M.-J. Yang et al.
of ce ment mort ar and the stre ngth var iat ions whe n usi ng fly ash a nd b last fur nace sla g to pa rtially substitute ce-
ment [2]. The stud y hopef ull y co uld pr ovid e via ble dir ection for futur e stud y of u sing I BA ag grega te s in ce ment
concrete products.
2. Research Purpose
For the time being, in Taiwan, the IBA aggregates are often used in permeable recycled concrete with lean con-
crete proportions. However, the low strength of permeable concrete mainly comes from low cement contains,
which cannot clea rly show the impact IBA aggregates on the concrete strength [3] [4]. I n per meable concrete the
cement weights around 1/8 of aggregate. To eliminate the effect of lean concrete on strength, the research adopts
high ceme nt co nt e nt mor tar to c o nduc t t he e xpe r i ment , i n w hic h the weight ratio o f cement/aggre gate is 1/2. The
experiment uses IBA fine aggregates, which passes through #16 sieve, and natural sand of the same size as the
aggregate, and separates mortar specimens into two main categories in which each contains 6 groups of speci-
men, based on different W/C ratio and mineral admixtures portions. The specimens consist of 5 × 5 × 5 cm cu-
bic blocks, Briquet pieces, and 4 × 4 × 16 cm rectangular bars and are used in performing compressive and ten-
sile strength measuring to discuss the basic properties of each group of cement mortar. Moreover, to comply
with economic and environme ntal principles, it adds different proportions of furnace slag and F-class fly ash to
replace a portion of cement so as to explore the influence on strength of IBA aggregates concrete by adding the
two admixtures [5].
3. Research Method
The experime nt uses I BA fine a ggregate s passin g throug h #16 sieve and natur al fine a ggrega tes with sa me siz e
as t he a ggre gate, a nd the ad mixtur e s ar e F-typ e fl y as h and blast furnace slag. Addi ng the t wo admixt ures is e x-
pected to increase the workability and strength of the mortar specimens. The experiment is divided into two
main groups based on W/C ratio. Each mai n group co ntains 6 subgroup s in which t he spec imens consi st of dif-
ferent percentage of IBA fine aggregates, fly ash, and furnace slag, so as to verify the effects of the ingredients
on the strength of the specimens. The proportions of mortar are as shown, by ratio of weight, in Table 1. The
test specimens are mainly divided into 12 groups, wherein the mortars, namely “Control 1” and “Control 2”,
contain 100% nature fine aggregate are as the controlled basis, the sub groups, namely gr oup A-J, use only IB A
fine a ggr egate s and di ffere nt po rti ons o f fly a sh and furnace slag partially replacing cement, so as to explore the
strength differences among the groups. The water cement ratio of the specimens are controlled by standard mor-
tar flow test, the mortar flow of each group falls between 100% - 150% to insure that no cement paste segrega-
tion occurs when casting the specimens.
4. Results and Discussion
4.1. Basic Physical Property Test of Incineration Bottom Ash
The test results of basic properties testing are shown in Table 2. As being expected, the IB A fine aggre gate s has
a higher water absorption capacity than natural fine aggregate, and its specific gravity and dry-rodded unit
weight are also lower than those of natural fine aggregate. For the bottom ash has a faster water absorption rate,
the 30 min. absorption rate, which is not a standard test, is mainly used as a reference in process of adding water
when mixing the cement mortar containing IBA fine aggregates. That can prevent higher absorption capacity of
IBA fine aggregates from affecting the designed water cement ratio during mixin g mortar.
4.2. Result Analysis
The material ages for each strength test are 7, 28 and 56 days. The tests performed are compressive, direct ten-
sile, and flexural tensile strengths of mortar specimens, which are to get a preliminary understanding of the in-
fluence of IBA fine aggregates and mineral admixture on strength of the mortars. The strength test result of each
specimen after 7, 28 and 56 days curing is sho wn in Table 3. In general, material age of 7 days has lower a nd
inconsistent co mpressive strength due to the incomplete hydration, so the 7-da y strength is only taken as refer-
ence. Unit weight of each specimen is shown in Table 4. When the ag gregate is replaced by IBA fine aggregates,
there is obvious difference on the unit weight, due to the lower specific gravity of IBA fine aggregates.
