Exploration of the Compressive Strength and Microscopic Properties of Portland Cement Taking Attapulgite and Montmorillonite Clay as an Additive

Abstract

The effects of attapulgite and montmorillonite calcinated at 750 °C for 2 h as supplementary cementing materials (SCMs) on the working properties, mechanical strength, phase composition, morphology, hydration and heat release of ordinary Portland cement (OPC) were studied. The results show that pozzolanic activity increased with time after calcination, and with the increase in content of calcined attapulgite and calcined montmorillonite, the fluidity of cement paste exhibited a downward trend. Meanwhile, the calcined attapulgite had a greater effect on the decrease in the fluidity of cement paste than calcined montmorillonite, and the maximum reduction was 63.3%. Within 28 days, the compressive strength of cement paste with calcined attapulgite and montmorillonite was higher than that of the blank group in the later stage, and the optimum dosages of calcined attapulgite and montmorillonite were 6% and 8%, respectively. In addition, the compressive strength of these samples reached 85 MPa 28 days later. The introduction of calcined attapulgite and montmorillonite increased the polymerization degree of silico-oxygen tetrahedra in C-S-H gels during cement hydration, thereby contributing to accelerating the early hydration process. In addition, the hydration peak of the samples mixed with calcined attapulgite and montmorillonite was advanced, and the peak value was lower than that of the control group.

Mitigation Measures of Swelling Characteristics in Alkali-Contaminated Red Earth using Fly Ash and GGBS Blends

“…It is characterized by an open-channel structure that gives rise to elongated, needle-shaped crystals [71]. Attapulgite is an effective supplementary cementitious material [69], [70], [71]. The introduction of a small quantity of attapulgite substantially impacted the formation of the cement paste's structural network, leading to a more flocculated internal arrangement.…”

Study on the Effect of Palygorskite on the Properties of Copper-Nickel Smelting Slag-Based Cementitious Materials

“…Due to its special structure, palygorskite is commonly used in the field of adsorption curing, such as curing heavy metal elements in sewage and soil [19,20]. Aconite is abundant and cheap, it can be modified by calcination and other methods and promote the early hydration reaction [21,22], improving the effect of the early mechanical properties of cementitious materials. palygorskite is mostly used in the construction field [23][24][25][26], but little research has been reported in the filling field.…”

Durability and Sustainability of Cement and Concrete Composites

“…It was found that its mechanical strengths were improved by consuming a large amount of Ca(OH) 2 and forming more compact hydration products. Furthermore, Yan et al [ 8 ] used natural minerals (calcined attapulgite and montmorillonite) as additives to improve the early and late compressive strength of cement paste.…”