Modulus of elasticity values at 28 days for TSC mixtures made with various binders are presented in Table 4.5. It can be observed that similarly to compressive and tensile strength, the TSC modulus of elasticity is affected by the binder type. For example, TSC mixtures incorporating 50% FA achieved a modulus of elasticity 12% lower than that of the control mixture. However, TSC mixtures made with 10% SF or 10% MK achieved modulus of elasticity values 3% and 7% higher than that of the control, respectively. The relationship between the TSC modulus of elasticity and its compressive strength differs from that of conventional concrete. It was reported that TSC exhibits higher modulus of elasticity than that of conventional concrete with comparable compressive strength (Abdul Awal, 1984). This can be ascribed to the fact that TSC has higher coarse aggregate (about 60% of the total volume) than that of conventional concrete (about 40% of the total volume). Thus, TSC has a skeleton of coarse aggregate particles resting on each other and the stresses are transferred through their contact points (Abdul Awal, 1984; Abdelgader, 1996; Abdelgader and Górski, 2003). An empirical relationship between the elastic modulus of TSC and its compressive strength was proposed in this study using nonlinear regression analysis as given in Eq. 4.5 (Figure 4.6).
𝐸 = 19.53 𝑓𝑐`0.195 Eq. 4.5 Where, E is the modulus of elasticity for TSC (GPa) and 𝑓𝑐` is its compressive (MPa). The RMSE, R2, and 𝑟𝑥𝑦 values were 0.67 MPa, 0.999 and 0.950, respectively, indicating satisfactory predictive ability of the proposed equation. Moreover, the modulus of elasticity of TSC can be estimated based on the compressive strength of the grout (i.e. Eq. 4.6, which is derived by substituting Eq. 4.2 in Eq. 4.5).
Figure 4.6 ‒Relationshipbetweencompressivestrengthandmodulusofelasticityof TSC.
4.5.CONCLUSIONS
In this study, the rheological and mechanical properties of two-stage concrete made with single, binary and ternary binders were explored. The following conclusions can be drawn: Partial replacement of OPC with FA improved the grout’s flowability while reducing its
resistance to bleeding.
Partial replacement of OPC with SF or MK increased the grout’s bleeding resistance and mechanical properties, while reducing its flowability. However, flowability can be adjusted using a proper dosage of HRWRA.
An empirical equation for predicting the compressive strength of TSC based on the corresponding grout’s compressive strength and considering the binder type was proposed.
There was no significant effect of the binder type on the relation between the compressive and tensile strengths of TSC.
0.0 0.8 1.6 2.4 3.2 4.0 4.8 5.6 6.4 7.2 4351 4851 5351 5851 6351 30 35 40 45 0 10 20 30 40 50
TSC Compresssive Strength (ksi)
TSC M odu lus of El ast ici ty ( ks i) T SC Modulus of E lastic ity (GPa)
TSC Compressive Strength (MPa)
Compressive Strength Vs. Modulus of Elasticity Curve fittingusing Eq. 4.5
An empirical relationship between the modulus of elasticity of TSC and its compressive strength was proposed in the present study. This equation can be extended to estimate the modulus of elasticity of TSC based on the grout’s compressive strength as outlined in Eq. 4.6.
However, it should be mentioned that the proposed model highlighted the existence of a relationship between the properties of TSC and its grout formulation and binder type. Such a relationship cannot be extrapolated beyond the domain of the data used in this study. It can, however, be extended beyond the current experimental domain and include other experimental variables should sufficient data needed for such an extension become available in the future.
4.6.REFERENCES
Abdelgader, H. S., (1996), “Effect of quantity of sand on the compressive strength of two- stage concrete,” Magazine of Concrete Research, Vol. 48, No. 177, pp. 353-360.
Abdelgader, H. S., (1999), “How to design concrete produced by a two-stage concreting method,” Cement and Concrete Research, Vol. 29, No. 3, pp. 331-337.
Abdelgader, H. S. and Ben-Zeitun, A. E., (2005), “Tensile strength of two-stage concrete measured by double-punch and split tests,” Proceedings of International Conference on Global Construction, Role of Concrete in Nuclear Facilities, University of Dundee, Scotland, UK, pp. 43-50.
Abdelgader, H. S. and Elgalhud, A. A., (2008), “Effect of grout proportions on strength of two-stage concrete,” Structural Concrete, Vol. 9, No. 3, pp. 163-170.
Abdelgader, H. S. and Górski, J., (2003), “Stress-strain relations and modulus of elasticity of two-stage concrete,” Journal of Materials in Civil Engineering, ASCE, Vol. 15, No. 4, pp. 329-334.
Abdul Awal, A. S., (1984), “Manufacture and properties of pre-packed aggregate concrete,”
Master Thesis, University of Melbourne, Australia, 121 p.
ACI 304.1, (2005), “Guide for the use of preplaced aggregate concrete for structural and mass concrete applications,” American Concrete Institute, Farmington Hills, USA, 19 p. ASTM C938, (2010), “Standard practice for proportioning grout mixtures for preplaced-
aggregate concrete,” American Society for Testing and Materials, West Conshohocken, PA, USA, 3 p.
ASTM C939, (2010), “Standard test method for flow of grout for preplaced-aggregate concrete (flow cone method),” American Society for Testing and Materials, West Conshohocken, PA, USA, 3 p.
ASTM C469/C469M, (2010), “Standard test method for static modulus of elasticity and Poisson's ratio of concrete in compression),” American Society for Testing and Materials, West Conshohocken, PA, USA, Vol. 4.02.
