Treatment of Soils With the Rbi-81 and Renolith Additives

8/12/2019 Treatment of Soils With the Rbi-81 and Renolith Additives

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Improvement of Soil Properties, Bratislava on June 4 5, 2007

TREATMENT OF SOILS WITH THE RBI-81 AND RENOLITH

ADDITIVES

Milorad Jovanovski, Spasen Gjorgevski, Jovan Papic, Josif Josifovski

ABSTRACT: This paper presents the results from field and laboratory testing on low bearing

natural subsoil and coarse grained material for pavement layers, stabilised with additives type

RBI-81 and RENOLITH. The effect of improvement of mechanical properties such as

Californian Bearing Ratio, Uniaxial Compressive Strength etc is analyzed for several soil

types. The methodology of testing is briefly explained. The improvement of named soil

properties is 2,36 - 4 times. Adequate recommendations about possible using of additives RBI

and RENOLITH, are discussed for cases of improvement of low bearing subsoil, as well asfor coarse grained material which can be used in pavement layers. The favorable aspects of

the treatment with such additives, as well as limitations are noted.

The problem needs a close communications between Geotechnics, Geology, Chemistry and

Civil Engineering experts, in order to minimize the expenses for construction of the roads and

the ecological influences on the natural media.

1. Introduction

During the design of traffic infrastructure, several main aspects of the natural

foundational media are of primary technical and economical interest. One of them can be the

problem of low-bearing capacity subsoil, which has a direct or indirect influence on thetechnical solution and economical impact on the project.

The other one can be a problem with providing of an adequate coarse-grained material

for pavement layers because of the strict technical criteria, that must be satisfied for such

materials.

Having in mind that the Geotechnical Department from the Faculty of Civil

Engineering at Skopje, R.Macedonia, during several years worked on some road projects in

the country with specific types of additives called RBI and RENOLITH, in the paper the

experiences from the tests are presented. This is a relatively new technology for stabilisation

of the natural soil or pavement layer of the roads, based on the reaction of the ecological

stabilisers with a natural soil. In general, the following effect with treatment of the low-

bearing subsoil with this stabilizer:

-Decreasing of the dry unit weight,

-Increasing of the strength properties,

-Decreasing of the soaking of water,

Finally, the effect in soil improvement is expressed in a higher bearing capacity of low

bearing soil or reducing in the thickness of the pavement layers.

_________________________________________________________________________________________________________________

Prof. Milorad Jovanovski, Prof. Spasen Gjorgevski, Assist. Jovan Papich & Assist. Josif Josifovski, Faculty ofCivil Engineering, Skopje, blvd.Partizanski odredi No24,1000,Skopje,Macedonia,

E-mail:[email protected]


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In some cases, for lower range of roads (local roads) construction of the road can be

without asphalt final covering. Having this in mind, it is clear that this problem has a large

practical and scientific importance.

2. Analysed soil types

The testing with stabilizers RBI and RHENOLITH are performed in the framework of

the geotechnical studies for the local road to the mountain Vodno (closely spaced to the

capital Skopje), and for some sections on the highway from Skopje to Negotino in

R.Macedonia. The products were from Israel. The chemical composition of the additives was

not declared by the Investor (company Makedonija pat). It seems that it is based on some

mixture of gypsum and carbonate material, with some specific ingredients.

An extensive program is applied in order to determine the physical and mechanical

characteristics of the soils before and after stabilization. All typical classification tests,

determination of the Californian Bearing Ratio (CBR), Optimal Moisture Content (OMC),Maximal Dry Density (MDD), and Uniaxial Compressive Strength (USC) etc are prepared on

a soil types given on figures 1, 2, 3 and 4.

Fig. 1. Typical granulometric curves for the tested samples along road to mountain Vodno

Fig. 2. Range of values for plasticity limits for fine grained soils along road to mountain

Vodno


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of natural CBR is usually around CBR=7-8%. These materials are usually in a class

A4 to A2-4, according to the AASHTO system

3. Methodology of testing with stabilizer RBI-81 and results

The main idea for testing was to define the optimal percent of added stabilizer and to

insure best possible improvement. Once the optimum water has been admixed, the samples

were left in airtight containers for 24 hours before commencing with a compaction effort.

After the compaction, the material was left for a 7 days in a suitable curing room to prevent

the compacted material from drying too quickly. After 7 days curing period, the samples were

submerged in water for a 4 days soaking period. This is a so-called 7+4 days procedure for

defining of the CBR value (table 1). The effect is also checked for the longer time period, in

order to the time-effect on the necessary properties.

