Manuscript MT/2008/023591
Recycled red-clay ceramic construction and demolition waste for mortars production J. Silva1, J. de Brito 2 and R. Veiga 3 2
DECivil-IST, Technical University of Lisbon, Av. Rovisco Pais, 1049-001, Lisbon, Portugal
Abstract: Recycled aggregates may make an important contribution towards decreasing the adverse consequences of the production and dumping of construction and demolition waste on the environment. The results of experimental research work carried out at Lisbon’s Instituto Superior Técnico (IST) and Laboratório Nacional de Engenharia Civil (LNEC) are presented in this article. Normalized laboratory tests to assess the performance of standard mortars were used to demonstrate the technical feasibility of recycling the waste produced by the ceramics industry and from the demolition of red clay bricks or tiles to produce mortars with less / no consumption of natural aggregates. Results are very promising up to a replacement ratio of sand with ceramic waste of at least 20%. The paper presents useful data for the ceramics industry, builders and mortar manufacturing companies in terms of minimizing the impact of Construction and Demolition Waste (CDW) and using eco-efficient materials.
Keywords: Recycled aggregates, Mortars, Ceramic bricks, Sustainable materials.
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Master in Construction, IST - Technical University of Lisbon, Av. Rovisco Pais, 1049-001, Lisbon, Portugal, e-mail:
[email protected] 2 Full Professor, Head of ICIST, Department of Civil Engineering and Architecture, Section of Construction, IST - Technical University of Lisbon, Av. Rovisco Pais, 1049-001, Lisbon, Portugal, email:
[email protected], Phone: (351) 218419709; Fax: (351) 21 8497650), Corresponding author 3 Senior Researcher, Department of Buildings, LNEC - National Laboratory of Civil Engineering, Av. do Brasil 101, 1700-066, Lisbon, Portugal, e-mail:
[email protected]
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CE Database Subject Headings: Mortars, recycling, waste utilization, bricks, sustainable development, renewable resources.
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INTRODUCTION The technical, environmental and economic advantages of recycling construction and demolition waste (CDW) as aggregates for the production of mortars are: use of the waste at the building site (eliminating transportation costs and energy consumption); saving raw materials by replacing conventional materials with waste; lessening pollution caused by waste accumulation; preservation of the natural reserves of raw materials (Nehdi & Khan 2004). The addition of red-clay brick powder may also have some drawbacks, however. These include its natural porosity, excessive water absorption due to the dehydration it is subjected to during its production (mostly from baking), and the fact that clays abundant in this material may lead to increased shrinkage of the mortars made with it (Lee 2005). Other practical problems, such as removing the mortar from old bricks before crushing them may also arise. The Instituto Superior Técnico (IST), the main engineering university in Lisbon, Portugal, has been working on a wide range of experimental projects in the field of construction and demolition waste recycling. One outcome of this work is a Master’s dissertation in construction, entitled “Incorporation of red-clay waste in cementitious mortars” (Silva 2006), some of whose main experimental results are analyzed in this article. Recycled aggregates for mortars may be obtained from waste from the ceramics industry and from pre-selected masonry waste (bricks and tiles), as in the present study, or from other masonry materials, demolished concrete or mortar elements. The resulting aggregate to be recycled may be stone, ceramic (the case under study), a mixture of both, or a mix of cement-based and ceramic elements with debris such as wood, plastics, glass, etc. The recycled aggregates themselves may correspond only to the coarse portion, the fine portion (the case under study), or both. Finally, the replacement of natural aggregates by recycled aggregates can be total or partial.
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The performance of the mortar (or concrete) made with recycled aggregates also has to be ascertained. For this purpose several properties must be analyzed, depending on the intended use of the mortar. In this study the objective was to produce plastering mortars, hence the relevant properties considered were: in the fresh state, workability and water retention; after hardening, flexural and compressive strength, modulus of elasticity, shrinkage, adhesion to the substrate, water vapor permeability, water absorption and resistance to climatic actions. An experimental research project in which some fractions of natural aggregates were replaced by recycled ceramic aggregates is reported here. This paper presents a procedure for reusing waste produced by the ceramics industry or by demolishing red-clay brick buildings, i.e. construction and demolition waste (CDW) such as solid, hollow or vaulted bricks that have been selected and crushed. A study incorporating red-clay waste in cementitious mortars intended to be used as plasters is presented, aiming at complete recycling while simultaneously maintaining an acceptable performance quality of the final product.
