terms and definitions   
For the purposes of this standard, the terms and definitions given in ISO 8157 and the following apply.  
3.1 
agricultural liming material   
©RSB 2020  - All rights reserved                  2 
 a product whose calcium and magnesium compounds are capable of neutralizing so il acidity  
3.2 
blast -furnace slag  
the non -metallic product, consisting  essentially of silicates and aluminosilicates of calcium andother bases, 
that is developed in a molten condition simultaneously  with iron in a blast furnace  
3.3 
blast -furnace slag, air-cooled  
the material resulting from  solidification of molten blast -furnace slag under atmospheric  conditions; 
subsequent cooling may be accelerated by application  of water to the solidified surface  
3.4 
blast -furnace slag, granulated  
the glassy, granular  material  formed when molten blast -furnace slag is rapidly chilled,  as by immersion in 
water  
3.5 
burnt lime (quick lime)  
a material, made from limestone which consists essentially of calcium oxide or combination of calciu m oxide 
with magnesium oxide  
3.6 
calcium carbonate equivalent (C.C.E.)  
the acidneutralizing capacity (of an agricultural liming material) of the material expressed as weig ht percent of 
calcium carbonate  
3.7 
fineness  
the percentage by weight of the material which will pass sieves of specifie d sizes  
3.8 
hydrated lime  DRS 280: 2020  
3                ©RSB 2020  - All rights reserved  
 a material, made from lime, which consists essentially of calcium hydroxide or a combination of calc ium 
hydroxide with magnesium oxide and/or magnesium hydroxide  
3.9 
limestone  
a material consisting essentially of calcium carbonate  or a combination of calcium carbonate with magnesium 
carbonate capable of neutralizing soil acidity  
4 Requirements  
4.1 Chemical composition  
Agricultural liming materials shall be classified in terms of calcium carbonate equivalent (C.C.E) a s shown in Table 
1. 
Table 1 — Agricultural liming materials requirements  
No. Material  Minimum Calcium carbonate 
equivalent (CCE), %  Test method  
i) Quicklime  140 Annex A  
ii) Hydrated lime  110  
iii) Limestone  80  
iv) Slag 80  
v) Shells  80  
NOTE  Marl and some by -product liming materials are used for neutralizing soil acidity, but due to their varying composition, their  
chemical limits are not included. In some economic circumstances limestone, slag, and shells of less  than 80 % C.C.E. may be used.  
4.2 Requirements for agricul tural limestone  
4.2.1  Sieve analysis classifications for agricultural  
The sieve analysis shall be done in accordance with ISO 8397. Agricultural limestone shall be classi fied 
according to the  minimum percentage passing the no. 8  (2.36 -mm) and no. 60  (0.25mm) as shown in Table 2.  
Table 2 — Sieve analysis classification for agricultural limestone  
S/N Class 
designation  Passing no. 8  (2.36mm)  sieve, 
min per cent  Passing no. 60  (0.25mm ) 
sieve, min, per cent  
i.  S 100 100 
ii.  T 99 75 
iii.  O 95 55 
iv.  N 90 40  
©RSB 2020  - All rights reserved                  4 
 v.  E 80 25 
NOTE 1  These  classifications apply where the agricultural limestone is obtained by the normal crushing procedure and 
the product contains the fines of fracture. In some economic circumstances, coarser products are use d. The No. 60 
(0.25mm) sieve was selected beca use research has shown that this sieve gives a more accurate representation of the 
particle size distribution of most agricultural limestones presently produced than a finer or coarse r sieve. The No. 8 (2.36 -
mm) sieve is used to control the upper limit on the amount of coarse limestone particles that may be in the product.  
NOTE 2  The relationship between increasing limestone fineness and reactivity is caused by having a larger surfa ce 
area exposed to chemical reaction. The surface area of liming material in creases proportionately with decreasing particle 
size, for example, the exposed area of a cube of 1 cm is 6 cm2: decreasing the particle size to 2 mm  (10 mesh), or 0.05 
mm (300 mesh) increases the exposed area to 30 and 1200 cm2, respectively.  
4.2.2  Neutralizing  requirements for calcitic limestone  
Calcite shall comply with the neutralizing requirement in Table 3.  
Table 3 — Requirements for calcitic limestone  
Characteristics  Grade I  Grade II  Test Method of  
i) Calcium Carbonate Equivalent (CCE), %, min  70 50 Annex A  
ii) Active lime (total available as CaCO3 + 
MgCO 3), %, min  50 40 Annex C  
iii) Magnesium,(as MgO) %, max  10 10 Annex D  
iv) Moisture content, %, max  10 12 Annex B  
NOTE  Another factor which influences the efficiency of a limestone is its neutralizing capacity. This is 
determined by reacting limestone with strong acids, either hydrochloric or sulphuric acid. The limes tone’s 
neutralizing capacity is expressed as a percentage value of pure calcium carbonate, which has a neut ralizing 
value of 100%. Commercial limestones may have neutralizing capacities greater or lesser than pure CaCO3. 