ASTM C940, (2010), “Standard test method for expansion and bleeding of freshly mixed grouts for preplaced- aggregate concrete in the Laboratory),” American Society for Testing
and Materials, West Conshohocken, PA, USA, Vol. 4.02.
ASTM C942, (2010), “Standard test method for flow of grout for compressive strength of grouts for preplaced-aggregate concrete in the laboratory),” American Society for Testing
and Materials, West Conshohocken, PA, USA, Vol. 4.02.
ASTM C943, (2010), “Standard practice for making test cylinders and prisms for determining strength and density of pre-placed-aggregate concrete in the laboratory),”
ASTM C496/C496M, (2011), “Standard test method for splitting tensile strength of cylindrical concrete specimens),” American Society for Testing and Materials, West Conshohocken, PA, USA, Vol. 4.02.
Bayer, R., (2004), “Use of preplaced aggregate concrete for mass concrete applications,”
Master Thesis, Middle East Technical University, Turkey, 160 p.
Bouzoubaâ, N., Bilodeau, A., Sivasundaram, V., Fournier, B. and Golden, D. (2004), “Development of Ternary Blends for High-Performance Concrete,” ACI Materials Journal, Vol. 101, pp. 19-29.
Bruce, D. A., Littlejohn, G. S. and Naudts, A., (1997), “Grouting materials for ground treatments: A practitioner’s guide. In Geotechnical Special Publication; Grouting: Compaction, Remediation and Testing, C. Vipulanandan (Ed.),” ASCE, New York, Vol. 66, pp. 306-334.
Chindaprasirt, P., Jaturapitakkul, C. and Sinsiri, T., (2005), “Effect of fly ash fineness on compressive strength and pore size of blended cement paste,” Cement and Concrete
Composites, Vol. 27, No. 4, pp. 425-428.
Hasan, H. A., (2012), “Effect of fly ash on geotechnical properties of expansive soil,”
Journal of Engineering and Development, Vol. 16, No. 2, pp. 306-316.
Hsing Huang, W., (1997), “Properties of cement-fly ash grout admixed with bentonite, silica fume, or organic fiber,” Cement and Concrete Research, Vol. 27, No. 3, pp. 395-406. Hwang, K., Noguchi, T. and Tomosawa, F., (2004), “Prediction model of compressive
strength development of fly ash concrete,” Cement and Concrete Composites, Vol. 34, No. 12, pp. 2269-2276.
Khatib, J. and Caly, R., (2004), “Absorption characteristics of metakaolin concrete,” Cement and Concrete Research, Vol. 34, No. 1, pp. 19-29.
Khayat, K., Vachon, M. and Lanctôt, M., (1997), “Use of blended silica fume cement in commercial concrete mixtures,” ACI Materials Journal, Vol. 94, No. 3, pp. 183-192. Kismi, M., Claude Saint, J. and Mounanga, P., (2011), “Minimizing water dosage of
superplasticized mortars and concretes for a given consistency,” Construction and Building Materials, Vol. 28, No. 1, pp. 747-758.
Mehta, P. K., (2004), “High-performance, high-volume fly ash concrete for sustainable development,” International workshop on sustainable development and concrete technology, Beijing, China.
Molhotra, V. M., (1993), “Fly ash, slag, silica fume, and rice- hush ash in concrete: a review,” Concrete International, Vol. 15, No. 4, pp. 23-28.
Narmluk, M. and Nawa, T., (2011), “Effect of fly ash on the kinetics of Portland cement hydration at different curing temperatures,” Cement and Concrete Research, Vol. 41, No. 6, pp. 579-589.
O’Malley, J. and Abdelgader, H. S., (2009), “Investigation into the viability of using two stage (pre-placed aggregate) concrete in an Irish setting,” GSBEIDCO -1st, Vol. 1, pp. 215-222.
Razak, H. and Wong, H., (2001), “Effect of incorporating metakaolin on fresh and hardened properties of concrete,” Special Publication, Vol. 200, pp.309-324.
Sarker, P. K., (2013), “Early-age tensile strength and calcium hydroxide content of concrete containing low-calcium fly ash,” Australian Journal of Structural Engineering, Vol. 14, No. 3, pp. 206-216.
Snelson, D., Wild, S. and O'Farrell, M., (2008), “Heat of hydration of Portland Cement– Metakaolin–Fly ash (PC–MK–PFA) blends,” Cement and Concrete Research, Vol. 38, No. 6, pp. 832-840.
Tan, O., Zaimoglu, A., Hinislioglu, S. and Altun, S., (2005), “Taguchi approach for optimization of the bleeding on cement-based grouts,” Tunneling and Underground Space
Technology, Vol. 20, pp. 167-173.
Weng, J. K., Langan, B. W. and Ward, M. A., (1997), “Pozzolanic reaction in Portland cement, silica fume, and fly ash mixtures,” Canadian Journal of Civil Engineering, Vol. 24, No. 5, pp. 754-760.
Yung Wang, H., Ten Kuo, W., Chung Lin, C. and Yo, C., (2013), “Study of the material properties of fly ash added to oyster cement mortar,” Construction and Building Materials, Vol. 41, No. 1, pp. 532-537.
Zhang, M. H., Swaddiwudhipong, S., Tay, K. Y. and Tam, C. T., (2008), “Effect of silica fume on cement hydration and temperature rise of concrete in tropical environment,” The IES Journal Part A: Civil & Structural Engineering, Vol. 1, No. 2, pp. 154-162.
(*)A version of this chapter was submitted to the Cement and Concrete Composites Journal (2016).