LITERATURE REVIEW Not many studies have been published on the use of fine recycled aggregates from CDW in the production of mortars, unlike similar research on concrete production. Miranda & Selmo (1999) state that this incorporation frequently leads to cracking and slumping problems, possibly due to lack of a rational control of the mortars’ composition, with a serious fluctuation in parameters such as water absorption, aggregate size distribution and fines ratio. Hendricks & Pietersen (1998) conclude that the greater water demand in the mortars with recycled aggregates (MRA), a trend confirmed by Miranda & Selmo (1999), is due to greater angularity of the crushed material. However, as various researchers have concluded in
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connection with concrete with recycled aggregates (CRA), Desmyter et al. (1999) stress the need to distinguish between the total and effective water/ cement ratio in MRA, in which the second results from the first by discounting the excess water absorbed by the recycled aggregates due to their higher porosity. Again like CRA, Knights (1998) concluded that the workability of MRA exhibits a clear diminishing trend compared with conventional mortars, especially for significant replacement ratios of natural with recycled aggregates. Both Miranda & Selmo (1999) and Levy & Helene (1997) report greater water retention in MRA with ceramic aggregates than with MRA with aggregates from mortars and concrete. In terms of bulk density, MRA present lower values than conventional mortars due to the greater porosity of the recycled aggregates. According to Miranda & Selmo (1999), MRA with ceramic aggregates present values lower than those of MRA with aggregates from concrete but higher than those of MRA with aggregates from mortars. Levy & Helene (1997), on the other hand, position MRA with ceramic values at the top of MRA in terms of bulk density. Kikuchi et al. (1998) explain the increased shrinkage in MRA compared with conventional mortars by the higher water demand. Mellman et al. (1999) add the following parameters as being influential in the shrinkage of MRA: aggregate bulk density; porosity of the adhering mortar, and level of saturation. Kikuchi et al. (1998) further report a 40% increase in the shrinkage of MRA when natural aggregates are totally replaced by ceramic aggregates, compared with a reference mortar without recycled aggregates, but also a lower shrinkage of MRA with this type of ceramic aggregates at the initial stages. Dillman (1998) reports that the compressive strength of MRA is negatively affected by the quality of the recycled aggregate, the replacement ratio, the cement content, and the
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water/cement ratio. Amorim et al. (2003) and Levy & Helene (1997), the latter also testing flexural strength, agree on the higher levels of this parameter achieved by MRA with ceramic aggregates compared with MRA with recycled aggregates from other CDW materials. Corinaldesi et al. (2000) corroborate this trend with emphasis on the 28 to 70-day period. According to Mellman et al. (1999) the modulus of elasticity in MRA is lower than for conventional mortars, especially if the recycled aggregates are ceramic (up to 30% lower). Studies on the durability of MRA are very rare; Miranda & Selmo (1999) describe a growing tendency to cracking; O’Farrell et al. (1999) report a positive influence of adding ceramic aggregates in terms of sulphate performance, and other preliminary studies dwell on the positive influence of metacaulin and burnt clay and wet curing on durability. This review shows that studies on MRA’s performance are scarce, especially in terms of durability. The experimental research presented below aims at clarifying some of the points on which there is no consensus.
SEQUENCE OF TESTING The advantages and drawbacks of this application were tested in the laboratory by analyzing the performance of mortars containing different replacement ratios of natural sand with red-clay waste. The powder was obtained by crushing defective bricks produced in a ceramics factory in order to simulate the use of CDW from unknown origin. The performance of modified mortars relative to a conventional cement and sand mortar was determined. The experimental analysis was divided into two stages. In stage one the main characteristics of a wide range of mortars with different ratios of replacement of sand by brick waste were briefly studied; the second stage used those results to study the mortars and replacement ratios that showed most promising performances in greater detail.
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MATERIALS The characteristics of the materials used are summarized in Tables 1 and 2. The mortars which incorporated brick waste instead of sand presented the same grading curve as the conventional mortar (with sand only) and so the influence of this parameter on the results obtained could be eliminated. This replacement was as follows: •
0% replacement - volumetric proportion 1:4 (cement: siliceous sand aggregate) III(0) - reference mortar;
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20% replacement - 1:4 (cement: siliceous sand and brick waste aggregate) - III(20);
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50% replacement - 1:4 - III(50);
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100% replacement - 1:4 - III(100).
METHODS, RESULTS AND DISCUSSION First stage Tests performed at this stage aimed at selecting the mortars that complied with the requirements for plastering mortars.
Consistency of fresh mortar This test defined the amount of water needed by each mortar to obtain an adequate plasticity for application on site. The test was performed by the flow table method, according to European Norm EN 1015-3 (1999). The norm indicates that the adequate consistency for rendering mortars is 175 mm ± 10 mm (6.89 in ± 0.39 in), which was taken as the target in terms of water quantity for each mortar. The results are presented in Table 3. The results obtained confirmed the conclusions of several authors - Hendricks & Petersen (1998), Desmyter et al. (1999), Fumoto & Yamada (2004), and Miranda & Selmo 7
(1999) - showing that the larger the incorporation of brick waste the more mixing water needed.
Bulk density of fresh mortar This test was performed by weighing a known volume of fresh mortar, according to European Norm EN 1015-6 (1998). The results are presented in Figure 1. Their variability (as measured by the standard deviation) was always small, even though it was higher for the mortars with recycled aggregates. Bulk density substantially decreased, almost linearly, as the primary aggregate (sand) was replaced with brick waste. This was because the bulk density of the brick waste is generally lower than that of sand. The value of the bulk density of the various mortars was divided by the value of the reference mortar and the results compared with those of Evangelista & de Brito (2005) and of Rosa (2002). Figure 2 clearly shows a decrease of the bulk density as the conventional aggregates are replaced with recycled, in every instance. It can be concluded that the addition of ceramic recycled aggregates caused a more significant decrease of bulk density than the addition of other types of recycled aggregates. In terms of concrete this trend was more influential on the bulk density than the difference between coarse and fine aggregates. In every case there is an approximately linear relationship between the replacement ratio and bulk density of fresh mortar. These results showed that bulk densities decreased as conventional aggregates were replaced with recycled ones. Furthermore, the degree of this shift greatly depended on the type of recycled aggregate used, particularly on its density.