Dolomitic limestone (a mixture of magnesium and calcium carbonates) has a theoretical neutralizing v alue of 
108%. Generally, limestones have neutralizing values  below 100%. Impurities such as clays in limestone 
reduce their relative neutralizing capacities.  
To determine the agricultural value (A.V.) of limestones, the particle size efficiency rating (E.R.)  has to be 
adjusted by the neutralizing value (N.V.) (syno nymous with neutralizing capacity), plus an adjustment for 
limestone moisture content (M.C.). For example, a limestone having an efficiency rating (E.R.) of 85 %, a 
neutralizing value (N.V.) of 95%, and a moisture content of (M.C.) 13%, has an agricultural value of:  
AV  =  85% (E.R.) X 0.95 (N.V.) X [1.00 – 0.13 M.C.]  
AV  =  70.25%  
4.3 Sieve analysis classifications for agricultural slag  
4.3.1  Air-cooled blast -furnace slag  
Air-cooled blast -furnace slag shall be classified the same as agricultural limestone as in Clause 4.2 . DRS 280: 2020  
5                ©RSB 2020  - All rights reserved  
 4.3.2  Granulated blast -furnace slag  
Granulated blast -furnace slag shall be classified in accordance with the minimum percentages passing the 
No. 8 (2.36 -mm) and the No. 60 (0.25mm) sieves.  
4.4 Requirements for hydrated lime and burnt lime  
4.4.1  Fineness  
Hydrat ed lime and quicklime for agricultural use shall be classified in accordance with the minimum 
percentages passing the No. 8 (2.36 -mm) and No. 60 (0.25mm) sieves, as follows:  
Table 4 — Particle size requirements for hydrated lime and quicklime  
Passing sieve  No. Min. %  
Test method  
Hydrated lime  Quick lime  
8(2.36 mm)  100 95 ISO 8397  
60(0.25mm)  97 35 ISO 8397  
4.4.2  Neutralizing requirements of hydrated lime and quicklime  
Hydrated lime and burnt lime shall comply with the requirement in Table 5. 
Table 5 — Requirements for hydrated lime and burnt lime as soil conditioners  
S/N Characteristics  Grade I  Grade II  Method of test  
i) Calcium Carbonate Equivalent (C CE), %, min  85 70 Annex A  
ii) Active lime (available as , Ca(HO) 2,  %, m/m, 
min  60 50 Annex C  
iii) Moisture content, %, m/m, max  10 12 Annex B  
4.4.3  Neutralizing requirements for dolomite  
Dolomite shall comply with the requirements in Table 6.  
Table 6 — Requirements for dolomitic limestone  
S/N Characteristics  Grade I  Grade II  Method of test  
i) Calcium Carbonate Equivalent (C CE), %, 
min 100 70 Annex A  
ii) Total magnesia lime (MgCO 3), %, min  35 10  
iii) Moisture content, %, max  10 12 Annex B   
©RSB 2020  - All rights reserved                  6 
 4.5 Heavy metal contaminants  
The heavy metal contaminants, if present, shall not exceed the limits stipulated in Table 7. 
Table 7— Limits for heavy metals  contaminants  for agricultural liming materials  
S/N Properties  Maximum  limits (mg/kg, dry 
weight)   Test method  
i) Arsenic (As)  10  ISO 17318  
ii) Zinc (Zn)  5  ISO 11047  
iii) Lead (Pb)  80  ISO 17318/ISO 11047  
iv) Copper (Cu)  300  ISO 11047  
v) Chromium (Cr)  150  ISO 17318/ ISO 11047  
vi) Nickel (Ni)  50  ISO 11047  
vii) Mercury (Hg)  2  ISO 17318  
viii) Cadmium (Cd)  5  ISO 17318/ ISO 11047  
5 Packaging and labelling  
5.1 Packaging  
The agricultural liming materials shall be packed in clean, non -defective and strong packages . The material for 
which the package  is made shall be such as to protect the contents from moisture and also not lead to easy 
rupture during handling, transportation and storage.  
