1 Introduction

The advancements in construction technology demands a versatile concrete which is workable and durable as well, so that the problems like remote casting, confined and enclosed spaces, long cantilever access areas and dense reinforcement configurations can be easily worked out. Development of self compacting concrete (SCC) provides one of the best answers of these aforementioned construction related problems and offers several economic and technological benefits. Self compacting concrete is highly flowable, non-segregating concrete that can spread into place, fills the formwork, and encapsulates the reinforcement without any mechanical compaction [1]. The concept of SCC was proposed by Okamura and Ouchi [2] and the first prototype was developed in Japan in the late 1980s. The use of SCC has gained wide acceptance all over the world as it has opened up new fronts for construction of a variety of civil engineering structures. Self compacting concrete is now being used in bridge structures, box culverts, airport and highway pavements, tunnel linings, off-shore structures, dams, retaining walls, water tanks and building components such as slabs, walls in seismic regions.

The darker side of modern day infrastructure is that the extensive increase in the rate of industrialization and urbanization has made the use of concrete as the most non-sustainable material because it is consuming the maximum amount of natural resources. Construction and demolition waste (CDW) is becoming one of the major problems of modern society. The CDW can be anything ranging from broken concrete and bricks from demolition sites, excavated materials from foundations, etc. It is generated due to the end of life cycle of structures, collapse and damage to the structures in natural disasters, etc. A huge quantity of CDW is produced every year and out of 48 million tons of solid waste generated annually in India, CDW makes up 25 % of it [3]. Recycled concrete aggregates (RCA) is the major constituents in CDW and it consists of coarse recycled concrete aggregate (CRCA) and fine recycled concrete aggregates (FRCA). The production of RCA from the demolished concrete debris involves several steps like crushing, screening, washing, sorting, etc. Higher quality aggregates can also be produced out of the CDW which involves time and effort and these can be used as a substitute for the natural aggregates (NA) [4]. The potential use of the RCA in SCC not only increases the ecological value but also solves the issues of waste disposal and minimizes the liability on natural resources.

Less dense and inhomogeneous high mortar content is the most noteworthy feature of CRCA, which makes it porous and therefore, has high water absorption capacity [5–8]. Furthermore, high porosity, the angular shape of CRCA increases the void content between aggregate particles. As CRCA is less resistant to the mechanical action due to the old adhered mortar which decreases the compressive strength of concrete compared to the conventional concrete. Up to 30 % reduction in compressive strength is reported in literature [9–11]. Efforts have been made to compensate the loss in compressive strength owing to use of RCA using steel fibres in concrete [12]. Also the efflorescence formation and its control in alkali activated phosphorus slag cement has been studied [13]. The service life of a structure and its performance over time is associated with durability which includes water permeability. Permeability may be defined as the property that governs the rate of flow of liquid into the porous solid. The more permeable the concrete is, the more vulnerable it would be to attack by frost, harmful ingredients and other weathering agents as the leaching of harmful chemicals primarily depend on permeability of concrete.

The permeability of concrete can be measured in different ways such as water permeability, capillary water absorption, air permeability and oxygen permeability. As per literature, it has been observed that permeability of concrete made with CRCA is more than that of concrete made with coarse natural aggregates (CNA) and it increases with the increase in CRCA content and w/c ratio [14–16]. In most of the studies, the use of FRCA in concrete mixes is restricted because of their unsatisfactory properties [17]. There are some studies, which claim that their use is not necessarily inauspicious and that good results similar to those obtained with the use of fine natural aggregates (FNA) are feasible [18, 19]. Furthermore, up to 30 % replacement of FNA with FRCA has not been found to adversely affect the mechanical properties of concrete [18].

Though the properties of SCC made with NA have been well explored, there has been little information on the use of CRCA and FRCA in SCC. Therefore, the emphasis of this study is to explore the water permeation properties of SCC made with CRCA as replacement of CNA and FRCA as replacement of FNA. Fresh properties of the SCC mixes have been evaluated using the slump flow test, V-funnel test and the L-box. Water permeation properties of the SCC mixes were investigated conducting tests such as initial surface absorption test (ISAT), water permeability test and capillary suction test (CST). The effect of RCA replacement level on the permeation properties of SCC mixes is reported and relevant recommendations have been made for the use of CRCA and FRCA.

