controlled low strength material (clsm) …...cite this article: anil jadhav, pramod bongirwar, r....

http://www.iaeme.com/IJCIET/index.asp 498 [email protected]

International Journal of Civil Engineering and Technology (IJCIET) Volume 8, Issue 10, October 2017, pp. 498–506, Article ID: IJCIET_08_10_051

Available online at http://http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=8&IType=10

ISSN Print: 0976-6308 and ISSN Online: 0976-6316

© IAEME Publication Scopus Indexed

CONTROLLED LOW STRENGTH MATERIAL

(CLSM) AS ROBUST BACKFILL MATERIAL

Anil Jadhav

Nexus Techno Consultants

Pramod Bongirwar

Indian Road Congress

R. R. Raut

Pune Municipal Corporation

D. P. Patil

Pimpri Chinchwad Municipal Corporation

ABSTRACT:

soil or improved soil/ aggregates with predefined gradation (GSB, WMM) are

primitively used for backfill, (both structural / non-structural back fill), pavement

bases, void filling etc., with its inherent limitations of air voids, stiffness, need for

compaction, susceptibility to water penetration, susceptibility of settlement etc.

Controlled low strength material (CLSM) eliminates the drawbacks of soil backfill

providing durability to the supporting structure. CLSM is compulsorily a back fill

material and not a low strength concrete, rather it can be well defined as material

which is designed as concrete with flow ability and strength as per the requirement

and used as backfill to avoid the drawbacks of the soil or murum backfill.

Contrary to the soil, the strength and thus the bearing strength of the fill can be

controlled allowing with scope for future changes. ACI 116R defines CLSM as per the

strength criteria, “CLSM as material that results in a compressive strength of less

than 8.3 Mpa”

CLSM can be designed with varying strength and density, considering the cost and

future needs, low strength CLSM shall be necessary to allow future excavation,

whereas if the there is no scope for future excavation the strength can be at higher

side, further the density of CLSM can be modified as per the cost and material needs.

Properties of CLSM can be enhanced as per the requirement to compensate

particular need like corrosion resistance, Exacavatability, strength flow ability etc.

Material properties such as shrinkage, subsidence and settlement are not

considered as specification performance or requirement properties. These properties

Anil Jadhav, Pramod Bongirwar, R.R Raut and D.P.Patil


are considered as inherent to CLSM and as such; do not require the establishment of

specification requirement.

Keywords: Clsm, Robust Backfill Material

Cite this Article: Anil Jadhav, Pramod Bongirwar, R. R. Raut and D. P. Patil,

Controlled Low Strength Material (Clsm) As Robust Backfill Material, International

Journal of Civil Engineering and Technology, 8(10), 2017, pp. 498–506

http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=10

1. INTRODUCTION:

Laying of new utility services is a continuous operation in all urban areas. The road side land

being public land is used for laying the services after taking permission from competent

authority. The depth of services could range from 30 centimeters to few meters in case of

sewer drains or water mains .Normally after making the trench the same material is backfilled

or even if new materials brought the strict control on quality is not maintained for being a

small quantity .Proper compaction in such narrow width also poses serious practical problem.

Sometimes trench width is increased to accommodate available compaction equipment .Due

to inadequate compaction the trench portion get settled, and lead to pot hole formations

leading to public criticism. Besides it requires continuous maintenance.

CLSM therefore proves an ideal material which addresses all these problems .The highly

flow able material fill all voids and uneven side, this gives additional support to moving

vehicles and settlement of trench does not take place hence the damage to road surface. In all

urban areas there is tendency to construct concrete roads .Edge strip of 1 to 1.5 m is left and

either flexible pavement is adopted or paver block is laid .This facilitates convenient laying of

services While laying the new services the entire top surface get disturbed. Improper

compaction leads to distortion to surface and hence car owners do not have tendency to use

this strip and thus there is permanent loss to road width .Solution to this, is a base of CLSM

and also restoration of trench by CLSM only. CLSM therefore can prove an ideal solution for

this typical urban problem

2. LITERATURE REVIEW – APPLICATIONS AND ADVANTAGES:

Flow ability without compaction makes it suitable for tight and restricted areas, compared to

traditional soil or modified soil backfill in various

2.1. Backfills:

The Ease of placing CLSM in restricted places without compaction facilitates the reduction in

trench width or excavation. Traditional methodology of backfilling in layers and compacting

will never provide with the uniformity of density as facilitated by CLSM. CLSM can be

placed in layers, allowing each layer to harden prior to placing the next layer.

2.2. Structural Fills:

CLSM with higher strength can be produced to act as structural fills, in case of BC soil it can

distribute structures load on greater area. CLSM can provide a uniform and level surface for

uneven sub-grades under foundation footings and slabs.

