An expansive additive composition for use in Portland cements and a method of using such an additive composition is provided. The additive composition can include a calcium aluminate cement additive and a lithium compound. The additive composition is capable of producing expansion in set cements when the temperature is at or below room temperature and minimizes the amount of calcium aluminate cement additive needed.

An expansive additive composition for use in Portland cements and a method of using such an additive composition is provided. The additive composition can include a calcium aluminate cement additive and a lithium compound. The additive composition is capable of producing expansion in set cements when the temperature is at or below room temperature and minimizes the amount of calcium aluminate cement additive needed.

The present invention relates to improved concrete elements, particularly to self-prestressed, high-performance concrete elements (SP-HPC elements); to cementitious compositions suitable, for producing such concrete elements; to methods of manufacturing such concrete elements and such cementitious compositions; to the use of specific components in concrete elements and cementitious mixtures. The compositions and elements described herein comprise an effective amount of expansive agents in combination with superabsorbent polymers (SAP) and shrinkage reducing admixtures (SRA), and optional further components as defined in the claims. The present invention further provides for improved tendons, suitable for SP-HPC elements.

The present invention relates to improved concrete elements, particularly to self-prestressed, high-performance concrete elements (SP-HPC elements); to cementitious compositions suitable, for producing such concrete elements; to methods of manufacturing such concrete elements and such cementitious compositions; to the use of specific components in concrete elements and cementitious mixtures. The compositions and elements described herein comprise an effective amount of expansive agents in combination with superabsorbent polymers (SAP) and shrinkage reducing admixtures (SRA), and optional further components as defined in the claims. The present invention further provides for improved tendons, suitable for SP-HPC elements.

Pre-stressed cementing methods involve preparing a cement slurry containing water, inorganic cement, and capsules of an expanding agent. The slurry is placed in an annular region in the well and hardened. Expansion of the set cement is delayed. Water infiltration activates the expanding agent to rupture the capsules and release the expanding agent. The expanding agent reacts to expand the set cement to a state of compression within the annular region. The state of compression can be maintained during changes in casing dimensions from temperature or pressure, mechanical disturbance, or mud contamination. The state of compression in the annular region may be monitored by acoustic impedance measurements.

Pre-stressed cementing methods involve preparing a cement slurry containing water, inorganic cement, and capsules of an expanding agent. The slurry is placed in an annular region in the well and hardened. Expansion of the set cement is delayed. Water infiltration activates the expanding agent to rupture the capsules and release the expanding agent. The expanding agent reacts to expand the set cement to a state of compression within the annular region. The state of compression can be maintained during changes in casing dimensions from temperature or pressure, mechanical disturbance, or mud contamination. The state of compression in the annular region may be monitored by acoustic impedance measurements.

The present disclosure concerns a cement dispersant for cement compositions wherein the cement dispersant is a polynaphthalene sulfonate salt having a weight average molecular weight of from 2500 g/mol to 3000 g/mol. The cement compositions are of from 10 weight percent to 70 weight percent of a cement precursor based on the total weight of the cement composition, from 5 weight percent to 70 weight percent water based on the total weight of the cement composition, and from 0.001 percent by weight of cement (BWOC) to 1.0 percent BWOC the cement dispersant. The cement dispersant provides improved rheological properties, allowing for good cement dispensing and increased presence of weighting agents.

The present disclosure concerns a cement dispersant for cement compositions wherein the cement dispersant is a polynaphthalene sulfonate salt having a weight average molecular weight of from 2500 g/mol to 3000 g/mol. The cement compositions are of from 10 weight percent to 70 weight percent of a cement precursor based on the total weight of the cement composition, from 5 weight percent to 70 weight percent water based on the total weight of the cement composition, and from 0.001 percent by weight of cement (BWOC) to 1.0 percent BWOC the cement dispersant. The cement dispersant provides improved rheological properties, allowing for good cement dispensing and increased presence of weighting agents.

A low-density, high-strength concrete composition that is lightweight and self-compacting or non-self-compacting, with a low weight-fraction of aggregate to total dry raw materials, and a highly-homogenous distribution of a non-absorptive and closed-cell lightweight aggregate such as glass microspheres or copolymer polymer beads or a combination thereof, and the steps of providing the composition or components. Lightweight concretes formed therefrom have low density, high strength-to-weight ratios, and high R-value. The concrete has strength similar to that ordinarily found in structural lightweight concrete but at a lower density, such as an oven-dried density as low as 40 lbs./cu.ft. Such strength-to-density ratios range approximately from above 30 cu.ft/sq.in. to above 110 cu.ft/sq.in., with a 28-day compressive strength ranging from about 3400 to 8000 psi.

A low-density, high-strength concrete composition that is lightweight and self-compacting or non-self-compacting, with a low weight-fraction of aggregate to total dry raw materials, and a highly-homogenous distribution of a non-absorptive and closed-cell lightweight aggregate such as glass microspheres or copolymer polymer beads or a combination thereof, and the steps of providing the composition or components. Lightweight concretes formed therefrom have low density, high strength-to-weight ratios, and high R-value. The concrete has strength similar to that ordinarily found in structural lightweight concrete but at a lower density, such as an oven-dried density as low as 40 lbs./cu.ft. Such strength-to-density ratios range approximately from above 30 cu.ft/sq.in. to above 110 cu.ft/sq.in., with a 28-day compressive strength ranging from about 3400 to 8000 psi.