Dr. Udeme Hanson Iron

Lecturer, Department of Civil Engineering, Faculty of Engineering, University of Uyo, Nigeria.

This study develops mathematical models for obtaining optimum flexural strengths of normal laterised(NLC) and high strength laterised concretes (HSLC). The models can be expressly used to evaluate the indirect tensile strengths of both types of concretes without going through the traditional methods of mix design. Optimum mixing ratios and optimum flexural strengths predicted are also supplied by the models. The three point load method was adopted for testing for the flexural strengths. Laterite, has been widely used to partially or wholly replace sand in concrete with resultant low strengths. The production of HSLC using superplasticiser was achieved in this study. Scheffe’s simplex theory based on (5, 2) simplex lattice (for NLC) and (6, 2) simplex lattice (for HSLC) was used to optimize the mix proportions for the flexural strengths of each respective laterised concrete. Conplast SP 430 superplasticiser (a sulphonated naphthalene formaldehyde admixture) was used to obtain the high strength laterised concrete. Mathematical models were developed for the mix proportioning of the laterised concretes and all strengths predicted by the models agreed with their corresponding experimentally observed values. Using the model, the optimum flexural strength and the corresponding mix proportions for the targeted strength of laterised concrete could be easily evaluated with the help of the written Q-BASIC computer programme.

Laterised concrete, simplex lattice, Flexural strength, Optimisation, Superplasticise, Q-Basic.

1) Adepegba, D. 1975. The Effect of water content on the compressive strength of laterized concrete. Journal of Testing and Evaluation. 3: 1-5.

2) Akhnazarova, S and Kafarov, V. 1982. Mixture design: simplex lattice method. Experiment Optimization in Chemistry and Chemical Engineering. Trans. Vladimir Matskovsky & Alexander Repyev. Moscow: MIR Publishers. Rpt.1982. Chapter 6: 240-293.

3) Ata, O., Olusola, K.O. and Aina, O.O. 2005. Factors Affecting Poisson's Ratio of Laterized Concrete, Jurnal Sains Dan Teknologi, EMAS, Jakarta, 15(2), 2005, pp.77-84.

4) Becker, N.G. 1968. Model for the Response of a Mixture. Journal of the Royal Statistical Society. Ser. B30: 349 – 358.

5) British Standards Institution, BS812. 1975. Methods of Testing Aggregates. London.

6) British Standards Institution, BS3148. 1980. Test for Water for Making Concrete (including Notes on the Suitability of the Water), London.

7) British Standards Institution. BS1881: Part 108. 1983. Method for Making Test Cubes from Fresh Concrete. London.

8) British Standards Institution. BS1881: Part 118. 1983. Method for Determination of Flexural Strength. London.

9) British Standards Institution. BS12 1991: Specifications for Portland cements. London.

10) British Standards Institution. BS882: 1992. Specifications for Aggregates from Natural Sources for Concrete. London.

11) Gidigasu, M.D. 1976. Laterite Soil Engineering. Oxford: Elservier Scientific publishers,.

12) Jackson, N. 1983. Civil Engineering Materials. Hong Kong: RDC Artser Limited.

13) Maruyama, I; & Noguchi, T. 1992. Optimization of the concrete mix proportions centered on fresh properties through the genetic algorithm. Architecture and Civil Engineering. 38.4: 77-78.

14) Neville, A.M. 1996. Properties of Concrete. 4th ed. Malaysia: ELBS/Longman.

15) Nwakonobi, T. U; Osadebe, N. N; & Mbajiorgu, C. C. 2007. Structural characteristics of laterized concrete at optimum proportion. Nigerian Journal of Technology 26.1: 12-17.

16) Scheffe, H. 1958. Experiments with mixtures. Royal Statistical Society Journal, B.20: 344-360.

17) Shilstone, J. M. 1990. Concrete mixture optimization. Concrete International 15.16: 33-40.

18) Udoeyo, F; Odim, O. & Iron, U. 2006. Strength performance of laterized concrete. Construction and Building Materials Journal. 20.10: 1057-1062.

Volume 05 Issue 07 July 2022

There is an Open Access article, distributed under the term of the Creative Commons Attribution – Non Commercial 4.0 International (CC BY-NC 4.0) (https://creativecommons.org/licenses/by-nc/4.0/), which permits remixing, adapting and building upon the work for non-commercial use, provided the original work is properly cited.