Performance of Concrete Slabs Containing Recycled Industrial Timber Aggregate (RITA) as Aggregate Replacement

Transcription

1 UNIMAS STEM International Engineering Conference 214(EnCon 214), "Advances in Process Engineering Green Energy and STEM Education", 8 th -9 th December 214, Kuching Sarawak Performance of Concrete Slabs Containing Recycled Industrial Timber (RITA) as Replacement Abstract Currently, the trend of using recycled construction materials is increasing globally to achieve sustainable development. The utilization of industrial waste in producing concrete with compliments of technology advancement is mostly carried out. This study examines the use of recycled industrial timber aggregate (RITA) as aggregate replacement in producing concrete slab. There are two types of concrete slabs specimens namely RCS1 (Fiber Glass-Reinforced) and RCS2 (Polyvinyl Chloride Pipe-Reinforced) were experimented. The strength development of RITA aggregate concrete slab were be determined. The serviceability limit state of the specimens was also studied. Superplastisizer was added to achieve the concrete workability. The test results were recorded at the age of 7, 14 and 28 days respectively. The result showed that higher percentage of RITA aggregate use tends to reduce the concrete strength. The replacement of 3% RITA aggregate reinforced with polyvinyl chloride pipe and E-Class glass fiber performs low strength development compared with normal concrete slabs. The deflection of the concrete slabs performs a linear relationship with the load applied. The preliminary findings demonstrated that 3% RITA aggregate has good potentials as partial aggregate replacement in concrete slab construction combined with E-Class glass fiber or polyvinyl chloride pipe(pvc). Keywords: recycled industrial timber aggregate (RITA), strength development, serviceability limit state, deflection, E-class glass fiber, polyvinyl chloride pipe(pvc). I. INTRODUCTION The most valuable property of concrete is commonly referred to the strength [1]. The strength of concrete is almost invariably a vital element of structural design and is specified for compliance purpose. Strength of the concrete was tested because it gives a direct indication of its capacity to resist loads in structural applications. Besides that, the correlations can be developed relating concrete strength to certain other concrete properties that involve much more complicated tests and it relatively easy to conduct [2]. The two principal reasons for determining the strength of a concrete are to measure the quality or uniformity of the concrete produced and provide a measure of load-carrying capacity in structures [3]. Among concrete strength properties, compressive strength of concrete is one of the most important technical properties. This is because in most structural applications, concrete is employed primarily to resist compressive stresses [4]. In structural concrete design, the characteristics strength of concrete refers to the 28 days compressive strength [], [6], [7]. The compressive strength of concrete or mortar is usually determined by submitting a specimen of constant cross section to a uniformly distributed increasing axial compression load in a suitable testing machine until failure occurs [4]. Compressive test is the most common test carried out because concrete has low tensile strength compared to its compressive strength, thus it is used primarily in compressive mode; (2) it is assumed that most of the important properties of concrete are directly related to the compressive strength; (3) the structural design codes are mainly based on the compressive strength of concrete; and (4) the test is easy and economical[8]. The shape of the specimens for compressive strength testing can be cubes [9] or cylinders [1]. ** 1. Chai Teck Jung, Lecturer, Department of Civil Engineering, Politeknik Kuching Sarawak, P. O. Box 394, KM 22, Jalan Matang, 93 Kuching, Sarawak, Malaysia ( tjchai@poliku.edu.my). 2. Mohd Agus Adib Eskandar, Department of Civil Engineering Heads, Politeknik Kuching Sarawak, P. O. Box 394, KM 22, Jalan Matang, 93 Kuching, Sarawak, Malaysia. ( agus@poliku.edu.my). 3. Tang Hing Kwong, Programme Head, Department of Civil Engineering, Politeknik Kuching Sarawak, P. O. Box 394, KM 22, Jalan Matang, 93 Kuching, Sarawak, Malaysia ( hktang@poliku.edu.my). 4. Lee Yee Loon, Professor, Senior Lecturer, Faculty of Civil and Environmental Engineering, Universiti Tun Hussein Onn Malaysia, 864 Parit Raja, Batu Pahat, Johor, Malaysia ( ahloon@uthm.edu.my).. Mohd Warid Hussin, Professor, Research Fellow, Construction Research Centre, Faculty of Civil Engineering, Universiti Teknologi Malaysia, UTM Skudai, 8131 Johor, Malaysia ( warid@utm.my) 6. Koh Heng Boon, Senior Lecturer, Faculty of Civil and Environmental Engineering, Universiti Tun Hussein Onn Malaysia, 864 Parit Raja, Johor, Malaysia (koh@uthm.edu.my)