This paper reports part of the results of a larger investigation which is being undertaken by the authors to study the durability performance of SCC made with different replacement levels of CNA and FNA with CRCA and FRCA, respectively. As expected, there may be deterioration in the durability/strength properties on account of substitution of the natural aggregates with the recycled aggregates. The objective of the comprehensive investigation is to first, quantify this deterioration at various replacement levels of CRCA and FRCA and second, to examine the possibility of compensating this loss using supplementary cementitious materials (SCMs) such as metakaolin (MK) and silica fume (SF). Finally, it is proposed to recommend suitable combination of materials for optimum performance in terms of both durability and compressive strength. The results of the mixes made with the SCMs are proposed to be reported later. In this paper, the results of the first part, i.e. quantification of the deterioration in the strength and durability properties has been reported.

2 Experimental Details

2.1 Materials

Ordinary Portland cement (PC) of grade 43 was used. Ordinary Portland cement was partially replaced with class F fly ash (FA) by 30 % of its weight. To obtain required workability of SCC mixes, polycarboxylic ether based superplasticizer was used as chemical admixture in the range 0.8–1.2 % by weight of PC. Use of viscosity modifying agent (VMA) in the range of 0.4–0.7 % was made for stabilizing the various SCC mixes.

Locally available crushed stone coarse aggregates and river sand was used as CNA and FNA are shown in Fig. 1a, b, respectively. The RCA were obtained by the crushing of laboratory produced waste concrete blocks. The replacement percentages of CNA with CRCA (Fig. 2a) in SCC mixes were kept at 0, 50 and 100 %. For each of the mix made with 50 and 100 % of CRCA, the replacement levels of FNA with FRCA (Fig. 2b) were kept as 0, 25 and 50 %. The CRCA and FRCA were sieved and remixed to get the gradation similar toCNA and FNA within the specified grading limits of IS 383:1970 [20]. The comparative representation of the grading curves of CRCA and FRCA with CNA and FNA are shown in Fig. 3a, b, respectively.

Fig. 1
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a Coarse natural aggregates. b Fine natural aggregates

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Fig. 2
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a Coarse recycled concrete aggregates. b Fine recycled concrete aggregates

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Fig. 3
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a Grading curves of CRCA and CNA. b Grading curves of FRCA and FNA

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2.2 SCC Mix Proportions and Casting of Specimens

Self compacting concrete mixes were prepared in two series, namely series 1 and series 2. In series 1, the percentage replacement level of CRCA was kept constant at 50 % and the FRCA were substituted at the percentage levels of 0, 25 and 50 %. In series 2, the percentage replacement level of CRCA was kept constant at 100 % and again the FRCA were substituted at percentage levels 0, 25 and 50 %. In both the series, the total binder content of 615 kg/m3 and water to binder ratio of 0.45 were kept constant. The mix composition, description, dosage of SP and VMA for all the SCC mixes are shown in Table 1.

Table 1 Mix compositions of SCC mixes
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Both RCA and NA were brought to saturated surface dry (SSD) condition before being introduced into the SCC mixes. This helps to keep the water/binder ratio constant for the SCC mixes. Self compacting concrete mixes were prepared in the laboratory using a tilting drum mixer. The workability of the SCC mixes was assessed using slump flow test (Fig. 4a), V-funnel test (Fig. 4b), L-box test (Fig. 4c) conducted using equipment as given in EFNARC 2005 [21]. The workability results of all the SCC mixes along with mix designations and description are presented in Table 2. The workability parameters of all the SCC mixes measured by slump flow test, V-funnel test and L-box test have found to conform to EFNARC 2005. For the purpose of quality control and for measuring the permeation properties of the SCC mixes, 100 mm size cubes for compressive strength tests, cylinders of 100 mm diameter and 200 mm height for CST and 150 mm sized cubes for water permeability and ISAT were cast. The specimens were demoulded 24 h after casting following which these were moist cured for either 7 or 28 or 56 or 120 days. Three nominally identical companion specimens were tested for each parameter under investigation and the reported test results were the averages of the results of the three companion specimens.

Fig. 4
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a Setup for slump flow test. b Setup for V-funnel test. c Setup for L-box test

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Table 2 Workability test results of SCC mixes
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2.3 Test Methods

2.3.1 Compressive Strength Test

The compressive strength tests were carried out on the cube specimens (100 mm × 100 mm × 100 mm) under compressive testing machine at the curing age of 7, 28, 56 and 120 days as per IS 516-1959 [22].

