The Effects of Diatomite as an Additive on the Macroscopic Properties and Microstructure of Concrete

Abstract

Diatomite is a siliceous sedimentary rock containing amorphous silica, which can be used as a green mineral admixture to improve the properties of concrete. This study investigates the affecting mechanism of diatomite on concrete performance by macro and micro tests. The results indicate that diatomite can reduce the fluidity of concrete mixture and change its water absorption, compressive strength, resistance to chloride penetration (RCP), porosity, and microstructure. The low fluidity of concrete mixture containing diatomite can reduce workability. With increasing diatomite as partial replacement for cement in concrete, water absorption of concrete decreases before increasing, while compressive strength and RCP rise first and then drop. When diatomite is added to the cement at a content of 5% by weight, the concrete has the lowest water absorption and the highest compressive strength and RCP. Through the mercury intrusion porosimetry (MIP) test, we determined that the addition of 5% diatomite reduces the porosity of concrete from 12.68% to 10.82% and changes the proportion of pores with different sizes in concrete, the proportion of harmless and less harmful pores increases, and the proportion of harmful pores reduces. Based on the microstructure analysis, the SiO2 in diatomite can react with CH and produce C-S-H. C-S-H is responsible for developing concrete because it fills pores and cracks, forms a platy structure, and makes the concrete much denser, thereby improving its macroscopic performance and microstructure.

Large-scale synthesis of LiMn2O4 cathode materials via a rheology-assisted solid-phase method using citric acid

“…This phenomenon can be explained by the fact that citric acid is a polycarboxylic acid, possessing multiple carboxylic functional groups. 47,48 These groups have the capacity to form complexes with metal ions. During the preparation process of lithium manganate, citric acid can complex with manganese ions.…”

Integrated Nanostructures of TiO2/g-C3N4/Diatomite Based on Low-Grade Diatomite as Efficient Catalyst for Photocatalytic Degradation of Methylene Blue: Performance and Mechanism

“…Diatomite is widely used in construction [1], petroleum [2], the light industry [3][4][5], the chemical industry [6], and other fields [7][8][9], with its unique physical and chemical properties, such as multi-level pore structure [10] and nano characteristics [11], making high-grade diatomite resources increasingly scarce [12]. There has been less development and utilization of low-grade diatomite, resulting in a serious waste of resources and great pressure on the environment.…”

Modified Natural Diatomite with Various Additives and Its Environmental Potential

“…One of the most dangerous effects of increasing anthropogenic impact is chemical pollution, which threatens all forms of life in the environment. Considering the level of risk, heavy metals, especially their mobile forms, pose the greatest threat [ 1 , 2 ]. Some heavy metals in the environment show significant reactivity even at low levels [ 3 ].…”

“…Limiting the toxicity of heavy metals in the environment through the use of various organic and inorganic materials has recently gained much interest [ 1 , 3 , 4 , 5 , 6 , 7 ]. Despite considerable knowledge in the use of different types of materials, the most environmentally friendly solutions are still being sought by explicitly promoting the use of substances and minerals of natural origin.…”

“…They are used in various industries: construction, engineering (for the removal of coolants and lubricants), refractory materials and chemical industries, among others. The great importance of diatomites is in their use in agriculture, animal husbandry and in broadly understood environmental protection as an effective material for water and wastewater treatment or immobilisation of heavy metals in soil [ 1 , 4 , 9 , 10 , 11 , 12 ]. According to Aksakal et al [ 10 ], the use of diatomite significantly increases the stability of soil aggregates and the moisture and field capacity of sandy soil.…”