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Dry bulk density of hardened mortar This test was performed in accordance with European Norm EN 1015-10 (1999). It consisted of measuring the mass of mortar prisms 40 mm x 40 mm x 160 mm (1.57 in x 1.57 in x 6.30 in) and dividing it by their volume. A sample of 3 specimens previously subjected to a curing period of 28 days was used for each mortar. Results are presented in Figure 3. Even though variability was higher for the mortars with recycled aggregates such variability was always small. These results show that the hardened mortars’ dry bulk density decreases as sand was replaced with brick waste. As for fresh mortar, the reason is the lower density of the brick recycled aggregates compared with that of sand.
Flexural and compressive strength of hardened mortar This test was performed according to European Norm EN 1015-11 (1999) by applying an increasing force in the mid span of a prism of mortar measuring 40 mm x 40 mm x 160 mm (1.57 in x 1.57 in x 6.30 in). Three specimens of each type of mortar that had previously been subjected to a 28 day curing period were used. Results are presented in Figure 4. Their variability is normal for mortars and shows no visible trend in terms of the addition of recycled aggregates. Flexural and compressive strength both increased for replacement ratios of sand with brick waste up to around 20 to 40%, respectively. For higher replacement ratios, both parameters decreased. This decrease agrees with the available literature, such as Dillman (1998), who reports that the addition of recycled aggregate can negatively influence compressive strength. The initial increase, on the other hand, may be due to the combination of some degree of pozzolanic effect (Akman 1992; Malolepszy & Pytel 2000) of these ceramic fines with a filler
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effect (Kasami 2001), even though the amount of ceramic fines added is only slightly higher than the one in the replaced sand. In fact, ceramic waste may have some pozzolanic reactivity, almost certainly in the case of fines, but also possibly for ceramic aggregates over 0.150 mm (5.9 x 10-3 in). It is well known that Roman mortars, for example, contained rather coarse aggregates with pozzolanic reactions (Velosa & Veiga 2003). It is also possible that other chemical (besides pozzolanicity) and physical (adsorption, shape, roughness) reactions between the materials may contribute to this increase of strength. For flexural strength, for example, a nailing effect of the cement paste to the recycled aggregates (due to their greater porosity and angularity) is a plausible explanation. When they replaced natural sand with fine recycled concrete aggregates to produce concrete Evangelista & de Brito (2005) obtained similar results, i.e. a positive evolution for low replacement ratios and afterwards a negative trend. A possible explanation is the hydration of cement from the recycled concrete fines that had previously been anhydrated (when the original concrete was produced), which of course does not apply in the present case. It is finally concluded that mortar III(100) showed poor characteristics, exhibiting lower strength than the reference mortar III(0). The value of the strength (flexural and compressive) of the various mortars was divided by the respective value of the reference mortar and the results obtained were compared with those of Evangelista & de Brito (2005) and of Rosa (2002). Figure 5 shows that both Silva (2006) and Rosa (2002) derived a decreasing trend of the flexural strength for certain replacement ratios (30 and 0%, respectively). But Evangelista & de Brito obtained strength results very close to each other, both for low and high replacement ratios. As for compressive strength, the results in Figure 6 were generally similar to those
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obtained for flexural strength. The slight differences concerned the replacement ratio threshold after which the strength started to decrease (40 to 50% for Silva) and the fact that Rosa’s results showed a more significant decreasing tendency.
Water absorption due to capillary action of hardened mortar This test was performed according to European norm EN 1015-18 (2002), by the partial immersion in water of the cut face of prisms originally measuring 40 mm x 40 mm x 160 mm (1.57 in x 1.57 in x 6.30 in), and periodical weighing. Three specimens (semi-prisms) of each kind of mortar that had previously been subjected to a curing period of 28 days and laterally waterproofed were used. Results are presented in Figure 7. Even though variability was higher for the mortars with recycled aggregates, it was always small. From these results it can be concluded that replacement of sand with brick waste caused a decrease of water absorption by capillary action in the mortars studied up to values of 20 to 30% replacement ratio. For higher values an approximately linear increasing trend was observed. The improved performance for water absorption for low replacement ratios may be due to the combination of some degree of pozzolanic effect (Toledo 2001) of these ceramic fines with a filler effect, as seen in the research programs of Nagataki et al. (2000) and Tamura et al. (2001). A nailing effect of the cement paste to the aggregates (due to their greater porosity and angularity) is another plausible explanation, since the pores that would otherwise contain water are occupied by cement paste. As for the flexural and compressive strength and with the same possible explanation, Evangelista & de Brito (2005) obtained similar results when they replaced sand with fine recycled concrete aggregates to produce new concrete, i.e. a positive evolution for low replacement ratios and a negative evolution afterwards.