2 Flexural strength or modulus of rapture (MOR) is a mechanical parameter for brittle material's ability to resist deformation under load. The transverse bending test is most frequently employed, in which a beam specimen in rectangular cross section is bent until fracture using a two point flexural test technique [11]. The flexural strength represents the ultimate strength of materials in bending is taken corresponding to the ultimate moment by the elastic relationship in terms of stress [12]. According to T. H. G. Megson, (27), the materials ultimate strength in bending is defined by the modulus of rapture (MOR). This is taken to be the maximum direct stress in bending (σ) which corresponding to the ultimate moment (M u ) and is assumed to be related to ultimate moment by elastic relationship in equation ( 1 ) [12]. Deflection for reinforced concrete slab refers to serviceability limit state and it is sufficient to check span-effective depth ratio, a procedure which is entirely satisfactory for most loading conditions in singular sections. Deflection take place at stage 1 where the floor slabs are being positioned at between 7 and 28 days after casting typically[13]. The deflection measurement is smaller than calculated value up to 2 percent because of unreliable Young s modulus and diversity in material possessions due to humidity vacillations and temperature during casting [14]. According to T. H. G. Megson (27), shear deflection are small compared with bending deflection generally. 2. MATERIALS AND METHODS 2.1 Materials The raw materials for the preparation of concrete mix are ordinary Portland cement (OPC), natural fine aggregate, coarse and fine recycled industrial timber aggregate (RITA) aggregate and water. The RITA aggregate used for this study was collected from Linshanhao Plywood Sarawak Sdn Bhd (A Subsidiary Company of WTK Holdings Berhad) located at Demak Laut Industrial Park, Jalan Bako, Kuching. The RITA aggregate was determined for the classification as lightweight aggregate according to BS 3797[1]. The RITA aggregate was sieved manually using mm sieve to separate it as fine and 1 mm sieve for coarse aggregate before it was used to replace the natural aggregate in this study. 2.2 Concrete Mix Proportions The concrete grade 3 was designed with the slump 1 mm and above to achieve self compacting concrete purpose. There are two series of concrete mix namely C, C3, C6 and C1 (Series 1 Concrete Mix ID) and CC, CC3, CC6 and CC1 (Series 2 Concrete Mix ID) for the experimental work in the present study. The concrete mix series 1 was used for glass fiber-reinforced concrete slab namely RCS1(), RCS1(3), RCS1(6) and RCS1(1). For concrete mix series 2, it was used for PVC-reinforced concrete hollow core slab namely RCS2(), RCS2(3), RCS2(6) and RCS2(1). The concrete mix consists of four types of mix proportion with the replacement of natural fine and coarse aggregate with fine and coarse RITA aggregate ranging from %, 3%, 6% and 1%. Series 1 concrete mix consist of Class-E Glass fiber with the amount of 1kg glass fiber /4 kg cement was added to identify the effect to the RITA aggregate concrete strength. The compressive strength, flexural strength and deflection are determined by the same concrete mix. For series 2 concrete mixes, 8 numbers of 2 mm diameter PVC pipe was used as RITA aggregate concrete hollow slab. Supracoat SP 8 was added to both series of concrete mixes to achieve the concrete workability. The mix proportions for the present study are tabulated in Table 1 and Table 2. Table 1: Mix Proportions for Series 1 Concrete Mix Mix ID Mix Proportion Replacement of Recycled Water Supracoat SP8 (ml) Industrial Timber Ash (RITA) Natural Fine Natural Water/ Ratio ClassE- Glass Fiber (kg) Fine C C C C Table 2: Mix Proportions for Series 2 Concrete Mix Mix ID Mix Proportion Replacement of Recycled Water Supracoat SP8 (ml) Industrial Timber Ash (RITA) Natural Fine Natural Water/ Ratio Fine CC CC CC CC Specimens Casting and Curing There are 36 numbers of cubes specimens (1mm x 1mm) and slab specimens (2mm x 6mm x mm) were prepared respectively for series 1 concrete mix with E-Class glass fiber. The same numbers of specimens were prepared for ( 1 )