2.3. Utilities Bedding:

CLSM provides an excellent bedding material for pipe, electrical, telephone, and other types

of conduits. The flow able characteristic of the material allows the CLSM to fill voids beneath

the conduit and provide a uniform support.

Controlled Low Strength Material (Clsm) As Robust Backfill Material


Encasing the entire conduit in CLSM also serves to protect the conduit from future

damage. If the area around the conduit is being excavated at a later date, the obvious material

change in CLSM versus the surrounding soil or conventional granular backfill would be

recognized by the excavating crew, alerting them to the existence of the conduit. Coloring

agents have also been used in mixtures to help identify the presence of CLSM.

2.4. Erosion Control:

Laboratory studies, as well as field performance, have shown that CLSM resists erosion better

than many other fill materials. CLSM can be used in riprap for embankment protection and

in spilling basins below dam spillways, to hold rock pieces in place and resist erosion. CLSM

is used to fill flexible fabric mattresses placed along embankments for erosion protection,

thereby increasing their strength and weight.

In addition to providing an erosion resistance under culverts, CLSM isused to fill voids

under pavements, sidewalks, bridges and other structures where natural soil or non-cohesive

granular fill has eroded away.

2.5. Void filling:

Tunnel shafts and sewers—filling abandoned tunnels and sewers, it is important to use a flow

able mixture. A constant supply of CLSM will help keep the material flowing and make it

flow greater distances.

Basements and underground structures—abandoned basements are often filled in with CLSM

by pumping or conveying the mixture through an open window or doorway.

2.6. CLSM has also been used to fill abandoned underground storage tanks

(USTs).

Nuclear Facilities:

CLSM can also be used in unique applications at nuclear facilities, such as waste stabilization,

encapsulation of Decommissioned pipelines and tanks, encapsulation of waste-disposal sites,

and new landfill construction.

3. RESEARCH SIGNIFICANCE:

With the exponential increase in rehabilitation of utilities and development of new utilities

like, fibre optical line, natural gas lines the linear and cross excavation along road have also

increased, the tradition practice of filling the trench with the same material usually resulted

into summit of loose soil along road or depression along road. Further there was no proper

control of procedure to handle this issue. The present study is taken up to resolve the above

problems by developing a robust material and construction procedure or technology which

would add aesthetic up gradation to city look up avoiding shabby patchwork. The main focus

of the study was to develop concrete with flow ability which will be used as backfill

facilitating its property control competing with the rates of local backfill soil.

CLSM developed had essentially all the materials locally available with which the local

contractors are well versed further the preparation techniques were bit modified for intended

use. The mix design procedure was as per IS10262:2009 using fly ash as main component and

cement as secondary also specially formulated admixture were developed for activating fly

ash to exhibit hydraulic characteristics as adding fly ash may result into increase in initial

setting time. The primary focus was to exhibit early setting with flow ability because of old

city layout which was unfavorable for diversions and proper excavation.



4. MATERIAL USED:

Conventional CLSM mixtures usually consist of same ingredients as that of normal concrete

Water, Portland cement, fly ash or other similar products, and finer or coarse aggregates or

both. The use of standardized materials is not always necessary provided the new materials

added are inactive in nature , Selection of materials should be based on availability, cost,

specific application, and the necessary characteristics of the mixture, including flowability,

strength, Exacavatability, and density.

Cement: Ordinary Portland Cement (OPC) of grade 53 confirming to IS 11269:2013 with

a specific gravity of 3.12 was used.

Fine Aggregates: Basalt rock chrused to confirm zone II of IS 383:1970 with specific

gravity ranging from 2.8-3.01 was used. Silt Content was not considered since the strength

aspect was not significant. Further it is suggested to use locally available non-reactive

aggregates like over burnt bricks in CLSM as it would be a wise decision to reduce the final

cost of CLSM.

Coarse Aggregates: Locally available, basalt stone aggregates with maximum nominal

size 20mm confirming to IS 383:1970 was used.

Water: Portable water was used to mixing and curing of CLSM

Admixture: Specially formulated admixture was used, the admixture was developed in two

components. The first component was Naphtha based retarder cum workability chemical used

for increasing the initial setting time and exhibiting flow ability like Self Compacting

concrete. The second component consists of accelerator cum activator to start the setting and

strength gain.

4.1. MIX DESIGN:

The proportioning of the ingredients was as per IS10262:2009, with fly ash as the main

ingredient and cement as supplementary material, further the focus of the mix design was to

develop substitute for backfill which matches its rate but consist the advantages of CLSM. So

the density was lowered to 1750 kg per cubic metre which can be advocated to match with the

density of traditional backfill material like murum, GSB etc. The design was formulated for

fine contents to match up with the requirements of Self compacting concrete to yield flow

ability without segregation.