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The decay in terms of quality of performance after a certain threshold (20 to 30% replacement) seems to be due to an excessive quantity of recycled ceramic aggregates, which absorb too much water and thus overcompensate the combination of the pozzolanic and filler effects that prevails until then. Nonetheless, it can be concluded that up to a 70% replacement ratio a more positive (less absorption) performance was obtained for modified mortars than for the reference mortar - III(0). The value of the water absorption coefficient of the various mortars was divided by the value for the reference mortar and the results compared with those of Evangelista & de Brito (2005). Figure 8 shows, for fine recycled concrete aggregates for concrete production, that from a 30% replacement ratio upwards the increase in the water absorption coefficient due to capillary action was overly high. However, it can be said that the global trend was similar for mortar and concrete, i.e. the absorption decreases until around 20% replacement ratio and then starts increasing.
Susceptibility to cracking The expedient test performed allowed sufficient qualitative data to be collected to detect that mortars may be liable to cracking. It consists of applying a 2 cm (0.79 in) mortar layer to a ceramic brick and observing whether cracking occurs within a pre-determined period. None of the mortars under test showed signs of cracking after 5 months observation. Even though the area of application was small (just the larger face of a brick), if previous experience (Soeiro & Sá et al. 2004) is taken into account it can be concluded that none of the modified mortar tested showed serious problems of potential cracking.
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Dimensional instability (shrinkage) The test was performed according to European Project-Norm prEN 1015-13 (1993) by measuring periodically the length variation of prisms measuring 40 mm x 40 mm x 160 mm (1.57 in x 1.57 in x 6.30 in). Three specimens (prisms) of each type of mortar were tested immediately after demoulding. Results are presented in Figure 9. Even though variability was higher for the mortars with recycled aggregates, it was always small, except for mortar III(20), and there was no obvious reason for this. It was concluded that the mortars with incorporation of recycled brick waste shrank substantially more than the reference mortar that contained no recycled aggregates, III(0). These results agree with various literature references, notably Kikuchi et al. (1998). However, there was no substantial difference between the 3 mortars with recycled incorporation (20, 50 and 100%), with a relative increase compared with the reference mortar of 33 to 43% at 80 days. The value of the dimensional variation of the various mortars after a pre-determined period was divided by the respective value of the reference mortar and the results obtained compared with those of Evangelista & de Brito (2005). Figure 10 shows a trend for shrinkage to increase relative to the reference mortar when recycled aggregates replace conventional ones. Contrary to the mortars, concrete with a replacement ratio of fine recycled concrete aggregates below 30% does not show a clear tendency for shrinkage to either increase or decrease. For that ratio there is a clear increase - less pronounced for mortar with recycled ceramics - as the replacement increases.
Selection of mortars for the second stage Following the analysis of the results obtained for mortars III(29, III(50) and III(100)
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in the first stage, the mortar that most satisfactorily fulfilled the objectives was selected. Mortar III(50), even though not maximizing the flexural strength (achieved by III(20)), still presented a higher value than the reference mortar. As for compressive strength, III(50) was very near the maximum value for all mortars. In terms of water absorption due to capillary action, an “optimal” value occurred around a 25% replacement ratio but the value for 50% was still lower than the reference mortar (implying better performance from this point of view). The shrinkage of the mortars with replacement of sand with waste did not vary much. Therefore, and considering that one of the main goals of this experimental analysis is recycling itself, the mortar chosen to be analyzed in further detail was III(50). Mortar III(20) was left out since a replacement of 50% of all the sand, more recycling-prone, apparently does not jeopardize the performance of the mortar as a plaster in comparison with the reference mortar. Mortar III(100) was also left out since total replacement yielded worse characteristics than the reference mortar in every test, and some of the results were unacceptable for a plastering mortar.
Second stage This stage consisted of analyzing other important characteristics of the mortar chosen after the first stage, III(50), to obtain more specific data about its performance.
Water retentivity of fresh mortar This test was performed according to European Project-Norm prEN 1015-8 (1998), by using filter paper to produce suction on the fresh mortar surface and measuring the retained water. Three (fresh) specimens of each mortar were used. Results are presented in Table 4 (before ageing cycles).
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It is concluded that in terms of water retentivity the best performance (greatest value) was achieved by the modified mortar III(50). This agrees with the results presented by Miranda & Selmo (1999) and Levy & Helene (1997). Water retentivity is a very positive feature since it avoids excessive loss of water due to suction of the background and improves hydration of the cement within the mortar since more water is retained.
Adhesive strength of hardened mortar This test was performed according to European Norm EN 1015-12 (2000) by measuring the force needed to separate the mortar from the background. Three specimens of each mortar were applied to a brick’s face and cured for 28 days before being subjected to a pulloff test. Results are presented in Table 5 (after ageing cycles). The best performance in terms of this characteristic was also obtained for the modified mortar, probably for the same reasons as for the mechanical characteristics: a combination of pozzolanic effect of the ceramic fines plus a filler effect. Furthermore, the nailing effect due to pores being filled with cement paste instead of water may be very efficient in this case.
