A method of making a structural lightweight and thermal insulating concrete is described. The concrete has a coarse aggregate partly replaced by recycled plastic pieces. This enables the concrete to maintain a high compressive strength, low thermal conductivity, and low weight, while providing a use for waste plastic. The waste plastic pieces may comprise polyethylene in the form of flakes, fibers, or granules. Due to its low unit weight, adequate compressive strength and high thermal resistance the developed concrete can be used as a structural lightweight and thermal insulating concrete. The use of this concrete leads to economic and environmental benefits.

A method may include providing a cement composition comprising ground vitrified clay, hydrated lime, and water; and introducing the cement composition into a subterranean formation.

The embodiments herein are directed to dry wall waste mixtures, formed under pressure into example embodiments referred to herein as dry wall waste blocks (DWBs) and/or gypsum wallboard waste blocks (GWWBs) and tile structures. DWBs/GWWBs mixtures in particular, often incorporate a higher percentage in the composite mixtures from about 60% up to 85% of dry wall waste than other mixtures and beneficially often incorporates substantially all of the wallboard facing paper as part of the composite mixture. That is, waste processing is simplified by comingling core and paper layers in the final product. DWBs/GWWBs mixtures utilize demolition and construction waste, replacing a high percentage of Portland cement with waste-derived binder.

The embodiments herein are directed to dry wall waste mixtures, formed under pressure into example embodiments referred to herein as dry wall waste blocks (DWBs) and/or gypsum wallboard waste blocks (GWWBs) and tile structures. DWBs/GWWBs mixtures in particular, often incorporate a higher percentage in the composite mixtures from about 60% up to 85% of dry wall waste than other mixtures and beneficially often incorporates substantially all of the wallboard facing paper as part of the composite mixture. That is, waste processing is simplified by comingling core and paper layers in the final product. DWBs/GWWBs mixtures utilize demolition and construction waste, replacing a high percentage of Portland cement with waste-derived binder.

The embodiments herein are directed to dry wall waste mixtures, formed under pressure into example embodiments referred to herein as dry wall waste blocks (DWBs) and/or gypsum wallboard waste blocks (GWWBs) and tile structures. DWBs/GWWBs mixtures in particular, often incorporate a higher percentage in the composite mixtures from about 60% up to 85% of dry wall waste than other mixtures and beneficially often incorporates substantially all of the wallboard facing paper as part of the composite mixture. That is, waste processing is simplified by comingling core and paper layers in the final product. DWBs/GWWBs mixtures utilize demolition and construction waste, replacing a high percentage of Portland cement with waste-derived binder.

Devices and methods of recycling cement waste. A cement waste recycling device (1) comprising a heater (2) with an inlet (3) for cement waste and an outlet (4) for processed cement waste, wherein the heater (2) is configured for transporting cement waste in a cement waste transportation direction from the inlet (3) to the outlet (4) while transporting heated gas in countercurrent with the cement waste transportation direction.

A method for preparation of 1 m.sup.3 of fresh concrete includes mixing 1000 to 2000 kg of aggregate in a forced circulation mixer, wherein 40% to 100% by weight of the aggregate is recyclate made from inert construction and demolition waste. Microsilica is added to the mixture under constant mixing, and the mixture is then mixed for 40 to 80 seconds, whereby the microsilica covers particles of the recyclate and fills up pores in the recyclate. Then under constant mixing, cement or cement and at least one substituent of cement is added to the mixture in a total amount of 135 to 600 kg, and the mixture is further mixed while sprinkling or spraying the mixture with 135 to 250 kg of mixing water for under constant mixing such that a surface of the cement is gradually wetted and a cementing compound being formed gradually adheres to the particles of the recyclate already coated with the microsilica. The mixture is continued to be mixed for 80 to 160 seconds, wherein fresh concrete is prepared.

A method for preparation of 1 m.sup.3 of fresh concrete includes mixing 1000 to 2000 kg of aggregate in a forced circulation mixer, wherein 40% to 100% by weight of the aggregate is recyclate made from inert construction and demolition waste. Microsilica is added to the mixture under constant mixing, and the mixture is then mixed for 40 to 80 seconds, whereby the microsilica covers particles of the recyclate and fills up pores in the recyclate. Then under constant mixing, cement or cement and at least one substituent of cement is added to the mixture in a total amount of 135 to 600 kg, and the mixture is further mixed while sprinkling or spraying the mixture with 135 to 250 kg of mixing water for under constant mixing such that a surface of the cement is gradually wetted and a cementing compound being formed gradually adheres to the particles of the recyclate already coated with the microsilica. The mixture is continued to be mixed for 80 to 160 seconds, wherein fresh concrete is prepared.

A method for preparation of 1 m.sup.3 of fresh concrete includes mixing 1000 to 2000 kg of aggregate in a forced circulation mixer, wherein 40% to 100% by weight of the aggregate is recyclate made from inert construction and demolition waste. Microsilica is added to the mixture under constant mixing, and the mixture is then mixed for 40 to 80 seconds, whereby the microsilica covers particles of the recyclate and fills up pores in the recyclate. Then under constant mixing, cement or cement and at least one substituent of cement is added to the mixture in a total amount of 135 to 600 kg, and the mixture is further mixed while sprinkling or spraying the mixture with 135 to 250 kg of mixing water for under constant mixing such that a surface of the cement is gradually wetted and a cementing compound being formed gradually adheres to the particles of the recyclate already coated with the microsilica. The mixture is continued to be mixed for 80 to 160 seconds, wherein fresh concrete is prepared.

An embodiment includes a Class C fly ash (CFA) cementitious composition with a controllable setting time comprising at least one Class C fly ash; at least one alkali hydroxide; at least one source of phosphate; and water. Alternate embodiments include a Class C fly ash (CFA) cementitious composition with a solid activator comprising at least one Class C fly ash; at least one alkali carbonate; at least one source of phosphate; and water.