Cement slurries, cured cements, and methods of making cured cement and methods of using cement slurries have, among other attributes, an extended thickening time, leading to improved retardation, flowability, and pumpability and may be used, for instance, in the oil and gas drilling industry. The cement slurry includes water, microfine cement material, and bisphenol-F diglycidyl ether resin.

A method for the continuous production of a mineral foam of which the density in the dry state (d) is from 40 to 600 kg/m.sup.3, includes (i) mixing cement; a water reducing agent; 0.5 to 10%, % by weight with respect to the total weight of cement, of ultrafine particles having a liquid-solid contact angle comprised from 30° to 140°, and of which the D50 is from 10 to 600 nm; water, with a water/cement weight ratio from 0.3 to 2.5; (ii) adding to the mixture from 0.5 to 10% of a pore-forming agent, % by weight with respect to the weight of cement; (iii) applying the mixture obtained at step (ii) on a support; (iv) leaving the mixture to expand on the support.

A method for the continuous production of a mineral foam of which the density in the dry state (d) is from 40 to 600 kg/m.sup.3, includes (i) mixing cement; a water reducing agent; 0.5 to 10%, % by weight with respect to the total weight of cement, of ultrafine particles having a liquid-solid contact angle comprised from 30° to 140°, and of which the D50 is from 10 to 600 nm; water, with a water/cement weight ratio from 0.3 to 2.5; (ii) adding to the mixture from 0.5 to 10% of a pore-forming agent, % by weight with respect to the weight of cement; (iii) applying the mixture obtained at step (ii) on a support; (iv) leaving the mixture to expand on the support.

Disclosed is a CO.sub.2 solidified fiber cement board and its preparation method. The matrix composition of the fiber cement board prepared in this disclosure is calcium carbonate, which has high compactness, and the crystal form of calcium carbonate is adjusted by adding shell powder to improve the toughness of the matrix, so that the fiber cement board has excellent mechanics and durability performance. In addition, the preparation process does not require high temperature maintenance, and has the characteristics of normal temperature preparation, which creates conditions for the introduction of organic synthetic fibers, so that the organic synthetic fibers can further improve the brittleness of cement fiberboard. While reducing energy consumption, the preparation process can also effectively solve the problem that excessive pressure is easily generated in the fiberboard under high temperature conditions in the existing high-temperature and high-pressure curing process.

Disclosed is a CO.sub.2 solidified fiber cement board and its preparation method. The matrix composition of the fiber cement board prepared in this disclosure is calcium carbonate, which has high compactness, and the crystal form of calcium carbonate is adjusted by adding shell powder to improve the toughness of the matrix, so that the fiber cement board has excellent mechanics and durability performance. In addition, the preparation process does not require high temperature maintenance, and has the characteristics of normal temperature preparation, which creates conditions for the introduction of organic synthetic fibers, so that the organic synthetic fibers can further improve the brittleness of cement fiberboard. While reducing energy consumption, the preparation process can also effectively solve the problem that excessive pressure is easily generated in the fiberboard under high temperature conditions in the existing high-temperature and high-pressure curing process.

A concrete comprises in relative parts by weight: 100 of Portland cement; 0.25 to 9 of a defoamer; 0.001 to 6 of a surfactant; 0 to 230 of coarse gravel and/or fine gravel and/or shear enhancers; 0 to 85 of sand; 0 to 60 of a particulate pozzolanic or non-pozzolanic material or a mixture thereof having a mean particle size less than 15 micrometers; 0 to 80 of a particulate pozzolanic or non-pozzolanic material or a mixture thereof having a mean particle size between 15 to 88 micrometers; 0.3 to 18 of a water-reducing superplasticizer; 0 to 14 of polyethylene fibers; and 5 to 40 of water. An air mixing process using a tightly sealed mixing tool is used to thoroughly mix the constituents of the concrete before adding the water for curing. By adjusting relative parts in the composition, concretes of high and ultrahigh performance can be achieved efficiently.

A concrete comprises in relative parts by weight: 100 of Portland cement; 0.25 to 9 of a defoamer; 0.001 to 6 of a surfactant; 0 to 230 of coarse gravel and/or fine gravel and/or shear enhancers; 0 to 85 of sand; 0 to 60 of a particulate pozzolanic or non-pozzolanic material or a mixture thereof having a mean particle size less than 15 micrometers; 0 to 80 of a particulate pozzolanic or non-pozzolanic material or a mixture thereof having a mean particle size between 15 to 88 micrometers; 0.3 to 18 of a water-reducing superplasticizer; 0 to 14 of polyethylene fibers; and 5 to 40 of water. An air mixing process using a tightly sealed mixing tool is used to thoroughly mix the constituents of the concrete before adding the water for curing. By adjusting relative parts in the composition, concretes of high and ultrahigh performance can be achieved efficiently.

The effectiveness of expansive cement systems may be diluted when, during a well cementing operation, commingling takes place between the cement slurry and a spacer fluid, a drilling fluid, or both. Incorporating expansive agents in the spacer fluid or drilling fluid may reduce or negate the loss of expansion at the cement slurry/spacer interface or the cement slurry/drilling fluid interface, thereby promoting zonal isolation throughout the cemented interval.

The effectiveness of expansive cement systems may be diluted when, during a well cementing operation, commingling takes place between the cement slurry and a spacer fluid, a drilling fluid, or both. Incorporating expansive agents in the spacer fluid or drilling fluid may reduce or negate the loss of expansion at the cement slurry/spacer interface or the cement slurry/drilling fluid interface, thereby promoting zonal isolation throughout the cemented interval.

Provided herein are compositions, methods, and systems related to bimodal, trimodal, and/or multi-modal distribution of reactive vaterite cement particles.