EFFECT OF VARIOUS TYPES RECYCLE AGGREGATE ON CONCRETE SHRINKAGE
(BM-081)
Sholihin As’ad1* and Endah Safitri1
1 Department of Civil Engineering , Universitas Sebelas Maret (UNS-Solo), Surakarta, Indonesia
*e-mail of corresponding author: sholihinasad@gmail.com
ABSTRACT
The recycling of demolished construction material can be reused as non-structural and structural concrete material with limited dosage and very strict aggregate quality control. This paper reports the investigation on the shrinkage of various recycled aggregate concretes. Eight groups of samples made from coarse recycle concrete aggregate, fine recycled concrete wall aggregate, coarse recycled clay roof tile aggregate as both normal and high strength concrete were prepare. On each group, a sample made of natural aggregate was mixed as reference. Each type of recycled aggregate was used as partial and fully replacement of natural aggregate. The total shrinkage up to 90 days was recorded. Samples contained coarse clay roof tile recycled aggregate and coarse recycled concrete aggregate recorded the most and the less shrinkage respectively.
Keywords: concrete aggregates, demolished construction material, recycled aggregate, recycled aggregate concrete,
1. INTRODUCTION
Demolished building wastes and ruins abundantly appeared when the changing the buildings and infrastructures with the new one and natural disaster such earthquakes, tsunamis and flooding occurs.
Some of this materials are able to be recycled as new aggregates for further various usage such as earth filled material, drainage porous media and concrete [1,2]. Figure 1 illustrated some recycled aggregates made of ruined buildings after earthquake.
Figure 1. Recycle aggregates produced from earthquake ruined buildings
Recycling of demolished construction material for new concrete has been applied in a few countries such as England, Germany, Austria, Finlandia Japan, Brazil and Australia etc. These countries allowed the usage of recycled materials for new concrete with strict limitation as stated on their code for recycling concrete materials [2,3,4,5 and 6]. However, in some countries recycling aggregates is not popular since its price could not compete to the natural aggregates price.
The following work studies the effect of various types of recycle aggregate on the concrete shrinkage. The aggregates were recycled of ruined concrete, ruined concrete wall and roof tile taken from ruined demolished materials. The maximum particle size of recycled fine aggregate and coarse aggregate is 5 and 30 mm respectively. The recycled aggregates were used as partial and full replacement for natural aggregate. Recycled aggregate concrete were made in form as normal strength concrete (25 MPa of compressive strength) and high strength concrete (50 MPa of compressive strength). The shrinkage development of some prisms made from various type recycled aggregates concretes were recorded for up to 90 days. Their ultimate and long term shrinkage were calculated using ACI formula. The recorded shrinkage curves were then compared.
2. MATERIALS AND METHODS
Some hardenend concrete prisms of 50 x 50 x 270 mm of various concrete mixtures were prepared.
Samples were grouped into six groups. Four groups were samples of normal and high strength concrete containing 20%, 40%, 60%, 80%, 100% fine and coarse recycled concrete aggregates as replacement for natural aggregate respectively (See Table 1 and Table 2). Two others were samples of normal and high strength concrete containing 10%, 25%, 50% and 100% coarse recycled clay roof tile as replacement for natural aggregate (See Table 3 and Table 4). As reference samples containing 100% recycled and 100%
natural aggregate of both coarse and fine aggregates were also made.
Table 1. Mixture composition of normal strength concrete (NSC) samples containing various fine and coarse recycled aggregate
Table 5 shows the basic properties and particle size distribution of used recycled and natural aggregate.
The sample shrinkage was recorded by demeg gauge of the two points on prism surface with original distance of 200 mm. The reduction distance between these two marked points indicates shrinkage. The shrinkage of speciment is defined of the cumulative distance reduction between the two marked points.
Shrinkage was recorded up to 90 days of specimen age. The final shrinkage data was the average of three specimen of each mixture. The time vs. shrinkage curves of each sample mixture were plotted and compared each other.
