RESEARCH ON RECYCLED CERAMIC WASTE IN THE COMPOSITION OF ECOLOGICAL MORTARS

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1 RESEARCH ON RECYCLED CERAMIC WASTE IN THE COMPOSITION OF ECOLOGICAL MORTARS C. Aciu Technical University of Cluj-Napoca, Romania - claudiu.aciu@ccm.utcluj.ro Received: / Accepted: / Revised: / Available online: KEY WORDS: Ecological Mortars, Recycling, Aggregate, Brick Waste, Sandstone Waste ABSTRACT: The problem of the rational management of material resources is a priority on the European agenda. The concerns of specialists in the construction industry are increasingly focused on the manufacture of ecological materials for the protection and improvement of the environment, while preserving natural resources. This paper approached the study of the manufacture of ecological mortars through ceramic waste recycling. For this, in the studied recipes, 33% and 50% of sand, respectively, was replaced with ceramic waste. The analyses performed demonstrated the possibilities to reduce the use of non-renewable aggregates and recover the embodied energy in ceramic waste, which has beneficial effects on the environment. The two types of mortars, both with brick waste and sandstone waste, have physico-mechanical characteristics that are superior to classical standard mortar even with 50% of the sand volume replaced. 1. INTRODUCTION The problem of the rational management of material resources is a priority on the European agenda, from the perspective of their conservation. In the construction industry, a modality to preserve natural resources is the adequate management of waste from construction and demolition. This contributes to significant energy savings, with no or low costs, contributing at the same time to the reduction of environmental impact. This study is in line with the concerns about the effective use of natural resources and the effective management of waste from construction and demolition. The study addresses the elaboration of new recipes for the manufacture of ecological mortars that contain ceramic waste as an aggregate, which were studied in terms of mechanical strengths and physical properties that demonstrate the qualities of the manufactured materials. The determinations were performed in two types of mortars, one in which 33% and 50% of sand, respectively, was replaced with brick waste, and one in which sand was replaced in the same proportions with sandstone waste. 2. MATERIALS AND METHODS 2.1 General considerations The aim of the research is justified by the fact that more than 25 billion tons of concrete are produced every year worldwide. Aggregates represent up to 80% of the concrete volume. Natural aggregates used for the production of concrete and mortar will soon be insufficient to satisfy all the needs in the construction industry. Consequently, the construction industry is in search of alternatives, in order to meet the requirements for the manufacture of concrete (Kockal, 2013). On the other hand, waste resulting from demolition represents up to 40% of all waste from dumps. Its

2 transportation to the dumps is expensive and its disposal results in the degradation of the environment. Table 1 presents the most common types of waste resulting from construction and demolition, as well as their percentages (after materials/waste-minimisation). Waste description Waste quantity - % of total weight Paper/cardboard 1 Wood/timber 10 Hard plastic 1 Ferrous 2 Soil rubble 36 Concrete 16 Ceramic materials 16 Plasterboard 2 Other/unknown 16 Total 100 Table 1. Percentage weight of typical building waste materials (after Waste from construction and demolition including cement, mortar and bricks are disposed of in dumps or is crushed and recycled. This happens despite the fact that bricks can resist for centuries. The production of new bricks is energy and resource consuming; consequently, the reuse of bricks has a major environmental impact by reducing CO 2 emissions and waste. Each reused brick allows saving 0.5 kg CO 2 emissions compared to the production of new bricks (after Overburned and damaged bricks that result as waste from brick factories can be crushed in order to obtain raw aggregates for concrete. In countries such as Bangladesh, where there is a lack of natural aggregates, even full bricks can be crushed in order to be turned into aggregates. Crushed bricks are widely used in Bangladesh as aggregates for concrete used both for structural and non-structural elements (Aciu and Cobirzan, 2011). The ceramic industry of tiling materials (sandstone, wall tiles), regardless of the improvements in the production processes, inevitably generates high amounts of waste every year (Medina et al., 2012). The reuse of waste in the composition of concrete or mortar might solve the problem of waste in the ceramic industry and, at the same time, it might reduce the use of non-renewable resources (aggregates), avoiding environmental problems related to their disposal (Pacheco-Torgal and Jalali, 2010). In this context, the attention of researchers (Boke, Akkurt et al., 2006; Gonçalves, Tavares et al., 2009; O'Farrell, Sabir and Wild, 2006; Senthamarai, Devadas Manoharan and Gobinath, 2011; Cobîrzan and Balog, 2013) has focused on the study of the influence of the use of ceramic waste for mortars, mainly analyzing the resistance and durability of mortars Experimental program Considering the above, the research aimed to use brick or sandstone waste aggregates in various proportions for the mortars included in the study. The materials used for the experimental part were Portland cement 42.5, sand, water, crushed bricks or sandstone. The aggregates used were sand and a mixture of sand and brick waste or sand and sandstone waste (Figure 1) with a 0-2 mm granularity. For the standard mortar (recipe I), a binder-sand ratio of 1:3 was chosen, which fitted in the category of medium mortars, with a recipe composed of 600 g Portland cement 42.5, 1800 g sand, and 300 cm 3 water. 8

