Development of SELF-COMPACTING CONCRETE using local materials
Self-compacting concrete was developed in late 1980s in Japan, to address these issues. SCC is a concrete made of conventional raw materials used for production of concrete such as cement, fine aggregate, coarse aggregate, super-plasticiser and viscosity modifying agent. However, it fills every corner of the formwork without the requirement of any external energy input like vibration, and gets compacted due to its self weight only. SCC has very high deformability in the fresh state, as well as high resistance to segregation. SCC uses higher extra powder content than normal concrete to keep the concrete cohesive at high flowability. Generally, the powder material and superplasticiser are the main ingradients affecting the cost of SCC. The choice of a particular powder material is affected by economic considerations specific to the particular location, as well as the characteristics of the powder or micro-filler material. Similarly, now there are choices available among super-plasticisers. SCC has great potential for improving the quality and durability of concrete construction under the severe weather conditions prevalent in the Kingdom. It will greatly improve concrete placement and eliminate the problem of honeycomb without the need for additional mechanical compaction resulting in higher quality and speed of construction, and more durable structures.
Electric Arc Furnace Dust (EAFD): From Waste By-product to Valuable Cementitious Material
Electric-Arc Furnace Dust (EAFD) is a waste by-product material generated during steel making process at a rate of 2% of the total steel output. Finding effective and safe method to dispose of the large quantities of EAFD produced in the Kingdom is a major environmental concern. This study is designed to promote the utilization of EAFD as a valuable additive in concrete through cooperation between the KSU, Ready-mixed concrete (RMC) suppliers, and local admixture manufacturers. The project is targeting at a successful utilization of EAFD in concrete industry with a valuable impact on the environment and performance of concrete in hot weather.
The research project has its target to develop and facilitate utilization of EAFD in concrete construction. Achieving this target will contribute to clean environment of otherwise a hazardous waste by product, beside improving the performance of fresh and hardened concrete under harsh and hot environment.
Summary and expected outcome:
The outcome of this project will be successful utilization of EAFD by the RMC industry in the Kingdom to counteract the negative impacts of hot weather on concrete. The use of EAFD will benefit the country by finding useful utilization of otherwise waste by product.
KSU Strategic Construction Program
Owner's Representative, Concrete Quality Assurance
CoE CRT staff members perform on-site observations for various phases of concrete construction for the new Girl's University, a Staff Housing Extension, a Medical Office Building Extension, and the Riyadh Techno Valley. We help to ensure Contractor compliance while trying to improve the role of the Project Management Consultants. Statistical analysis of variability enables up to date monitoring of project performance. Site visit reports are produced to focus efforts on areas needing improvement. Our quality assurance consulting helps minimize project risk, while maximizing project efficiency.
INVESTIGATION OF HIGH CORROSION RATE AT INTERSECTION POINTS IN STEEL REBAR MESH OF RC STRUCTURES UNDER VARIABLE SPACING OF REBARS AND BINDING WIRE TYPES
This CoE-CRT research project originated from field observations obtained from a typical residential building complex in Riyadh, Saudi Arabia which was built about 30 years ago and is suffering from severe corrosion in the foundations especially at the reinforcement steel rebar intersection points. The interesting point is that the reinforcement bars show severe corrosion at the intersection points of the horizontal and vertical steel bars in the mesh and literally no corrosion between the intersection points. This was a rather new finding and needed deep experimental as well as analytical investigation to clarify the mechanisms involved therein. Therefore, for this purpose specific experimentation was devised and performed in which chloride contaminated reinforced concrete panels having dimensions 1.0mx1.0mx0.2m were cast with perpendicularly intersecting steel rebar mesh having variable C/C spacing in order to observe its effect on the high corrosion rate expected to occur at the rebar intersection points. Furthermore, three different types of binding wires (copper binding wire, steel binding wire and nylon binding wire with insulating plastic spacers between the two intersecting bars) were used at the rebar intersection points. The specimens were cured for 28 days under 60% R.H condition and 20 ̊C temperature. Half-cell potential, corrosion current and concrete resistivity were measured by the use of standard electrode after every three days time interval. The measurements were taken at the intersection points of steel bars as well as in between them to observe the difference at the two places. The last step was physical observation of the corroded rebars after breaking the concrete slabs and gravimetric mass loss due to corrosion of steel was determined after one year of exposure. In addition to that corrosion model FEM analysis of a typical intersecting round deformed steel bar mesh in concrete was also carried out to clarify the scientific reasons involved in the concentration of corrosion products at the intersection points and compared with the experiment results. The final outcome of this research is expected form the basis for evaluating the adequacy of current durability provisions for corrosion protection of reinforced concrete, improved steel rebar fixing, spacing and placement methods, appropriate bar bending schemes and improved overall quality and efficacy of RC structures against corrosion.