5.2 Labelling  
5.2.1  Each package of the agricultural liming material shall be legibly and indelibly marked with the 
following particulars:  
a) Name of product as agricultural liming materials;  
b) Types (such as Calcite, Dolomite, Hydrated lime or Burnt lime.);  
c) Grade: such as Grade I or Grade II;  
d) Elemental calcium and magnesium  percentage by weight;  
e) Calcium Carbonate Equivalent (CCE);  
f) net weight;  
g) Effective Neutralizing Value (ENV);  
h) Lot number or batch number;  DRS 280: 2020  
7                ©RSB 2020  - All rights reserved  
 i) Name and physical address of the manufacturer;  
j) Instructions for use  and handing;  
k) Storage  conditions;  
l) date of manufacture and best before or expiry date; and  
m) Country of origin  
5.2.2  Where the agricultural liming materials is distributed in bulk, the marking  information shall 
accompany the delivery note to the purchaser.  
6 Sampling  
Sampling and sample preparation for inspection and testing shall be carried out in accordance with ISO 14820 
parts 1 and 2 . 
  
©RSB 2020  - All rights reserved                  8 
 Annex  A 
(normative)  
 
Determination of calcium carbonate equivale nt (neutralizing value)  
A.1 Coverage  
The calcium carbonate equivalence (CCE) testis used to determine the neutralizing capability of a ca lcareous  
material and to report this value in terms of percent calcium  carbonate equivalents (% CaCO 3). 
A.2 Significance and use 
Calcareous materials such as  crushed limestone, hydrated lime and pulverized slags (from  the production of 
steel) have been used extensively as soil  modifiers or agricultural liming materials. A measure of their  
neutralizing capability can be determine d through the use of  this method of test. Not all neutralizing 
components of a  calcareous  material may be beneficial, therefore, the chemical  analysis is suggested.  
A.3 Apparatus  
A.3.1  pH meter A.3.2  Mechanical Stirrer  
A.3.3  Sieve, No 60 (250 -µm) 
A.4 Reagents  
A.4.1  Standard hydrochloric acid – 0.5 N  
A.4.2  Standard sodium hydroxide solution – 0.5 N  
A.4.3  Phenolphthalein indicator solution – Dissolve 0.1 g of phenolphthalein in 60 mL of rectified spirit and 
dilute with water to 100 mL.  
A.5 Procedure  
A.5.1  Weigh accur ately about 0 .5 g of the previously ground  sample to pass through 250 µm sieve,  in a 
250-ml stoppered  conical flask. Add 40 ml of standard hydrochloric acid, with swirling.  Heat to gentle boiling, 
agitating continuously. Boil for 5 minutes and  then cool to room temperature. Titrate against standard sodium  
hydroxide solution using 2 to 3 drops of phenolphthalein indicator.  
A.5.2  Carry out a blank test us ing the same quantities of all reagents  but without adding the sample.  DRS 280: 2020  
9                ©RSB 2020  - All rights reserved  
 A.6 Calculation  
Neutralizing value (as C aCO 3), % by mass = ହ(஻ି஺)×ே
ெ 
Where;  
B = volume in ml of standard sodium hydroxide solution  used in the blank determination,  
A = volume in ml of standard sodium hydroxide solution  used with the sample,  
N = normality of standard sodium hydroxide solution, and 
M = mass in g of the sample taken for the test.  
 
   
©RSB 2020  - All rights reserved                  10 
 Annex  B 
(normative)  
 
Determination of moisture content  
B.1 Procedure  
Weigh accurately 2 g of the powdered sample in a platinum or  silica dish. Place It in an Oven maintained at 
105° ± 2°C, until on  cooling in a desiccator and weighing, constant mass (± 2 mg) is  obtained. Calculate the 
percent moisture m the sample.  
B.2 Calculation  
Moisture, percent by mass = ଵ଴଴ (ெమିெమ)
ெమିெ 
where  
M1= mass III g of the moisture dish with the material before  drying,  
M2= mass in g of the moisture dish with the material after  drying, and  
M = mass in g of the empty moisture dish.  DRS 280: 2020  
11                ©RSB 2020  - All rights reserved  
 Annex  C 
(normative)  
 
Determination of available lime index  
C.1 Scope  
The available lime index of high -calcium quicklime and hydrated lime designates those constituents tha t enter 
into the reaction under the conditions of this specified test method, otherwise known as the “rapid sugar test 
method.” The interpretation of results obtained by this test method shall be restricted by this defi nition.  
C.2 Summary of test method  
The sample is slaked and dispersed with water. The lime is solubilized by reaction with sugar to form calc ium 
sucrate which is then determined by titration against standard acid using phenolphthalein as the ind icator.  
C.3 Reagents  
C.3.1  Hydrochloric acid, standard ( 1.000 N) – Prepare a solution by diluting 83 mL of HCl to 1 L with CO 2-
free water.  