3 Figure 1. Sandstone waste For the test ceramic material samples, 33% and 50%, respectively, of the sand in the recipe of standard mortar was replaced with brick waste (recipes II and III) or sandstone waste (recipes IV and V), the volume amount of sand in the standard recipe being maintained. For this, the density of sand and its substitutes was determined: - density of sand: ρ sand =1395 kg/m 3 ; - density of brick waste: ρ brick = 1046,5 kg/m 3 ; - density of sandstone waste: ρ sandstone = 1128 kg/m 3. The study was carried out in five mortar recipes whose composition is shown in Table 2. Physico - mechanical determinations were performed after 28 days in test samples cast and stored during this period according to standards. Cement 42.5 Aggregate Recipe Water Sand (0-2) Replaced sand Waste [g] [cm 3 ] [g] [g] [g] [%] I Standard mortar II Brick waste 33% III Brick waste 50% IV Sandstone waste 33% V Sandstone waste 50% Table 2. Mortar recipes Percent-age of replaced sand 3. RESULTS The following physico-mechanical characteristics were determined in the test samples: the apparent density of the set mortar, bending, compressive strengths, adhesion to the support layer, and water absorption by capillarity. The results obtained following physico-mechanical determinations are synthesized in Table 3. 9

4 Recipe Apparent density Adhesion to the support layer Bending strength Compressive strength [kg/m 3 ] [N/mm 2 ] [N/mm 2 ] [N/mm 2 ] Water absorption by capillarity [Kg/ (m 2 *min 0.5 )] I II III IV V Table 3. Technical characteristics obtained 4. DISCUSSIONS Table 3 shows that the apparent density of both brick waste and sandstone waste mortar samples decreases with the increase of the replaced sand amount, but this decrease is insignificant, and the category of heavy mortars is maintained. The greatest decrease of 4% was obtained in the case of recipe III, in which an amount of 50% sand was replaced with brick waste. Table 3 shows that compared to the standard test sample, the adhesion to the support layer of ceramic waste mortars increases, with the highest values obtained in the case of the replacement of sand with sandstone waste (Figure 2). the strengths of standard mortar, depending on the amount of replaced sand. The bending strength increases in the case of brick waste mortars with the increase in the amount of replaced sand. This is not found in the case of sandstone waste mortars, where with the increase of the replaced sand to 50%, there is a decrease of the bending strength compared to recipe IV, which however remains superior to the standard recipe. Regarding compressive strength, the same phenomenon as in the case of bending strength is noted. From the point of view of the values obtained for compressive strength, all mortars are categorized in class M30 of masonry mortars and class CS IV of plaster mortars. Compared to the conclusions drawn by Bektas, Wang, and Ceylan, 2009, who support that the replacement of 10% and 20%, respectively, of the aggregate with brick does not have a negative influence on compressive strengths, the research performed shows that on the contrary, when the replaced sand percentage increases to 33%, there is a 6% increase of compressive strength and in the case of a 50% sand replacement, compressive strength increases by approximately 8%. Figure 2. Adhesion to the support layer Following the determinations, a significant increase of mechanical strengths was found compared to The determination of water absorption by capillarity evidences the following: 10