Modulus of elasticity of hardened mortar This test was performed according to French Norm NF B10-511F (1975), based on the resonance frequency method. Three prismatic specimens of each mortar measuring 40 mm x 40 mm x 160 mm were cured for 28 days. Results are presented in Table 4. The modulus of elasticity values obtained were substantially lower in the mortar with partial replacement of sand with brick waste. After both 2 and 5 months mortar III(50) showed a drop of around 40% in comparison with the reference mortar, III(0). The variability of these results was negligible.
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These results agree with the conclusions drawn by Mellman et al. (1999) and Mansur et al. (1999) in relation to the modulus of elasticity being lower for recycled aggregates than for natural aggregates. These two references both report that the difference is more conspicuous if the recycled aggregates derive from masonry, leading to a 10 to 30% decrease in the corresponding mortar’s modulus of elasticity. The reduction of the modulus of elasticity, if not excessive, is a favorable characteristic for plastering mortars since it allows a better accommodation of stresses and reduces the tendency to cracking. The results of the same mortar type obtained at 2 and 5 months were very similar, showing that this property does not seem to be sensitive to the mortar’s age after a certain period. The value of the modulus of elasticity of the various mortars was divided by the respective value of the reference mortar and the results obtained compared with those of Evangelista & de Brito (2005). Figure 11 shows that there was a clear trend in both studies for a proportional decrease of the modulus of elasticity when conventional aggregates were replaced with recycled ones, a trend that is more conspicuous for recycled ceramics than for concrete aggregate, due to the latter’s higher stiffness.
Water vapor permeability of hardened mortar This test was performed in accordance with European Norm EN 1015-19 (1998), based on producing a difference of pressure between the two faces of a specimen and measuring the water vapor flow through it. Three specimens of each mortar were used. They consisted of mortar disks 20 mm thick which had previously been cured for 60 days. Results are presented in Table 4. The water vapor permeability of the mortar with incorporation of recycled brick ag-
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gregates was significantly better than that of the reference mortar, thus improving its performance quality from this point of view, since this characteristic provides a more efficient drying of the water within the plaster, and it favors both the evaporation of the water infiltrated in the walls and the exit of the water vapor produced inside the buildings.
Compatibility with substrates (ageing) This test was performed based on European Norm EN 1015-21 (2002). Three specimens of each mortar were used. They were applied to the face of 2 bricks, joined face-to-face and cured for 3 weeks. The test consisted of subjecting the specimens to climatic cycles, whose effects on water permeability and adhesive strength were assessed. A second test was also performed, as seen in Table 4, before the artificial ageing of the specimens. Results are presented in Table 5. The (liquid and under pressure) water permeability of mortar III(50) was around 7% lower than that of reference mortar III(0). Since a mortar should not be very permeable to liquid water it can be said that mortar III(50) performs better. The adhesive strength of mortar III(50) was around 18% higher than for the reference mortar. This surpassed the expectations created by Silva et al. (1999) who reported that the incorporation of recycled aggregates, which give mortars a more fluid consistency, also reduces their adhesive strength. The adhesive strength increased with ageing (see Tables 4 and 5), which was possibly related to the evolution of hydration during the moistening / drying cycles and the consequent growth of etringite crystals or other constituents that form within the pores and improve the bond.
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CONCLUSIONS The tests performed allowed conclusions to be drawn on the feasibility of replacing fine natural aggregates (sand) with powder obtained from crushed red clay waste from a brick factory. The comparison of a reference mortar without recycled aggregates and mortars with replacement ratios of 20%, 50% and 100%, using exactly the same composition and aggregate size distribution, allowed the following conclusions. Based on the values of the various characteristics tested at the first stage (whose main purpose was to calculate the maximum replacement ratio that would not jeopardize the mortar’s performance), it was concluded that globally only mortar III(100) (total replacement of sand with brick waste) performed worse than the reference mortar (without recycled aggregates). Mortar III(20) (20% replacement of sand with brick waste) generally performed better than the reference mortar. Emphasis is given to flexural and compressive strength (around 12% higher) and the water permeability coefficient under capillary action (approximately 16% lower). Mortar III(50) (50% replacement of sand with brick waste) also generally presented positive characteristics and better performances than the reference mortar. The following properties stand out: flexural, compressive and adhesive strength (8, 13 and 18% higher, respectively); water permeability coefficient under capillary action (9% lower); water retentivity (9% higher): modulus of elasticity (40% lower); water vapor permeability coefficient (57% higher); water permeability under pressure after ageing (6% lower), and adhesive strength after ageing (18% higher). The only characteristic that presented a negative trend was dimensional instability, for which a shrinkage value around 39% higher was obtained.
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The results clearly indicate the advantages of incorporating ceramic waste in rendering mortars, with the twin benefits of enabling their recycling and improving the plaster’s performance.
