King Saud University

Postnikov

Abdulaziz Al-Negheimish

Abdulrahman Alhozaimy

Raja Rizwan Hussain

Rajeh Zaid Al-Zaid

Devendra Deo Narain Singh

Mohammad Iqbal Khan

Mohd Saleh Jaafar

Galal Fares

Jamaloddin Noorzaie

Ahmed B Shuraim

Ddn Singh

Omer A Alawad

The method of curing reinforced concrete uses a liquid membrane-forming curing compound for the curing of reinforced concrete, but without fully coating the reinforced concrete with the curing compound, thus allowing for oxygen permeation through the reinforced concrete to effect passive layer formation on steel rebar embedded in the reinforced concrete. Prior to curing, a mask is applied to at least one surface of a slab of reinforced concrete, such that the mask covers about 10% of the surface area of the at least one surface. The at least one surface of the slab of reinforced concrete is then coated with a liquid membrane-forming curing compound. The liquid membrane-forming curing compound is allowed to dry, thus forming a curing compound layer on the at least one surface of the slab of reinforced concrete. The mask is then removed to form at least one uncoated region.

Method of curing reinforced concrete

The corrosion-preventing additive for reinforced concrete is a concrete additive for preventing corrosion of steel rebars in steel-reinforced concrete. The corrosion-preventing additive is a solution with an organic solvent, the solute being either gallic acid (3,4,5-trihydroxybenzoic acid), at least one ester of gallic acid, or combinations thereof. The weight-to-volume concentration of the solute to the organic solvent may be between 1% and 10% w/v. Reinforced concrete may be made using the corrosion-preventing additive by mixing the corrosion-preventing additive with a conventional concrete mixture (i.e., a mixture of an aggregate, water, and cement), with at least one steel rebar being embedded in the mixture, similar to conventional steel rebar reinforced concrete. The concentration of the corrosion-preventing additive with respect to the cement of the mixture may be between 0.0125 wt % and 1.0 wt %.

Corrosion-preventing additive for reinforced concrete

The coupled borate/silicate salts-based additive for mortar or concrete controls chloride induced pitting and uniform corrosion of steel rebars embedded in the mortar or concrete with no detrimental effect on compressive strength of mortar/concrete. The silicate compounds may include one or more of the salts of sodium, potassium, lithium, calcium, magnesium, manganese, iron, zinc, aluminum and other transition and valve metals. The borate compounds may include one or more of the salts of alkali and alkaline earth metals, transition, non-transition and valve metals such as sodium, potassium, lithium, calcium, magnesium, manganese, iron, zinc, aluminum and others. The combination of the borate and silicate salts as an additive has been shown to impart high protection to steel rebar surfaces against corrosion, and particularly chloride induced pitting corrosion. The additives are equally effective for mortar as well as concrete. They are also eco-friendly, economical, and are easily applied at construction sites.

Coupled borate/silicate salts-based additives for mortar or concrete

The additive for reinforced concrete is a concrete additive for preventing corrosion of steel rebars in steel-reinforced concrete, improving the workability of the cast concrete, and reducing water absorption/permeability in the cast concrete. The reinforced concrete may be a conventional reinforced concrete, such as that formed from a mixture of water, an aggregate and cement, having at least one steel rebar embedded in the mixture. The additive is added to the mixture prior to curing and casting. The additive may for example, have a concentration with respect to the cement of between 0.25 wt % and 1.0 wt %. The additive includes a triazole and a non-ionic surfactant including a poly oxy ethoxylated reaction product of sorbitan and a fatty acid. The triazole and the non-ionic surfactant are dissolved in the solvent.

Additive for reinforced concrete

The corrosion-preventing additive for reinforced concrete is a concrete additive for preventing corrosion of steel rebars in steel-reinforced concrete. The corrosion-preventing additive is powdered scoria, including concentrations of about 45 wt % SiO, 14 wt % FeO, and 15.5 wt % AlO, with the remainder being standard components found in volcanic rock. The average particle size of the powdered scoria is 45 microns or less. Reinforced concrete treated with the corrosion-preventing additive includes a mixture of an aggregate, water, and cement (such as Portland cement), along with at least one steel rebar embedded in the mixture, and the powdered scoria.

A concrete product is produced by providing red dune sand having a particle size of 45 microns or less and mixing the red dune sand with hydraulic cement in a ratio of about 30% of the cement being replaced by the red dune sand. The cement and red dune sand are then mixed with fine and course aggregate, water and a superplasticizer and cast after pouring into a mold cavity. Then within 24 hours of casting, the cast article is steam cured for 12 hours under atmospheric pressure, demolded and placed in an auto clave at 100% humidity. The temperature in the auto clave is raised to 180&#xb0; C. within one to two hours and maintained at that temperature for 4 to 5 hours. The temperature also increases the pressure to about 10 bars. The pressure is released to reach atmospheric pressure within 20-30 minutes and the temperature reduced gradually, so that the article can be removed.