5 - the water absorption by capillarity coefficient of standard mortar is 0.24 Kg/(m 2 *min 0.5 ), which places it in class W1; - in the case of recipes II and III, with the increase of the sand percentage replaced by brick waste, a decrease of the water absorption by capillarity coefficient occurs compared to standard mortar, i.e and 0.13 Kg/(m 2 *min 0.5 ), both mortars being included in class W2; - in the case of recipe IV, with the increase of the sand percentage replaced by sandstone waste, there is the same phenomenon of decrease in the value of the water absorption by capillarity coefficient to the value of 0.1 Kg/(m 2 *min 0.5 ), which places it in class W2; - in the case of recipe V, with the increase of the sand percentage replaced by sandstone waste, there is an increase in the value of the water absorption by capillarity coefficient to 0.23 Kg/(m 2 *min 0.5 ), a value close to that of standard mortar, which places it in class W1. From the point of view of appearance, as shown in Figure 3, brick waste mortars have a pleasant characteristic color, given by the waste used, which recommends them as decorative plaster mortars. Type text single-spaced, with one blank line between paragraphs and following headings. Start paragraphs flush with left margin. 5. CONCLUSIONS Ceramic waste recycling in the building materials industry is an effective solution with beneficial consequences both for the construction industry and the protection and improvement of the environment, preserving at the same time natural resources. The research demonstrates the very good opportunity provided by the use of ceramic waste for the manufacture of mortars. The technology for the production of ceramic waste mortar is the classical one, with the only difference in composition. Both mortar with 50% of sand replaced by brick waste and mortar with sandstone waste show an improvement of mechanical strengths, adhesion to the support layer and water absorption by capillarity. In the case of brick waste mortars, the increase in the proportion of the replaced sand results in an increase in the bending and compressive strengths and a decrease in the water absorption by capillarity. Mortar with up to 33% of sand replaced by sandstone waste presents a significant increase of mechanical strengths and a decrease of water absorption by capillarity, with a decrease of values in the case of mortar with up to 50% of sand replaced by sandstone waste, values that however remain higher than the values of standard mortar. Figure 3. Test samples using the five mortar recipes From the point of view of the fire reaction, it can be considered that the prepared mortars do not contain organic materials, thus being categorized as fire reaction class A1. Regarding compressive strength values, all mortars are included in class M30 of masonry mortars and class CS IV of plaster mortars. In terms of water absorption by capillarity, mortars based on recipes II, III and IV are categorized in class W2, while recipe V belongs to class W1, like standard mortar. 11

6 From the point of view of the fire reaction, the obtained mortars are included in the fire reaction class A1. Regarding appearance, brick waste mortars have a pleasant color, which recommends them as decorative plaster mortars. By comparing the results obtained for the two types of ceramic waste mortars, it can be concluded that the best results in the case of sand replaced with brick waste are obtained for the proportion of 50%, and in the case of sand replaced with sandstone waste, the best results are obtained for the proportion of 33%. The results obtained in this study open the way for new types of recipes for plaster mortars, with the reduction of the proportion of Portland cement, which has a high embodied energy, or with the total replacement of sand by brick waste, without affecting the characteristics of classical plaster mortars. 6. REFERENCES Aciu, C. and Cobirzan Nicoleta, Materiale de construcţii sustenabile (Sustainable building materials), U.T. Press, Cluj-Napoca. Bektas, F., Wang, K. and Ceylan, H. (2009), Effects of crushed clay brick aggregate on mortar durability, Construction and Building Materials, Vol. 23, No. 5, pp Böke, H., Akkurt, S., Ipekoğlu, B. and Uğurlu, E., Characteristics of brick used as aggregate in historic brick-lime mortars and plasters, Cement and Concrete Research, vol. 36, No. 6, pp , org/ /j.cemconres Cobirzan Nicoleta and Balog Anca-Andreea, Analysis of rendering mortars decay due to salt attack, Journal Of Applied Engineering Sciences, vol. 3(16), issue 2, pp , noradea.ro/jaes/latest_issue/jaes_decembrie _2013/JAES_VOL3(16)_ISSUE2_2013/FULL_TE XT/COBIRZAN.pdf. Gonçalves, J.P., Tavares, L.M., Toledo Filho, R.D. and Fairbairn, E.M.R., Performance evaluation of cement mortars modified with metakaolin or ground brick, Construction and Building Materials, vol. 23, No. 5, pp , Kockal, N.U., 2013, Role of construction industry wastes on the properties of mortars, The Online Journal of Science and Technology, Vol. 3, No. 4, pp Medina, C., Sánchez de Rojas, M.I. and Frías, M., Reuse of sanitary ceramic wastes as coarse aggregate in eco-efficient concretes, Cement and Concrete Composites, vol. 34, No. 1, pp , O Farrell, M., Sabir, B.B. and Wild, S., Strength and chemical resistance of mortars containing brick manufacturing clays subjected to different treatments, Cement and Concrete Composites, vol. 28, No. 9, pp , Pacheco-Torgal, F. and Jalali, S., Reusing ceramic wastes in concrete, Construction and Building Materials, vol. 24, No. 5, pp , Senthamarai, R.M., Devadas Manoharan, P. and Gobinath, D., Concrete made from ceramic industry waste: Durability properties, Construction and Building Materials, vol. 25, No. 5, pp , *** viewed at *** viewed at