ACKNOWLEDGEMENTS The experimental work presented in this paper was performed in LNEC, the Portuguese National Laboratory of Civil Engineering in Lisbon, as part of a Master’s thesis prepared within the Master’s in Construction course of the Department of Civil Engineering and Architecture of the Instituto Superior Técnico (IST), Lisbon. The authors also gratefully acknowledge the support of the ICIST Research Institute of IST, Technical University of Lisbon and of FCT (Foundation for Science and Technology).
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University of Lisbon, Lisbon, Portugal. Silva, J. (2006) “Incorporation of red-brick waste in cementitious mortars” (in Portuguese), Masters in Construction Dissertation, Instituto Superior Técnico, Technical University of Lisbon, Lisbon, Portugal. Silva, V.; Libório, J.; Silva, C. (1999) “Coating mortars using burnt clay pozzolan” (in Portuguese), III Brazilian Symposium of Mortars Technology (SBTA), Vitória (Brazil), pp. 433-442. Soeiro e Sá, A.; Veiga, R.; Branco, F. (2004) “Incorporation of marble sawing mud in cement and sand mortars” (in Portuguese), A Pedra, No. 89, Lisbon, Portugal, pp. 52-59. Tamura, H.; Nishio, A.; Ohashi, J.; lmamoto, K. (2001) “High quality recycled aggregate concrete (HiRAC) processed by decompression and rapid release”, SP-200, ACI (American Concrete Institute), Farmington Hills, MI (USA), pp. 491-502. Toledo Filho, R.; Americano, B.; Fairbairn, E.; Rolim, J.; Filho, J. (2001) “Potential of crushed waste burnt clay brick as a partial replacement for portland cement”, SP-202, ACI (American Concrete Institute), Farmington Hills, MI (USA), pp. 147-160. Velosa, A.; Veiga, R. (2003) “Performance of lime mortars with brick powder; influence of the baking temperature of the bricks” (in Portuguese), 3rd Encore Meeting on Conservation and Rehabilitation of Buildings, National Laboratory of Civil Engineering (LNEC), Lisbon, pp. 539-545.
STANDARDS USED IN THE EXPERIMENTAL WORK EN 1015-3, European Standard (1999) “Methods of test for mortar for masonry - Part 3: Determination of consistence of fresh mortar (by flow table)”, European Committee for Standardization (CEN), Brussels, February. EN 1015-6, European Standard (1998) “Methods of test for mortar for masonry - Part 6: De-
22
termination of bulk density of fresh mortar”, European Committee for Standardization (CEN), Brussels, October. prEN 1015-8, draft European Standard (1998) “Methods of test for mortar for masonry - Part 8: Determination of water retentivity of fresh mortar”, European Committee for Standardization (CEN), Brussels, October. EN 1015-10, European Standard (1999) “Methods of test for mortar for masonry - Part 10: Determination of dry bulk density of hardened mortar”, European Committee for Standardization (CEN), Brussels, August. EN 1015-11, European Standard (1999) “Methods of test for mortar for masonry - Part 11: Determination of flexural and compressive strength of hardened mortar”, English European Committee for Standardization (CEN), Brussels, August. EN 1015-12, European Standard (2000) “Methods of test for mortar for masonry - Part 12: Determination of adhesive strength of hardened rendering and plastering mortars on substrates”, European Committee for Standardization (CEN), Brussels, February. prEN 1015-13, draft European Standard (1993) “Methods of test for mortar for masonry Part 13: Determination of dimensional stability of hardened mortars”, European Committee for Standardization (CEN), Brussels, February. EN 1015-18, European Standard (2002) “Methods of test for mortar for masonry - Part 18: Determination of water absorption coefficient due to capillary action of hardened mortar”, European Committee for Standardization (CEN), Brussels, December. EN 1015-19, European Standard (1998) “Methods of test for mortar for masonry - Part 19: Determination of water vapour permeability of hardened rendering and plastering mortars”, European Committee for Standardization (CEN), Brussels, September. EN 1015-21, European Standard (2002) “Methods of test for mortar for masonry - Part 19: Determination of the compatibility of one-coat rendering mortars with substrates”, Eu-
23
ropean Committee for Standardization (CEN), Brussels, March. NF B 10-511, Norme Française Homologué (1975) “Mesure du module d´élasticité dynamique”, Association Française de Normalisation (AFNOR), Paris, Avril.