Cement/aggregate composition, concrete product and method for making a concrete product

The EAFD stabilizer for returned concrete and mixer drum wash water includes various methods of using EAFD as a stabilizer in making concrete. The potentially hazardous stockpile of EAFD can be used in practical construction, which has a positive impact on the environment. A certain amount of EAFD is added to cement being mixed or to wash water and acts as a stabilizer, the wash water being used to make a cement mixture. This resultant EAFD stabilized concrete mixture stabilizes overnight.

EAFD stabilizer for returned concrete and mixer drum wash water

The method of ascertaining fully grown passive film formation on steel rebar embedded in concrete utilizes electrochemical impedance spectroscopy (EIS) to determine, in situ, the degree of passive film formation on steel rebar embedded in concrete. A length of steel rebar and a counter electrode are both embedded in a concrete slab. A reservoir is supported on an external face of the concrete slab and filled with an electrolytic solution. A reference electrode is then positioned in the electrolytic solution, and the length of steel rebar, the counter electrode and the reference electrode are electrically connected an EIS test instrument to perform electrochemical impedance spectroscopy. The quality of passive film formation on the length of steel rebar is determined based on comparison of the electrochemical impedance spectroscopy results with known passive film formation data.

Method of ascertaining fully grown passive film formation on steel rebar embedded in concrete

The present invention contemplates a cementitious additive that contains electric-arc furnace dust (EAFD) and a precursor as a replacement for up to about 30% of the cement in concrete. The additive includes about 50% by weight EAFD and about 50 wgt. % of precursor. The precursor includes about 55 wgt. % silica, about 10 to 20 wgt. % lime, about 2 to 5 wgt. % soda, about 5 to 15 wgt. % potash, about 2 to 6 wgt. % alumina and about 1 to 3 wgt. % magnesia. The method also contemplates the step of homogenizing the electric-arc furnace dust (EAFD) and precursor to produce engineered dust (ED) and then replacing up to 30% of the cement with a mixture referred to as ED i.e. homogenized EAFD and precursor.

Supplementary cementitious material and method for disposing of electric-arc furnace dust (EAFD)

The anti-corrosion treatment composition for steel rebar embedded in concrete is a composition for coating steel rebar before the steel rebar is embedded in concrete. The coating of the steel rebar with the anti-corrosion treatment composition forms a treatment film on the steel rebar which controls both uniform corrosion and pitting corrosion of the steel rebar after it has been embedded in the concrete. The anti-corrosion treatment composition includes an inorganic acid, an organic acid, polyethylene glycol and water. The inorganic acid forms between approximately 3.9 wt % and approximately 15.0 wt % of the anti-corrosion treatment composition, the organic acid forms between approximately 0.1 wt % and approximately 2.9 wt % of the anti-corrosion treatment composition, the polyethylene glycol forms between approximately 2.0 wt % and approximately 10.7 wt % of the anti-corrosion treatment composition, and the remainder of the anti-corrosion treatment composition is water.

Anti-corrosion treatment composition for steel rebar embedded in concrete

A system for determining longitudinal moments in a one-way joist floor comprising a supporting girder includes at least one computer configured to determine boundaries of at least one equivalent frame, determine a longitudinal moment within a column-beam portion of the at least one equivalent frame based at least in part on a vertical rigidity of the supporting girder, the column-beam portion having at least one column, and determine a longitudinal moment within a lateral section of the at least one equivalent frame based on the longitudinal moment within the column-beam portion, and based at least in part on the vertical rigidity of the supporting girder, the lateral section being lateral to the column-beam portion.

System and method for determining longitudinal moments in one-way joist floors

A raw batch composition for concrete or concrete wherein the raw batch composition comprises Portland cement of about 15 wgt. % to about 45 wgt. % and dune sand preferably red dune sand is present in an amount of about 40 wgt. %. The dune sand has a particle size of less than or equal to 45 microns. The composition also includes limestone powder ranging from about 15 wgt. % to 45 wgt. % with particle sizes less than or equal to 45 microns to form a base material. To this base material suitable amounts of fine aggregate, coarse aggregate, water and superplasticizer are added. A method for producing a cast concrete product having a compressive strength of between 62 MPa and 90 MPa is disclosed. The method comprises a step of providing Portland cement, dune sand and limestone powder.

Cement composition containing dune sand and limestone powder, concrete products and method for making concrete products

A method for manufacturing concrete bodies or forms containing electric arc furnace dust in an amount of up to about 4% at elevated temperatures to provide concrete bodies is disclosed. The concrete bodies have improved compressive strength and slump retention capability. The method for producing the bodies includes the steps of providing pre-selected amounts of electric arc furnace dust, water, cement and aggregate. The electric arc furnace dust is mixed with water and then added to the cement and aggregate and mixed together at a temperature of about 32&#xb0; C. and 45&#xb0; C. to form a hot mixture. The hot mixture is added to a mold and cast at an elevated temperature to form a body with improved strength and slump retention characteristics.

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Riyadh, Saudi Arabia

Abdulaziz Al-Negheimish