Abstract
This paper describes an experimental investigation into the compaction characteristics of cement-stabilized macadam base materials (CSMBM) in a saline soil area. Through the field tests, the main causes of arch expansion in an existing road were analyzed. Based on this, the compaction tests and microscopic tests were designed to analyze the impacts of temperature, sodium sulfate content and cement content on the compaction characteristics of CSMBM. Then, the orthogonal test was designed to analyze the effects of the degree of the temperature, the cement content, and the sodium sulfate content on the compaction results of the CSMBM. Feld tests results show that the temperature, sodium sulfate content and cement content may be the main causes of arch expansion. The compaction tests show that with the temperature increasing, the optimal water content (OWC) decreases, but the maximum dry density (MDD) increases; with the sodium sulfate content increasing, the OWC increases, but the MDD decreases; with the cement content increasing, both MDD and OWC increase. The microscopic tests show that the increase of temperature and cement content is beneficial to the compactness between cementitious materials and aggregates, while the increase of sodium sulfate content makes the whole structure of cementitious materials and aggregates increasingly rough. The orthogonal test shows that the temperature has the greatest influence on the MMD, and the sodium sulfate content has the greatest influence on the OWC. Thus, in a sulfate saline soil area, the construction temperature, the sodium sulfate content and the cement content should be controlled to ensure the compaction quality of CSMBM.
Highlights
In the area of Ejina, Inner Mongolia, China, there is a special form of pavement disease on many roads, named the arch expansion of the pavement [1,2]
Solubility of of thenardite thenardite and and mirabilite mirabilite versus versus temperature temperature
The construction temperature will affect the solubility of sodium sulfate to change the nge of the optimal water content (OWC) and the maximum dry density (MDD), and affects the compaction quality of cement-stabilized macadam base materials (CSMBM)
Summary
In the area of Ejina, Inner Mongolia, China, there is a special form of pavement disease on many roads, named the arch expansion of the pavement [1,2]. Most previous study showed that the arch expansion mainly occurs in the subgrade structure layer due to the existence of sodium sulfate and variation temperature [3,4,5]. The sodium sulfate can exist in three forms: sodium sulfate solution, thenardite, mirabilite (Na2 SO4 ·10H2 O), which was caused by the content of sodium sulfate and environment temperature. When it was at temperature below 32.4 ◦ C, the Na2 SO4 ·10H2 O is the only stable phase; when it was at temperature above 32.4 ◦ C, the thenardite is the only stable phase [6,7,8,9]. The environmental temperature during construction may Materials 2020, 13, 3610; doi:10.3390/ma13163610 www.mdpi.com/journal/materials
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