This work aims to study the effect of Ca(C 18 H 35 O 2 ) 2 (calcium stearate) on the properties of concrete by using Portland composite cement (PCC) and fly ash as binders. The calcium stearate content used in the concrete here consists of 0, 1, 5, and 10 kg per m 3 of concrete volume, or alternatively, 0 to 2.85% by the weight of cement. We have performed several tests for each of the contents, namely, compressive strength, water absorption, chloride ion infiltration, and accelerated corrosion tests. According to the testing, we have found that with the addition of calcium stearate at 1 kg/m 3 in self-compacting concrete (SCC) with 10% fly ash, the mechanical and physical properties of SCC can be improved significantly when compared to the SCC without fly ash and calcium stearate, resulting in a stable compressive strength, lower water absorption, lower chloride ion infiltration, and lower degree of corrosion attack.Materials 2020, 13, 1394 2 of 16 calcium silicate hydrate mineral referred to as C-S-H (tobermorite) [9]. Calcium hydroxide itself is one of the compounds formed when tricalcium silicate (C3S), dicalcium silicate (C2S), or tricalcium aluminate (C3A) reacts with water (H 2 O). The use of fly ash in concrete as a substitute for cement further increases the amount of C-S-H/calcium silicate hydrate (tobermorite) formed during the cement hydration process. It can reduce cement the consumption by 3.2-5 kg·m −3 ·MPa −1 [10]. In the process of cement production, millions of tons of CO 2 gas (a pollutant) is released because of combustion to make clinker. Reducing cement consumption in concrete consequently decreases the CO 2 emissions. Besides that, the appearance of fly ash in concrete also raises the alkalinity of concrete [11]. The higher the alkalinity of concrete, the greater the passive layer protected steel bar in concrete is from corrosion attack.Not only additives such as fly ash, slag, and silica fumes, but superplasticizers such as water reducers [12] in concrete also can reduce the capillaries and pores [13] in concrete. Although the water/cement ratio used in concrete is very small, the workability of fresh concrete remains good, and this is easily maintained by adding a superplasticizer to the concrete [14]. Because of the low water/cement ratio used, autogenous shrinkage is reduced. Other effects include increasing the elastic modulus [15] and raising the anti-carbonation of the concrete [16].A large contact angle makes it more difficult for water to seep into concrete [17]. As a result, the water absorption of concrete also drops significantly. Furthermore, in general, chloride ions penetrate into concrete along with water because of the greater contact angle. Automatically, concrete-containing large silica particles are more resistant to corrosion attack. On the contrary, in concrete made with the addition of a water-entraining agent [18], chloride ions enter into concrete more easily, especially in young concrete [19,20]. Corrosion attack on the concrete reinforcement surface causes cracks ...
