Ali Alnuaimi

Causes, Effects, Benefits, and Remedies of Change Orders on Public Construction Projects in Oman

Change orders are usually issued to cover variations in scope of work, material quantities, design errors, and unit rate changes. This paper discusses variations in public construction projects in Oman by investigating causes of variations, studying their effects on the project, identifying the beneficial parties, and suggesting remedies to alleviate related problems. Tasks included an analysis of four actual case studies and conducting a field survey via a questionnaire. It was determined that the clients additional works and modifications to design were the most important factors causing change orders, followed by the nonavailability of construction manuals and procedures. The most important effects of change orders on the project were found to be the schedule delays, disputes, and cost overruns. The contractor was found to be the party most benefiting from the change orders followed by the consultant and then the client. A set of remedial actions were suggested and respondents viewed that the revision of registration of consulting offices would be the most important action followed by establishing standard documents for design procedures and building a national database about soil conditions and services.

Use of Cement By-pass Dust in Flowable Fill Mixtures

Flowable fill is a self-compacted, cementitious material used primarily as a backfill in lieu of compacted fill. It is generally a mixture of sand, small amount of cement, fly ash, and water. Sand is the major component of most flowable fill mixes. Waste materials such as fly ash, ground granulated blast furnace slag, and foundry sand are commonly used to ensure low maximum compressive strength. Cement by-pass dust (CBPD) is considered a waste material of the production of cement. An estimated 25,000 tons of CBPD are produced annually in the Sultanate of Oman by Oman Cement Company alone. Most of this material is not effectively used and is disposed of on-site without any reuse causing environmental concerns. The main objective of this research is to investigate the potential use of CBPD in flowable fill mixtures as an alternative to fly ash and as a partial substitute for cement. The physical and chemical properties of both CBPD and cement were determined. Cube and cylindrical samples were prepared using different proportions of CBPD and water-to-cement ratios in order to select the optimum mixes that can be used in flowable fill applications. The optimum mixtures were cured in air and covered in plastic bags in order to study the effect of curing method on the compressive strength of flowable fill mixtures. Promising results were obtained with respect to the use of CBPD as a partial or full substitute for cement in flowable fill mixtures. Results also demonstrated that air cured samples gave a higher compressive strength than samples cured in the plastic bags for the mixes where CBPD was used as a partial substitute for cement. However, in mixes where CBPD was used to fully replace cement, samples that were cured in plastic bags produced higher strength than air cured samples at longer curing periods.

Flexural Behaviour Of Ferrocement Roof Panels

This paper presents the experimental results of nine roof panels made of Ferrocement. Two types of channel sections and one type of box section were tested. All panels were 2m long, 470mm wide and 20mm thick. Channel type A had side edge beams 95mm deep and channel type B had side edge beams 50mm deep. The depth of the box section was 95mm. Thin hexagonal wire mesh was used as reinforcement. The number of wire mesh layers was varied between two to six. The wires were impregnated midway through the thickness of the panels. The panels were tested for bending moment with simple supports. The main variables studied were the number of wire mesh layers, the cross sectional shape of the panel and the depth of edge beam. Tests revealed that all panels showed acceptable strength for roofing systems. The increase in the number of wire mesh layers leads to an increase in the flexural strength. The box section showed strength similar to that of the channel section with 95mm edge beam. The channels with 50mm deep edge beams showed strength much less than the ones with 95mm edge beam and box section.

Demonstration of Sustainable Crop Growth Using Production Water Treated with Solar Membrane Distillation Technology: A Case Study

ABSTRACT This paper summarizes the establishment of a demonstration pilot farm at a dessert environment for sustainable crop growth using reed-bed-outlet production water that was treated with solar membrane distillation (i.e., Solar Dew) technology. Specifically, land preparation, plot layout, and the design and installation of an irrigation system were described. Plant tissue analysis indicated that there was no build-up of heavy metals. Analysis of soil over the test period showed that there was a slight build-up of salts. This was attributed to the use of sewage treatment plant water prior to irrigation with Solar Dew water. The salt content of the treated water varied from low (i.e., 11 mg/L) to acceptable (i.e., 122 mg/L). Due to the lower than expected fresh water production capacity of the solar membrane distillation system (i.e., 4 L/m2d vs. 5 L/m2d), the field testing of crops was limited to date palm and citrus trees. Some problems were encountered with the novel desalination system. Recommendations were included in the paper. Overall, it was successfully demonstrated that sustainable crop growth could be achieved using reed-bed-outlet production water that had been treated with Solar Dew membrane technology.