C.3.2  Phenolphthalein indicator (4%) – Dissolve 4 g of dry phenolphthalein in 100 mL of 95% alcohol.  
C.3.3  Sucrose solution – (40 g of pure cane sugar in solid  form may be used per sample in place of a sugar 
solution ). Prepare a 40 % solution (w/v) using pure cane sugar andCO 2-free water in a large beaker and stir 
until dissolved. Add  several drops of phenolphthalein indicator solution. Add 0.1 N  NaOH solution dropwise 
with stirring until a faint pink colour  persists. Stock solution of sugar may be made for convenience;  however, it 
should not be stored for more than two days. As an  alternative the acidity of each lot of sugar can be 
determined,  and a correction applied to the  titration.  
C.4 Procedure  
C.4.1  Procedure for quicklime  
C.4.1.1  The sample as received at the laboratory shall be  thoroughly mixed and a representative sample with 
minimum  weight of 100 g shall be taken and pulverized to pass a No. 50sieve for analysis. Weigh rapidly 
2.804 g of the finely pulverized  sample, brush carefully into a 500 -mL Erlenmeyer flask  containing about 40 
mL of CO 2-free water, and  immediately stopper the flask.  
NOTE  Water should not be added to the sample because, especially  with quicklime, th ere is a tendency for the 
material to cake and form  lumps difficult to completely dissolve in the sugar solution later. On the  other hand, if the lime is 
added to a little water, a better dispersion of the  fine particles occurs, leading to a more rapid dis solution of the sample. Itis 
possible that in the case of quicklime, some slaking action occurs to  facilitate the dispersion and solution.   
©RSB 2020  - All rights reserved                  12 
 C.4.1.2  Remove the stopper. Place the flask on a hot plate  and immediately add 50 mL of boiling CO 2-free 
water to the  flask. Swirl the flask and boil actively 1 min for complete  slaking. Remove from the hot plate, 
stopper the flask loosely,  and place in a cold -water bath to cool to room temperature.  
C.4.1.3  Add 100 mL of the neutralized sugar solution (or  approximately 40 g of pure cane sugar). Stopper the 
flask,  swirl, and let stand for 15 min to react. (Reaction time should  not be less than 10 min nor more than 20 
min.) Swirl at 5 -minintervals during reaction. Remove stopper, add 4 to 5 drops of4 % phenolphthalein 
indicator solution and wash down the  stopper and sides of the flask with CO 2-free water.  
C.4.1.4  When titrating, first add about 90 %of the acid requirement from a 100 -mL burette. Finish the  titration, 
more carefully at approximately one drop per second,  to th e first disappearance of the pink colo ur, which 
persists for  3 s. Note the endpoint and ignore any further return of colour.  
NOTE  A mechanical stirrer may be used during the titration if  desired. Put a clean magnetic stirrer bar into the flask 
and place th e flask  on the magnetic stirrer. Adjust to stir as rapidly as possible without  incurring any loss by spattering. 
Unless the operator is familiar with  previous analyses of the lime under test, and in cases where the available  lime content 
varies to extremes , it is good practice to run a preliminary test  by slow titration to determine the proper amount of acid 
required to  neutralize the sample.  
C.4.2  Procedure for hydrated lime  
The procedure for  determining Ca(OH) 2 is the same as for CaO with the exception  that cold CO 2-free water is 
used and the boiling and  cooling steps are omitted.  
C.5 Calculation  
C.5.1  Calculate for CaO as follows:  
Available lime CaO , % = ே×௏×ଶ.଼଴ସ
ௐ 
where:  
N = normality of acid solution,  
V = standard HCl used (1.000 N), mL,  
W = weight of sample, g, and2.804 = CaO, g, equivalent to 1 mL of standardacid × 100 
or 1 mL of standard HCl = 1 %CaO  if exactly 2.804 g of sample is used.  
Calculate for Ca(OH) 2 as follows:  
Available lime [Ca (OH)2, % = ே×௏×ଷ.଻଴ସ
ௐ 
where:  DRS 280: 2020  
13                ©RSB 2020  - All rights reserved  
 N = normality of acid solution,  
V = standard HCl (1.000 N), mL,  
W = weight of sample, g, and  
3.704  = Ca(OH) 2, g, equivalent to 1 mL of standard  acid × 100 or 1 mL of standard HCl = 1.32 % 
Ca(OH) 2 when exactly 2.804g of sample is used.   