The typical all in aggregate gradation was as below:



4.2. CONCRETE MIX DESIGN:

Materials Unit Weight %

M.C. W.A Correct T.Correct 1.00cum

Cement Kg 50

50

Fly Ash Kg 200

200

Micro silica Kg 0

0

20 mm Kg 313 0.60 1.28 0.68 2.13 311

10 mm Kg 364 0.85 1.31 0.46 1.68 363

R.Sand Kg 0 0.05 1.47 1.43 0.00 0

C.Sand Kg 567 1.21 3.65 2.44 13.85 554

Water Kg 195

17.65 213

Admixture Kg 1.50

1.50

4.3. RATE ANALYSIS OF CLSM:

Sr.NO. Description of Material Average

Rate / kg Design 1 Amount RS.

1 10 MM 0.41 363 148.83

2 Crush Sand 0.55 554 304.7

3 River Sand 0 0 0

4 20 MM 0.41 311 127.51

5 Cement 5 50 250

6 Fly Ash 1.5 200 300

7 Admixture 60 3 180

8 Water 0.05 213 10.65

9 Transportation 150 1694 150

10 Operating Cost 300

300

TOTAL

1772

GRAND TOTAL

RS 1772

5. LABORATORY TRIAL:

Laboratory trials were conducted to study workability and strength behaviour of CLSM.

Observations of CLSM workability was noted in laboratory for intial flow which was

intentionally kept at 600mm considering the lead time of 30 min. The sole purpose of 1st

component of admixture added was to retard the setting or dropping of slump of CLSM.

Figure 1 Flow observed after 30 min around 580mm average



After adding second component which necessarily consists of accelerator and fly ash

activator, the slump of 170 mm was noted after 60 min

Figure 2 Slump: 170 mm after 60 min

Final settings of CLSM in casted cubes were around 4 hours in laboratory. Compressive

strength of cubes was noted after 28 days curing as per IS 516:

Sr.no Cube Size Strength Average

1 150x150x150 3.25

2 150x150x150 3.10 3.11 Mpa

3 150x150x150 2.98

5.1. PILOT FIELD TESTS:

CLSM field trails were conducted with the help of Pune Municipal Corporation at Ideal

Colony, Kotrud Pune. The trail was intended for backfill the conduit excavation along the

road.

The Second field trail was conducted with the aid of Pimpri Chinchwad Municipal

Corporation at Dapodi for backfilling the MNGL conduit excavation across the busy Pune-

Mumbai Expressway.

5.2. Kotrud-Pune Trial: (Along the Road) Dated: 06-09-2016

CLSM was produced with mechanized plant (Ready Mix Concrete Plant) of 0.5 cubic

metre per batch capacity and transported through transit mixer with a lead time of about 30

min

The first component was primarily used at mixing point i.e. RMC plant which gave a flow

of about 400-600 mm till 1 hour, again since strength didn’t play a major role in CLSM the

water content can be at higher side to retain the flow ability depending upon the lead time or

distance of point of discharge. The second components which consist of accelerator with

activators were mixed in transit mixer/miller with measured quantity at the point of discharge

10 min before discharge of CLSM with proper mixing. This component enable the CLSM set

early for facilitating human movement, but vehicular movement both light and heavy were

not advised.

Addition of second component reduces the flow ability after 30 minutes, so considering

the distance of discharge point it should be accordingly added.

CLSM was placed in trenches of about 600mm deep, initial flow was good enough to

make the CLSM to flow in all corners and notches on the trench; the trench was filled once

till the surface. The surface was roughed after two hours on initial setting.



Figure 3 Actual Site Photo after 4 hour.

CLSM was hardened enough to bear the load of human which satisfied the design

considerations of setting within 6 hours and avoided the practical problems of citizen

interference.

6. RESULTS:

The 28-day compressive strength of the CLSM was determined using cube specimen of

150mmX150mmX150mm as per IS 516.The compressive strength developed was 3.43Mpa in

28 days.

Sr.no Cube Size Strength Average

1 150x150x150 3.25

2 150x150x150 3.60 3.43 Mpa

3 150x150x150 3.45

6.1. Dapodi-MNGL line Trail –Pimpri Chinchwad Dated: 15-08-2017

CLSM was produced with mechanized plant (Ready Mix Concrete Plant) of 1.25 cubic metre

per batch capacity and transported through transit mixer with a lead time of about 60 min

Going with the experience, the first component was primarily used at mixing point i.e.

RMC plant which gave a flow of about 550-700 mm, the second component was mixed in

transit mixer/miller with measured quantity at the point of discharge 10 min before discharge

of CLSM with proper mixing.