2.3.2 Initial Surface Absorption Test

Initial surface absorption test gives the rate of flow of water into concrete per unit area at a stated interval from the start of the test and at a constant applied head. Estimation of the volume flow was obtained by measurement of the length of flow along a capillary of known dimension. The initial surface absorption of the various SCC mixes was determined using 150 mm × 150 mm × 150 mm specimens at the curing ages of 28, 56 and 120 days in accordance with the BS 1881-208:1996 [23]. The specimens were oven-dried to constant weight prior to the test and left to cool to the laboratory temperature. The contact area is defined by a plastic cell sealed onto the concrete surface and should not be less than 5000 mm2. Water was introduced into the cell via a connecting point and maintained at a head of 200 mm using a filter funnel. A second connection point to the cap leads to a horizontal capillary tube. The connection to the reservoir was closed and the absorption was measured by observing the movement of the end of the water line in the capillary tube with an affixed scale at 10 min. The Initial Surface Absorption at 10 min (ISA-10) was calculated as per the procedure laid down in the standard. The test setup used is shown in Fig. 5.

Fig. 5
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Setup for initial surface absorption test

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2.3.3 Water Permeability Test

Water permeability test was performed in accordance with BS EN 12390-8:2000 [24] using specimens of size 150 mm × 150 mm × 150 mm at the curing ages of 28, 56 and 120 days. The specimens are kept under the water pressure of 500 ± 50 kPa for 72 ± 2 h (Fig. 6). After the specified interval, the specimens were removed from the apparatus and were split in half, perpendicularly to the face on which the water pressure was applied. As soon as the split face has dried to such an extent where the water penetration front can be clearly seen, the water front on the specimen as shown in Fig. 7 was marked. The maximum depth of penetration under the test area was measured and recorded it to the nearest millimeter.

Fig. 6
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Setup for water permeability test

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Fig. 7
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Typical depth of penetration after water permeability test

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2.3.4 Capillary Suction Test

Capillary suction test was used to determine the rate of absorption of water by various SCC mixes by measuring the increase in the mass of a specimen resulting from absorption of water as a function of time when only one surface of the specimen was exposed to water. Capillary suction test was conducted in accordance with ASTM C 1585-04 [25] at the curing ages of 28, 56 and 120 days. Discs of 100 mm diameter 50 mm thickness were cut from 100 mm × 200 mm cylinders. The sides of the discs were suitably sealed. The end of the specimen, which was not in contact with water, was also sealed using a loosely attached plastic sheet. The mass of the specimen was recorded with a precision balance. As shown in Fig. 8, the specimens were placed on support devices so that the exposed end of each specimen was in touch with water. The mass of the specimens was recorded at suitable interval as laid down in the Standard. The initial rate of absorption (IRA) of water was calculated as per the procedure given in the aforesaid standard.

Fig. 8
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Setup for capillary suction test

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3 Results and Discussion

3.1 Compressive Strength Test Results

The results of the compressive strength tests conducted on different SCC mixes at various percentage replacements of CNA and FNA with CRCA and FRCA, respectively, are shown in Figs. 9 and 10. Figure 9 shows the comparison of compressive strength for the SCC control mix C0F0 with the SCC mix series 1. It was observed in general that, the SCC mixes show a decrease in the compressive strength for 50 % replacement of CNA with CRCA. For example, at 28 days of curing, a marginal decrease of the order of 4.5 % in the compressive strength was observed for SCC mix C50F0 with respect to the control mix C0F0. Furthermore, when either 25 or 50 % of FNA were replaced with FRCA (i.e. for either SCC mix C50F25 or mix C50F50), the SCC mixes show an increase in the compressive strength. This increase in compressive strength on substitution of FRCA in place of FNA may be due to the self-cementing properties of FRCA [26]. The values of compressive strength of these SCC mixes are at par with the SCC control mix. Out of SCC mixes C50F0, C50F25 and C50F50, it was observed that mix C50F25 gives the maximum compressive strength at all the curing periods of 7, 28, 56, and 120 days.