Table 2. Mixture composition of high strength concrete (HSC) samples containing various fine and coarse recycled aggregate
Cement Water
Type of mixture w/c
[%] [kg] [%] [kg] [%] [kg] [%] [kg] [kg] [kg]
Fine Recyled Aggregate Concrete
Reference NSC_FNA1 100 614.51 100 1046.33 0 0 0 0 466.67 210 0.45
NSC-FRA 20 80 491.61 100 1046.33 20 122.9 0 0 466.67 210 0.45
NSC-FRA 40 60 368,71 100 1046.33 40 245.81 0 0 466.67 210 0.45
NSC-FRA 60 40 245.81 100 1046.33 60 368.71 0 0 466.67 210 0.45
NSC-FRA 80 20 122.90 100 1046.33 80 491.61 0 0 466.67 210 0.45
NSC - FRA 100 0 0 100 1046.33 100 614.51 0 0 466.67 210 0.45
NSC-CFRA 100 0 0 0 0 100 614,51 100 1046.33 466.67 210 0.45
Coarse Recycled Aggregate Concrete
Reference NSC_CNA1 100 614.51 100 1046.33 0 0 0 0 466.67 210 0.45
NSC-CNA 20 100 614.51 80 837.06 0 0 20 209.27 466.67 210 0.45
NSC-CNA 40 100 614.51 60 627.80 0 0 40 418.53 466.67 210 0.45
NSC-CNA 60 100 614.51 40 418.53 0 0 60 627.80 466.67 210 0.45
NSC-CNA 80 100 614.51 20 209.27 0 0 80 837,06 466.67 210 0.45
NSC-CNA 100 100 614.51 0 0 0 0 100 1046.33 466.67 210 0.45
NSC-CFRA 100 0 0 0 0 100 614.51 100 1046.33 466.67 210 0.45
natural
fine coarse fine coarse
Aggregate
concrete recycle
Cement Water
Type of mixture w/c
[%] [kg] [%] [kg] [%] [kg] [%] [kg] [kg] [kg]
Fine Recyled Aggregate Concrete
Reference HSC_FNA1 100 597.00 100 1108 0 0 0 0 531.72 185.13 0.35
HSC-FRA 20 80 477.60 100 1108 20 119.40 0 0 531.72 185.13 0.35
HSC-FRA 40 60 238.80 100 1108 40 245.81 0 0 531.72 185.13 0.35
HSC-FRA 60 40 245.81 100 1108 60 238.80 0 0 531.72 185.13 0.35
HSC-FRA 80 20 119.40 100 1108 80 477.60 0 0 531.72 185.13 0.35
HSC - FRA 100 0 0 100 1108 100 597.00 0 0 531.72 185.13 0.35
HSC-CFRA 100 0 0 0 0 100 597.00 100 1108 531.72 185.13 0.35
Coarse Recycled Aggregate Concrete
Reference HSC_CNA1 100 597 100 1108.00 0 0 0 0 531.72 185.13 0.35
HSC-CNA 20 100 597 80 886.40 0 0 20 221.60 531.72 185.13 0.35
HSC-CNA 40 100 597 60 664.80 0 0 40 443.20 531.72 185.13 0.35
HSC-CNA 60 100 597 40 443.20 0 0 60 664.80 531.72 185.13 0.35
HSC-CNA 80 100 597 20 221.60 0 0 80 886.40 531.72 185.13 0.35
HSC-CNA 100 100 597 0 0 0 0 100 1108.00 531.72 185.13 0.35
HSC-CFRA 100 0 0 0 0 100 597 100 1108.00 531.72 185.13 0.35
Aggregate
natural concrete recycle
fine coarse fine coarse
Table 3 Mixture composition of normal strength concrete (NSC) samples containing various roof tile recycle aggregates
Table 4 Mixture composition of high strength concrete (HSC) samples containing various roof tile recycle aggregates
Table 5 . Basic properties of natural and recyled aggregate
The ultimate shrinkage and shrinkage prediction were calculated following ACI formula [7] as shown in equation (1). The shrinkage prediction was plotted up to the period of 1000 days.
ult
t
S
t S t
35
(1) where St is shrinkage prediction at time t, t is time in days and Sult is the ultimate shrinkage of sample.3. RESULTS AND DISCUSSIONS
3.1. Samples containing recycled concrete aggregates
Figure 2 presents the recorded shrinkage on normal strength concrete containing various portion of recycled concrete aggregates as replacement for natural aggregate on normal strength concrete and Figure 3 for high strength concrete. Their long term shrinkage prediction of ACI formula can be seen on Figure 4 and Figure 5. The recorded shrinkage is proportional to the amount of recycled concrete aggregates in mixtures. The more recycled concrete aggregates in samples the higher shrinkage. It is clear that combination of 100% fine and 100% coarse recycled concrete aggregate instead of natural aggregates recorded the highest shrinkage in all groups of samples.
Sample contained fine recycled concrete aggregate shows much shrinkage than coarse one. This trend is seen on normal and high strength concrete. The discrepancy of recorded shrinkage between samples contained fine and coarse recycled concrete aggregate get larger as the percentage of recycled concrete aggregate increases. The similar trend is shown in shrinkage prediction on Figure 4 and Figure 5. .
