Olabosipo I. Fagbenle

Appraising the Barriers to Public-Private Partnership as a Tool for Sustainable Development of Infrastructures in a Developing Economy

The quest for sustainable development has been a subject discourse across the globe. Sustainable development has been deemed to be the pathway to all that is good and desirable in the society. Undoubtedly, social and economic infrastructure desirability in any economy is nsecond-to-none and its sustainability needs to be prioritised. The worsened state of infrastructures and wide gap in its supply in developing economy have warranted this study. The study identified the sustainable tool (PPP) through which infrastructural supply can be enhanced and sustained and it revealed through literature review the major barriers to the tool performance in delivering infrastructures in developing country. Among the major challenges identified from literatures include inadequate consultation of stakeholders for greater acceptance of PPP, conflict of interest among PPP stakeholders, negative behaviour of the people towards PPP, lack of confidence and mistrust in PPP by stakeholders, poor enabling environment for PPP, weak or poor regulatory frameworks, law and regulation changes and weak and poor enabling policies. The barriers identified are due to more to the public than the nprivate and the people. Therefore, the study recommends that beyond the need for stronger collaboration between the public and private sector, government should integrate the people in planning phase of the sustainable tool adoption for public infrastructures delivery. Also, government should build confidence and trust in the parties to PPP by creating enabling environment that can guarantee investors security.

Pulverized Calcined Clay and Carbide Waste as Alternative Binder in Concrete and Mortar Applications for Sustainable Construction

Portland cement (PC) based concrete is the world’s most consumed man-made material and this consequently puts lots of demand on cement as a binder. The CO2 gas emission during cement clinker production has placed this important material into non-environmental-friendly classification with quest for greener alternatives being on the rise. A recent study showed combination of Pulverized Calcined Clay (PCC) and Calcium Carbide Waste (CCW) as possible alternative for total PC replacement with resulting appreciable mortar strength but delayed setting times and lower strength than PC mortars. This paper reports on effects of PCC-CCW as alternative binder on strength properties of mortars. The mortar mixes had superplasticizers added to reduce water/binder ratio while the CCW was treated to reduce impurities with a view to improving the strength development and a bid to mitigate the observed setbacks of earlier study. The pozzolanic activity indices of the PCC was determined via X-Ray Fluorescence(XRF) and strength determination (strength activity index). The PCC was combined with Purified CCW to determine the binder’s strengths at varying PCC:CCW replacements to determine the prescribed mix combination for optimum strength. Improved optimised mortar strength of 13.11MPa was achieved compared to 11.89MPa in the previous study

A Comparative Analysis of Batching by Weight and Volume towards Improved Concrete Production

Batching of concrete is generally the proportioning of the different constituents of nconcrete before mixing which could be by weight or volume. Mix-design justified by trial test is nthe best method to achieve a concrete of desired properties. Standardized prescribed concrete n(SPC) mix-design is mostly adopted in mass concreting to high strength concreting applications nin most developing nations. British standards accept volume batching for SPC only in mass nconcrete (<15 MPa) but batching by weight for normal and higher strength concrete. Structural nconcrete like in storey buildings requires at least a normal strength concrete (>20 MPa) nrecommended to be batched by weight. Designs batched by volume have been identified as the nmost commonly used method in concrete production in Nigeria and most developing nations, nespecially by medium to small scale construction firms due to the very high cost of employing nbatching plants. This research work developed a modified volumetric batch mix-design that will nbe equivalent to SPC design mix batched by weight in normal and higher strength concrete. The nphysical properties of the constituent concrete materials, fine aggregate, 12 and 19 mm sized ncoarse aggregates were determined. The strength of SPC mix of ST2, ST4, and ST5 to British nstandard were determined when batched by weight and their volume equivalents mix-design nbatch determined. The strengths of these SPC mixes were batched by volume and their weight nequivalent batch-design determined. A relationship was determined between both batching mixdesign nmethods for all the prescribed mixes and strengths using the binder-aggregate and coarsefine naggregate ratios, such that the preferred weight batching design mix could be achieved by a nmodified mix-design batched by volume. This study concludes that concrete mix-design batched nby weight is superior to when batched by volume and the desired design batching by weight ncould be achieved by generating a modified mix-design-batch by volume. This will improve the nquality of concrete storey buildings in most developing nations.