Table 1: Results from laboratory tests of Californian Bearing Ratio

(stabilization with RBI-81 after 7+4 days tretment period)

SERIAE % of RBI CBR(%)

I (coarse grained

material)0 64

I (coarse grained

material)2 151

I (coarse grained

material)4 157

I (coarse grained

material)6 172

II (natural claylike

material)0 7,1


material)2 15,7


material)4 18


material)5 22,85

From the table is visible that the value of Californian Bearing Ratio for coarse grained

material after treatment with stabilizer gets very high values. The values are usually higherthan the standard CBR-curve. The regression lines which shows the influence of the added

percentage of RBI-81 on the CBR value are given in figures 5 and 6. The effect of

improvement is evident. Namely, for a coarse grained material, improvement is from 2,36 -

2,68 times. For a silty to claylike material, 2.1 - 3.21 times compared with a relevant basic

value at RBI = 0%.

The results from the constructional phase along road to Vodno are given in a table 2.

As for a case from laboratory tests, it is visible that the value of Californian Bearing Ratio

after treatment with stabilizer gets high values. One example is given on a figure 7. Here, it is

important to note that a serial of tests were performed after 27 and 56 days curing period,

because it was noticed that RBI-81 needs a longer time to exceed optimal degree of chemical

reaction (several months). The time effect of improvement is given on a figure 8.


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CBR = -4.4375%RBI2+ 43.075%RBI + 68.65

R2= 0.9391

0

20

40

60

80

100

120

140

160

180

200

0 1 2 3 4 5 6 7

% of RBI- 81

Fig. 5. Correlation between % of added RBI and CBR for tampon(coarse grained material)

clayike material

CBR = -0.2087(%RBI)2+ 3.92538x(%RBI) + 7.4656

R2= 0.9546

0

5

10

15

20

25

0 1 2 3 4 5 6

% of RBI-81

CBR(%)

Fig. 6. Correlation between % of added RBI and CBR for natural soil (claylike material)

Table 2: Results from CBR testing on field during constructional phase

SAMPLE DATE OF TEST CBR (%)

1 Natural 34

Km 0+550 7+4 days procedure 208Km 0+900 7+4 days procedure 267

Km 1+400 7+4 days procedure 204











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Fig. 7. Comparison between standard CBR curve (1) and curve from testing (curve 2)

0

50

100

150

200

250

300

350

400

450

500

natural 7+4 days 28+4 days 56+4days

time

CalifornianBearingRa

tio(%)

0+550

0+900

1+400

2+540

Fig. 8. Time dependent improvement effect in a value of CBR

4. Results from testing with stabilizer RHENOLITH

The results are given in a brief form in following tables and figure for the parameters

CBR and UCS. It is visible that in some cases the cement was added.

Table 4. Results from testing of the Californian Bearing Ratio

CASE OF TESTING

CBR

[%]

Sample from E75 road Negotino to DemirKapija

(natural sub-soil, with gd=17,25 kN/m3

and with optimal moisture content opt=17,6%)2,54

Sample from E75 road Negotino to DemirKapija

(treated with 5% Renolith and 9% cement)100


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Table 5: Results from testing of the Uniaxial Compressive Strength

CASE OF TESTINGUCS

[kPa]

Sample from E75 road Negotino to Demir Kapija

(natural sub-soil) 291Sample from E75 road Negotino to Demir Kapija

(treated with 5% Renolith and 9% cement)1198

Sample gravel treated with 5% Renolith and 5%

cement1758

Sample cobbles treated with 5% Renolith and 5%

cement1646

Sample from E75 road Negotino to Demir Kapija412

Fig. 9. Increasing in a CBR value with increasing of the added percentage of

RENOLITH stabiliser (from the natural value of CBR = 2,54% to CBR = 100%)

The improvement in the mechanical properties is very visible, esspecially in CBR

value for low-bearing silty material. The improvement in a value of UCS, is also veryimportant, because from UCS = 291 kPa for the natural conditions, the value is increased up

to UCS = 1198 kPa. This is improvement of about 4 times. The naturally non-cohesive

materials as gravel samples after adding of Renolith, gets properties of cohesive material

which is also very important effect.

5. Conclusions

The technology of improvement of the subsoil and pavement layers in the road

construction is a field where every positive experience of the development of "new" additives

is very important for future scientific and practical researches. This is a field where we feelnecessity of mutual close communications between Geotechnics, Geology, Chemistry and


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Treatment of Soils With the Rbi-81 and Renolith Additives