Fig. 9
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Compressive strength of SCC mixes of series 1 and control mix

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Fig. 10
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Compressive strength of SCC mixes of series 2 and control mix

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A noticeable reduction of 13.4 % in compressive strength was observed for 100 % replacement of CNA with CRCA as indicated in series II mixes in Fig. 10. This decrease in the compressive strength was much higher than that observed for 50 % replacement of CNA with CRCA after 28 days of curing. This loss in compressive strength may be due to the adhered mortar on the surface of CRCA and responsible for the degradation of the mechanical properties of CRCA itself. Furthermore, this reduction in the strength was comparatively less as compared to that reported in the case of non-SCC mixes [8]. It was also to be noticed here that the strength behaviour shown by mix C100F25 and mix C100F50 was better than mix C100F0, which also becomes evident from the Fig. 10. Among the SCC mixes C100F0, C100F25 and C100F50, the mix C100F25 gives the maximum compressive strength at all curing periods. For instance, it can be seen that mix C100F25 shows only marginal 7 % loss in strength with respect to the control mix C0R0 after 28 days curing. But the reduction in the compressive strength for the other mixes, i.e., C100F50 and C100F0 is 11 and 13.4 %, respectively.

3.2 Initial Surface Absorption Test Results

The ISA-10 test results of SCC control mix C0F0 and other SCC mixes of series 1 are shown in Fig. 11. It can be seen here that 50 % replacement of CNA with CRCA causes an increase in ISA-10 value from 0.563 ml/m2/s (mix C0F0) to 0.634 ml/m2/s (mix C50F0) i.e. an increase of 12.6 % after 28 days of curing. This increase may be due to the old mortar attached to the CRCA which makes it porous and more susceptible towards permeation of water. At 25 % replacement of FNA with FRCA (mix C50F25), decrease in ISA-10 values were observed as compared to the SCC mix C50F0 for all curing periods tested in this investigation. For example, at 28 days of curing, the ISA-10 value decreased from 0.634 ml/m2/s (mix C50F0) to 0.580 ml/m2/s (mix C50F25). On the other hand, any further increment in the replacement level of FNA with FRCA, the ISA-10 value lies in between those of SCC mixes C50F50 and C50F0. The ISA-10 values of mixes C50F0, C50F25 and C50F50 are higher than that of the control mix C0F0 which indicates that both CRCA and FRCA increase the surface absorption capacity of SCC mixes but the FRCA has less adverse effect than CRCA as far as ISA-10 is concerned.

Fig. 11
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ISA-10 of SCC mixes of series 1 and control mix

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The high porous structure of CRCA gives an obvious increase in the ISA-10 values when 100 % of CNA were replaced with CRCA, the results of which are shown in Fig. 12 (series 2 mixes). The ISA-10 value for SCC control mix C0F0 increases from 0.563 to 0.732 ml/m2/s for mix C100F0 at the curing age of 28 days resulting in 30 % increase. This increase in the ISA-10 value was much higher as compared to the 12.6 % increase for mix C50F0. This indicates that the increasing content of CRCA leads to an increase in the water flow rate within the concrete surface zone. The replacement of 25 and 50 % FNA with FRCA in the SCC mixes containing 100 % CRCA, the ISA-10 values have been found to be 20.7 and 24 % higher than that of control SCC mix (C0F0) at 28 days of curing. Thus, the addition of FRCA has been found to be beneficial in improving the ISA-10 values up to some extent. It can be seen from Fig. 12 that the negative effects of FRCA were comparatively less as compared to that of CRCA. This trend was almost similar to the one exhibited by the SCC mixes of series 1. The SCC mix containing 25 % FRCA gives the least value of ISA-10 amongst the mixes C100F0, C100F25 and C100F50 but is slightly more than that of control SCC mix (C0F0).

Fig. 12
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ISA-10 of SCC mixes of series 2 and control mix

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3.3 Water Permeability Test Results

The results of depth of water penetration of SCC mixes of series 1 are shown in Fig. 13. The replacement of 50 % CNA with CRCA (mix C50F0) results in increase in the depth of water penetration of the order of 11.2 % compared to the SCC control mix C0F0 at 28 days of curing. However, this increase in the water depth penetration was limited to 3.7 and 7.4 % for mix C50F25 and mix C50F50, respectively, at 28 days of curing period. The introduction of FRCA as partial replacement of FNA has been found to marginally improve the performance of SCC mixes. The self-cementing property of the FRCA makes the SCC mixes C50F25 and C50F50 to perform better than that of mix C50F0. The better performance of the mixes C50F25 and C50F50 than the mix C50F0 was observed at 56 and 120 days of curing as well.