CLSM was placed in trenches of about 750mm deep, initial flow was good enough to

make the CLSM to flow in all corners and notches on the trench, the trench was filled in

layers to prevent the excess pressure transfer on sides bracing. The surface was roughed after

two hours on initial setting.

A compressive strength result for 28 days using cube moulds of specimen 150x150x150

as per IS 516 was 4.25 Mpa Average.



7. CONCLUSION:

Based on the lab studies and pilot projects Conducted, the following conclusion can be drawn.

In the view of problems faced due to disadvantages of convention backfill material results

are in favour of CLSM.

The desired engineering properties of CLSM in fresh and hardened state can be altered or

modified depending upon the project requirement gives CLSM upper hand over the

convention soil back fill.

The rate analysis of CLSM further advocates its use compared to the convention backfill

material which will never give the uniformity in density of back fill and involvement of

labour dependency.

REFERENCES:

[1] ACI Committee 229 (Reapproved 2005) Controlled Low Strength Materials American

Concrete Institute Journal

[2] AASHTO Guide for Design of Pavement Structures, American Association of State

Highway and Transportation Officials, Washington, D.C., 1986.

[3] Ramme, B. W., Progress in CLSM: Continuing Innovation, Concrete International, V. 19,

No. 5, May 1997, pp. 32-33.

[4] Adaska, W. S., Controlled Low-Strength Materials, Concrete International. 19, No. 4,

Apr. 1997, pp. 41-43.

[5] IS 12269-2013 Indian Standard Specification for Ordinary Portland Cement-53 Grade

(First Revision) Bureau of Indian Standards, New Delhi

[6] IS 383-1970 (Reaffirmed 1997) Indian Standard Specification for coarse and fine

Aggregates from Natural Source for Concrete Bureau of Indian Standards, New Delhi.

[7] IS 9103-1999 Indian Standard Specification for Concrete Admixtures, Bureau of Indian

Standards, New Delhi.



[8] IS 10262-2009 Indian Standard Concrete Mix Proportioning Guidelines (First Revision)

Bureau of Indian Standards, New Delhi.

[9] IS 516-1959 Method of test for Strength of Concrete Bureau of Indian Standards, New

Delhi. India

[10] K. V. Ramesh, R. Goutham and I. Siva Kishore An Experimental Study on Partial

Replacement of Bagasse Ash in Basalt Concrete Mix, International Journal of Civil

Engineering and Technology, 8(5), 2017, pp. 335–341.

[11] K. Kiran and I. Siva Kishore, An Experimental Study On Partial Replacement of Cement

with Bagasse Ash In Concrete Mix. International Journal of Civil Engineering and

Technology, 8(1), 2017, pp. 452–455.

[12] Salman A. Al-Duheisat and Amjad Saleh El-Amoush, Bend Cracking Behavior of

Hydrogenated Low Strength Structural Steel Under Different Heat Treatment Conditions,

International Journal of Advanced Research In Engineering and Technology (IJARET),

Volume 5, Issue 4, April (2014), pp. 111-118

AUTHORS BIOGRAPY:

Anil Jadhav: is certified Concrete Technologist, holds Diploma, Bachelors, Degree in Civil

Engineering and PGPCM (Construction Management) from AICTE, PUNE UNIVERSITY

and NICMAR respectively. Presently working as Chief Consultant with NEXUS TECHNO

CONSULTANTS and visiting Industrial faculty for Advanced Concrete Technology with

MIT Academy of Engineering, Alandi, Pune. He has 10 years of experience with

Transportation Engineering and Concrete Technology. His Prime area of focus is to research

and develop Innovative Construction Materials and Technology.

Pramod Bongirwar, Retired in March 2003 in the capacity of Principal Secretary,

PWD.Was involved in executing several prestigious projects as Mumbai, Pune expressway,

50 Flyover in Mumbai, 25 ROB, Planning for 20000 tenements for project affected persons

etc. Introduced several cost effective and innovative designs of bridges After retirement

served as part time Advisor with IDFC for 11 years and now with Larsen and Toubro for last

12 years Has experience of 20 years on BOT projects and major highway projects Served as

members of several IRC Committees and Government advisory committees. Written several

articles in National and International conferences Recipient of Distinguished Alumnus Award

of IIT, Mumbai.

Rajendra Raut, Chief Engineer (Roads) Pune Municipal Corporation, is Graduate Civil

Engineer from Pune University having 28 years’ experience with almost 20 years in Road

department of PMC was involved in much technological innovative initiative undertaken by

PMC.

Deepak Patil: Deputy Engineer (BRTS) Pimpri Chinchwad Municipal Corporation is

Graduate Civil Engineer from Pune University having 15 years’ of experience. Currently

involved with BRTS Division of PCMC.

controlled low strength material (clsm) …...cite this article: anil jadhav, pramod bongirwar, r....

Documents