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A higher ratio gives a too fluid concrete mix resulting in a too porous hardened concrete of poor quality. Often, the concept also refers to the ratio of water to cementitious materials, w/cm. Cementitious materials include cement and supplementary cementitious materials such as ground granulated blast-furnace slag (GGBFS), fly ash (FA), silica ...
There are four types of grouting methods used in practice: compaction, chemical (permeation), slurry, and jet grouting. Chemical and slurry are low- pressure, jet and compaction are high pressure. Compaction is a technique that was developed in the United States. Compaction grouting was used in the Bolton Hill subway in Baltimore.
A slurry wall is a civil engineering technique used to build reinforced concrete walls in areas of soft earth close to open water, or with a high groundwater table. [1] This technique is typically used to build diaphragm (water-blocking) walls surrounding tunnels and open cuts, and to lay foundations .
Adding an air entrainment agent during the mixing of fresh concrete induces the formation of tiny air bubbles in the fresh concrete slurry. This creates numerous small air-filled micro-cavities in the hardened concrete serving as empty volume reserve to accommodate the volumetric expansion of ice and delays the moment tensile stress will develop.
Sulfur concrete has a low porosity and is a poorly permeable material. Its low hydraulic conductivity slows down water ingress in its low porosity matrix and so decreases the transport of harmful chemical species, such as chloride (pitting corrosion), towards the steel reinforcements (physical protection of steel as long as no microcracks develop in the sulfur concrete matrix).
Unlike air-entrained concrete, which introduces tiny air bubbles through an admixture during mixing, foam concrete replaces coarse aggregates with these air bubbles, resulting in a significant difference in density, with foam concrete typically ranging from 400 kg/m3 to 1600 kg/m3, whereas air-entrained concrete maintains its density.
CLSM consists of a mixture of Portland cement, water, aggregate and sometimes fly ash. Unlike ordinary concrete, CLSM has much lower strength. The strength of CLSM is less than 1,200 pounds per square inch (8.3 MPa), while ordinary concrete has strengths exceeding 3,000 pounds per square inch (21 MPa) [citation needed]. As a result, CLSM is not ...
This slurry is further mixed with a synthetic aerated foam in a concrete mixing plant. [9] The foam is created using a foaming agent , mixed with water and air from a generator. The foaming agent must be able to produce air bubbles with a high level of stability, resistant to the physical and chemical processes of mixing, placing, and hardening.