24
TABLE CAPTIONS
Table 1 - Particle size distribution of aggregates (average of 3 samples) Table 2 - Density of mortar constituents (average of 3 samples) Table 3 - Mixing water needed in order to achieve the target workability and respective results of the consistency test (average of 3 samples) Table 4 - Test results performed before and after ageing cycles (average of 3 specimens)
25
Table 1 - Particle size distribution of aggregates (average of 3 samples) Mesh size (mm) Retained particles (%) Sand Ceramic particles 0.063
0.17
7.19
0.125
0.16
2.87
0.150
2.46
15.64
0.250
28.45
16.65
0.500
44.72
26.04
1.000
16.88
12.76
2.000
4.38
7.10
4.000
1.15
3.21
5.600
0.89
3.21
8.000
0.62
5.33
26
Table 2 - Density of mortar constituents (average of 3 samples) Density Units (kg/dm3) (lb/in3)
Cement Sand Ceramic particles 0.994
1.143
1.035
0.0359 0.0413
0.0374
27
Table 3 - Mixing water needed in order to achieve the target workability and respective results of the consistency test (average of 3 samples)
Mortar
III(0) III(20) III(50) III(100)
(ml/dm3) 190.0 200.00 Mixing
233.33
300.00
0
water
Consissis-
(fl oz/in3) 0.105
0.111
0.129
0.166
(mm)
172,5
170.0
172.0
169.0
(in)
6.79
6.69
6.77
6.65
tence
28
Table 4 - Test results performed before and after ageing cycles (average of 3 specimens) III(0)
III(50)
72.24
78.39
(S.D. = 1.84)
(S.D.=2.68)
0.35; 50.8
0.40; 58.0
(S.D. = 0.068; 9.87)
(S.D. = 0.112; 16.26)
14.560; 2.112
8.731; 1.266
(S.D. = 0.13; 0.019)
(S.D. = 0.27; 0.039)
13.898; 2.016
8.326; 1.208
Water vapor permeability (ng/(m.s.Pa(oz/(ft.s.psi)) x 10-9)
23.10; 1.712
36.19; 2.683
Thickness of the diffusion air layer equivalent to 20 mm of
0.16; 0.52
0.10; 0.33
(S.D. = 0.00; 0.00)
(S.D. = 0.01; 0.03)
620; 20.96
580; 19.61
(S.D. = 16.0; 0.54)
(S.D. = 10.0; 0.34)
0.70; 101.5
0.80; 116.0
(S.D. = 0.11; 0.016)
(S.D. = 0.09, 0.013)
Mortar Before ageing cycles Water retentivity (%)
Adhesive strength (MPa; psi)
Modulus of elasticity (GPa;
(after 2 months)
psi)
(after 5 months)
mortar (m; ft)
After ageing cycles Liquid water permeability under pressure - water absorbed (ml; fl oz)
Adhesive strength (MPa; psi)
S.D. - Standard deviation
29
FIGURES CAPTIONS
Figure 1 - Bulk density of fresh mortar for the different replacement ratios studied (average of 3 specimens) Figure 2 - Comparison of non-dimensional results obtained for bulk density of fresh mortar with those of Evangelista & de Brito (2005) and Rosa (2002) Figure 3 - Dry bulk density of hardened mortar for the different replacement ratios studied (average of 3 specimens) Figure 4 - Flexural and compressive strength of hardened mortar for the different replacement ratios studied (average of 3 specimens). (S.D. flexural (MPa; ksi): 0%-0.22; 0.032; 20%-0.07; 0.010; 50%0.19; 0.028; 100%-0.19; 0.028); (S.D. compressive (MPa, ksi): 0%-1.09; 0.158; 20%-0.69; 0.100; 50%-1.13; 0.164; 100%-0.52; 0.075) Figure 5 - Comparison of non-dimensional results obtained for flexural strength of hardened mortar with those of Evangelista & de Brito (2005) and Rosa (2002) Figure 6 - Comparison of non-dimensional results obtained for compressive strength of hardened mortar with those of Evangelista & de Brito (2005) and Rosa (2002)
Figure 7 - Water absorption due to capillary action of hardened mortar for the different replacement ratios studied (average of 3 specimens). (S.D. (kg/(m2.min0.5); lb/(ft2.min0.5): 0%0.034; 0.007; 20%-0.062; 0.013; 50%-0.065; 0.013; 100%-0.038; 0.008) Figure 8 - Comparison of non-dimensional results obtained for the water absorption coefficient at 24 h of hardened mortar with those of Evangelista & de Brito (2005) Figure 9 - Time versus dimensional variation (average of 3 specimens). (S.D. (%): 0%-0.0013; 20%0.0081; 50%-0.0031; 100%-0.0034) Figure 10 - Comparison of results obtained for dimensional variation of hardened mortar with those of Evangelista & de Brito (2005) Figure 11 - Comparison of non-dimensional results obtained for the modulus of elasticity of hardened mortar with those of Evangelista & de Brito (2005)
30
Bulk density of fresh mortar 2100.0
131.1 0
2050.0
127.9
2000.0
124.8 20
121.7 3
1900.0
118.6
50
1850.0
115.5
1800.0
112.3 100
1750.0 1700.0 0
20
40
60
80
100
lb/ft
kg/m
3
1950.0
109.2 106.1 120
% of replacement Figure 1 - Bulk density of fresh mortar for the different replacement ratios studied (average of 3 specimens) (S.D. (kg/m3; lb/ft3): 0%-2.3; 0.14; 20%-20.1; 1.25; 50%-28.3; 1.77; 100%-9.4; 0.59)
31
Bulk density (BD) of fresh composite
