Civil Engineering Reference
In-Depth Information
Portland cement
55% Pozzolan no. 6
55% Pozzolan no. 7
25
20
15
10
5
0
3 days
7 days
28 days
91 days
Age of pastes
7.2
Free Ca(OH)
2
content of HVNP cement pastes containing 55% by
weight of zeolitic pozzolan (adapted from Uzal and Turanli, 2012).
Portland cement
55% Pozzolan no. 6
55% Pozzolan no. 7
6
5
4
3
2
1
0
28 days
91 days
7.3
Percent volume of pores larger than 50 nm in hardened cement
pastes (adapted from Uzal and Turanli, 2012).
in higher mechanical strength and lower permeability in HVNP cement
pastes (Fig. 7.3). as shown in Fig. 7.3, a pozzolanic reaction progressing
beyond 28 days refines larger pores and reduces their percent amount more
drastically when compared to the ordinary Portland cement paste. Uzal
and Turanli (2012) also reported that XRD analysis and scanning electron
microscopy (SEM) observations on hardened cementitious pastes indicated
the dissolution of the crystalline zeolite phase in natural pozzolan to exhibit
a pozzolanic reaction.
Sato and Trischuk (2008) investigated the hydration process of cementitious
pastes containing 50% natural pozzolans (chabazite and clinoptilolite types of
natural zeolite) using a conduction calorimetry technique. They reported that
