تصرف الأعمدة الخرسانية المسلحة المغمورة في أنواع مختلفة من الترب العدوانية

Behavior of Reinforced Concrete Columns Buried into Different Types of Aggressive Soils

Concrete resistance to sulfate attack is one of the most important properties
for maintaining durability of concrete. The main objective of this research is to
evaluate the performance of several types of reinforced concrete columns buried
in two pits at a 3-meter depth in one of the agricultural areas in the holy city of
Kerbala, one contains a sandy soil with sulfur salts (SO3 = 10.609%) and the other
contains a clayey soil with salinity ratio of (SO3 = 2.61%). In this research, three
types of concrete mixes have been produced and utilized: normal strength
concrete, polymeric concrete, and high strength concrete. A total of 21 reinforced
concrete columns, 126 concrete cubes, and 63 concrete cylinders were prepared.
The columns and reference concrete specimens were cured for 28 days with tap
water and then buried in soils for (60, 150, 240) days. A number of laboratory
testing methods have been carried out on the specimens: (axial compression
strength of concrete columns, compressive strength test for concrete cubes,
splitting tensile strength of concrete cylinders, absorption test, voids ratio and
density of concrete cubes). These tests have been conducted at different ages of
exposure.

Test results showed that the aggressive soils (containing sulfates and
chlorides) affect the performance of all types of concrete mixes negatively with
age of exposure. The deterioration was more for specimen buried in sandy soils.
It is found that the resistance of high-strength concrete to aggressive soils was
better than other types of concrete.
The percentage of decrease in compressive strength of concrete columns
exposed to aggressive solutions in the clayey soil for normal, polymer, and highstrength
concretes ranged from (0.95-12.51) %, (20.28-24.96) %, and (1.5-15.62)
% respectively. The percentage of decrease in compressive strength capacity of
polymer, and high-strength concrete columns exposed to aggressive solutions in the sandy soils ranged between (20.03-37.52) %, and (0-18.74) % respectively,
compared to the reference concrete columns not buried in soils.
In contrast a development in strength was observed for normal concrete
columns exposed to aggressive sandy soils, it reads up to (11.7 %) after (240
days) of exposure. The durability test results (absorption and voids ratio) showed
a deterioration (increases) for polymer and high strength concrete mixes, while it
was not observed in normal concrete mix.