Cement Water
Type of mixture w/c
[%] [kg] [%] [kg] [%] [kg] [kg] [kg]
Reference NSC_CNA2 100 722 100 919 0 0 409 225 0,55
NSC-CRTA 10 100 722 90 837,1 10 91,9 409 225 0,55
NSC-CRTA 25 100 722 25 689,25 25 229,75 409 225 0,55
NSC-CRTA 50 100 722 75 459,5 50 837,1 409 225 0,55
NSC - CRTA 100 100 722 0 0 100 919 409 225 0,55
Natural
fine coarse
roof tile recycle Aggregate
coarse
Cement Water Fly Ash Silica Fume
Type of mixture w/c
[%] [kg] [%] [kg] [%] [kg] [kg] [kg] [kg] [kg]
Reference HSC_CNA2 100 746.40 100 622,75 0 0 596,84 213,16 0.36 149,21 29,84
HSC-CRTA 10 100 746.40 90 560,47 10 62,27 596,84 213,16 0.36 149,21 29,84
HSC-CRTA 25 100 746.40 75 467,06 25 155,69 596,84 213,16 0.36 149,21 29,84
HSC-CRTA 50 100 746.40 50 311,37 50 311,37 596,84 213,16 0.36 149,21 29,84
HSC - CRTA 100 100 746.40 0 0 100 622,75 596,84 213,16 0.36 149,21 29,84
Aggregate
Natural roof tile recycle
fine coarse coarse
Aggregate type Gs abbration absorption fine modulus 0.15 mm 0.30 mm 0.85 mm 1.18 mm 2.36 mm 4.75 mm 9.5 mm 12.5 mm 19 mm
[%] [%] [%] [%] [%] [%] [%] [%] [%] [%] [%]
Coarse natural 2,52 43.65 2,16 5,54 0,00 0,00 0,00 0,00 0,00 5,03 47,07 94,31 100,00
Fine natural 2,48 0,80 3,10 1,60 8,12 47,61 68,66 88,71 98,76 100,00 100,00 100,00
Coarse recycled concrete 2,54 56,00 6,83 6,32 0,00 0,00 0,00 0,00 0,00 10,98 60,74 96,75 100,00 Fine recycled concrete 2,08 5,40 3,40 0,73 9,04 37,40 46,51 69,37 96,73 100,00 100,00 100,00 Coarse recyled roof tile 2,21 50,00 14,10 7,44 0,00 0,00 0,00 0,00 0,00 2,02 9,75 43,03 98,66
Particle passing
(a) (b)
Figure 2. Shrinkage on samples of normal strength concrete (NSC) with various fine (a) and coarse(b) recycled concrete aggregates as replacement for natural aggregate
Figure 3. Shrinkage on samples of high strength concrete (HSC) with various fine (a) and coarse(b) recycled concrete aggregates as replacement for natural aggregates
(a) (b)
Figure 4. Shrinkage prediction of ACI formula of normal strength concrete (NSC) with various fine (a) and coarse(b) recycled concrete aggregates as replacement for natural aggregate
0 100 200 300 400 500 600 700 800 900 1000 1100
0 10 20 30 40 50 60 70 80 90 100
Shrinkage (microstrain)
Time (d)
Reference NSC‐FNA NSC‐FRA 20 NSC‐FRA 40 NSC‐FRA 60 NSC‐FRA 80 NSC‐FRA 100 NSC‐CFRA 100
0 100 200 300 400 500 600 700 800 900 1000 1100
0 10 20 30 40 50 60 70 80 90 100
Shrinkage (microstrain)
Time (d)
Reference NSC‐CNA NSC‐CRA 20 NSC‐CRA 40 NSC‐CRA 60 NSC‐CRA 80 NSC‐CRA 100 NSC‐CFRA 100
0 100 200 300 400 500 600 700 800 900 1000 1100
0 10 20 30 40 50 60 70 80 90 100
Shrinkage (microstrain)
Time (d)
Reference HSC‐FNA HSC‐FRA 20 HSC‐FRA40 HSC‐FRA 60 HSC‐FRA 80 HSC‐FRA 100 HSC‐CFRA 100
0 100 200 300 400 500 600 700 800 900 1000 1100
0 10 20 30 40 50 60 70 80 90 100
Shrinkage (microstrain)
Time (d)
Reference HSC‐CNA HSC‐CRA 20 HSC‐CRA 40 HSC‐CRA 60 HSC‐CRA 80 HSC‐CRA 100 HSC‐CFRA 100
(a) (b)
Figure 5. Shrinkage prediction of ACI formula of high strength concrete (HSC) with various fine (a) and coarse(b) recycled concrete aggregates as replacement for natural aggregates
In this work, shrinkage on high and normal strength concrete looks nearly the same. The cement content of high strength and normal strength concrete was not much different where 532 kg and of 462 kg per cubic meter (See Table 1). This causes that the strong effect of cement on shrinkage on these samples did not exist. Therefore the recorded shrinkage of those two groups only shows a slightly different where samples contained fine recycled aggregate concrete shrunk much than coarse one.