©RSB 2020  - All rights reserved                  14 
 Annex  D 
(normative)  
 
Determination of magnesium oxide  content  
D.1 Scope  
Magnesium oxide in lime and limestone may  vary from a few tenths to 2 % for high -calcium limestone to as  
much as 22 % for dolomitic limestone. The pyrophosphate  gravimetric method has been used successfully 
throughout the  industry to determine magnesium within this wide range.  
D.2 Summary of test method  
In this test method, magnesium  is doubly precipitated as magnesium ammonium phosphate  from the filtrate 
after removal of calcium. The precipitate  is ignited and weighed as magnesium pyropho sphate  (Mg 2P2O7). 
The MgO equivalent is then calculated.  
D.3 Reagents  
D.3.1  Ammonium Phosphate, Dibasic Solution (250 g/L)  — Dissolve 250 g of dibasic ammonium 
phosphate((NH 4)2HPO 4) in 1 L of water.  
D.3.2  Ammonium Hydroxide Wash Solution (5 + 95)  — Dilute 50 mL of NH 4OH with 950 mL of water and 
add 1 or 2mL of HNO 3. 
D.4 Procedure  
Add 2 drops of methyl red indicator to the combined  filtrates from the determination of calcium, acidify with 
HCl, and concentrate to about 250 mL. Add to this solution about 10mL of the (NH 4)2HPO 4 solution, 250 g/L, 
and cool the solution  to room temperature. Add NH 4OH slowly while stirring  constantly until the solution is 
alkaline or the crystalline  magnesium ammonium phosphate begins to form; then add  about 15 to 20 mL of 
NH 4OH in excess  and continue stirring  for several more minutes. Allow the beaker and precipitate to  stand in 
a cool place overnight. Filter and wash with cold dilute  ammonium hydroxide wash solution (5 + 95).  
Dissolve the precipitate with hot diluted HCl (1 + 9)  and wash  the filter paper well with hot diluted HCl (1 + 99).  
Dilute the solution to 100 mL, cool to room temperature, and  add 1 mL of the 20 % solution of (NH 4)2HPO 4. 
Precipitate the  magnesium ammonium phosphate as before and allow to stand  for about 2 h in a cool place.  
Filter the precipitate on paper or in a tared Gooch  crucible, washing with diluted NH 4OH (5 + 95). If filtered  
through a Gooch, place directly in a muffle at 400 °C and raise  heat to 1100 °C. If filtration was through paper, 
place paper and  precipitate in a weighed platinum or porcelain crucible. Slowly  char the paper without 
inflaming and carefully burn off the  resulting carbon ( Warning ! Extreme caution should be exercised  during 
this ignition. Reduction of the phosphate precipitate  can result if carbon is in contact with it at high 
temperatures.  There is also a danger of occluding carbon in the  precipitate if ignition is too rapid.). Ignite at 
1100 °C for  ½ h, cool in desiccator, and weigh as Mg 2P2O7. DRS 280: 2020  
15                ©RSB 2020  - All rights reserved  
 NOTE  For research purposes or in the most e xacting types of work,  the manganese content of the pyrophosphate 
residue should be determined  and deducted as Mn 2P2O7. 
D.5 Calculation  
Calculate the percentage of MgO to the  nearest 0.01 % as follows:  
MgO, %  = ஺×ଷ଺.ଶ
஻ 
where:  
A = Mg 2P2O7, g, 
B = sample, g, and 
36.2  = molecular ratio of 2MgO to Mg 2P2O7× 100.  
©RSB 2020  - All rights reserved                  16 
 Bibliography  
[1] ISO/IEC Directives, Part  2, Rules for the structure and drafting of International Standards , 2016  
[2] ISO/IEC  TR 10000 -1, Information technology  — Framework and taxonomy of International  
Standardized Profiles  — Part 1: General principles and documentation framework  
[3] ISO 10241  (All parts) , Terminological entries in standards  
[4] ISO 128-30, Technical drawings  — General principles of presentation — Part 30: Basic conventions 
for views  
[5] ISO 128-34, Technical drawings  — General principles of presentation  — Part 34: Views on 
mechanical engineering drawings  
[6] ISO 128-40, Technical drawings  — General principles of presentation  — Part 40: Basic conventions 
for cuts and sections  
[7] ISO 128-44, Technical drawings  — General principles of presentation  — Part 44: Sections on 
mechanical engineering drawings  
[8] ISO 31 (all parts), Quantities and units  
[9] IEC 60027 (all parts), Letter symbols to be used in electrical technology  
[10] ISO 80000 -1, Quantities and units -- Part 1: General  
[11] ISO 690, Documentation  — Bibliographic references  — Content, form and structure  
 DRS 280 : 2020  
 
Price based on  nnn pages  
©RSB 2020  - All right s reserved