3 series 2 concrete mixes without E-glass fiber content. The total of 8 numbers of 2 mm diameters PVC pipe were used for each hollow core slabs specimens casting. All the specimens were de-mould after 24 hours and cured in water subjected to temperature varied between 27 c - 32 c. 2.4 Determination of Strength, Mid-Span Deflection, Concrete Density and Workability The specimens will be tested for compressive strength and flexural strength development, slump, concrete density and midspan deflection versus load during the age 7, 14 and 28 days. The compressive strength and flexural strength tests were conducted using cubes specimens and slab specimens accordance to BS 1881[9],[12] procedures. The average values of three specimens for each mix condition were recorded during 7, 14 and 28 days. The concrete slump will be determined accordance to BS 1881[16]. The concrete density and mid-span deflection versus load were be determined accordance to BS 3797[1] and BS 811: Part 1[] and BS EN 1992, Eurocode 2 [6]. 3. RESUTLS AND DISCUSSIONS The chemical composition of RITA aggregate was determined by using X-Ray Fluorescence (XRF) method at University of Tun Hussein Onn Malaysia (UTHM). The results are shown in Table 3. The mechanical properties of Class-E Glass Fiber and PVC Pipe are shown in Table 4 and Table respectively. Table 3 : Chemical composition of recycled timber aggregate(rita) Name Formula Concentration Carbon dioxide CO 2.1% Silicon dioxide SiO % Calcium oxide CaO 18.4% Barium oxide BaO 14.4% Aluminium oxide Al 2O % Sodium oxide Na 2O.88% Iron oxide Fe 2O 3.7% Magnesium oxide MgO 4.78% Potassium oxide K 2O 4.38% Sulfur Trioxide SO % Nitrogen Dioxide P 2O 1.23% Manganese oxide MnO.62% Titanium oxide TiO 2.7% Strontium oxide SrO.34% Vanadium V < LLD Table 4 : The mechanical properties of E-class glass fiber Parameters Values Tensile Strength (MPa) 3-36 Modulus Elastic (GPa) 74-7 Expansion (%) 4.8 Density 26 Perimeter (µm) 8-12 Table : The mechanical properties of 2 mm diameter polyvinyl chloride (PVC) Pipe Parameters Values Test Method Tensile Strength (MPa) 1.37 ASTM D638 Tensile Modulus of Elasticity (MPa) ASTM D638 Flexural Strength (MPa) ASTM D79 Flexural Modulus (MPa) ASTM D79 Compressive Strength (MPa) 66.2 ASTM D Properties of Raw Materials The bulk densities of fine and coarse RITA aggregate, natural fine and coarse aggregate and ordinary Portland cement (OPC) are summarized in Table 6. Table 6: Bulk Densities of Raw Materials Materials Loose Bulk Density Compacted Bulk Density Ordinary Portland (OPC) Natural Fine Sand Natural Fine Recycled Industrial Timber (RITA) Recycled Industrial Timber (RITA) The results indicated that fine and coarse RITA aggregate have fulfilled the requirement as lightweight aggregate according to BS The density of the lightweight aggregate must not more than 12 kg/m 3 for fine aggregate and 1 kg/m 3 for coarse aggregate [16]. 3.2 Concrete Density and Slump The dry densities and slump test of the specimens are shown in Table 7. The replacement of natural aggregate with RITA aggregate had reduced the density of concrete. A weight reduction of 2% for cube specimens and 28%(Glass fiber-

4 reinforced) to 32%(PVC pipe-reinforced) for slab specimens at the age of 28 days was achieved when 3% to 1% of natural fine and coarse aggregate was replaced by fine and coarse RITA aggregate. The reduction in weight of the RITA aggregate concrete compared to the control specimen is due to the higher porosity of RITA aggregate with a lower bulk density compared to natural aggregate. The weight reduction of RITA aggregate concrete is significant especially for 1% recycled RITA aggregate concrete with a reduction up to 2 % for cubes and 28 % to 32% for slabs compared to natural aggregate concrete. The slump for concrete mix was achieved between the ranges of 1 mm to 17 mm. The results showed that the high volumes of RITA aggregate replacement results in higher water