Fig. 13
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Depth of water penetration of SCC mixes of series 1

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The test results of water depth penetration of SCC mixes of series 2 are presented in Fig. 14. The results show that incorporation of CRCA as 100 % replacement of CNA in SCC mix C100F0 increases the water depth penetration by 30 % compared to control SCC mix C0F0. This significant increase in the water penetration depth may be due to the adverse effect of residual mortar adhered on the surface of CRCA which increases the capillary zone within the concrete matrix. On the other hand, the water penetration depth decreases with the incorporation of FRCA as replacement of FNA. As a consequence, the percentage increase in the water depth penetration was limited only up to 18 and 22 % for mix C100F25 and mix C100F50, respectively, after 28 days of curing. Furthermore, the percentage increase in the water depth penetration for SCC mixes belonging to series 2 was more than that of series 1 which was due to more CRCA content in series 2.

Fig. 14
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Depth of water penetration of SCC mixes of series 2

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3.4 Capillary Suction Test Results

It has been observed from the capillary suction results interpreted in the form of IRA that replacement of CNA with CRCA has been found to increase the IRA compared to control SCC mix. However, the addition of FRCA as partial replacement of FNA has been found to compensate this up to some extent. As shown in Fig. 15, for series 1, the IRA of mix C50F0 increases up to 10 % as compared to the control mix C0F0 after 28 days of curing. The addition of FRCA as partial replacement of FNA at 25 and 50 % has been found to yield results of IRA comparable to that of control SCC mix at 28 days of curing. Similar trends have been obtained at other curing ages tested in this investigation.

Fig. 15
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IRA of SCC mixes of series 1

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Figure 16 shows the IRA results of the SCC mixes of series 2, wherein the effect of CRCA seems more prominent at 100 % replacement of CNA with CRCA. An increase of 40 % in the IRA value was observed at the age of 28 days for SCC mix C100F0 as compared to the control mix C0F0. This increase was limited to 24.5 % after 120 days of curing period which shows that the deteriorating effect of CRCA becomes less pronounced with increase in the curing period. At 28 days of curing period, the IRA value decreases from 0.0254 mm/√s (C100F0) to 0.0215 mm/√s mix (C100F25) for mix C100F25 showing an approximate decrease of 15.3 %. A similar decrease of 11.3 % was observed for SCC mix C100F50 when compared to the SCC mix C100F0.

Fig. 16
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IRA of SCC mixes of series 2

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4 Conclusion

The results of the water permeation of SCC mixes containing CRCA and FRCA have been reported. The compressive strength tests were also conducted on various SCC mixes. From the results of this investigation, following conclusions can be drawn:

  1. 1.

    In comparison to the control SCC made with CNA, the 28 day compressive strength decreased by approximately 13 % when all the CNA were replaced with the CRCA. However, this reduction in the compressive strength was marginal when 50 % of the CNA were substituted by 50 % CRCA. The replacement of FNA with FRCA has been found to marginally increase the compressive strength of SCC mixes made with CRCA.

  2. 2.

    Initial surface absorption of the SCC mixes measured in terms of ISA-10 has been found to increase with the increase in the replacement of CNA with CRCA. An increase of the order of 12.6 and 30 % was observed with the replacement of 50 and 100 % CNA with CRCA, respectively, at 28 days of curing. The replacement of FNA with FRCA at 25 % has been found to be most effective in arresting the ISA-10 values.

  3. 3.

    Water penetration depths increased by 11.2 and 30 % with the replacement of 50 and 100 % CNA with CRCA, respectively, at 28 days of curing. The substitution of FNA with FRCA has less pronounced effect in increasing the water penetration depth as compared to the CRCA.

  4. 4.

    The IRA results illustrate similar trends as in case of other permeation properties. At 100 % replacement of CNA with CRCA, an increase of the order of 40 % in the IRA was observed at 28 days of curing. The IRA values of SCC mixes with 25 % of FRCA content have been found to be closest to the control mix as compare to other SCC mixes.