3.2 Samples containing recycled roof tile aggregates
The shrinkage development up to 90 days of normal and high strength concrete containing various roof tile recycled aggregate is presented in Figure 6 and their long term shrinkage prediction following ACI formula
(a) (b)
Figure 6. Shrinkage on samples of normal strength concrete (NSC) (a) and high strength concrete (HSC) (b) containing various coarse roof tile recycled aggregates
Figure 7. Shrinkage of ACI formula on samples of normal strength concrete (NSC) (a) and high strength concrete (HSC) (b) containing various coarse roof tile recycled aggregates
0 250 500 750 1000 1250 1500 1750 2000 2250 2500
0 20 40 60 80 100
Shrinkage (microstrain)
Time (d)
Reference CNA2 NSC‐CRTA 10 NSC‐CRTA 25 NSC‐CRTA 50 NSC‐CRTA 100
0 250 500 750 1000 1250 1500 1750 2000 2250 2500
0 10 20 30 40 50 60 70 80 90 100
Shrinkage (microstrain)
Time (d)
Reference HSC‐CNA2 HSC‐CRTA 10 HSC‐CRTA 25 HSC‐CRTA 50 HSC‐CRTA 100
is presented on Figure 7. Similar to the previous case, the recorded shrinkage is also proportional to the amount of recycled aggregate on mixture.
Recycled aggregate tend to absorb much water in mixture. Table 5 indicates that absorption of recycled aggregate is much higher than natural aggregate. Among the three recycled aggregate, the clay roof tile material absorb most water than others. In mixtures, this aggregate causes much volume change in concrete that leads to concrete shrinkage. It seems that clay roof tile contains more pores which potentially store much water and leads to much shrinkage when water released during evaporation and cement hydration.
The effect of cement on shrinkage is obvious where high strength concrete contained cement of 596 kg per cubic meter concrete recorded much shrinkage than normal strength concrete of 409 kg. Here, the amount of cement dominates effect of shrinkage as recorded much shrinkage in high strength concrete compared to the normal strength one. This different was not clearly seen in previous group since the cement content of high strength and normal strength is 532 kg and 467 kg per cubic meter concrete respectively.
4. CONCLUSION
The following is the conclusion that can be drawn,
a. In general, recycled roof tile aggregate influences much the shrinkage on recycled aggregate concrete. The shrinkage is proportionally to the amount of recycled aggregates in concrete. In this study the recycled clay roof tile aggregate is most susceptible to shrinkage among concrete recycled aggregates since it was made from burned clay containing much pores and absorbed much water. This leads to volume change due to the water evaporation and hydration and causes shrinkage. The same reason can be based for the higher shrinkage of concrete containing fine recycle aggregate than the coarse one.
b. There is tendency that the recycled aggregates type do not indicate the different effect whether there were applied on normal and high strength. The recorded of much shrinkage in high than normal strength concrete is dominantly affected by high cement content.
5. ACKNOWLEDGEMENT
The authors acknowledge the support of provided by Directorate General of Higher Education of the Republic of Indonesia through competitive grant in 2012.
6. REFERENCES
[1] O’Mahony M. M. (1990). Recycling of Materials in Civil Engineering, Thesis. University of Oxford.
[2] German Committee for Reinf. Concrete (1996), Concrete with Recycled Aggregate. DafStb. DIN 1045
[3] Building Research Establishment (1998), Specification and Guidelines for Recycled Concrete Aggregate, BRE, UK.
[4] Japan Industrial Standard (2005), Specified Value of Recycled Aggregate. JIS ( A 5021-5024).
Tokyo.
[5] CSIRO (1998), Guide for specification of Recycled Concrete Aggregates (RCA) for Concrete Production. Ecorecycle, Victoria. Australia.
[6] Oliveira M.J.E. (2004), Recycled Aggregate Standardization in Brazil, Univ. Estadual Paulista, Brazil
[7] ACI 209R-92 (1994), Prediction of creep, shrinkage and temperature effects in concrete structure, ACI Manual of Concrete Practice, Part 1: Materials and General Properties of Concrete, Detroit, Michigan.