consumption in concrete mixture as compared to normal aggregate concrete. Mix ID Table 7: Concrete Density and Slump Dry density Slump (mm) 7 Days 14 Days 28 Days Remark C C Series 1 Concrete Mix : C Cube Specimens C CC CC Series 2 Concrete Mix : CC Cube Specimens CC RCS1() Series 1 Concrete Mix : RCS1(3) Glass Fiber Reinforced Concrete RCS1(6) Slab Specimens RCS1(1) RCS2() Polyvinyl Chloride Pipe RCS2(3) RCS2(6) RCS3(1) Reinforced Concrete Hollow Core Slab Specimens 3.4 Compressive Strength The compressive strength developments for series 1 and series 2 concrete mix are shown in Figure 1 and Figure 2 respectively. The results showed that all RITA aggregate concrete (C3, C6 and C1) for series 1 concrete mix and RITA aggregate concrete (CC3, CC6 and CC1) for series 2 concrete mix achieved lower compressive strength compared to the natural aggregate concrete (C and CC). Strength (MPa) Compressive Strength vs Age Age (Days) C C3 C6 C1 Figure 1 : Compressive strength for series 1 concrete mix cube specimens Strength (MPa) Compressive Strength vs Age Age (Days) Figure 2 : Compressive strength for series 2 concrete mix cube specimens CC CC3 CC6 CC1 Referring to Figure 1 and Figure 2, the replacement of 3% RITA aggregate achieved 32 MPa at the age of 28 days. According to J. Newman and S. C. Ban (23), the compressive strength development excess 2 MPa can be used for

5 structural purposes and according to BS811, the specify value is 1 MPa. The others series 1 concrete mix (C6 and C1) and series 2 concrete mix (CC6 and CC1) gain a lower compressive strength which achieved 16 MPa and 12 MPa respectively. The strength development for C3 (Figure 1) and CC3 (Figure 2) is 8.6% lower than the control specimen strength. This is maybe due to the mechanical properties of the RITA aggregate even admixture (Supracoat SP 8) was added. 3. Flexural Strength The flexural strength developments for the glass fiber-reinforced concrete slab specimens and PVC pipe-reinforced concrete hollow core slab specimens are shown in Figure 3 and Figure 4. Referring to Figure 3, the results showed that RITA aggregate concrete slab with glass fiber RCS1(3) produced higher flexural strength which is 1 MPa lower compared with control specimen RCS1(). The flexural strength for 3% RITA aggregate with glass fiber is 4. MPa while the control specimen is. MPa at the age of 28 days. The result also showed that RCS1(6) and RCS1(1) produced lower flexural strength which is 3 MPa and 2 MPa respectively. This result showed that the concrete mixes with E-class glass fiber and Supracoat SP 8 can develope the higher strength even though the aggregate is not from the natural resources. The mechanical properties of E-class glass fiber also indicate that it behavior is more benefit to flexural strength development. Referring to Figure 4, the results showed that RITA aggregate pvc-reinforced concrete hollow core slab RCS2(3) produced. MPa compared with RCS2() 6.4 MPa. For RCS2(6) and RCS2(1), the flexural strength is lower which is 3.8 MPa and 3 MPa respectively. The flexural strength development graph showed that pvc-reinforced concrete hollow core slabs performs better strength compared with E-class glass fiber-reinforced concrete slabs. Strength (MPa) Flexural Strength vs Age Age Figure 3 : Flexural strength for RCS1 specimens RCS1() RCS1(3) RCS1(6) RCS1(1) Strength (MPa) Flexural Strength vs Age Age (Days) Figure 4 : Flexural strength for RCS2 specimens RCS2() RCS2(3) RCS2(6) RCS2(1) 3.6 Mid-Span Deflection The deflection versus load for RITA aggregate glass fiber-reinforced concrete slabs and RITA pvc pipe-reinforced hollow core slabs specimens are shown in Figure and Figure 6. Load, P (KN) 2 Load Versus Deflection Mid span deflection, y (mm) Figure : Load vs mid-span deflection for RCS1 specimens RCS1() RCS1(3) RCS1(6) RCS1(1)