(Modified composite BD) / (Convencional composite BD)
1.05 Silva (recycled ceramics)
1 Evangelista (fine recycled concrete in concrete)
0.95
Rosa (coarse recycled ceramics in concrete)
0.9 0.85 0.8 0
50
Replacement ratio (%)
100
Figure 2 - Comparison of non-dimensional results obtained for bulk density of fresh mortar with those of Evangelista & de Brito (2005) and Rosa (2002)
32
Dry bulk density of hardened mortar 1900.0
118.6
1850.0
115.4
0
1800.0
112.3
1750.0
109.2 3
1700.0
106.1
50
1650.0
103.0
1600.0
99.8
1550.0
100
1500.0 0
20
40
60
80
100
lb/ft
kg/m
3
20
96.7 93.6 120
% of replacement Figure 3 - Dry bulk density of hardened mortar for the different replacement ratios studied (average of 3 specimens) (S.D. (kg/m3; lb/ft3): 0%-1.8; 0.11; 20%-23.8; 1.49; 50%-30.9; 1.93; 100%-3.4; 0.21)
33
10.00 9.00 8.00 7.00 6.00 5.00 4.00 3.00 2.00 1.00 0.00
1.450 1.305 1.160 1.015 0.870 0.725 0.580 0.435 0.290 0.145 0.000
50
20 0
100
20
0
0
20
50
40
60
100
80
100
ksi
MPa
Flexural and compressive strength of hardened mortar
120
% of replacement Flexural strength
Compressive strength
Figure 4 - Flexural and compressive strength of hardened mortar for the different replacement ratios studied (average of 3 specimens) (S.D. flexural (MPa; ksi): 0%-0.22; 0.032; 20%-0.07; 0.010; 50%-0.19; 0.028; 100%-0.19; 0.028); (S.D. compressive (MPa, ksi): 0%-1.09; 0.158; 20%-0.69; 0.100; 50%-1.13; 0.164; 100%-0.52; 0.075)
34
(Modified composite FS) / (Conventional composite FS)
Flexural strength (FS) of hardened composite 1.2 1
Silva (recycled ceramics)
0.8
Evangelista (fine recycled concrete in concrete) Rosa (coarse recycled ceramics in concrete)
0.6 0.4 0.2 0 0
50
100
Replacement ratio (%) Figure 5 - Comparison of non-dimensional results obtained for flexural strength of hardened mortar with those of Evangelista & de Brito (2005) and Rosa (2002)
35
(Modified composite CS) / (Conventional composite CS)
Compressive strength (CS) of hardened composite 1.4
Silva (recycled ceramics)
1.2 1
Evangelista (fine recycled concrete in concrete) Evangelista (fine recycled concrete in mortar) Rosa (coarse recycled ceramics in concrete)
0.8 0.6 0.4 0.2 0 0
50
100
Replacement ratio (%) Figure 6 - Comparison of non-dimensional results obtained for compressive strength of hardened mortar with those of Evangelista & de Brito (2005) and Rosa (2002)
36
Water absorption coefficient due to capillary action 0.205
0.70
0
0.164 50 0.144
20
0.60
0.123
0.50
0.103
0.40
0.082 120
0
20
40
60
80
100
0,5
0,5 2
kg/(m .min )
0.80
0.185
2
100
0.90
lb/(ft .min )
1.00
% of replacement
Figure 7 - Water absorption due to capillary action of hardened mortar for the different replacement ratios studied (average of 3 specimens)
(S.D. (kg/(m2.min0.5); lb/(ft2.min0.5): 0%-0.034; 0.007; 20%-0.062; 0.013; 50%-0.065; 0.013; 100%-0.038; 0.008)
37
Water absorption (WA) due to capillary action (Modified composite WA coefficient) / (Conventional composite WA coefficient)
2.6 2.4 2.2 2
Silva (Recycled ceramics)
1.8 1.6
Evangelista (fine recycled concrete in concrete)
1.4 1.2 1 0.8 0
50
100
Replacement ratio (%) Figure 8 - Comparison of non-dimensional results obtained for the water absorption coefficient at 24 h of hardened mortar with those of Evangelista & de Brito (2005)
38
Dimensional variation (%)
Dimensional instability (shrinkage)
-0.005
3
6
7
10
14
21
28
40
56
70
80
-0.015
III(20)
-0.025
III(50)
-0.035
III(100)
-0.045
III(0)
-0.055 -0.065
Time (days) Figure 9 - Time versus dimensional variation (average of 3 specimens) (S.D. (%): 0%-0.0013; 20%-0.0081; 50%-0.0031; 100%-0.0034)
39
(Modified composite DV) / (Conventional composite DV)
Dimensional variation (DV) 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1 0.9 0.8
Silva (recycled ceramics) after 80 days Evangelista (fine recycled concrete in concrete) after 90 days
0
50
100
Replacement ratio (%) Figure 10 - Comparison of results obtained for dimensional variation of hardened mortar with those of Evangelista & de Brito (2005)
40
(Modified composite ME) / (Conventional composite ME)
Modulus of elasticity (ME) of hardened composite 1.2
Silva (recycled ceramics) after 2 months
1
Silva (recycled ceramics) after 5 months
0.8 0.6
Evangelista (fine recycled concrete in concrete) after 1 month
0.4 0.2 0 0
50
100
Replacement ratio (%) Figure 11 - Comparison of non-dimensional results obtained for the modulus of elasticity of hardened mortar with those of Evangelista & de Brito (2005)
41