6 Load, P (KN) 2 Load Versus Deflection Mid span deflection, y (mm) Figure 6 : Load Vs mid-span deflection for RCS2 specimens RCS2() RCS2(3) RCS2(6) RCS2(1) The deflection shows in the plots is the maximum deflection obtained at the mid-span of the specimens. For RCS1 specimens, the first crack was observed at the load of 4 kn for RCS1(), 3 kn for RCS1(3), 2 kn for RCS1(6) and 1. kn for RCS1(1). Meanwhile for RCS2 specimens, the first crack was observed at the load of. kn for RCS1(), 4. kn for RCS1(3), 3 kn for RCS1(6) and 2 kn for RCS1(1). The plots show that the deflection for all specimens is linearly proportion to the applied load for both RCS1 and RCS2 specimens. It means that, the higher load applied will create higher deflection at the mid span of the slabs. The maximum mid span deflection for RITA aggregate glass fiber-reinforced concrete slabs is RCS1(3). The maximum reading was recorded which is 13 mm with the applied load of 8. kn at the age of 28 days. Meanwhile for RITA aggregate pvc pipe-reinforced hollow core slabs, the maximum deflection was recorded for RCS2(3) specimens. The deflection value is 14. mm with the applied load of 9 kn at the age of 28 days. The results indicated that 3% replacement of RITA aggregate in slab construction perform higher linear relationship between load and deflection value. 4. CONCLUSIONS The preliminary study on effect of recycled industrial timber aggregate (RITA) aggregate as natural aggregate replacement on the strength properties of glass fiber-reinforced concrete slabs and pvc pipe-reinforced concrete hollow core slabs can be summarized as follows: 1. The strength development of the RITA specimens in generally were found to be lower than control specimens. 2. The results indicated that optimum percentage of partial replacement of RITA aggregate as natural aggregate in producing concrete is 3%. 3. The concrete workability containing high volume of RITA aggregate is low and admixture such as superplasticizer need to be used to achieve workability purpose. 4. The deflection of the RCS1 and RCS2 slabs performs a linear relationship with the load applied.. The flexural strength development is subjected to the materials used as reinforcement in slabs construction. The results showed that pvc pipe-reinforced hollow core slabs performs better strength compared with E-class glass fiber-reinforced slabs. 6. The weight density of specimens RCS1 and RCS2 were reduced up to 28% and 32% respectively compared to the control specimens. The weight density for cube specimens also reduced up to 2% compared with the OPC specimens. 7. The preliminary experimental results showed that RITA aggregate possesses the potential to be used in construction for partial materials replacement. However, more research needs to be done before the findings can be considered conclusive. REFERENCES [1] Neville, A.M. (199). Properties of Concrete 4 th Edition. Longman, London. [2] Klieger, P. & Lamond, J.F. (Editor) (1994). Significance of Tests and Properties of Concrete and Concrete-Making Materials. ASTM, USA. [3] Bloem, D.L. (1968). Concrete Strength in Structures. ACI Journal, Proc. Vol. 6, No.3. [4] Popovics, S, (1998). Strength and related properties of concrete A quantitative approach. New York : John Wiley & Sons. [] British Standards Institution (1997). Structural use of concrete Part 1: Code of practice for design and construction. London : (BS 811). [6] British Standards Institution (24). Design of concrete structures Part 1.1: General rules and rules for buildings. London : (BS EN 1992, Eurocode 2). [7] B. K. Marsh, (1997). Design of Normal Concrete Mixes. Second Edition. Construction Research Communications Ltd : United Kingdom. [8] Mindess, S and J. F. Young (1981). Concrete. New Jersey : Prentice-Hall. [9] British Standards Institution (1983). Testing concrete Part 116: Method for determination of compressive strength of concrete cubes. London : (BS 1881). [1] British Standards Institution (1983). Testing concrete Part 11: Method for making test cylinders from fresh Concrete. London : (BS 1881). [11] British Standards Institution (1983). Testing concrete Part 118: Method for determination of flexural strength. London : (BS 1881). [12] T. H. G. Megson, (27). Structural and Stress Analysis. Second Edition. United Kingdom : Elsevier Ltd. [13] Elliott, Kim S. (22). Precast Concrete Structure. United Kingdom : Butterworth-Heinemann. [14] Armin Ghadiri, Abdul Kadir Marsono. (212). Ultimate Strength of Post-Tension Hollow Core Slab for IBS Constructions. International journal of Civil and Building Materials (ISSN X). Vol. 2 No.2, pp [1] British Standards Institution (199). Specification for lightweight aggregates for masonry units and structural concrete. London : (BS 3797). [16] British Standards Institution (1983). Testing concrete Part 12: Method for determination of Slump. London : (BS 1881).